Cooperative autonomous distributed system interconnection system, system interconnection method, and program

Abstract

The invention provides an interconnection system for cooperative autonomous distributed systems, which can synchronize a plurality of cooperative autonomous distributed devices and independently operate unit power grids, and can be synchronously connected to a main system all the time. A cooperative autonomous distributed system interconnection system according to one aspect of the present invention is characterized in that: each of the cooperative autonomous distributed devices (DGR40) receives frequency information and phase information transmitted from the system interconnection controller on the basis of a standard time signal; each of the cooperative autonomous distributed machines (DGR40) is controlled so as to synchronize the voltage phase of the unit grid system with the voltage phase of the main system when the circuit breaker (21) with the synchronous verification is open, or is controlled so as to synchronize the voltage phase of the unit grid system with the voltage phase of the main system when the circuit breaker (21) with the synchronous verification is closed, or is controlled so as to synchronize the voltage phase of the unit grid system with the voltage phase of the main system. Each of the collaborative autonomous distributed machines (DGR40) controls a power flow flowing between the primary system and the unit grid system.

Description

Technical Field

[0001] The present invention relates to a collaborative autonomous distributed system interconnection system, a system interconnection method, and a program Background Art

[0002] In recent years, there has been an increasing demand for self-production and self-sale of power generated by power generation equipment using renewable energy and consumed in the region. Therefore, there is a known method of managing power systems including one or more power generation equipment separately, called mini-grid or micro-grid. The AC system in the mini-grid is synchronized by an inverter installed on the output side of the power generation equipment.

[0003] Patent document 1 describes a method for independently managing a microgrid. In patent document 1, the inverters of the outputs of the multiple power generation devices respectively set in the microgrid adjust the output voltage value and phase based on the time signal obtained from the GPS (Global Positioning System). In addition, feedback control of the effective power and the ineffective power is performed based on the actual series impedance of the microgrid. In order to interconnect with other microgrid systems, a central energy management system is required.

[0004] Reference 2 describes a power conversion device that uses inverters at the outputs of multiple power generation equipment in a microgrid to correct the internal clock based on a time signal obtained from GPS or the like, and controls the same phase. In Reference 2, since the microgrid has a fixed frequency, an asynchronous interconnected power converter that performs AC-DC-AC power conversion is provided to connect the system in the microgrid with the main system.

[0005] Reference 3 describes a method of controlling a microgrid independently at a fixed frequency using a PMU (Phasor Measurement Unit). The PMU measures the voltage phase and current phase of the system in the microgrid, and the measured phase information is used as a reference in the synchronous fixed frequency control of the inverter connected to the output of each power generation device. In addition, it is described that the impedance from the output of each power generation device to the system in the microgrid is regarded as a common reference impedance, and compensation is performed by compensating the virtual impedance.

[0006] Reference 4 describes a method for controlling the current of a power converter in a microgrid. The method regards the converter connected to the AC (Alternating Current) power supply as a virtual voltage source with virtual impedance, and controls the waveform of the AC voltage by operating the phase of the effective current and the ineffective current. In addition, as a method for operating the instantaneous current, a droop control method is adopted, which is combined with a current limit tracking method or a maximum power point tracking method (MPPT).

[0007] Background Art Literature

[0008] Patent Literature

[0009] Patent Document 1: U.S. Patent Publication No. 2016 / 0329709

[0010] Patent Document 2: Patent Publication No. 6863564

[0011] Patent document 3: LU 500171B1

[0012] Patent Document 4: U.S. Patent Registration No. 10008854 Summary of the invention

[0013] [Inventions are meant to solve problems]

[0014] According to the method of independently managing a microgrid in Patent Document 1, in order to seek cooperation with the main system, a central energy management system that centrally controls the entire other system is required. Therefore, the system for interconnecting the systems in the microgrid with the main system becomes a large-scale system that centrally controls the entire system, and the communication system also becomes a large-scale system, which has the problem of being unable to follow up on rapid changes due to the communication delay.

[0015] In the power conversion device of the patent document 2, since the microgrid has a fixed frequency, an asynchronous interconnection power converter for converting AC-DC-AC power is provided in order to interconnect the system in the microgrid with the main system, so when the system is interconnected, it is not necessary to synchronize the frequency and phase of the system in the microgrid with the main system. However, in the asynchronous system interconnection device of the patent document 2, an asynchronous system interconnection device via an AC-DC-AC converter is used to interconnect the system in the microgrid with the main system, so the power capacity that can be interconnected is limited, and the current that can be energized is limited, resulting in a large device. In addition, the protection measures for consumers in the system of the area including the power equipment using renewable energy are set in accordance with the size of the short-circuit current supplied from the main system, so when the AC-DC-AC converter is sandwiched in the middle, the short-circuit current cannot be fully supplied, and there is a problem that even if a short-circuit accident occurs in the consumer's home, the protection circuit does not operate.

[0016] In the synchronous fixed frequency control method of Patent Document 3, the systems in the microgrid independently operate synchronously at a fixed frequency. However, since the main system frequency fluctuates at 50 Hz ± 0.2 Hz in Japan, for example, when the frequency of the system in the microgrid is fixed, there is a problem that the system cannot be interconnected with the main system.

[0017] According to the method of controlling the amplitude and phase of the inverter in Patent Document 4, a suitable droop technology for determining the desired effective phase and ineffective phase currents as a function of the voltage and frequency of the system in the microgrid can be adopted, such as phase shift virtual voltage-virtual impedance droop, but it is a patent related to the control method of the inverter connected to the system. It does not include the content of making the microgrid operate independently and synchronously by the control method of the inverter as proposed, and does not mention the method for synchronous access to the main system.

[0018] Therefore, the object of the present invention is to provide a collaborative autonomous distributed system interconnection system that can synchronize multiple collaborative autonomous distributed machines in a distribution system (hereinafter referred to as a "unit grid") that is separated at least at one point by a circuit breaker that can separate the main system, enable the unit grid to operate independently, and can always be synchronously connected to the main system.

[0019] [Technical means to solve the problem]

[0020] The object of the present invention can be achieved by the following configuration. That is, the cooperative autonomous distributed system interconnection system of the first aspect of the present invention is characterized in that the cooperative distributed system interconnection system comprises: a circuit breaker (21) with a synchronous detection function, which can connect or disconnect the main system (15) and the unit power grid system (28); a system interconnection controller (MGC30), which detects the power information of the main system (15) and the power information of the unit power grid system (28); and a cooperative autonomous distributed machine (DGR40), more than one of which is connected in the unit power grid system to perform power conversion in a mutually synchronously interconnected manner; and the system interconnection controller (MGC30) and each of the cooperative autonomous distributed machines (DGR40) have the ability to obtain standard A device for acquiring a standard time signal of a time signal, each of the cooperative autonomous distributed machines (DGR40) receives frequency information and phase information, or a composite signal of frequency information and phase information, sent from the system interconnection controller (MGC30) based on the standard time signal. When the circuit breaker (21) with synchronization verification is opened, each of the cooperative autonomous distributed machines (DGR40) is controlled in such a way that the voltage phase of the unit power grid system is synchronized with the voltage phase of the main system. When the circuit breaker (21) with synchronization verification is closed, each of the cooperative autonomous distributed machines (DGR40) controls the power flow flowing between the main system and the unit power grid system.

[0021] The cooperative autonomous distributed system interconnection system of the second aspect of the present invention is based on the cooperative autonomous distributed system interconnection system of the first aspect, characterized in that the system interconnection controller (MGC30) generates a system-to-system phase difference signal (φglobal) and sends it to each of the cooperative autonomous distributed machines (DGR40). When the circuit breaker (21) with a synchronization verification function is closed, each of the cooperative autonomous distributed machines (DGR40) uses the system-to-system phase difference signal (φglobal) to control the power flow and the reverse power flow. When the circuit breaker (21) with a synchronization verification function is opened and cannot receive information from the system interconnection controller (MGC30), each of the cooperative autonomous distributed machines (DGR40) can also synchronize the control unit power grid system based on the standard time signal.

[0022] The cooperative autonomous distributed system interconnection system according to the third aspect of the present invention is based on the cooperative autonomous distributed system interconnection system according to the first or second aspect, characterized in that the standard time signal acquisition device includes a first standard time acquisition unit (32) for acquiring a first standard time signal, and a second standard time acquisition unit (42) for acquiring a second standard time signal, and the system interconnection controller (MGC30) is provided with the first standard time acquisition unit (32), and generates a phase synchronization signal (Ncyc) by causing the first standard time signal (t) to act on the main system frequency (f) and the main system rotation phase angle (θref). _ref_Sync), as a composite signal of the frequency information and the phase information, is output to the cooperative autonomous distributed machine (DGR40), and the cooperative autonomous distributed machine (DGR40) has the second standard time acquisition unit (42), which demodulates the unit grid system rotation phase angle signal (θref) synchronized with the main system rotation phase angle (θref) by making the second standard time signal (t′) act on the phase synchronization signal (Ncyc_ref_Sync) output by the system interconnection controller (MGC30) and the main system frequency (f).

[0023] The cooperative autonomous distributed system interconnection system of the fourth aspect of the present invention is based on the cooperative autonomous distributed system interconnection system of the first or second aspect, characterized in that the system interconnection controller (MGC30A) inputs the power information of the main system and / or the power information of the unit grid system, measures the main system frequency measurement value (f), and simultaneously generates an inter-system phase difference signal (φglobal), which is output to the cooperative autonomous distributed machine (DGR40A), and the cooperative autonomous distributed machine (DGR40A) generates a unit grid system phase angle signal (θpll) and a unit grid system angular velocity signal (ωpll) from the unit grid system voltage (Vgrid_mini), and calculates the unit grid system rotation phase angle signal (θref) from the unit grid system phase angle signal (θpll), the unit grid system angular velocity signal (ωpll), the main system frequency measurement value (f), and the inter-system phase difference signal (φglobal).

[0024] The cooperative autonomous distributed system interconnection system of the fifth aspect of the present invention is based on the cooperative autonomous distributed system interconnection system of the fourth aspect, characterized in that the system interconnection controller (MGC30B) measures the main system frequency measurement value (f) through the first phase synchronization circuit (96a), the cooperative autonomous distributed machine (DGR40B) generates the unit power grid system phase angle signal (θpll) and the unit power grid system angular velocity signal (ωpll) through the second phase synchronization circuit (83), and the standard time signal acquisition device includes a first standard time acquisition unit (32) for inputting the first standard time (t) to the first phase synchronization circuit (96a), and a second standard time acquisition unit (42) for inputting the second standard time (t′) to the second phase synchronization circuit (83).

[0025] The cooperative autonomous distributed system interconnection system of the sixth aspect of the present invention is based on the cooperative autonomous distributed system interconnection system of the first or second aspect, and is characterized in that the unit power grid system (28) can be connected to multiple main systems (15a, 15b) via the circuit breaker (21a, 21b) with a synchronous detection function. When an abnormality occurs in the first main system (15a) among the main systems, the unit power grid system (28) can be interconnected with the second main system (15b) other than the first main system (15a), and at the same time, power can be supplied to the area (15a1) in the first main system (15a) where no abnormality occurs.

[0026] The cooperative autonomous distributed system interconnection system of the seventh aspect of the present invention is based on the cooperative autonomous distributed system interconnection system of the first or second aspect, characterized in that, when the circuit breaker (21) with a synchronous verification function is closed and the main system (15) is out of power, the circuit breaker (21) with a synchronous verification function is set from closed to open, and at the same time, each of the cooperative autonomous distributed machines (DGR40) makes the unit power grid system (28) operate independently. When the circuit breaker (21) with a synchronous verification function is opened and an accident occurs in the unit power grid system, the circuit breaker (21) with a synchronous verification function is closed, and at the same time, the power flow is controlled to supply an accident current to the accident point, so that the protection relay at the accident point is activated to cut off the accident point.

[0027] The collaborative autonomous distributed system interconnection system of the eighth aspect of the present invention is based on the collaborative autonomous distributed system interconnection system of the first or second aspect, characterized in that the collaborative autonomous distributed machine includes a common unit (120) having a motherboard (123) and one or more individual units (130), and the motherboard (123) performs control operations including generating pulse waves.

[0028] The cooperative autonomous distributed system interconnection system according to the ninth aspect of the present invention is based on the cooperative autonomous distributed system interconnection system according to the eighth aspect, characterized in that hysteresis control is used for the operation of pulse wave generation in the motherboard (123).

[0029] The system interconnection method of the cooperative autonomous distributed system interconnection system of the tenth aspect of the present invention is characterized in that it is the system interconnection method of the cooperative distributed system interconnection system, and the cooperative autonomous distributed system interconnection system comprises: a circuit breaker (21) with a synchronous detection function, which can connect or disconnect the main system (15) and the unit power grid system (28); a system interconnection controller (MGC30), which detects the power information of the main system (15) and the power information of the unit power grid system (28); and a cooperative autonomous distributed machine (DGR40), one or more of which are connected in the unit power grid system to perform power conversion in a mutually synchronously interconnected manner; and the system interconnection method comprises the following steps: the system interconnection controller (MGC30) and each of the units The cooperative autonomous distributed machine (DGR40) obtains a standard time signal; each of the cooperative autonomous distributed machines (DGR40) receives frequency information and phase information, or a composite signal of frequency information and phase information, sent from the system interconnection controller (MGC30) based on the standard time signal; when the circuit breaker (21) with synchronization verification is opened, each of the cooperative autonomous distributed machines (DGR40) is controlled in such a way that the voltage phase of the unit power grid system (28) is synchronized with the voltage phase of the main system; when the circuit breaker (21) with synchronization verification is closed, each of the cooperative autonomous distributed machines (DGR40) controls the power flow flowing between the main system (15) and the unit power grid system (28).

[0030] The program according to the 11th aspect of the present invention is characterized in that each step of the system interconnection method of the cooperative autonomous distributed system interconnection system according to the 10th aspect is executed by a computer.

[0031] [Effects of the Invention]

[0032] According to the cooperative autonomous distributed system interconnection system of the first aspect of the present invention, each cooperative autonomous distributed machine is dispersedly arranged in the unit grid, functions as a voltage source that is synchronously interconnected with each other, and can establish the voltage of the unit grid. In addition, the unit grid system (28) can always be set to a state where the frequency and phase are synchronized with respect to the main system (15), and can be synchronized even if the number of cooperative autonomous distributed machines is large, so it can be miniaturized. Since the capacity of each cooperative autonomous distributed machine is set according to the connected power generation equipment, the protection action of short-circuit current in abnormal conditions is also appropriately performed. In addition, the power capacity in the unit grid can be arbitrarily adjusted by the number of cooperative autonomous distributed machines, so on the basis of ensuring sufficient power capacity, the protection action of short-circuit current in abnormal conditions is also appropriately performed by the current limiting function, time limit disconnection function, etc. of the cooperative autonomous distributed machine (DGR40). In addition, even if a part of the cooperative autonomous distributed machines (DGR40) is disconnected due to the protection action of the fault, the remaining cooperative autonomous distributed machines (DGR40) can continue to distribute power to the unit grid system (28). Furthermore, by connecting the unit grid system (28) to the main system (15) via a circuit breaker (21) with a synchronous verification function, the unit grid system (28) can be connected to the main system (15) when the main system (15) and the unit grid system (28) are synchronized, and the unit grid system (28) cannot be connected to the main system (15) when the main system (15) and the unit grid system (28) are not synchronized, so the main system (15) can be reliably connected to the unit grid system (28). In addition, the system interconnection controller (30) can be set up as a cloud, for example. In addition, in the circuit breaker (21) with a synchronous verification function, by obtaining system voltage information or unit grid voltage information and performing calculations, a part of the system interconnection controller (30) can also be shared.

[0033] Furthermore, when the main system (15) is powered off during system interconnection, the power outage of the main system (15) can be detected, and the circuit breaker (21) with a synchronous detection function can be opened to allow the unit grid system (28) to operate independently. The time for setting the circuit breaker (21) with a synchronous detection function from closed to open is rated at 3 to 5 cycles, i.e., a delay of about 0.06 to 0.1 seconds, when a high-voltage vacuum circuit breaker (VCB) is used. Therefore, when the main system is powered off during system interconnection, the unit grid system voltage (Vgrid_mini) may sometimes decrease along with the decrease in the main system voltage (Vgrid_main). Therefore, when the main system (15) is powered off during system interconnection, even if the circuit breaker (21) with a synchronous detection function is quickly opened from closed, it may become a so-called black start in which the unit grid system voltage (Vgrid_mini) is started from a state close to 0V.

[0034] Therefore, by using the standard time signal obtained from the standard time signal acquisition device, each cooperative autonomous distributed machine (DGR40) can be black-started based on the standard time signal from the GPS clock (42) or the like. As a standard time signal, the highest level in a general crystal oscillator is ±10μsec, and the error of each cooperative autonomous distributed machine (DGR40) may be accumulated. The standard time signal acquisition device requires that the time error between cooperative autonomous distributed machines (DGR40) meet the accuracy within ±5μsec.

[0035] For example, a method for obtaining a standard time signal is listed in the following manner, namely, based on the configuration of the GPS clock, the atomic clock, and each cooperative autonomous distributed machine (DGR40), the time is precisely distance corrected, or the zero crossing of the AC voltage and its time are measured, and the information is transmitted to each cooperative autonomous distributed machine (DGR40), and compared with the zero crossing time of each cooperative autonomous distributed machine (DGR40), and the internal clock is corrected.

[0036] According to the cooperative autonomous distributed system interconnection system of the second aspect of the present invention, when the circuit breaker (21) with a synchronous verification function is closed, each of the cooperative autonomous distributed machines (DGR40) can use the inter-system phase difference signal (φglobal) to control the power flow and the reverse power flow. In addition, when the circuit breaker (21) with a synchronous verification function is opened and cannot receive information from the system interconnection controller (MGC30), each of the cooperative autonomous distributed machines (DGR40) can also synchronously control the unit power grid system based on the standard time signal. Therefore, each of the cooperative autonomous distributed machines (DGR40) can continue to independently operate the unit power grid system when the main system is out of power, or when the system interconnection controller (MGC30) fails, or when the communication with the system interconnection controller (MGC30) fails.

[0037] According to the cooperative autonomous distributed system interconnection system of the third aspect of the present invention, a phase synchronization signal (Ncyc_ref_Sync) generated by the system interconnection controller (MGC30) and applying the first standard time signal (t) to the main system frequency (f) and the main system rotation phase angle (θref) is transmitted to each cooperative autonomous distributed machine (DGR40), and each system interconnection controller (DGR40) applies the second standard time signal (t') to the phase synchronization signal (Ncyc_ref_Sync) and the main system frequency (f) to demodulate the unit grid system rotation phase angle signal (θref) synchronized with the main system rotation phase angle (θref), thereby the unit grid system (28) is always synchronized with the main system (15). Therefore, the unit grid system can be connected to or disconnected from the main system (15) at any time via the circuit breaker (21) with synchronization detection function. In the event of an accident in the main system (15), by opening the circuit breaker (21) with a synchronous detection function, the unit grid system (28) can continue to maintain the state of supplying power from the power generation equipment in the unit grid system.

[0038] According to the cooperative autonomous distributed system interconnection system of the fourth aspect of the present invention, the system interconnection controller (MGC30) inputs the power information of the main system (15) and / or the power information of the unit grid system (28), such as the main system voltage, the main system effective power, the main system reactive power, etc., measures the main system frequency measurement value (f), and simultaneously generates an inter-system phase difference signal (φglobal), which is output to the cooperative autonomous distributed machine (DGR40). The cooperative autonomous distributed machine (DGR40) generates a unit grid system phase angle signal (θpll) and a unit grid system angular velocity signal (ωpll) from the unit grid system voltage (Vgrid_mini), and calculates the unit grid system rotation phase angle signal (θref) from the unit grid system phase angle signal (θpll), the unit grid system angular velocity signal (ωpll), the main system frequency measurement value (f) and the inter-system phase difference signal (φglobal), thereby appropriately controlling the frequency and phase of the power converters, such as inverters, of each cooperative autonomous distributed machine (DGR40), and performing synchronous control of the unit grid system (28). In this aspect, since only voltage information is used, a standard time signal is not required.

[0039] The main system frequency measurement value (f) is measured by the first phase synchronization circuit (96a), and in addition, when the unit grid system phase angle signal (θpll) and the unit grid system angular velocity signal (ωpll) are generated by the second phase synchronization circuit (83), the phase information or frequency information is generated from the voltage signal through PLL, etc., so even if the cooperative autonomous distributed machine (DGR40) is connected to a Y-Δ converter and the phase is shifted by 30 degrees, or when the impedance connected to the cooperative autonomous distributed machine (DGR40) is large and the phase is shifted, these phase shift problems are eliminated because they are based on the voltage signal itself. In addition, when the phase information or frequency information is generated from the detection voltage through PLL, etc. from the voltage signal, since it always operates based on the voltage signal, the cooperative autonomous distributed machine (DGR40) can easily comply with the protection function required as a single operation detection protection device.

[0040] According to the cooperative autonomous distributed system interconnection system of the fifth aspect of the present invention, the first phase synchronization circuit (96a) and the second phase synchronization circuit (83) periodically use the standard time signal from the standard time signal acquisition device, for example, at a frequency of about once a second, and the synchronization of the PLL clock, etc. can be obtained through the standard time signal. Therefore, the standard time signal is not always required, which not only reduces the computing load accordingly, but also can always keep the PLL clock of each cooperative autonomous distributed machine (DGR40) synchronized.

[0041] In addition, since each cooperative autonomous distributed machine (DGR40) is synchronized, the unit power grid system (28) can be black-started. In the case where no signal is obtained from the system interconnection controller (MGC30), for example, when the system interconnection controller fails, the phase difference signal between the systems cannot be obtained. In the case of φglobal = 0, when the system interconnection controller (MGC30) fails, or when the communication with the system interconnection controller (MGC30) is abnormal, the synchronization of each cooperative autonomous distributed machine (DGR40) can be maintained. In addition, in the case where the main system frequency measurement value cannot be obtained from the system interconnection controller (MGC30), a fixed signal equivalent to the main system frequency value is generated by each cooperative autonomous distributed machine (DGR40). For example, when the main system frequency is 50 Hz, f = 50 Hz, and the unit power grid system can continue to operate independently.

[0042] According to the cooperative autonomous distributed system interconnection system of the sixth aspect of the present invention, when the unit grid is a hollow system, even if an abnormality occurs in the first main system (15a), the unit grid system can not only continue to supply power independently, but also continue to be interconnected with the normal second main system. In addition, power can be transmitted to the area (15a1) where no abnormality occurs within the jurisdiction of the substation included in the first main system. In the above case, the unit grid system (28) can transmit power from the normal second main system (15b) to the area (15a1) where no abnormality occurs within the jurisdiction of the substation included in the first main system (15a).

[0043] (Response to main system power outages and unit power system accidents)

[0044] According to the cooperative autonomous distributed system interconnection system of the seventh aspect of the present invention, when the unit grid system (28) is interconnected with the main system (15), in the event of a power outage in the main system (15), the unit grid system (28) can be operated independently and power can continue to be supplied from the power equipment in the unit grid system. In addition, when the unit grid system (28) is operated independently, in the event of a fault in the unit grid system, by setting the circuit breaker (21) with a synchronous detection function to be closed, a short-circuit current can be supplied from the main system (15) to the accident point, so that the protection relay at the accident point is actuated, the accident point is disconnected, and power is continued to be supplied to the normal part in the unit grid system.

[0045] According to the system interconnection method of the cooperative autonomous distributed system interconnection system of the eighth aspect of the present invention, all motherboards (123) can perform control operations for pulse wave generation including one or more individual units (130). As a result, the common units (120) are made common and the interfaces between boards are standardized, so that the individual units (120) can be provided as various application products. The operation of the system can be realized in the cloud through all system interconnection controllers (MGC30). In addition, the motherboard software is updated through the system interconnection controller (MGC30) via the cloud, so that the latest software can always be used.

[0046] According to the system interconnection method of the cooperative autonomous distributed system interconnection system of the ninth aspect of the present invention, it is possible to appropriately perform pulse wave calculations for all individual units (130) through the hysteresis control of the motherboard (123).

[0047] According to the system interconnection method of the cooperative autonomous distributed system interconnection system of the tenth aspect of the present invention, it is possible to provide a system interconnection method that achieves the same effects as the cooperative autonomous distributed system interconnection system of the first aspect.

[0048] According to the program of the eleventh aspect of the present invention, it is possible to provide a program that produces the same effects as the cooperative autonomous distributed system interconnection system of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a block diagram of a cooperative autonomous distributed system interconnection system according to Embodiment 1 of the present invention.

[0050] Figure 2A It is a circuit diagram of a collaborative autonomous distributed machine.

[0051] Figure 2B yes Figure 2A Detailed circuit diagram.

[0052] Figure 2C yes Figure 2B Action description diagram.

[0053] Figure 2D This is a circuit diagram of a cooperative autonomous distributed system interconnection system according to Embodiment 1 of the present invention.

[0054] Figure 2E yes Figure 2D An illustration of the rotation phase angle.

[0055] Figure 2F yes Figure 2D An illustration of the adjusted rotation phase angle.

[0056] Figure 3A This is a block diagram of synchronization control of GPS synchronization according to Embodiment 1 of the present invention.

[0057] Figure 3B This is a control block diagram of the master system connection state of GPS synchronization according to the first embodiment of the present invention.

[0058] Figure 3C This is a control block diagram of the GPS-synchronized unit power grid system independent state (synchronous control) according to the first embodiment of the present invention.

[0059] Figure 3D This is a control block diagram of the GPS-synchronized unit power grid system in an independent state (when the main system is powered off) according to the first embodiment of the present invention.

[0060] Figure 4A This is a control block diagram of a main system connection state of voltage synchronization according to Embodiment 1 of the present invention.

[0061] Figure 4B This is a control block diagram of a voltage-synchronized unit grid system independent state (synchronous control) according to the first embodiment of the present invention.

[0062] Figure 4C This is a control block diagram of a voltage-synchronized unit power grid system in an independent state (when the main system fails) according to the first embodiment of the present invention.

[0063] Figure 5A This is an explanatory diagram of a first state of a unit grid connection form according to Embodiment 2 of the present invention.

[0064] Figure 5B This is an explanatory diagram of the second state of the unit grid connection type according to the second embodiment of the present invention.

[0065] Figure 5C This is an explanatory diagram of the third state of the unit grid connection type according to the second embodiment of the present invention.

[0066] Figure 5D This is an explanatory diagram of the fourth state of the unit grid connection type according to the second embodiment of the present invention.

[0067] Figure 5E This is an explanatory diagram of the fifth state of the unit grid connection type according to the second embodiment of the present invention.

[0068] Fig. 5F This is an explanatory diagram of the sixth state of the unit grid connection type according to the second embodiment of the present invention.

[0069] Figure 5G This is an explanatory diagram of the seventh state of the unit grid connection type according to the second embodiment of the present invention.

[0070] Figure 5H This is an explanatory diagram of the eighth state of the unit grid connection form according to the second embodiment of the present invention.

[0071] Fig.5I This is an explanatory diagram of the ninth state of the unit grid connection type according to the second embodiment of the present invention.

[0072] Figure 5J This is an explanatory diagram of the tenth state of the unit grid connection type according to the second embodiment of the present invention.

[0073] Figure 5K This is an explanatory diagram of the eleventh state of the unit grid connection type according to the second embodiment of the present invention.

[0074] Figure 5L This is an explanatory diagram of the twelfth state of the unit grid connection type according to the second embodiment of the present invention.

[0075] Figure 5M This is an explanatory diagram of the thirteenth state of the unit grid connection type according to the second embodiment of the present invention.

[0076] Figure 5N This is an explanatory diagram of the fourteenth state of the unit grid connection type according to the second embodiment of the present invention.

[0077] Figure 6 It is a block diagram of a collaborative autonomous distributed system interconnection system according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0078] The following describes a cooperative autonomous distributed system interconnection system according to an embodiment of the present invention with reference to the accompanying drawings. However, the embodiments shown below are examples of embodiments of the cooperative autonomous distributed system interconnection system used to embody the technical concept of the present invention, and the present invention is not limited thereto, and can be applied to other embodiments included in the claims.

[0079] [Implementation Method 1]

[0080] refer to Figures 1 to 4C , the collaborative autonomous distributed system interconnection system of embodiment 1 of the present invention is described. Figure 1 It is a block diagram of a cooperative autonomous distributed system interconnection system according to Embodiment 1 of the present invention.

[0081] [Overall composition of cooperative autonomous distributed system interconnection system]

[0082] The power generated by the power station 10 is boosted to an ultra-high voltage by the ultra-high voltage transformer station 11, and then the power is further stepped down at the transformer station 13 via the power transmission equipment 12 and supplied to the main system, that is, the power distribution equipment 15 (hereinafter referred to as the "main system"). The main system 15 is connected to a plurality of unit power grids 20. The voltage of the power distributed in the main system 15 is not limited to high voltage (exceeding 600V and below 7,000V in AC), for example, it can be ultra-high voltage (exceeding 7,000V in AC), and conversely, it can be low voltage (below 600V in AC).

[0083] In a power distribution system (hereinafter referred to as a "unit grid") separated at least at one point by a circuit breaker 21 with a synchronization check function capable of separating a main power distribution system (hereinafter referred to as a "main system"), the unit grid 20 includes a circuit breaker 21 with a synchronization check function, a unit grid system 28 connected to the main system 15 via the circuit breaker 21 with a synchronization check function, one or more cooperative autonomous distributed machines 40 (hereinafter sometimes referred to as Digital Grid Router, "DGR") with a power conversion function connected to the unit grid system 28, and various power equipment connected to the unit grid system 28. In addition, the unit grid 20 may be, for example, a residential area, a block, or an electric power source of a complex or an industrial park, which means an electric power source that does not rely on the power of a large-scale nuclear power plant or thermal power plant outside the area, and can self-produce and sell the power of distributed power sources such as natural energy power generation equipment in the area. In Japan, it is sometimes referred to as "microgrid", but in this specification, it is sometimes referred to as "Mini grid" in English. These are used as the same meaning as the unit grid 20. In addition, the system interconnection controller 30 is sometimes omitted and referred to as "MGC (Mini Grid Controller)"

[0084] When considering a residential area as a unit grid 20, its size can be as large as 52% of residential areas in Japan, for example, the area of ​​residential areas is more than 100 hectares ("About the actual situation of residential areas", Housing Bureau of the Ministry of Land, Infrastructure, Transport and Tourism, December 2009). The scale of a unit grid 20 can also be set to more than 100 hectares, and can be applied to residential areas of any size by increasing or decreasing the number of DGR40.

[0085] Various distributed power sources such as wind power generation device 23a, solar power generation device 23b, fuel cell device, hydrogen power generation device, biomass power generation device, internal combustion engine power generation device (for example, diesel engine or gas engine, etc.) 23d, gas turbine power generation device, geothermal power generation device, hydroelectric power generation device (for example, about 200kW) can be connected to DGR40 as power generation equipment 23. In addition, power equipment such as power storage device 22b, 23c or electric vehicle charging and discharging device 22c can also be connected to DGR40. Power converter such as inverter is provided in DGR40, which can convert DC voltage generated by solar power generation device 23b into AC voltage and supply it to unit grid system 28.

[0086] The unit grid system 28 distributes power to each household device 22a as the power demand device 22. The power demand device 22 is not particularly limited, and examples thereof include each household device 22a, the power storage device 22b, the electric vehicle charging and discharging device 22c, and the electric vehicle 22d. In addition, since the power storage device 22b, the electric vehicle charging and discharging device 22c, and the electric vehicle 22d can be charged and discharged, they are the power demand device 22 when charging, and also have the function of the power generation device 23 when discharging. Figure 1 In the figure, the power demand device 22 is illustrated, but the present embodiment is not limited to this, and the power demand device 22 may be connected to the cooperative autonomous distributed machine 40 as a power generation device 23.

[0087] Each power generation device 23 such as a wind power generation device 23a, a solar power generation device 23b, an internal combustion engine power generation device 23d, and an electric storage device 23c are connected to the unit grid system 28 via the DGR 40. As described later, each DGR 40 performs synchronization control of the unit grid system 28 in a manner synchronized with the frequency and phase of the main system 15 based on, for example, the main system frequency measurement value f sent from the MGC 30 set in the cloud, and the phase synchronization signal Ncyc_ref_Sync. In addition, by adjusting the inter-system phase difference φglobal between the main system 15 and the unit grid system 28, the flow or reverse flow of each of the effective and reactive power can be controlled. That is, when the unit grid system 28 receives power from the main system 15, that is, when the unit grid system receives the power flow, by reducing the inter-system phase difference φglobal1, the power flow from the main system to the unit grid system can be increased. Furthermore, on the contrary, for example, in the case where the surplus power generated by the power generation equipment 23 such as the solar cell power generation device in the unit grid 20 is transmitted to the main system 15, that is, in the case of reverse flow, the amount of power transmitted to the main system 15 can be increased by increasing the phase angle of the unit grid system 28 by increasing the phase difference φgloba1 between the systems.

[0088] The circuit breaker (DG circuit breaker) 21 with synchronization verification function can connect the unit grid system 28 to the main system 15 when the main system 15 is synchronized with the unit grid system 28, and cannot connect the unit grid system 28 to the main system 15 when the main system 15 and the unit grid system 28 are not synchronized. In this way, the circuit breaker 21 with synchronization verification function has PLL, and can also detect the phase difference between the main system 15 and the unit grid system 28, and can set the circuit breaker 21 with synchronization verification function to be closed only when the two systems are synchronized. In other words, synchronization verification can also be performed with PLL.

[0089] The circuit breaker 21 with a synchronous detection function can detect the main system frequency f and the main system rotation phase angle θref. In addition, the circuit breaker 21 with a synchronous detection function is equipped with a PLL and can also detect the phase difference between the main system 15 and the unit power grid system 28. The main system frequency f, the main system rotation phase angle θref, and the phase difference between the main system 15 and the unit power grid system 28 detected by the circuit breaker 21 with a synchronous detection function are transmitted to the DGR40 for phase synchronization control. In this way, the circuit breaker 21 with a synchronous detection function can also share a part of the system interconnection controller 30 by obtaining the system voltage information or the unit power grid voltage information and performing calculations.

[0090] Here, an example in which the main system frequency f, the main system rotation phase angle θref, and the PLL are provided in the circuit breaker with a synchronous detection function 21 has been described, but the present embodiment is not limited to this, and the detectors of the main system frequency f and the main system rotation phase angle θref may be provided separately from the circuit breaker with a synchronous detection function 21. In addition, the PLL may also be provided separately from the circuit breaker with a synchronous detection function 21.

[0091] Since multiple DGR40s are dispersed in the unit grid system 28, the range covered by one DGR40 can be subdivided, so there is no need to centrally configure large-scale system interconnection equipment in the unit grid system 28, which has the advantages of shortening the distribution line and reducing the diameter of the wire. The range covered by one DGR40 is not particularly limited, and can be set to a unit of about 10 residential buildings, for example. In the above case, although not particularly limited, the DC (Direct Current) input of the DGR40 can be set to, for example, 750V, 40kW, the AC output can be set to, for example, 380V, 3 phases, 40kW, and the built-in battery capacity of 20kWh can be set to 1 to 4 units. Moreover, in a smaller case, for example, the DC input can be set to 350V, 20kW, the AC output can be set to, for example, 200V, 3 phases, 20kW, and the built-in battery capacity of 20kWh can be set to 1 to 4 units.

[0092] The system of this embodiment synchronizes the frequency and phase of the unit grid by transmitting the frequency and phase of the main system side to all DGR40 in the unit grid using the method described later when the main system is not connected to the unit grid system, and controls the power flow between the two systems when connected. Moreover, when connected, when the voltage of the main system drops for a short time, synchronization is continued (Fault Ride Through: FRT), and when the main system is powered off, it is disconnected, and the unit grid can be black-started. The voltage level is information that is greatly related to the reactive power, and this is also transmitted to all DGR40 in the unit grid. Since the transmission method is a prior art, the details are not described. Thus, when the voltage is fixed, the power flow or reverse power flow of the power generation equipment 23 connected to the unit grid system 28, such as the renewable energy power generation equipment, is controlled, and the power generated by the power generation equipment 23 in the unit grid system 28 is self-generated and self-sold, and autonomous operation can be performed when the main system 15 is powered off.

[0093] MGC30 uniformly controls each DGR40 within the unit grid 20, performs interconnection control of the total power demand of the unit grid 20, the power generation of the power generation equipment 23, phase and frequency, accident control, system power outage / repowering control, demand planning control, etc.

[0094] Each DGR 40 performs synchronization control using accurate time information, such as time information from GPS using artificial satellite 17. In addition, MGC 30 transmits signals such as primary system frequency f, phase synchronization signal Ncyc_ref_Sync, and inter-system phase difference φglobal to each DGR 40 as primary system synchronization information.

[0095] [Equivalent circuit of DGR40 in unit grid]

[0096] Figure 2A to Figure 2F It is a schematic diagram of a cooperative autonomous distributed system interconnection system according to Embodiment 1 of the present invention. Figure 2A is a circuit diagram of a cooperative autonomous distributed machine 40, and is an equivalent circuit when one DGR 40 in the unit grid system 28 is taken out. All DGR 40 are as follows Figure 2A As shown, it acts as an AC voltage source Vdgr_i with output impedance. i is a subscript indicating the number of DGR40. Each DGR40 is connected in parallel to the unit grid voltage Vgrid via the system interconnection resistor RG and the inductor LG, and a current Idgr_i flows out from each DGR40. Since the unit grid voltage Vgrid is common to all DGR40, each DGR40 can control Idgr_i by changing the internal voltage Vdgr_i.

[0097] Under normal conditions, Idgr_i is controlled to be equal to all i, so that the load sharing of each DGR 40 is equal. However, there are cases where the load sharing is changed according to the state of the DGR 40, or the flow direction of Idgr_i into the DGR 40 is controlled in order to charge the internal battery. These can be controlled by the setting method of the target value of Vdgr_i.

[0098] [Vdgr voltage control with current hysteresis control]

[0099] Figure 2B yes Figure 2A The detailed circuit diagram shows the components of DGR40, which is the half-bridge inverter. Figure 2C yes Figure 2B The operation explanation diagram shows that IL is repeatedly increased and decreased by alternately turning on the upper and lower switches of the half bridge. The upper and lower bandwidths are set for the target current value Iref. When the measured current value IL exceeds the upper frequency band, the upper switch of the half bridge is cut off and the lower switch is turned on. When the measured current value IL is lower than the lower frequency band, the lower switch is cut off and the upper switch is turned on. The above operation is repeated continuously. This is called current hysteresis control. The details of hysteresis control are described in the following embodiment 3.

[0100] Generally speaking, the problem of hysteresis control is that the switching cycle varies, making it difficult to design a filter, etc. In the present invention, a variable bandwidth method is developed to solve the above problems. Figure 2C The lines on the upper and lower sides of the target current value Iref are frequency bands. If the width is narrowed, the switching cycle is advanced, and if it is widened, the switching cycle is slowed down. Since the slope of the reactor current IL of the half-bridge changes due to the difference between Vdc and Vdgr, an operation is applied such that the bandwidth is changed according to the difference and the switching frequency is almost fixed. Thus, control is performed in such a way that the target current value Iref is equal to Idgr, and open-loop control is performed in such a way that the filter voltage of the half-bridge is equal to the target Vdgr. The control object is current, and as a result, high-speed voltage control can be performed. The following description is based on the premise of directly controlling Vdgr according to the above method.

[0101] Figure 2D is a circuit diagram of a cooperative autonomous distributed system interconnection system according to Embodiment 1 of the present invention, showing that N Figure 2AThe DGR40 shown is connected in parallel to the unit grid. It shows that the unit grid voltage Vgrid is common. In contrast, each DGR40 is connected via a different output impedance ZG_i (i=1~N) with a different voltage Vdgr_i, and the current of Idgr_i flows in respectively. In this way, if the parallel connection operation of multiple voltage sources cannot achieve voltage synchronization with high precision, then a transverse current will flow between the voltage sources, so the synchronization force is important. In the present invention, a method of using a standard time signal as the synchronization signal is adopted. In this embodiment, the virtual impedance technology further described below is used to make ZG_i virtually equal, Vdgr_i and Idgr_i are also equal, and the load sharing is equalized. In addition, by controlling Vdgr, Idgr is also changed, and the load sharing can also be changed according to each DGR40.

[0102] The actual output impedance of DGR40 varies depending on the installation location, the influence of the export transformer, the distance of the distribution line, the thickness of the wire, etc. Since these values ​​are not known, it is difficult to equalize the load sharing ratio among multiple DGR40 even if the internal voltage Vdrg of DGR40 is operated. As a solution to this problem, it is effective to introduce a virtual impedance that increases the ratio of the known impedance. If the virtual impedance including the actual impedance is defined and its value is equal between each DGR40, and it is added to the control of Vdgr, the load sharing ratio can be easily equalized.

[0103] Specifically, it is achieved by controlling the control target value of Vdgr by subtracting the voltage drop of the virtual impedance (= (virtual reactor - real reactor) × time differential value of Idgr). As an example of the setting value of the virtual impedance, it is set so that when the rated current flows, including the real impedance, a voltage drop of about 15% of the rated voltage occurs. Therefore, it is important to accurately grasp the real impedance for each installation location of the DGR40 and enter it as a control constant.

[0104] In order to synchronize the frequency and phase of all DGR40 in the unit power grid, the following two synchronization methods are adopted. They are (A) the synchronization method of GPS time signal and (B) the synchronization method based on voltage. The two methods can complement each other and can be used in combination or alone. As a way to obtain the standard time signal, all DGR40 are equipped with GPS receivers, but as long as the accuracy of the standard time signal can be obtained, it is not limited to GPS. When the GPS signal is interrupted, all DGR40 can operate synchronously even without the standard time signal through the synchronization method based on (B) voltage. Both use the well-known method of phase-locked loop (PLL) to detect frequency and phase from the voltage vector. The following is a detailed description of the two synchronization methods. In addition, regarding reactive power, the voltage correction information is sent to all DGR40 via MGC30, and the reactive power can be adjusted by PI control of background technology. First, (A) is described for the synchronization method of GPS time signal.

[0105] [(A) Description of the GPS time signal synchronization method]

[0106] Figure 2E The figure shows the relationship between the current Idgr of a DGR 40 and the internal voltage phase Vdgr of the DGR 40 under GPS time synchronization control, and the voltage phase Vgrid of the unit grid.

[0107] In addition, the symbol "*" added to the right shoulder like Vgrid* indicates the target value. The figure shows the state where the target and the actual value are consistent. The following description expresses the actual value. Since Vgrid is based on the GPS time signal, it is synchronized in all DGR40. Vgrid rotates at the speed of the frequency based on the global angle reference θref calculated from the GPS time reference, but Figure 2E In the D axis, it is fixedly expressed as the D axis. Idgr becomes a current delayed by a phase angle φ based on the load in the unit grid and the grid impedance. If Idgr is decomposed into the DQ axis, it becomes ID and IQ, ID is in phase with Vgrid, and IQ becomes a component delayed by 90°.

[0108] The voltage drop of the DQ axis is generated by the virtual impedance including Idgr and the physical impedance. The voltage drop of the D axis component is ID×RG+IQ×XG, and the voltage drop of the Q axis component is ID×XG-IQ×RG. In addition, Figure 2E and Figure 2FIn the figure, the multiplication symbol "×" is written as "." Since the voltage drop of these D-axis and Q-axis components is equivalent to the voltage drop between Vdgr and Vgrid, Vdgr is obtained by compensating for the voltage drop. The phase angle between the internal voltage Vdgr generated at this time and the unit grid system voltage Vgrid is set to δ. Since Vgrid is synchronized in all DGR40, Vdgr also has a phase difference, but rotates synchronously. Therefore, by adjusting the phase angle δ, the output sharing of each DGR40 can be changed, or it can function as a negative output, that is, a load, for charging the built-in battery.

[0109] In the GPS time synchronization method, when the unit grid is connected to the main system, the target Vgrid* vector is made based on the frequency of the main system. Both the internal voltage target Vdgr* and the current target Idgr* of the DGR40 are changed according to the virtual impedance as follows: Figure 2E The actual unit grid voltage Vgrid, the internal voltage Vdgr of the DGR40, and the current Idgr are all controlled to be almost equal by incorporating their respective target values ​​Vgrid*, Vdgr*, and Idgr*. The excess or deficiency of power generated by the imbalance between the total output of all DGR40 and all the demands in the unit grid is supplied from the main system or flows back to the main system.

[0110] However, when the unit grid is separated from the main system and operates independently, since there is no power adjustment of the main system, the total output of all DGR40 must be completely consistent with the total of all demands in the unit grid. Since DGR40 does not have demand information, control is performed to make the actual Vdgr consistent with the target DGR40 internal voltage Vdgr*. As a result, Figure 2F As shown, the actual current Idgr corresponding to the actual demand flows, and the effective power part and the ineffective power part of the demand are appropriately supplied according to the actual Vgrid and the actual Idgr. As a result, the actual current Idgr deviates from the target current value Idgr*. The actual voltage Vgrid also deviates from the target Vgrid*. The phase difference between the actual unit grid voltage Vgrid and the target unit grid voltage Vgird* is set to Δδ. Since the Daxis* axis is synchronized with the frequency of the main system, in order to change the unit grid from independent operation to interconnected operation, the Δδ is close to zero and synchronized with the main system. Therefore, this is achieved by using a signal such as φgloba1 described later.

[0111] In order to synchronize all DGR40, it is necessary to make the correct standard time work. If a synchronization error occurs, a voltage difference will be generated between DGR40. Since a voltage drop of 10% to 20% occurs depending on the impedance between DGR40, even if the allowable voltage error is set to 1%, the control error of the current becomes about ±10% to ±5%, so the voltage error should be as small as possible. A voltage error of 1% is equivalent to a phase angle of 0.0015 radians. If it is converted into time, it is equivalent to an accuracy of 5μsec. Although there are crystal oscillators with an accuracy of about ±10μsec, if a common correction is not applied, the error between DGR40 will increase. The GPS time signal is a common time signal that can ensure the above accuracy and is available at a relatively low price. The accuracy of radio wave clocks or network time protocols is insufficient. Although atomic clocks are expensive, they are also an option.

[0112] In the present embodiment, as a standard time signal acquisition device, a standard time signal acquisition method having the following manner is listed: based on the GPS clock, atomic clock, and the configuration of each cooperative autonomous distributed machine (DGR40), the time is precisely distance corrected, or the zero crossing of the AC voltage and its time are measured, and the information is transmitted to each cooperative autonomous distributed machine (DGR40), and the internal clock is corrected by comparing it with the zero crossing time of each cooperative autonomous distributed machine (DGR40).

[0113] [(A) Block diagram of synchronous control]

[0114] Figure 3A This is a block diagram of GPS synchronization control according to Embodiment 1 of the present invention. Figure 3A , the synchronous control method based on the GPS time signal is described. This method is characterized in that the main system frequency signal f is received via the MGC 30, and the phase synchronization signal Ncyc_ref_Sync obtained by making the GPS time signal work is combined with the GPS time signal inside the DGR 40, thereby each DGR 40 can produce a phase angle signal θref synchronized with the main system within ±5μsec. The details are shown below.

[0115] Figure 3AIn the operation block, the operation in the system interconnection controller (MGC) 30 is performed as follows. The main system frequency f is measured by the main system frequency measuring device 31, and the GPS time t32 is obtained in the first time acquisition unit as the first time information (t). The two are multiplied and subtracted from the sawtooth main system rotation phase angle θref34 of each cycle. When the "function for extracting the decimal part" shown below, such as a floor function, is applied to the result, the phase synchronization signal Ncyc_ref_Sync39 (equivalent to Δδ) can be calculated. The two signals, the main system frequency signal f and the phase synchronization signal Ncyc_ref_Sync, are sent from the MGC30 to each DGR40. The sending method can be a server method or a broadcast method. In addition, the operation unit is a function inside the MGC30, but it is physically built into the circuit breaker 21 with an internal verification function and operates, and can also be sent to each DGR40 via the cloud using a mobile line or by power line transmission.

[0116] As a function for extracting the decimal part, the floor function can be replaced by a frac function, a ceil function, a round function, a MOD function, etc. Since the two signals, the main system frequency signal f and the phase synchronization signal Ncyc_ref_Sync, change slowly, they can be treated as constants compared to the operation speed or the signal transmission time from the MGC30 to the DGR40. The communication rate between the MGC30 and the DGR40 is allowed to be about 0.1 seconds to 10 seconds.

[0117] also, Figure 3A In the operation block, the operation in the cooperative autonomous distributed machine (DGR) 40 is performed as follows. First, in the system interconnection controller (MGC) 30 of the DGR40, the main system frequency measurement value acquisition unit 41 receives the main system frequency f obtained from the circuit breaker 21 with a synchronous verification function. In addition, the second time information (t′) is obtained from the second time acquisition unit as the GPS time t'42. In addition, for each DGR40, Ncyc_shift_local44 is prepared in case an inherent adjustment value corresponding to the configuration location of the DGR40 is required. In addition, the DGR40 receives the Ncyc_ref_Sync39 calculated by the MGC30 and sets it as the Ncyc_ref_Sync45 inside the DGR40.

[0118] Next, the main system frequency measurement value f41 is multiplied by the GPS time t'42 by a multiplier 43 to obtain f·t' as a sign of a continuously increasing characteristic. If an operation 50 is performed on the f·t', in which Ncyc_shift_loca144 and Ncyc_ref_Sync45 are added by adders 46 and 47, and then the output of the floor function 51 is subtracted by a subtractor 52, Ncyc_ref_bas can be obtained as a sign of a sawtooth shape. The floor function operation 50 is not limited to this, and for example, it can be replaced by a function that extracts other decimal parts as described above.

[0119] In DGR40, a subtractor 53 is provided for feeding back Ncyc_ref and subtracting it after the frac function operation 50. Furthermore, an adder 54 adds a value of 0.5 and then performs a frac function operation 55. The frac function operation 55 is performed at Figure 3A In the above, the output of floor function 56 is subtracted by subtractor 57, but the present embodiment is not limited to this. For example, as described above, the function of extracting the decimal part can be replaced. Then, the value of -0.5 is added by adder 58, and further multiplied by multiplier 59.

[0120] f=2πf0·10 3 (1) is calculated to obtain f+Δf. For f, after passing through the limiter 60 of f-α and f+α, Ncyc_ref is demodulated by the operation of the integrator 61. Through the above operation, the phase of the system phase angle θref34 of the main system 15 and the output system phase angle θref62 of each DGR40 are synchronized, and the frequency is also consistent.

[0121] The input signal of the limiter 60 becomes f+Δf, which is the sum of the frequency and the rate of change of frequency (ROCOF). By setting the limiter 60 of the rate of change, it becomes a factor that determines the speed and magnitude of the phase tracking of the unit power grid. In other words, if the width of the limiter 60 is widened, the phase change of the main system is quickly followed, but the phase change is slightly larger. If the width of the limiter 60 is narrowed, it takes time to follow the phase change of the main system, but the phase change is small.

[0122] In this way, the transmission delay of the frequency / phase tracking of MGC30 can be controlled by the limiter 60 to have the effect of suppressing the frequency change rate (ROCOF) within a certain range. Since it is a first-order transfer function, rather than a second-order transfer function of a synchronous machine simulating a general grid-type inverter, it becomes a very stable structure. In addition, the main system rotation phase angle θref is originally a signal of 0 to 2π, but here it is divided by 2π and processed as a sawtooth signal between 0 and 1.

[0123] The block from the subtractor 53 to the integrator 61 functions as a low-pass filter, and has the function of removing noise contained in Ncyc_ref_bas, such as so-called whisker noise, but the present embodiment is not limited to the above-mentioned block, and may be configured as a discontinuous time control using 1 / Z conversion, for example.

[0124] [(A) Description of system interconnection, independent operation, and main system power failure status]

[0125] Next, refer to Figure 3B , Figure 3C , Figure 3D , describing the following three states.

[0126] Main system connection status: Figure 3B This is a control block diagram of the master system connection state of GPS synchronization according to the first embodiment of the present invention.

[0127] Unit grid independence status: Figure 3C This is a control block diagram of the GPS-synchronized unit power grid system independent state (synchronous control) according to the first embodiment of the present invention.

[0128] ·Main system power outage·Unit power grid independent operation status: Figure 3D This is a control block diagram of the GPS-synchronized unit power grid system in an independent state (when the main system is powered off) according to the first embodiment of the present invention.

[0129] [(A) Main system connection status]

[0130] Figure 3B In the process, the circuit breaker 21 with synchronization verification function is closed, and the main system 15 and the unit grid system 28 are synchronously interconnected. Therefore, the main system voltage Vgrid_main is equal to the unit grid system voltage Vgrid_mini. The main system effective power Pgrid_main and the main system reactive power Qgrid_main are input to the MGC 30, and the inter-system phase difference signal φglobal1 is calculated. In the system interconnection state, φglobal controls the flow of effective power / reactive power between the two systems. In addition, φglobal can also transmit different values ​​for each DGR 40 without changing the total, so that different outputs are output.

[0131] The GPS receiver 91 as a first time acquisition unit inputs the GPS time information tref as the first time information (t) to the MGC 30. On the other hand, the GPS receiver 92 as a second time acquisition unit inputs the DGR 40a as the second time information (t').

[0132] In MGC30, the phase synchronization signal (Ncyc_ref_Sync) is calculated, and two pieces of information, the main system frequency and Fgrid_ref, are transmitted and input to DGR (GPS-based phase calculation block) 40a. These two pieces of information are sufficient for synchronization control, but as a power flow control, a φglobal signal is also transmitted. In DGR40a, the unit grid system rotation phase angle θref of DGR40 is calculated. In adder 93, θref and φglobal are added to calculate θref_adj. Based on θref_adj, DGR40b is operated to output the output current Idgr of each DGR40. The output current of each DGR40 is summed up and made to flow into the unit grid (expressed as adder 94 in the figure). The inflow current Igrid_main from the main system is also added and supplied to the unit grid system load 90. As a result, the unit grid system voltage Vgrid_mini (=unit grid system load voltage Vload) is established. The voltage is input to MGC30 to create a stable feedback loop.

[0133] [(A) Unit grid independent state (when the main system is operating)]

[0134] Figure 3C In the embodiment, the circuit breaker 21 with synchronization verification function is opened to disconnect the main system 15 from the unit grid system 28, and the phase synchronization method of the two systems when the unit grid is in an independent operation state is described. When the two systems are disconnected, generally speaking, the main system voltage Vgrid_main and the unit grid system voltage Vgrid_mini are different, but in this GPS time synchronization method, the main system frequency f31 and the phase synchronization signal Ncyc_ref_Sync39 are transmitted and Figure 3A The calculation of θref of the two systems is always synchronized. During independent operation, the phase difference signal φgloba1 between the systems can be used for fine adjustment. In this way, the voltage phase of the unit power system 28 is synchronized with the voltage phase of the main system 15, so the unit power system 28 can be connected to the main system 15 at any time by setting the circuit breaker 21 with a synchronization detection function to close.

[0135] [(A) Unit grid independent state (when the main system is powered off)]

[0136] Figure 3D How the DGR 40 in the unit grid is synchronized when the main system of GPS synchronization is powered off and the unit grid system is in an independent state (main system power failure) in Embodiment 1 is described. When the main system is powered off, the circuit breaker with synchronization verification function is disconnected, and the information from the MGC 30 is lost. On the other hand, tref, which is the second time information (t′), is continuously input to the DGR 40a from the GPS receiver 92 as the second time acquisition unit.

[0137] Therefore, in the DGR40, if the main system frequency measurement value Fgrid_ref is replaced with the value of the previous moment, or a predetermined fixed value (such as 50 Hz, etc.), and the phase synchronization signal Ncyc_ref_Sync is also replaced with the value of the previous moment, or a predetermined fixed value (such as 0, etc.), then all DGR40 can obtain θref synchronized with the GPS time as a common index. In addition, since the inter-system phase difference signal φgloba1 is optional, θref adj is also synchronized by setting it to a predetermined fixed value (such as 0, etc.). Therefore, even when the main system is out of power, all DGR40 of the unit grid can be synchronized and operated independently. When the main system is restored, the GPS time synchronization operation can be restarted, and after synchronization is achieved, the circuit breaker with a synchronization detection function can be closed to switch to the system interconnection operation, or the unit grid independent operation can be continued as it is.

[0138] In order to prevent the unit power grid from continuing to operate independently even if the main system (15) fails to power on, the circuit breaker (21) with a synchronization verification function is not opened, and the system interconnection controller (MGC30) has a system interconnection protection function including a separate operation detection. During active separate operation detection, the output of reactive power of each cooperative autonomous distributed machine (DGR40) can be adjusted to activate the protection function and set the circuit breaker (21) with a synchronization verification function to open. In addition, in order to keep the circuit breaker (21) with a synchronization verification function in a closed state when the main system fails for a short time, an FRT function is also provided.

[0139] [(A) Black start operation of unit grid]

[0140] In the case of a power outage in the main system when the systems are interconnected, the time from the closing to the opening of the circuit breaker 21 with a synchronous detection function is detected, for example, when a high-voltage vacuum circuit breaker (VCB) is used, is rated to be 3 to 5 cycles, that is, a delay of about 0.06 seconds to 0.1 seconds. In addition, it is also considered that when the system is interconnected, in the case of a power outage in the main system, the unit grid system voltage drops along with the drop in the main system voltage and becomes 0V. Restoring to independent operation from the above situation is a so-called black start.

[0141] In the above case, if it is predetermined that the main system frequency measurement value f41 is maintained at the previous value or replaced with the rated value, and the phase synchronization signal Ncyc_ref_Sync45 is maintained at the previous value or replaced with a predetermined fixed value, then even if the voltage becomes zero, it is possible to disconnect from the main system and perform a black start while maintaining synchronization within all DGRs 40, and to switch to independent operation of the unit grid. This is because all DGRs 40 have GPS time t'42 ( Figure 3A) is tref92( Figure 3D ), and perform calculations based on this.

[0142] [(A) Time synchronization error]

[0143] When the main system is disconnected from the unit power grid, the main system frequency f31 and the phase synchronization signal Ncyc_ref_Sync are fixed without change, so that the θref (=2π·Ncyc_ref) obtained in each DGR 40 is synchronized with the θref of the main system within a voltage error of 1% (equivalent to a time error of 5μsec). In the case of the above-mentioned error, the main system and the unit power grid can be said to be synchronized, so even if the circuit breaker 21 with a synchronization detection function is connected to connect the two systems, no abnormal current will flow between the two systems.

[0144] [(A) Influence of transmission delay time]

[0145] When the main system is disconnected from the unit grid, if the frequency or phase of the main system changes, it will temporarily become a state of synchronization deviation from the main system due to the time delay from the MGC30 that transmits the change to the DGR40 to the DGR40, or the operation time in the MGC30 and the DGR40. In the above state, even if you want to connect the circuit breaker 21 with a synchronization verification function to connect the two systems, the synchronization verification function may be activated and the circuit breaker cannot be connected. However, after the transmission delay time, the voltage phase of the unit grid is synchronized with the main system and the circuit breaker is connected. The transmission delay time is the delay degree of network communication. Although it depends on the communication environment, it is usually within about 0.1 seconds to 1 second.

[0146] [(A) Inertial force and synchronization force]

[0147] When the main system and the unit power grid are connected, since the two systems are physically connected, the frequency f and the rotation phase angle signal θ of the two systems become common values. Here, when the frequency or rotation phase angle of the main system changes, the MGC30 cannot transmit the change to each DGR40 during the transmission delay time. Therefore, the frequency and rotation phase angle of each DGR40 are delayed by the delay time. Therefore, from the main system side, it can be seen that each DGR40 and the unit power grid act as if they have strong inertia. Moreover, since they start to follow the main system after the delay time, it can be seen that each DGR40 and the unit power grid have a strong synchronization force.

[0148] In addition, the limiter 60 in the controller of DGR40 also limits the frequency change of the main system of transmission. If the limit width is narrow, it is not easy to follow the frequency change of the main system, so it acts in a way that the inertia force becomes larger. If the limit width is wide, it is easy to follow the frequency change, so it acts in a way that the inertia force becomes smaller. The same is true when there are multiple unit grids. In a separate system such as an isolated island, even if the scale of the unit grid is small here, but the whole accounts for more than half of all demands, then by narrowing the limit width of the frequency change rate, it can be made robust against frequency changes, and the unit grid side can be gradually replaced to perform the same action as the main system. In other words, the unit grid becomes an electric power system with controllable inertia.

[0149] Next, “(B) voltage-based synchronization method” of two synchronization methods for synchronizing the frequencies and phases of all the DGRs 40 in the unit grid will be described.

[0150] [(B) Basic explanation of the voltage-based synchronization method]

[0151] The voltage-based synchronization method is the standard method in system-interconnected microgrids. The method is widely installed, tested and implemented around the world. When connected to the main system, changes on the unit grid side are absorbed by the main system and will not cause adverse effects. However, it is difficult to maintain frequency when the central unit grid is operated independently from the independent inverter group of the main system. In addition, the unit grids cannot be black-started at the same time. The following is a method to solve these problems.

[0152] First, the voltage-based synchronous control method has the following advantages.

[0153] The synchronization signal uses the voltage of the distribution line of the unit grid.

[0154] -No special additional equipment such as GPS signals or receivers is required.

[0155] -The voltage synchronization signal is very strong.

[0156] - As long as the power line is not faulty or broken, then operation can continue.

[0157] The voltage synchronization signal automatically adjusts the following issues.

[0158] - Transformer voltage change and phase shift.

[0159] -Voltage drop and phase shift across circuit impedance.

[0160] When DGR40 is connected to the unit grid, it can be installed and removed without special configuration.

[0161] DGR40 is flexible in manual or automatic changes of unit grid circuit configuration.

[0162] On the other hand, it also has the following disadvantages.

[0163] · When the unit grid is disconnected from the main system and operates independently, it cannot achieve synchronization.

[0164] -Under the general frequency droop control, the fluctuation becomes too large.

[0165] - A synchronization signal of the MGC30 proposed here is required.

[0166] · Black start is not possible when the unit grid is out of power.

[0167] - Requires GPS time synchronization signal.

[0168] The following explains why synchronization cannot be achieved when the unit grid is disconnected from the main system and operates independently. When the unit grid is operating independently, the total output of all DGR40s must be consistent with the total demand in the unit grid. Figure 2F As shown, the actual current Idgr flowing in accordance with the actual demand deviates from the target Idgr*. As a result, the actual unit grid voltage Vgrid has a phase difference of Δδ relative to the target Vgrid*. If Δδ is zero, the frequency / phase is stable, but once the balance between the total output and all demands collapses and Δδ becomes positive or negative, |Δδ| increases.

[0169] For example, when the effective power output of DGR40 exceeds the actual load effective power, the phase of the actual voltage Vgrid is ahead of the target voltage Vgrid*, and Δδ is always positive. Since the target voltage Vgrid* moves in a way that is consistent with the actual voltage Vgrid through the PLL, positive feedback is applied to increase the phase of θref. As a result, the PLL frequency continues to increase.

[0170] In addition, on the contrary, when the effective power output of DGR40 is less than the actual load effective power, the phase of the actual voltage Vgrid is delayed from the target voltage Vgrid*, and Δδ is always negative. The PLL continuously reduces the phase of θref in a positive feedback loop. As a result, the PLL frequency continues to decrease. In either case, the phase difference between the PLL and the mini-grid is unstable, and the frequency is also unstable.

[0171] Thus, voltage-based synchronization cannot be used in a unit grid that is not dependent on the grid and operates independently. This is because there is no stable power source for receiving or providing the actual reactive power difference between the DGR 40 and the load. On the contrary, if there is a stable power source, the actual voltage Vgrid is stable, and the target voltage Vgrid* will not fall into a positive feedback loop even if it is controlled to be close to the actual voltage Vgrid.

[0172] [(B) Importing the inter-system phase difference signal φglobal]

[0173] In order to prevent the unit grid from falling into this positive feedback loop even if it is placed in an independent operation state that does not depend on the main system, the following method has been developed. That is, a method is proposed to transmit the main system frequency signal f and the inter-system phase difference signal φglobal to all DGR40 through MGC30, thereby stabilizing the frequency and phase of the unit grid. First, Figure 4B As shown, first, the phase angle signal θref is fed back through the feedback control Kθctrl85 to reduce the error between the reference angular frequency ωref and the mini-grid angular frequency ωgrid to produce φsync. The phase angle signal θpll obtained by the PLL of each DGR 40 is added to it in the adder 86 to produce a local system phase angle signal Ncyc_ref89. However, if only the above control is used, the voltage phase of the unit grid is positively fed back and unstable as described above.

[0174] Therefore, if Figure 4B As shown, φglobal 80 is further added to the adder 86. φglobal is a signal indicating the phase difference between the main system and the unit grid. Although the main system is disconnected from the unit grid, if the phase of the unit grid is expanded compared to the phase of the main system, φglobal changes. By adding φglobal, the positive feedback loop of the phase expansion can be suppressed, and the instability of the phase and even the frequency of the unit grid can be suppressed. Even if it is not directly connected to the main system, the frequency of the unit grid is stabilized by using only the above information. As a result, when operating independently without being connected to the main system, all DGR40 in the unit grid are synchronized, and the frequency can be stabilized. In addition, since the two systems are synchronized, the two systems can be connected at any time by connecting a circuit breaker with a synchronization detection function.

[0175] use Figure 4A This means that φglobal is effective even when the main system is connected to the unit grid. If the phase difference between the two systems is expanded, effective power will flow, so φglobal measures the power flow 17 flowing between the two systems, creates a phase difference signal φglobal required for comparison with the target effective power / reactive power, and sends it to all DGR40. In this way, the output of all DGR40 can be increased or decreased, and the power flow between the two systems can be controlled to match the target value.

[0176] In addition, when the unit grid operates independently due to a power outage in the main system, the reference voltage phase of the internal clock is created to replace the voltage phase of the main system, and the phase difference signal with the unit grid voltage phase is transmitted as φglobal to all DGR40 through MGC30, so that the frequency and phase of the unit grid can be synchronized.

[0177] Next, the reason why the standard time signal is required during the black start when the MGC 30 is stopped and the unit power grid is stopped is explained. As described above, when the main system is connected to the unit power grid, the voltage phase of the main system becomes the reference, and when they are separated, the voltage phase information of the main system can be obtained through the MGC 30. In addition, even if the main system is powered off, the phase of the clock inside the MGC 30 can be used as a common reference and transmitted to all DGRs 40 through the MGC 30.

[0178] However, when the MGC 30 is stopped, all DGRs 40 do not have common voltage phase information in a state separated from the main system. In addition, when the unit power grid is stopped, all DGRs 40 do not have common voltage phase information. In this case, it is necessary to supply a common synchronization signal to all DGRs 40 in another way. If the DGR 40 obtains the standard time information and corrects the internal clock based on it, it is possible to create a voltage phase synchronized with all DGRs 40.

[0179] Thus, a method is proposed for stabilizing the frequency and phase of the unit grid using standard time information during a black start after a unit grid power outage or during independent operation of the unit grid when the MGC 30 is stopped.

[0180] [(B) Detailed description of the voltage-based synchronization method]

[0181] refer to Figure 4A , Figure 4B , Figure 4C The voltage-based synchronous control method is described. Figure 4A This is a control block diagram of a main system connection state of voltage synchronization according to Embodiment 1 of the present invention. Figure 4B 1 is a control block diagram of a voltage-synchronized unit grid system independent state (synchronous control) according to Embodiment 1 of the present invention. Figure 4C This is a control block diagram of a voltage-synchronized unit power grid system in an independent state (when the main system fails) according to Embodiment 1 of the present invention. The block diagrams and control methods in each state will be described below.

[0182] [(B) Synchronization method when connecting to the main system]

[0183] In the voltage-based synchronization method, when the unit grid is connected to the main system, the difference between the signal based on the frequency of the main system and the signal based on the frequency detected by the PLL of each DGR40 is controlled to be small, and the phase angle signal is also detected and added, so that the target voltage Vgrid* and the actual voltage Vgrid are almost consistent. Figure 2E This indicates that the state described above becomes the same state as when the time is synchronized with the GPS time.

[0184] [(B) Description of the block diagram when connecting to the main system]

[0185] refer to Figure 4A , a block diagram illustrating calculation of Ncyc_ref89 in a cooperative autonomous distributed machine (DGR) 40A when the unit grid system is connected to the main system. Figure 4A This is a block diagram of voltage-based synchronous control according to Embodiment 1 of the present invention, and becomes a control diagram of a system interconnection state. It includes a system interconnection controller (MGC) 30A and a cooperative autonomous distributed machine (DGR) 40A. In the system interconnection controller (MGC) 30A, the system phase angle φglobal is generated by the system phase difference signal φglobal calculation unit 80 from the main system active power Pgrid_main and the main system reactive power Qgrid_main measured by the system active power Pgrid_main measurement unit 98 and the main system reactive power Qgrid_main measurement unit 99, taking into account the power flow between the main system 15 and the unit power grid system 28.

[0186] First, the main system frequency measuring device 31 will be described. The main system voltage acquisition unit 97 acquires the main system voltage Vgrid_main. In the state connected to the main system, since the main system voltage is the same as the unit grid voltage, Vgrid_main=Vgrid_mini.

[0187] PLL96 calculates the main system frequency measurement value f31 from the main system voltage V grid_main, and transmits the signal to DGR40 via MGC30. The calculation unit of the inter-system phase difference signal φglobal80 calculates the inter-system phase difference signal φglobal based on the difference between the measured main system active power P grid_main and the main system reactive power Q grid_main flowing between the main system and the unit grid and each target value (not shown), and transmits the signal to DGR40 via MGC30. If the direction of the power flow flowing to the unit grid side is set to positive, then when the inter-system phase difference signal φglobal is increased, the phase angle difference of the unit grid system relative to the main system is delayed, so the power flow from the main system to the unit grid system increases. In addition, if the inter-system phase difference signal φglobal is reduced, the phase angle of the unit grid system is increased, and the reverse power flow from the unit grid system to the main system increases. In this way, the output of DGR40 is changed so that the power flow flowing between the two systems coincides with the target value. In addition, regarding the reactive power, the voltage correction signal is sent to the DGR 40 via the MGC 30 instead of the φglobal 80. The method is the same and the detailed description is omitted.

[0188] The PLL 83 of the cooperative autonomous distributed machine (DGR) 40A generates a unit grid system phase angle signal θpll and a unit grid system angular velocity signal ωpll according to the unit grid voltage V grid_mini. The main system frequency measurement value acquisition unit 41 receives the main system frequency measurement value f measured by the main system frequency measurement device 31, and calculates the main system angular velocity signal ωref=2π·f. The PLL 83 calculates the unit grid system angular velocity signal ωpll from the unit grid voltage V grid_mini. Then, the inter-system angular velocity error signal ωerr=ωref-ωpll is calculated through the comparator. Then, ωerr is input to the controller kθ_ctr185, and PI operation is performed to calculate the control phase signal φsync. kθ_ctrl has a proportional gain and an integral gain, but the gain of the low-frequency component is fixed, the gain of the high-frequency component becomes small, and it is not easily affected by sudden frequency changes.

[0189] In the adder 86, the control phase signal φsync is added with the unit grid system phase angle signal θpll and the inter-system phase angle φglobal, and the obtained signal is divided by 2π through a divider, and only the decimal part is extracted through the division remainder of the MOD function to obtain a sawtooth output, that is, Ncyc_ref89. In addition, by multiplying Ncyc_ref by 2π, a unit grid system rotation phase angle signal (hereinafter sometimes referred to as "unit grid system phase angle signal") is obtained. θref = 2π·Ncyc_ref. This embodiment uses the MOD function, but it can also be replaced by a function that extracts the decimal part.

[0190] In this way, the unit grid system phase angle signal θref=2π·Ncyc_ref obtained in each cooperative autonomous distributed machine (DGR) 40A is synchronized with the main system voltage (=unit grid voltage). In the case of a system that is stable in a steady state, since the PLL frequency is fixed, ωref=ωpll, ωerr=0, φsync=0. Therefore, θpll produced by the PLL of each DGR40 becomes dominant. By adding the inter-system phase angle φglobal to it, the power flow and reverse power flow between the unit grid system and the main system can be controlled.

[0191] In the case of a sudden change in system frequency and phase, ωref≠ωpll, resulting in a transmission time delay. However, PLL83 observes the unit grid voltage (= main system voltage) and produces θpll, so even if it changes suddenly, it will immediately follow (about 1 cycle). The power flow between the main system and the unit grid changes suddenly, and the transmission of φglobal will have a time delay. Limits are set on the rise and fall of φglobal to avoid sudden changes. In this way, the synchronization force and inertia force of the unit grid are maintained by connecting the power flow of the two systems and PLL.

[0192] [(B) When the unit grid is independent)]

[0193] refer to Figure 4B , a block diagram illustrating calculation of Ncyc_ref in a cooperative autonomous distributed machine (DGR) 40B when the unit grid is in an independent state. Figure 4B This is a block diagram of voltage-based synchronous control according to Embodiment 1 of the present invention, and is a control diagram of a unit grid that is isolated from the grid and operates independently. It includes a grid interconnection controller (MGC) 30B and a cooperative autonomous distributed machine (DGR) 40B. Figures 1 to 4A The same components are denoted by the same reference numerals, and their description is omitted. The inter-system phase difference signal φglobal calculation unit 80 calculates the difference in phase angle between the measured main system voltage Vgrid_main and the unit grid voltage Vgrid_mini using the PLL 96b, and obtains the inter-system phase difference signal φglobal.

[0194] Figure 4B The input content of φglobal is the same as Figure 4A The φglobal of the case is different. Figure 4B In the case of a power outage, the two systems are disconnected, so the purpose is to make the voltage phase of DGR40B consistent with the main system, and the circuit breaker 21 with a synchronous detection function can be connected at any time. Figure 4Bφglobal calculates the voltage phase difference between the two systems. During independent operation, when both the main system and the unit grid system are stable and in a constant state, by sending a signal of φglobal=0, the voltage phases of the two systems are consistent, and they can be connected at any time. In the case of a sudden change in system frequency or phase, ωref≠ωpll. However, since the two systems are disconnected, the phase angle difference between the main system and the unit grid is temporarily increased, but after a transmission time delay, the voltage phases are consistent again, and the two systems are restored to a state where they can be connected at any time.

[0195] [(B) Adoption of standard time signal]

[0196] As mentioned above, Figure 4A , Figure 4B In the form of, no standard time signal is required. However, the details are described below, but Figure 4C As shown, when the MGC30C is stopped or black-started, the voltage-based synchronization method cannot be used. This is because even if the target frequency is switched to a fixed value, the common index φglobal related to the phase is lost. At this time, a target voltage signal Vgrid* with a phase common to all DGR40Cs is required. Just use the standard time signal for it. If based on the standard time, the voltage phase common to all DGR40Cs can be ensured. In this way, the feature of this aspect is that, in the case of voltage-based synchronization control, Vgrid* is synchronized in all DGR40s by internal clock correction of the standard time signal.

[0197] [(B) When the main system is out of power and the unit grid is in independent state]

[0198] Figure 4C A method for realizing independent operation of the unit power grid by making all DGR40Cs continue to operate synchronously when the main system stops is described. When the main system stops, the circuit breaker with synchronization verification function is disconnected, and the information from the MGC30C is lost. In the above case, by maintaining the main system frequency measurement value f41 at the previous value or replacing it with the rated value, and maintaining the inter-system phase difference signal φglobal at the previous value or replacing it with a pre-prepared fixed value (including zero), the independent operation of the unit power grid can be continued while all DGR40Cs maintain synchronization.

[0199] [(B) When MGC30C stops]

[0200] Even if the main system voltage is not lost, the MGC 30C may stop. In this case, as described above, each DGR 40C has a voltage vector and rated frequency information based on the GPS time, and the voltage vector is set to Figure 2EBy setting Vgrid* in the input frequency, DGR40C can be operated at rated frequency, thus enabling continuous operation.

[0201] When MGC30C is in operation, even if some DGR40Cs (capacity is set to less than 20%) among all DGR40Cs become in a state of not receiving information from MGC30C, the entire unit power grid becomes stable through the remaining DGR40Cs, so the DGR40Cs that do not receive information from MGC30C can continue to operate synchronously by switching to the usual voltage-based synchronization method.

[0202] [(B) Implementing Black Start]

[0203] When the main system loses voltage, even if the circuit breaker with synchronous detection function is disconnected, the voltage in the unit grid may become zero. The recovery of the unit grid from zero voltage is equivalent to the so-called black start. In the present invention, as described above, each DGR40C has a reference voltage vector based on GPS time. During the black start, the reference voltage vector is set to Figure 2E The Vgrid* in the DGR40C makes it possible to black start.

[0204] [Implementation Method 2]

[0205] refer to Figure 5A to Figure 5N , the collaborative autonomous distributed system interconnection system of embodiment 2 of the present invention is described. Figure 5A to Figure 5N 14 is an explanatory diagram of the first to fourteenth states of the unit grid connection mode according to the second embodiment of the present invention. Figure 1 to Figure 4C The same reference numerals are given to the common configurations, and the description thereof is omitted. The configuration of the unit power grid 20 is the same as that of the first embodiment. The second embodiment is an example in which the unit power grid system 28 is connected to a plurality of master systems 15 .

[0206] Figure 5A to Figure 5N The main system 15a including the main system 15a1 and the main system 15a2 connected to the substation A and the main system 15b including the main system 15b1 and the main system 15b2 connected to the substation B are connected to the unit grid 20 via the circuit breakers 21a and 21b with synchronization verification function, respectively. In this way, the connection of the unit grid 20 connected to the two main systems 15a and 15b is sometimes called a "hollow system".

[0207] As in the first embodiment, a plurality of cooperative autonomous distributed machines (DGRs) 40 are provided in the unit grid 20. Each DGR 40 is controlled by a control signal from a system interconnection controller (MGC) 30 and can be interconnected with the main system 15a or 15b. The circuit breakers 21a and 21b with a synchronous verification function are both controlled by a control signal from the MGC 30, and the connection and disconnection of the unit grid system 28 with the main system 15a and the main system 15b are controlled by a control signal from the MGC 30. In addition, the MGC 30 also has a part that is physically integrated with the circuit breaker with a synchronous verification function. In the unit grid 20, two circuit breakers 21a and 21b with a synchronous verification function are provided. One circuit breaker 21a with a synchronous verification function is connected to the system of the substation A 13a, that is, the main system 15a, and the other circuit breaker 21b with a synchronous verification function is connected to the system of the substation B 13b, that is, the main system 15b.

[0208] In the main system 15a, the power company differentiation switch 16a is installed between the circuit breaker 21a with a synchronous verification function and the substation A13a, the main system 15a1 is installed between the circuit breaker 21a with a synchronous verification function and the differentiation switch 16a, and the main system 15a2 is installed between the differentiation switch 16a and the substation A13a.

[0209] In the main system 15b, the power company differentiation switch 16b is installed between the circuit breaker 21b with a synchronous verification function and the substation B13b, the main system 15b1 is installed between the circuit breaker 21a with a synchronous verification function and the differentiation switch 16b, and the main system 15b2 is installed between the differentiation switch 16b and the substation B13b.

[0210] [Post-accident recovery control of the main system 15a]

[0211] refer to Figure 5A to Figure 5K , which illustrates the state from when the system 15a2 fails to recover and continues to supply power as before. When the system 15a2 fails, the unit grid system 28 also continues to supply power through the power generation equipment 23 in the unit grid.

[0212] exist Figure 5A In the state, the circuit breakers 21a and 21b with synchronous detection function are both opened, and the unit power grid 20 operates independently.

[0213] exist Figure 5BIn the state, the circuit breakers 21a and 21b with synchronous verification function are closed, and the unit grid 20 operates independently. The differentiation switch 16a is closed, and the power of the substation A13a is supplied to the system 15a1 through the system 15a2, and the system 15a1 and the system 15a2 are charged by the power of the substation A13a. Similarly, the differentiation switch 16b is closed, and the power of the substation B13b is supplied to the system 15b1 through the system 15b2, and the system 15b1 and the system 15b2 are charged by the power of the substation B13b.

[0214] exist Figure 5C When a certain system 15a2 has an accident, such as a short circuit accident, etc. Figure 5D As in the state of FIG. 1 , the distinguishing shutter 16a is immediately opened.

[0215] exist Figure 5D In the state, since the differentiated breaker 16a is open, the system 15a1 is not supplied with power. In the above case, the circuit breakers 21a and 21b with synchronous verification function are both open, and the unit grid 20 operates independently, so the unit grid system 28 continues to supply power through the power generation equipment in the unit grid 20.

[0216] exist Figure 5D In the state, since there is no abnormality in the system 15a1, the MGC 30 and the power supply department of the power company plan to control the power supplied by the system 15a1 to the substation B13b. First, the frequency and phase synchronization control is performed in a manner that the unit grid system 28 and the system 15b1 can be synchronously interconnected.

[0217] exist Figure 5E In the state, after the unit power grid system 28 is synchronized with the system 15b1, the circuit breaker 21b with a synchronization detection function is closed to synchronize and interconnect with the system 15b1.

[0218] exist Fig. 5F In the state, the unit grid system 28 is interconnected with the system 15b1, and the power of the substation B13b can be supplied to the unit grid system 28 via the system 15b2, the system 15b1 and the circuit breaker 21b with a synchronous verification function. Thus, the unit grid system 28 can be charged with the power of the substation B13b.

[0219] exist Figure 5G In the state, by closing the circuit breaker 21a with a synchronous detection function, the unit power grid system 28 becomes a normal system and is connected to the system 15a1 that is in power outage.

[0220] exist Figure 5HIn this state, the circuit breaker 21a with synchronous verification function is closed, and the system 15a1 is powered by the substation B13b via the unit grid system 28, so the system 15b2, the system 15b1, the unit grid system 28 and the system 15a1 are charged with electricity from the substation B13b.

[0221] exist Fig.5I Here, MGC30 cooperates with the power supply department of the power company and plans to control the system 15a1 supplied with power from the substation B13b via the unit grid system 28 so that the system 15a1 is supplied with power from the substation A13a as before.

[0222] exist Figure 5J In the state, the circuit breakers 21a and 21b with synchronization verification function are opened. By opening the circuit breakers 21a and 21b with synchronization verification function, the unit grid 20 operates independently. At this time, no power is supplied to the system 15a1 from any of the substations 13a and 13b.

[0223] exist Figure 5K In the state, by closing the differentiation switch 16a, the power from the substation A13a is supplied to the system 15a1 via the system 15a2, thereby restoring the power outage caused by the accident in the system 15a2.

[0224] [Recovery control when an accident occurs in the unit grid during independent operation]

[0225] refer to Figure 5L to Figure 5N , the recovery control when an accident occurs in the unit grid 20 when the unit grid 20 operates independently is described.

[0226] exist Figure 5L In the state, the unit grid is in an independent operation state. Each DGR40 in the unit grid 20 is synchronously controlled in a manner that is synchronized with the system 15a1. At this time, an accident occurs in the unit grid 20. When the unit grid is operating independently, when an accident such as a short circuit occurs in the unit grid, a short-circuit current of a magnitude that cuts off the protective relay at the accident point may not be supplied from the power generation equipment in the unit grid to the accident point. In the case where the protection level of the protective relay is set in conjunction with the main system, the protective relay cannot operate and the accident point may not be disconnected. If the accident continues for a certain period of time and the voltage is not restored, it will be transferred to Figure 5M status.

[0227] exist Figure 5MIn the state of , since the unit power grid system 28 is synchronized with the system 15a1, the circuit breaker 21a with a synchronous verification function can be closed immediately. By closing the circuit breaker 21a with a synchronous verification function, a short-circuit current is supplied from the main system to the accident point in the unit power grid. When a short-circuit current above the cut-off level is supplied to the accident point, the protection relay in the accident point is activated to disconnect the accident point.

[0228] exist Figure 5N In the state of , the voltage is restored because the accident point in the unit grid 20 is disconnected. The system interconnection operation can be continued as it is, and the unit grid 20 can be operated independently by opening the circuit breaker 21a with synchronous verification function again.

[0229] Here, it has been described that by interconnecting the unit power grid system 28 with the system 15a1, a short-circuit current is supplied to the accident point in the unit power grid 20 to cut off the protection relay of the accident point, but the present embodiment is not limited to this. For example, the unit power grid system 28 and the system 15b1 may be interconnected instead of the system 15a1, thereby supplying a short-circuit current to the accident point in the unit power grid 20 to cut off the protection relay of the accident point.

[0230] [Implementation method 3]

[0231] refer to Figure 6 , the cooperative autonomous distributed system interconnection system of embodiment 3 of the present invention is described. Figure 1-5N The same reference numerals are used for common structures, and the description thereof is omitted. Figure 6 It is a block diagram of a collaborative autonomous distributed system interconnection system according to Embodiment 3 of the present invention.

[0232] The cooperative autonomous distributed machine (DGR) 40 is composed of a common unit 120 and an individual unit 130, and communicates with the system interconnection controller (MGC) 30 through a mobile circuit. MGC30 is set on the cloud as a cloud for common units. In addition, a part of MGC30 is built into the control unit of the circuit breaker 21 with a synchronous verification function. MGC30 can obtain various information of the individual unit 130 by communicating with the cloud 110 for individual units.

[0233] The common unit 120 has the same structure in all DGR40. The common subunit 121 provided in the common unit 120 is composed of a DGR controller 122 and a motherboard 123. LAN (Local Area Network) communication is performed between the DGR controller 122 and the motherboard 123. The motherboard 123 has a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array). The FPGA is an LSI (Large Scale Integration) that can be programmed from the MGC30. Since it can be rewritten, the common unit 120 can be used in common with all types of DGR40.

[0234] The individual unit 130 is composed of an individual subunit 131, a BMU (Battery Management Unit) board 136, and a battery unit 137. The individual unit 130 is provided with a plurality of, for example, three individual subunits 131, and each of the individual subunits 131 is connected to the motherboard 123 via a LVDC (LoW Voltage Differential Signa1ing: low voltage differential signal) cable.

[0235] The individual subunit 131 is composed of an ADC (Analog-to-Digital Converter) board 132, a power board 133, an auxiliary power board 134, and an AC or DC filter 135. The ADC board 132 outputs a switching pulse signal transmitted through an LVDS cable to the power board 133. The power board 133 is connected to the ADC board 132 through a FLAT (flat) cable. The power board 133 uses the power from the auxiliary power board 134 as a control power source, outputs a switching pulse according to the switching pulse signal from the ADC board 132, and supplies the switching pulse to the power interface 140 through the AC or DC filter 135.

[0236] The voltage and current values ​​detected in the power interface 140 are input to the ADC board 132 via the AC or DC filter 135 and the power board 133. In the ADC board 132, the detected voltage and current values ​​are input as digital signals to the motherboard 123 via the LVDS cable.

[0237] The BMU board 136 communicates with the motherboard 123 via CAN (Controller Area Network). A plurality of, for example, eleven battery cells 137 are provided in the individual unit 130. The BMU board 136 and each battery cell 137 are connected via a cable.

[0238] The battery unit 137 is composed of a CMU (Cell Management Unit) 138 and a battery subunit 139. The BMU board 136 monitors and controls the status of each battery unit 137 based on the command signal from the motherboard 123. The CMU 138 communicates with the BMU board 136 to control and protect the battery subunit 139. The BMU board 136 controls and monitors abnormalities of the entire battery unit based on the information of each CMU 138, for example, it can prevent fire accidents of lithium-ion batteries, etc. In addition, the BMU board 136 and the battery unit 137 can be set integrally with the DGR40 or separately.

[0239] In the DGR 40 , the motherboard 123 of the common unit 120 centrally performs all control operations, and the individual unit 130 drives hardware based on control signals output through the control operations of the motherboard 123 .

[0240] The motherboard 123 outputs the switching pulse to the ADC board 132 via the LVDS cable, and the ADC board 132 supplies the control signal including the switching pulse of the LVDS cable to the power board 133 via the FLAT cable. The power board 133 uses the auxiliary power board 134 as a control power source, and supplies the switching pulse to the power interface 140 via the AC or DC filter 135 based on the switching pulse calculated in the power board 123. In addition, the voltage value and current value detected in the power interface 140 are sent to the ADC board 132 via the AC or DC filter 135 and the power board 133, and are converted into digital signals in the ADC board 132, and collected to the motherboard 123 through the communication of the LVDS cable for control calculation.

[0241] The motherboard 123 also centrally performs control calculations for the battery units 137. That is, the BMU board 136 controls, protects, and monitors all the battery subunits 139 via the CMU 138 based on control signals calculated by the motherboard 123.

[0242] In addition, the FPGA and CPU on the motherboard 123 can freely rewrite programs from the MGC30. Therefore, the DGR40 can be freely set and changed through the cloud, for example, it can be set for three-phase, single-phase, 380V, 200V, solar DC, battery, fuel cell, etc. Therefore, even if it is the same hardware, different units can be realized by changing the software through the cloud, so that the DGR40 can be used not only in various places in the country, but also in all parts of the world.

[0243] The individual unit 130 does not need a main control device such as a microcomputer at all. All control operations are performed through the motherboard 123, and the individual unit 130 is driven by the control signal from the motherboard 123. For example, the three half bridges of the three individual sub-units 131, that is, a total of nine half bridges, are supplied with a switching pulse signal calculated by the motherboard 123. The number of these units or the number of half bridges can be increased or decreased. In addition, on the motherboard 123 side, the voltage value, current value and other detection signals from the power interface 140 at various locations are obtained through the LDVS cable, and all control operations of the DGR40 are performed as digital data.

[0244] By making the common unit 120 common and standardizing the interface between boards, the individual unit 130 can be provided as various application products. The operation of the system can be realized in the cloud through all MGC30. In addition, the software of the motherboard 123 can be updated through the cloud through MGC30, so that the latest software can always be used.

[0245] In addition to the power and voltage information from the motherboard 123, the DGR controller 122 can also extract information from the solar energy or generator connected to the half bridge or battery information, and send it to the cloud for comprehensive use. The information of the DGR40 scattered on the surface can also make use of weather information, etc. In addition, by encrypting the necessary information and sending it to the blockchain account book, etc., it is also possible to create the basis for regional currency, etc.

[0246] The operation of the switching pulse in the motherboard 123 is preferably performed using hysteresis control. Figure 2B and Figure 2C , the hysteresis control is explained. Hysteresis control is a current control method with hysteresis current control, which is different from the generally popular PWM (Pulse Width Modulation) control. In PWM control, when the unit grid is operating alone, if a short circuit occurs, an overcurrent will flow instantly, and the inverter will stop due to overcurrent protection. In contrast, in hysteresis control, since the current is controlled, the current can be suppressed even in the event of a short circuit.

[0247] According to the following equation (2), the target current Iref for achieving the target voltage Vref is calculated.

[0248]

[0249] Here, Tsw = 1 / fsw is the switching period. Idgr is the current flowing in the load of the unit grid, and the target current Iref changes according to the load current Idgr. In addition, the second term on the right is the correction current used to achieve the target voltage Vref, corresponding to ΔI = C·dV / dt.

[0250] According to the hysteresis control, the current can be directly controlled and Vdgr can be made to follow the target voltage Vref. That is, by making IL follow the target current Iref through the hysteresis control and further controlling Vdgr so as to reach the target voltage Vref, the target power can be obtained in the DGR 40.

[0251] In the hysteresis control, an upper frequency band Δib and a lower frequency band -Δib are set above and below the target current Iref respectively, and the following actions are repeated: if IL exceeds the upper frequency band Δib, the switch of the upper arm is cut off and the switch of the lower arm is turned on; if IL is lower than the lower frequency band -Δib, the switch of the lower arm is cut off and the switch of the upper arm is turned on.

[0252] Figure 2C In the example, at time t0, since IL is lower than the lower frequency band -Δib, the switch of the lower arm is turned off and the switch of the upper arm is turned on, so +Vdc is applied to Lfilter. Then, at time t1, when IL exceeds the upper frequency band Δib, the switch of the upper arm is turned off and the switch of the lower arm is turned on, so -Vdc is applied to Lfilter. Then, at time t2, since IL is lower than the lower frequency band -Δib, the switch of the lower arm is turned off and the switch of the upper arm is turned on, so +Vdc is applied to Lfilter. The time from time t0 to time t2 is the switching period Tsw.

[0253] At this time, as the slope of IL changes according to the voltage difference across Lfilter, the switching frequency changes. Therefore, in order to suppress the change of the switching frequency, the bandwidths of the upper band Δib and the lower band -Δib are changed according to the following formula (3).

[0254]

[0255] The switching frequency is always changing, and it is difficult to design an EMC (Electromagnetic Compatibility) filter when its bandwidth is wide. By using variable bandwidth control, the switching frequency can be converged to fws, making it easy to design an EMC filter.

[0256] The embodiments described above do not limit the present invention to these, and are similarly applicable to other embodiments included in the claims. In addition, the embodiments can be appropriately changed or appropriately combined.

[0257] [Explanation of symbols]

[0258] 10 Power Station

[0259] 11 Ultra-high voltage substation

[0260] 12 Power transmission equipment

[0261] 13 Substation

[0262] 15 Main System

[0263] 16a, 16b Differentiate between closers

[0264] 17. Satellite

[0265] 20-unit grid

[0266] 21 Circuit breaker with synchronous verification function

[0267] 22 Power demand equipment

[0268] 22a Home Equipment

[0269] 22b Power storage device

[0270] 22c Electric vehicle charging and discharging device

[0271] 22d Electric car

[0272] 23 Power generation equipment

[0273] 23a Wind power generation device

[0274] 23b Solar power generation device

[0275] 23c Power storage device

[0276] 23d Internal combustion engine power generation device

[0277] 28-unit power grid system

[0278] 30 System Interconnect Controller (MGC)

[0279] 31 Main system frequency measurement value acquisition device

[0280] 32 GPS receiver

[0281] 33 Multiplier

[0282] 34 Main system rotation phase angle

[0283] 35 Subtractor

[0284] 36 Operation blocks

[0285] 37 Floor function

[0286] 38 Subtractor

[0287] 39 Phase synchronization signal

[0288] 40 Collaborative Autonomous Distributed Machines (DGR)

[0289] 41 System frequency measurement value acquisition unit

[0290] 42 GPS receiver

[0291] 43 Multiplier

[0292] 44 Adjustment value getter

[0293] 45 Phase synchronization signal

[0294] 46 Adder

[0295] 47 Adder

[0296] 50 operation blocks

[0297] 51 floor function

[0298] 52 Subtractor

[0299] 53 Subtractor

[0300] 54 Adder

[0301] 55 Operation Block

[0302] 56 floor function

[0303] 57 Subtractor

[0304] 58 Adder

[0305] 59 Multiplier

[0306] 60 Limiter

[0307] 61 Integrator

[0308] 62 Output system phase angle

[0309] 80 Operation unit

[0310] 81 Multiplier

[0311] 82-unit grid system voltage detector

[0312] 83 PLL

[0313] 84 Subtractor

[0314] 85 Controller

[0315] 86 Adder

[0316] 87 Multiplier

[0317] 88 Remainder operation

[0318] 89 System phase angle signal

[0319] 90 units grid system load

[0320] 91, 92 GPS receiver

[0321] 93, 94, 95, 96 PLL

[0322] 97 System voltage acquisition unit

[0323] 97b PLL

[0324] 98 System effective power

[0325] 99 System Ineffective Power

[0326] 110 Individual units use cloud

[0327] 120 common units

[0328] 121 common subunits

[0329] 122 DGR controller

[0330] 123 Motherboard

[0331] 130 individual units

[0332] 131 individual subunits

[0333] 132 ADC Board

[0334] 133 Power Board

[0335] 134 Auxiliary power board

[0336] 135 DC filter

[0337] 136 BMU board

[0338] 137 Battery Cell

[0339] 138 CMU

[0340] 139 Battery subunit

[0341] 140 Power interface.

Claims

1. A collaborative distributed system interconnection system, characterized in that: have: A circuit breaker with synchronous verification function can connect or disconnect the main system with the unit power grid system; A system interconnection controller, detecting power information of the main system and power information of the unit power grid system; and Cooperative autonomous distributed machines, more than one of which is connected within the unit grid system, to perform power conversion in a mutually synchronously interconnected manner; and The system interconnection controller and each of the cooperative autonomous distributed machines are equipped with a standard time signal acquisition device for acquiring a standard time signal. Each of the cooperative autonomous distributed machines receives frequency information and phase information, or a composite signal of frequency information and phase information, sent from the system interconnection controller based on the standard time signal. When the circuit breaker with synchronization verification is opened, each of the cooperative autonomous distributed machines is controlled in such a way that the voltage phase of the unit power grid system is synchronized with the voltage phase of the main system. When the circuit breaker with synchronization verification is closed, each of the cooperative autonomous distributed machines controls the power flow flowing between the main system and the unit grid system.

2. The collaborative distributed system interconnection system according to claim 1, characterized in that: The system interconnection controller generates an inter-system phase difference signal and sends it to each of the cooperative autonomous distributed machines. When the circuit breaker with synchronous verification function is closed, each of the cooperative autonomous distributed machines uses the phase difference signal between the systems to control the power flow and the reverse power flow. When the circuit breaker with synchronization verification function is opened and cannot receive information from the system interconnection controller, each of the cooperative autonomous distributed machines can also synchronously control the unit power grid system based on the standard time signal.

3. The collaborative distributed system interconnection system according to claim 1 or 2, characterized in that: The standard time signal acquisition device includes a first standard time acquisition unit for acquiring a first standard time signal and a second standard time acquisition unit for acquiring a second standard time signal. The system interconnection controller includes the first standard time acquisition unit, which generates a phase synchronization signal as a composite signal of the frequency information and the phase information by causing the first standard time signal to act on the main system frequency and the main system rotation phase angle, and outputs the composite signal to the cooperative autonomous distributed machine. The cooperative autonomous distributed machine has the second standard time acquisition unit, which demodulates the unit power grid system rotation phase angle signal synchronized with the main system rotation phase angle by making the second standard time signal act on the phase synchronization signal output by the system interconnection controller and the main system frequency.

4. The collaborative autonomous distributed system interconnection system according to claim 1 or 2, characterized in that: The system interconnection controller inputs the power information of the main system and / or the power information of the unit power grid system, measures the main system frequency measurement value, and generates an inter-system phase difference signal, and outputs it to the cooperative autonomous distributed machine. The collaborative autonomous distributed machine generates a unit grid system phase angle signal and a unit grid system angular velocity signal from the unit grid system voltage, and calculates the unit grid system rotation phase angle signal from the unit grid system phase angle signal, the unit grid system angular velocity signal, the main system frequency measurement value, and the inter-system phase difference signal.

5. The collaborative autonomous distributed system interconnection system according to claim 4, characterized in that: The system interconnection controller measures the main system frequency measurement value through the first phase synchronization circuit, The cooperative autonomous distributed machine generates the unit power grid system phase angle signal and the unit power grid system angular velocity signal through the second phase synchronization circuit. The standard time signal acquisition device includes a first standard time acquisition unit that inputs a first standard time to the first phase synchronization circuit, and a second standard time acquisition unit that inputs a second standard time to the second phase synchronization circuit.

6. The collaborative autonomous distributed system interconnection system according to claim 1 or 2, characterized in that: The unit power grid system can be connected to multiple main systems via the circuit breaker with a synchronous detection function. When an abnormality occurs in the first main system among the main systems, the unit power grid system can be interconnected with the second main system other than the first main system, and power can be supplied to the area in the first main system where no abnormality occurs.

7. The collaborative distributed system interconnection system according to claim 1 or 2, characterized in that: When the circuit breaker with synchronous verification function is closed and the main system is powered off, the circuit breaker with synchronous verification function is set from closed to open, and at the same time, each of the cooperative autonomous distributed machines enables the unit power grid system to operate independently, When the circuit breaker with synchronous verification function is opened and an accident occurs in the unit power grid system, the circuit breaker with synchronous verification function is closed, and the power flow is controlled at the same time to supply the accident current to the accident point, so that the protection relay at the accident point is activated and the accident point is disconnected.

8. The collaborative distributed system interconnection system according to claim 1 or 2, characterized in that: The collaborative autonomous distributed machine includes a common unit having a motherboard and one or more individual units, and the motherboard performs control operations including generating pulse waves.

9. The collaborative distributed system interconnection system according to claim 8, characterized in that: The pulse wave generation operation in the motherboard uses hysteresis control.

10. A system interconnection method of a collaborative distributed system interconnection system, characterized in that: The invention relates to a system interconnection method of a cooperative distributed system interconnection system, and the cooperative distributed system interconnection system has: A circuit breaker with synchronous verification function can connect or disconnect the main system with the unit power grid system; A system interconnection controller, detecting power information of the main system and power information of the unit power grid system; and The cooperative autonomous distributed machines are connected in the unit power grid system at least one to perform power conversion in a mutually synchronously interconnected manner; and the system interconnection method comprises the following steps: The system interconnection controller and each of the cooperative autonomous distributed machines obtain a standard time signal; Each of the cooperative autonomous distributed machines receives frequency information and phase information, or a composite signal of frequency information and phase information, sent from the system interconnection controller based on the standard time signal; When the circuit breaker with synchronization verification is opened, each of the cooperative autonomous distributed machines is controlled in such a way that the voltage phase of the unit power grid system is synchronized with the voltage phase of the main system; When the circuit breaker with synchronization verification is closed, each of the cooperative autonomous distributed machines controls the power flow flowing between the main system and the unit grid system.

11. A program, characterized in that Each step of the system interconnection method of the cooperative autonomous distributed system interconnection system according to claim 10 is executed by a computer.

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