Power system control device and power system control method

Abstract

To provide a power system control device capable of remotely controlling an output adjustable device without laying a new communication path.SOLUTION: A power supply command office server 115 comprises: an output adjustment necessity determination section 502 which determines whether or not an output adjustment is necessary; an output adjustment target distribution system determination section 503 which determines an adjustable load and a distributed power source 217 subjected to the output adjustment; a control command destination setting section 505 which sets a destination of a control command to a voltage transformation ratio adjustment section interlocked to a distribution system 119; and an outside destination command transmission section (communication) 504 which transmits a control command, having a time slot to which a plurality of voltage transformation ratio adjustment sections interlocked to the distribution system 119 is synchronized, for deviating timing of the voltage adjustment by the voltage transformation ratio adjustment section, to which the destination is set, temporally with the time slot defined as a reference to the adjustable load and the distributed power source 217 interlocked to a terminal side of the voltage transformation ratio adjustment sections.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a power system control device and a power system control method.

Background Art

[0002] Conventionally, the distribution system, which is a lower-level system, has not been provided with a power source having a capacity that can contribute to the supply-demand adjustment of the upper-level system. However, in recent years, various forms of devices and loads (hereinafter referred to as "distributed power sources"), such as various electric vehicles, solar power generation systems, and system batteries, have been installed in the distribution system. Therefore, by adjusting the output of the distributed power sources installed in the distribution system and taking on part of the supply-demand adjustment, it may be possible to contribute to the stabilization of the upper-level system. Conventionally, when a higher-level command center controls devices connected to the power system, various types of information have been transmitted to downstream devices using a communication line.

[0003] Patent Document 1 describes an example of a system for controlling a voltage regulator in a distribution system using a communication network.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the method using the communication network described in Patent Document 1, it was necessary to separately lay a communication network. Also, when using a line of an external communication company, there was a possibility of being affected by communication failures including increased costs and congestion.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to remotely control a device capable of adjusting the output of a distributed power source or the like (hereinafter referred to as an "output-adjustable device") without laying a new communication line.

Means for Solving the Problem

[0007] The power system control device according to the present invention includes an external information acquisition unit that acquires external information, and output adjustment possible devices that are distributed and connected in the power system and can adjust at least one of input or output power. An output adjustment necessity determination unit that determines the necessity of output adjustment for the output adjustment possible device based on external information, an output adjustment target determination unit that determines an output adjustment possible device to be an output adjustment target when it is determined that output adjustment is necessary, and a destination setting unit that sets a destination of control information for instructing output adjustment to the output adjustment possible device for a voltage ratio adjustment unit connected to the power system. A plurality of voltage ratio adjustment units connected to the power system each have a time slot synchronized in time, and control information that temporally shifts the timing of discrete voltage adjustment of the voltage ratio by the voltage ratio adjustment unit with the set destination based on the time slot is transmitted to the output adjustment possible device connected to the end side of the voltage ratio adjustment unit. It includes a control information transmission unit.

Effect of the Invention

[0008] According to the present invention, it is possible to remotely control output adjustment possible devices such as distributed power sources without laying a new communication line. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0009]

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[0010] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same function or configuration are denoted by the same reference numerals, and redundant description is omitted.

[0011] [Conventional power distribution system] First, before explaining the power distribution system according to the present embodiment, the configuration of a conventional power distribution system will be described. In accordance with the recent trend of making renewable energy the main power source, development plans for large-scale megasolar power plants and wind farms are underway. On the other hand, a large number of distributed power sources are connected and operated below the high-voltage system, including rooftop PV (photovoltaics) for general households and medium-scale middle solar power plants.

[0012] In the future, due to factors such as global warming prevention and resource depletion, it is conceivable that the amount of output adjustment at thermal power plants and the like will be insufficient. Therefore, if distributed power sources can be collectively controlled, they can be used for power supply and demand adjustment, leading to the stabilization of power supply. When sending commands to a large number of connected distributed power sources individually via communication lines, costs will increase due to the laying of communication lines and usage fees for communication companies. Therefore, in the following embodiments, the configuration and method of a system that transmits output increase / decrease commands and the like to a large number of controlled devices in a simple manner via power lines will be described.

[0013] The power distribution system is generally configured as a radial system, repeating branches from the distribution substation side with a power source toward the terminal side. In a radial system, when a discrete voltage regulator such as an LRT (Load Ratio Transformer) or an SVR (Step Voltage Regulator) changes its tap near the power source, the voltage change propagates to the terminal side.

[0014] This property is in contrast to the property that the effective range of a power capacitor used for the same voltage regulation application is localized near the installation point. The reason that reactive power is difficult to propagate is that it is easily attenuated due to the L (inductance) of the line. Similarly, for devices that adjust voltage with reactive power such as SVC, the range where voltage can be adjusted is limited to a short distance.

[0015] On the one hand, in this embodiment, in the radial system, the voltage change due to the tap operation of the LRT and SVR, that is, the operation of adjusting the transformation ratio, is used to transmit various information to the terminal side. Therefore, the SVR, LRT, etc. are used as devices that discretely adjust the voltage as the information transmission side. In these voltage regulators, voltage adjustment is performed by switching the transformation ratio of the built-in transformer with a tap. Therefore, in this embodiment, the voltage change is necessarily discrete.

[0016] The SVR without a communication function determines tap switching with the control device in its own station based on the voltage and passing power (active power, reactive power, current) measured in its own station. The SVR with a communication function also basically determines tap switching based on the measured values in its own station.

[0017] Note that the entity that determines the increase or decrease in the output of the controlled device is a power supply command station that monitors the supply and demand status in a wider area than the distribution system at a higher level. That is, the determining entity such as the power supply command station determines the increase or decrease in the output of the controlled device in consideration of various information including weather conditions. In this embodiment, as a method of using weather conditions, for example, when it is found that the temperature has changed to be higher than the initial prediction and the power demand for air conditioning has increased more than expected, controls such as relaxing the output suppression of solar power generation are realized. Here, the initial prediction refers to the prediction at the time of determining the PV output suppression on the previous day or in the morning of the current day. Note that the operation of increasing the power supply amount can also be performed by suppressing the load or shifting the time.

[0018] First, the relationship between the conventional power supply command station and the LRT or the SVR with a communication function will be described. The information determined by a power supply command station or the like at the upper level of the radial system is transmitted to the LRT or the SVR with a communication function via a normal communication path. Upon receiving the information, the LRT or the SVR with communication function performs a tapping operation with modulation based on the information at the timing of the tapping operation. In this modulation process, an operation is performed to relatively shift the tapping operation timing during the time slot by a time based on the information. The tapping operation propagates as a voltage change to the end side from the installation position of the LRT or SVR.

[0019] Therefore, devices connected to the system can acquire information almost simultaneously by detecting changes in the line voltage. Such an information acquisition method has less communication overhead compared to a method of establishing individual connection-type sessions for a large number of devices to be controlled. In addition, in an information distribution method using radio wave broadcast, it is necessary to secure the radio wave band to be used, but it is extremely difficult to secure a new band. Conversely, the ISM band available for various applications has a high frequency and a short propagation distance, so it is not suitable for medium- and long-distance information transmission in the suburbs. In addition, the ISM band available for various applications may also be interfered with by other users in the same band.

[0020] In the recent trend of using renewable energy as the main power source, there has been an attempt to replace part of the power regulation function previously borne by thermal power generation with the coordinated control of a large number of distributed power sources. Even if the adjustment amount of each individual distributed power source is small, if the individual adjustment amounts can be aggregated and the distributed power sources can be controlled with a relatively small delay time, it can contribute to power stabilization.

[0021] As a series of control processes, first, based on the supply and demand situation grasped by a higher-level power supply command center or the like, the increase or decrease of the output of the distributed power sources is determined. The information determined by the higher-level power supply command center is transmitted to the LRT or the SVR with communication function connected to the higher-level power supply command center via a communication path. The LRT or the SVR with communication function that has received the output increase / decrease command delays or advances the timing of the tapping operation relative to the virtual time slot.

[0022] A virtual time slot refers to a time slot with a cycle such as 15 seconds or 30 seconds. The virtual time slot is a time slot that is maintained in temporal synchronization at least between the LRT or SVR, and the distributed power source to be controlled, or the adjustable load. The SVR considered in the virtual time slot is regardless of the presence or absence of a communication function.

[0023] In addition, those that receive the output increase / decrease command include an SVR without a communication function, a power source with at least partially adjustable output, a power source or load with at least partially adjustable output adjustment of the amount and time of power consumption. Therefore, the information transmission path is in the order of the upper power supply command station, communication line, LRT with a communication function or SVR with a communication function, distribution line, SVR without a communication function, or adjustable load or load.

[0024] The SVR without a communication function is located on the power supply side (substation side) as seen from the SVR, and receives the output increase / decrease command based on the tap operation timing of the SVR that has already received the output increase / decrease command via the communication path or the high-current electric wire (distribution line).

[0025] The power source or load with adjustable output also receives the output increase / decrease command from the tap operation timing of the SVR that is located on the power supply side as seen from the power source or load and has already received the output increase / decrease command via the communication path or the high-current electric wire.

[0026] The adjustable power source that has received the output increase / decrease command, if it is a PV, makes as much output adjustment as possible within the limit range such as the rated value and solar irradiance. The adjustable power sources include PCS (Power Conditioning System) for PV and other renewable energies, and chargers for EVs (Electric Vehicles). Depending on the type of power source such as an EV charger, adjustment in both polarities of power output or consumption (discharge and charge) is possible. Also, in the PV PCS during output suppression, by reducing the output suppression amount for the output increase request, it can lead to an increase in output. Also, in the PV PCS during power factor control, if the power factor is made closer to 1 at high output, the active power P can be increased.

[0027] In addition, an adjustable load that has received an output increase / decrease command adjusts the amount of load and changes the power usage schedule within the possible range. Examples of adjustable loads include those with relatively high power consumption, such as EV chargers, water heaters, and heaters, and those with arbitrary operating times. In addition, adjustable loads include terminals such as a consumer's HEMS (Home Energy Management System) terminal that can request adjustments to increase or decrease the power of subordinate devices.

[0028] [One Embodiment] Next, a distributed power control system 1 according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing an example of the overall configuration of the distributed power control system 1. The distributed power control system 1 includes a power supply command center server 115, an LRT 214, an SVR 215 with a communication function, an SVR 216 without a communication function, and an adjustable load or distributed power source 217.

[0029] The power supply command center server 115 is an example of a power system control device. The power supply command center server 115 acquires voltage, power values, frequencies, etc. measured by measuring devices installed in a higher-level power system 118 and a distribution system 119 with a voltage class of extra-high voltage or higher via a communication path (not shown). The power system 118 is an example of a general power system including a backbone system, a local system, and other distribution systems. At least one function of the power supply command center server 115 is to predict the power supply and demand and grasp the current state. Using this function, the power supply command center server 115 determines the increase or decrease in output for the distributed power source and sends an instruction.

[0030] In order for the power supply command center server 115 to collect measurement data over a wide range, such as the power grid 118 with a voltage class of extra-high voltage or higher, it is necessary to use communication. Measurement values at various locations in the power grid, weather prediction information, the current weather conditions, etc. are input to the power supply command center server 115. Therefore, the power supply command center server 115 acquires weather information and the like necessary for predicting power demand via a communication path (not shown). At least one software module executed by the hardware of the power supply command center server 115 is called a power grid control device.

[0031] The power grid 118 shown in FIG. 1 with a voltage class of extra-high voltage or higher is an example of a power grid with a high voltage class. Power plants such as wind power plants and thermal power plants (synchronous generators G: Generator) are connected to the power grid 118 with a voltage class of extra-high voltage or higher.

[0032] The distribution grid 119 is an example of a power grid to which an adjustable load or distributed power source 217, which is the target of output control in this embodiment, is connected. The distribution grid 119 includes an LRT 214, an SVR 215 with a communication function, an SVR 216 without a communication function, and an adjustable load or distributed power source 217. Converters (G1 to Gn) such as GFM (Grid Forming Inverter) and GFL are connected to the distribution grid 119. The adjustable load or distributed power source 217 is connected to the distribution line 120. Note that, to avoid making the drawing complicated, the connection lines from the distribution line 120 to the loads L1 to Ln are not shown.

[0033] Loads L1 to Ln (Load 1 to Load n) are shown inside the adjustable load or distributed power source 217. For example, G1 and L1 show an example of an electric vehicle (EV) and a charger. G2 and L2 show an example of a system battery. Gn and Ln show an example of a solar power generation system and an electric vehicle (EV). However, as long as the device can adjust its output, any of GFM, GFL, and the load can be applied as converters.

[0034] Conventionally, when the power demand is higher than predicted, the power supply command center server 115 gives instructions to increase or decrease the output of thermal power reserves, fast-starting gas turbines, pumped-storage power plants, etc., taking economic efficiency into consideration. However, with the increasing proportion of renewable energy power sources in recent years, assistance from a large number of distributed power sources connected to the distribution system 119 is becoming inevitable.

[0035] The adjustable loads L1 to Ln include converters with adjustable output. Here, "adjustable" means that the input and output power can be at least partially increased or decreased. Also, the objects of increase and decrease include power sources and loads that operate such that the values of the input and output power are adjusted from the original plan at a certain time section by changing the schedule of the input and output of power.

[0036] SVRs 215 and 216 are installed in the middle of the distribution line 120. SVRs 215 and 216 are installed for the purpose of adjusting the voltage of the distribution line 120. As SVRs 215 and 216, for example, three-phase tapped voltage regulators in a high-voltage system such as 6.6 kV of the distribution system 119 are assumed.

[0037] LRT 214 is, for example, a distribution substation and is installed at the sending point of the distribution line 120. For LRT 214 and SVR 215 having a communication function, a graphic indicating an antenna is described, which shows that LRT 214 and SVR 215 have a communication function. Note that the actual communication paths with LRT 214 and SVR are mainly composed of wired connections. The dashed arrows from LRT 214 and SVR in the figure towards the adjustable load or distributed power source 217 indicate the flow of control commands.

[0038] LRT 214 and SVRs 215 and 216 are voltage adjustment devices whose transformation ratios can be discretely adjusted by switching taps. LRT and SVR have the function of adjusting the voltage of the distribution line 120 within a predetermined range by correcting the voltage drop caused by load fluctuations and the voltage rise caused by the output of distributed power sources. The SVR includes a communication-enabled SVR 215 having a communication function and a communication-disabled SVR 216 without a communication function. The LRT 214, the communication-enabled SVR 215, and the communication-disabled SVR 216 are examples of a voltage ratio adjustment unit that temporally shifts the timing of discrete voltage adjustment of the voltage transformation ratio based on time slots. In the following description, when the communication-enabled SVR 215 and the communication-disabled SVR 216 are not distinguished, they are abbreviated as SVR.

[0039] An output increase / decrease command 117 is transmitted from the power supply command center server 115 toward the distributed power source 217 at the end via the high-current wire. For this reason, the output increase / decrease command 117 is first transmitted to the LRT 214 and the communication-enabled SVR 215 via the communication path 116. The LRT 214 and the communication-enabled SVR 215 that have received the output increase / decrease command 117 shift the timing of tap switching temporally according to a predetermined rule with respect to the virtual time slot.

[0040] The deviation of the tap switching timing from the virtual time slot is observed at the communication-disabled SVR 216, the adjustable load, or the distributed power source 217 that is connected to the distribution line 120 on the terminal side as seen from the LRT 214 and the communication-enabled SVR 215. For the communication-disabled SVR 216, the output increase / decrease command 117 is transmitted to the communication-disabled SVR 216 via the high-current wire from the communication-enabled SVR 215. The communication-disabled SVR 216 that has received the output increase / decrease command 117 performs an operation of shifting the tap switching timing in the same manner as the communication-enabled SVR 215.

[0041] The adjustable load and the distributed power source 217 are distributed and connected to the power distribution system 119 (an example of a power system), and at least one of the input or output power can be adjusted. That is, the adjustable load and the distributed power source 217 are an example of an output adjustable device. The adjustable load or distributed power source 217 that has received the output increase / decrease command 117 executes output adjustment according to the command. In addition to output adjustment, the adjustable load or distributed power source 217 that has received the output increase / decrease command 117 may also execute an increase or decrease in load according to the command, or a change in the schedule regarding power input / output.

[0042] Next, regarding the shared range of virtual time slots and the temporal position of the default tap operation, an explanation will be given with reference to FIGS. 2, 3, and 5. Hereinafter, the temporal position of the tap operation refers to the relative position on the time axis of the timing of the tap operation with respect to the reference point (reference point 405 in FIG. 3) of the periodically arriving virtual time slot. The default position where commands such as output increase / decrease are not transmitted (or commands with an output increase / decrease value of 0 are transmitted) is assumed to coincide with the reference point 405 of the virtual time slot, and is indicated by, for example, timing 407. The horizontal axis in FIGS. 2, 3, and 5 indicates time t, and the vertical axis indicates the rate of change of the voltage after change with respect to the voltage before change of the secondary-side voltage of SVRx.

[0043] FIG. 2 is a diagram showing an example of the shared range of virtual time slots and the temporal position of the default tap operation. SVRx indicates that the SVR215 with a communication function and the SVR216 without a communication function shown in FIG. 1 are not distinguished.

[0044] As described above, the LRT214, SVR, and adjustable loads and power sources installed on the distribution line 120 share the virtual time slot 404 synchronized in time. The virtual time slot 404 represents a time unit used for processing by the LRT214, SVR, and adjustable loads and power sources, etc., and is different from the standard time. Therefore, the virtual time slot 404 only needs to be relatively synchronized among the devices participating in control, such as converters like LRT, SVR, GFM, GFL, and adjustable loads, and does not necessarily need to be synchronized with absolute time such as standard time. The synchronization of the virtual time slot 404 means that the reference point 405 is synchronized among the devices participating in control.

[0045] However, it does not prevent synchronization among at least some of the devices that have communication functions and participate in control by using a time synchronization protocol via communication. Also, the LRT214 and the SVR215 with a communication function installed on the power distribution line 120 may use a method of assisting the time synchronization of the SVR216 without a communication function, for example, by accurately moving some taps at 1:00 am. By using such a method, the virtual time slots 404 managed by each device installed on the power distribution line 120 can be synchronized with the absolute time to improve convenience. Also, by always setting either the tap raise or the tap lower to the temporal position of the default tap operation, the boundary 405 of the virtual time slot can be made known among the devices participating in control, and it may be used as a method of synchronizing relatively frequently.

[0046] The reference point 405 on the time axis of the virtual time slot arrives periodically every Ts which is the time length of the virtual time slot 404. In FIG. 2, it is assumed that the SVRx is in a normal state where it has not received the output increase / decrease command 117. In the normal state (default state, or a state where no command such as output increase / decrease is transmitted, or a state where a command with an output increase / decrease value of 0 is transmitted), the LRT or SVR sharing the virtual time slot 404 performs a tap operation at the timing 407 that coincides with the reference point 405.

[0047] When the adjustable load and distributed power source 217 installed on the end side of the power distribution system 119 detects a discrete change in voltage at the timing 407 that coincides with the reference point 405, it interprets that adjustment of the input / output power is not necessary and performs an operation without normal power adjustment.

[0048] Next, the temporal position of the tap operation during information transmission will be described. FIG. 3 is a diagram showing an example of the virtual time slot and the temporal position of the tap operation during information transmission. FIG. 3 shows an example in which information is transmitted by a tap operation in which the secondary voltage of the SVRx changes to a relatively high voltage.

[0049] LRT214, SVR215 with communication function, and SVR216 without communication function indicate a first command, which is an example of the output increase / decrease command 117, to the adjustable load and distributed power source 217 by advancing the timing of changing from the original voltage with respect to the reference point 405 of the virtual time slot 404. Also, LRT214, SVR215 with communication function, and SVR216 without communication function can also indicate a second command, which is an example of the output increase / decrease command 117, to the adjustable load and distributed power source 217 by delaying the timing of changing from the original voltage with respect to the reference point 405 of the virtual time slot 404.

[0050] The difference between the first command and the second command is the difference in whether the deviation from the time position (timing) of the default tap operation is relatively early or late. For example, the output increase can be assigned to the first command and the output decrease can be assigned to the second command. Also, as will be described later, it is possible to indicate the degree of output increase or decrease by the amount of temporal deviation from the time position of the default tap operation.

[0051] Also, the discrete voltage adjustment of the SVR or LRT has two types: the direction in which the secondary voltage becomes relatively higher than before the tap operation (conveniently referred to as the tap-up direction) and the direction in which it becomes lower (referred to as the tap-down direction). FIG. 3 shows an example of the tap-up direction. These are distinguished as the first tap-up command and the second tap-up command.

[0052] Even in the tap-down direction (not shown), it is possible to transmit commands by the deviation from the time position (timing) of the default tap operation. Hereinafter, these are referred to as the first tap-down command and the second tap-down command. As described above, the "up" and "down" in the first tap-up command, the second tap-up command, the first tap-down command, and the second tap-down command mean the tap-up and tap-down of the SVR, and do not indicate the up and down (increase and decrease) of the output of the content to be commanded.

[0053] In the adjustable load and distributed power source 217, the adjustable items may include not only active power but also voltage, power factor, or the schedule of power transfer. Therefore, the increase first command and the increase second command can be assigned to commands for increasing or decreasing active power, and the decrease first command and the decrease second command can be assigned to commands for increasing or decreasing voltage, etc. Also, by assigning the increase in active power to the first command of increase and decrease and the decrease in active power to the second command of increase and decrease, the frequency of transmitting commands to the adjustable load and distributed power source 217 can be increased, and power can be adjusted with a short response time, thus contributing to the stabilization of the power system.

[0054] Also, in a system where the operation frequency of the SVR or LRT is low, the tap may be operated to transmit commands. Although there is an upper limit to the number of tap operations, in a system where the original operation frequency is low, even if the number of tap operations for command transmission increases, the probability of reaching the upper limit of the number of tap operations within the service life is low.

[0055] Figure 3 shows an example of the increase first command and the increase second command. Since the tap operates in the direction of relatively increasing the voltage on the secondary side of the SVR at a timing ahead of time Ta from the reference point 405 of the virtual time slot, the upward arrow of the thick line in the figure corresponds to the increase first command. Similarly, the upward arrow of the broken line where the tap operates at a timing delayed by time Td corresponds to the increase second command.

[0056] The thick line 410 in Figure 3 schematically shows the time variation of the voltage at a certain location of the distribution line 120 shown in Figure 1. For example, let a certain location on the distribution line 120 be point A on the distribution line 120 between the SVR 215 with communication function and the SVR 216 without communication function in Figure 1. In this case, the SVR and LSR on the substation side from point A correspond to the LRT 214 and the SVR 215 with communication function. Also, let a certain location on the distribution line 120 be, for example, point B on the distribution line 120 on the end side from the SVR 216 without communication function in Figure 1. In this case, the SVR and LSR on the substation side from point B correspond to the LRT 214, the SVR 215 with communication function, and the SVR 216 without communication function.

[0057] As shown in line 410, the secondary-side voltage of the SVRx changes discretely. This voltage change is due to the voltage regulator such as the LRT214 or the SVR215 with communication function (see Figure 1) installed on the power supply side (substation side) changing the tap, rather than at the point of interest on the distribution line 120 where the voltage is observed.

[0058] The amount of adjustment that the adjustable loads and distributed power sources 217 perform is proportional to the deltaPa or deltaPd in Figure 4 with respect to the adjustable range in each of the individual adjustable loads and distributed power sources 217. Note that the vertical axis in Figure 4 indicates the increase or decrease amount shown by the increase or decrease command of the output transmitted due to the deviation from the time position (timing) of the default tap operation, and the horizontal axis indicates time. When the output adjustment is only in one direction of increase or decrease, only the adjustable direction is adjusted.

[0059] As shown in Figure 3, assume that a discrete voltage change (tap change) occurs Ta time after the reference point 405 of the virtual time slot. The adjustable load or distributed power source 217 adjusts the output according to the time Ta.

[0060] Here, for example, consider the case where the output adjustment amount deltaPa (see Figure 4) corresponding to the shifted time Ta is 0.65. In a system battery with an output adjustment range of ±100kW that has received the output increase / decrease command 117, in addition to the output of 300kW before reception, an output increase of 100kW × 0.65 = 365kW occurs. Also, in a megasolar power plant where 1MW of output is suppressed, an output increase of 1MW × 0.65 = 0.65MW occurs. As a result, the system battery can increase the output from the output before reception, which is 2MW, to 2.65MW. Note that an example of decreasing the output can also be explained in the same way.

[0061] In Figure 3, the time Td in the range indicated by the arrow 412 is only different in the polarity of power adjustment from the time Ta in the range indicated by the arrow 411, and the basic operation is the same as in the case of time Ta. For example, assume that a discrete change in voltage (tap change) occurs after a time Td from a reference point 405 of a virtual time slot. The input and output power of the adjustable load or distributed power source 217 is changed according to the amount of deviation in the timing of the voltage change indicated by this time Td.

[0062] FIG. 4 is a diagram showing an example of the relationship between the amounts of deviation Ta and Td in timing and the amount of power adjustment. The horizontal axis of FIG. 4 indicates the amount of deviation in timing from the reference point 405 of the virtual time slot, and the vertical axis indicates the amount of power adjustment deltaP. For example, when the amount of deviation in timing is the time Ta, deltaPa becomes the adjustment amount. In this case, compared with the reference point 405 of the virtual time slot, the output is increased in the direction where the tap operation timing is early (advanced). Note that in this case, the direction of decreasing the output may also be used. Similarly, when the amount of deviation in timing is the time Td, the power adjustment amount becomes deltaPd.

[0063] FIG. 4 shows an example where the power adjustment range is ±1. This power adjustment range indicates the ratio when the adjustable power amount of each adjustable load or distributed power source 217 is set to 1. Also, the adjustable power amounts of each adjustable load or distributed power source 217 may be made different for each of the power input and output. Alternatively, for example, the maximum value of the adjustable amount in each direction of the input and output of the adjustable load or distributed power source 217 may be set to +1 or -1.

[0064] The times Tg1a, Tg2a, Tg1d, and Tg2d shown in FIG. 4 are guard times for the stable operation of the adjustable load or distributed power source 217. Also, the times Tg1a and Tg1d correspond to dead zones. By providing the times Tg1a and Tg1d, the influence of the measurement error of the tap operation timing is mitigated, and frequent switching of charge and discharge based on the error can be prevented.

[0065] The times Tg2a and Tg2d are guard times to avoid confusion with adjacent virtual time slots 404. For example, the rate of change of the discrete change in voltage due to tap switching may exhibit different slopes during rise and fall due to various factors such as the characteristics of the associated devices. Therefore, different values may be set for the forward times Tg1a and Tg2a and the backward times Tg1d and Tg2d, respectively.

[0066] As a countermeasure against the measurement error of the tap operation timing, as shown in the slope portion 432, there is a method of gradually changing the adjustment amount from the maximum adjustment amount of “+1” to the guard time side of the time Tg2a. By this method, it is possible to prevent the adjustment amount of power from frequently changing between the maximum value and 0 due to the measurement error of the tap operation timing. Note that the same applies to the Tg2d side, and it is also possible to perform processing so as to gradually change the adjustment amount from the minimum adjustment amount of “-1” to the Tg2d side which is the guard time.

[0067] FIG. 3 shows the waveform of the tap operation in the direction in which the voltage rises. That is, both the times Ta and Td in FIG. 3 are in the direction in which the tap rises. Here, the adjustment of the transformation ratio in the direction in which the secondary voltage relatively rises is defined as the direction in which the tap rises. Conversely, the tap operation in the direction of lowering the secondary voltage may be used for information transmission.

[0068] FIG. 5 shows examples of the lower first command and the lower second command. Since the tap operates in the direction in which the voltage on the secondary side of the SVR relatively decreases at a timing ahead of the time Ta from the reference point 405 of the virtual time slot, the downward arrow of the thick line in the figure corresponds to the lower first command. Similarly, the downward arrow of the broken line where the tap operates at a timing delayed by the time Td corresponds to the lower second command.

[0069] FIG. 5 is a diagram showing an example of the virtual time slot and the temporal position of the tap operation during information transmission. FIG. 5 shows an example in which information is transmitted by a tap operation in which the secondary side voltage of SVRx changes from a relatively high voltage to a relatively low voltage.

[0070] Also in Fig. 5, similar to Fig. 3, the time Ta shifted by the arrow 411 is shown, and the time Td shifted by the arrow 415 is shown. For example, it is assumed that a discrete change in voltage (a change in taps) occurs Ta time ahead from the reference point 405 of the virtual time slot. Then, the adjustable load or distributed power source 217 adjusts the output according to the time Ta.

[0071] Conversely, it is assumed that a discrete change in voltage (a change in taps) occurs Td time after from the reference point 405 of the virtual time slot. In this case, the adjustable load or distributed power source 217 changes the input / output power according to the amount of deviation in the timing of the voltage change shown by the time Td.

[0072] Note that different information may be transmitted respectively by the values of Ta and Td in the upward direction of the taps as shown in Fig. 3, and the values of Ta and Td in the downward direction of the taps as shown in Fig. 5. For example, in the upward direction of the taps, the adjustment amount of the output may be transmitted, and in the downward direction of the taps, the expected value of the duration of the output adjustment may be transmitted.

[0073] In this way, by transmitting different information in the upward direction and the downward direction of the taps, it becomes easier to establish an operation schedule for a system battery with a limited output power amount Wh. For example, if the output increase is scheduled to continue for 1 hour, the system battery executes the output increase as required by the value of the time Ta. Also, if the output increase is scheduled to continue for 10 hours, it is assumed that the system battery restricts the output increase to be less than the requirement. By establishing the operation schedule in this way, it is possible to prevent the output increase from suddenly stopping due to the battery capacity of the system battery. Therefore, there is also an advantage on the side of the power supply command station server 115.

[0074] In addition, it is also possible to transmit different information in the direction in which the voltage increases and in the direction in which the voltage decreases. For example, the power adjustment amount may be transmitted based on the timing deviation in the direction in which the voltage increases, and the scheduled duration of power adjustment or the like may be transmitted based on the timing deviation in the direction in which the voltage decreases. Further, for example, power adjustment information with deltaPa = 0.2 may be transmitted in the direction in which the voltage increases, and information on the duration of this power adjustment may be transmitted in the direction in which the voltage decreases.

[0075] Thus, since the power system control device of the present embodiment can estimate the end time of voltage adjustment, for example, it can be known that the adjustment of power increase ends, that is, the supply-demand pinch ends, after one hour. Therefore, according to the power system control device of the present embodiment, it is useful when determining the charging schedule of EVs that have been refrained from use or the operation schedule of water heaters.

[0076] Next, an example of the internal configuration of the power supply command center server 115 and an example of processing will be described with reference to FIGS. 6 and 7. FIG. 6 is a block diagram showing an example of the internal configuration of the power supply command center server 115. The power supply command center server 115 includes an external information acquisition unit 501, an output adjustment necessity determination unit 502, an output adjustment target power distribution system determination unit 503, an external command transmission unit (communication) 504, a control command destination setting unit 505, and a general control unit 506.

[0077] The external information acquisition unit 501 acquires external information. This external information includes the current value of power supply and demand, measurement information of the power system under its jurisdiction, and weather information. Therefore, the external information acquisition unit 501 acquires information such as external measurement information, the current value and predicted value of power supply and demand via a communication path, a console, or the like. The external measurement information includes, for example, weather data such as temperature. Further, the predicted value includes information that can change power supply and demand and information that can calculate the difference from the predicted value of power supply and demand. In addition, if the external information acquisition unit 501 also considers day-of-week information, holiday information, and operation information of large consumers, it will lead to better supply-demand control.

[0078] The output adjustment necessity determination unit 502 determines the necessity of output adjustment for the adjustable load and the distributed power source 217 based on external information. For example, when the power supply and demand is more pressing than predicted, or considering the change in the water storage volume of the pumped-storage power plant, etc., the output adjustment necessity determination unit 502 determines whether it is necessary to send a control command for output adjustment to the adjustable load or the distributed power source 217. In the following description, the command 117 for increasing or decreasing the output shown in FIG. 1 is referred to as a "control command". The control command is also an example of control information for instructing output adjustment for the adjustable load and the distributed power source 217.

[0079] The power distribution system determination unit 503 for output adjustment target is an example of an output adjustment target determination unit that determines the adjustable load and the distributed power source 217 to be the target of output adjustment when it is determined by the output adjustment necessity determination unit 502 that output adjustment is necessary. For example, the power distribution system determination unit 503 for output adjustment target determines the power distribution system 119 in which the power value of the adjustable load or the distributed power source 217 can be changed, considering the capacity limit and voltage adjustment of the power distribution system 119. For example, if the power distribution system 119 to which many solar power generation systems are connected is used as the adjustable load or the distributed power source 217, it is necessary to suppress the output of the solar power generation system on sunny days. Therefore, the power distribution system determination unit 503 for output adjustment target can also determine the power distribution system 119 to be the target of output adjustment using weather information, etc.

[0080] The control command destination setting unit 505 sets the destination of the control command for the LRT 214 and the SVR 215 with a communication function associated with the power distribution system 119. The control command includes an output adjustment command for instructing output adjustment of the adjustable load or the distributed power source 217.

[0081] The external destination command transmission unit (communication) 504 is an example of a control information transmission unit that transmits a control command. The external destination command transmission unit (communication) 504 transmits a control command, which is an example of control information for temporally shifting the timing of voltage adjustment based on time slots, to the LRT 214 or the SVR 215 with a communication function determined by the control command destination setting unit 505.

[0082] The power supply command center server 115 can transmit different control commands to different power distribution systems 119 through each functional unit shown in FIG. 6. For example, the output adjustment target power distribution system determination unit 503 determines different output adjustment amounts for different power distribution systems 119. The control command destination setting unit 505 sets the destination of the control command for each determined different power distribution system 119. The external destination command transmission unit (communication) 504 transmits control commands with different output adjustment amounts for each set destination. Note that in the power supply command center server 115, since control commands are transmitted in telegrams using normal communication, it does not have virtual time slots. What needs to have virtual time slots are LRT214, SVR215 with communication function, SVR216 without communication function, and 217 to be controlled.

[0083] The overall control unit 506 overall controls the above-described operations in each block within the power supply command center server 115. It also controls the execution of the logic of the flowchart shown in FIG. 7.

[0084] FIG. 7 is a flowchart showing an operation example of the power supply command center server 115. The flowcharts illustrated in the following description represent an example of a power system control method by the power supply command center server 115. First, the external information acquisition unit 501 acquires the current supply and demand value including the current power load and generation amount, and the measurement information including the frequency, voltage, etc. (S1). Next, the external information acquisition unit 501 acquires the predicted value of power supply and demand several minutes, several tens of minutes, or about several hours after the current time, and the prediction correction information (such as weather information) (S2).

[0085] For example, when the temperature changes higher than predicted, it is assumed that the demand for electricity increases more than expected. That is, the demand for electricity may exceed the adjustment range of adjustable power plants such as thermal power plants or hydroelectric power plants. Alternatively, for the demand for electricity, power adjustment by power plants such as thermal power plants or hydroelectric power plants may not be appropriate for economic or other reasons. Also, events such as the water storage level of a pumped-storage power plant changing lower than predicted may occur. In these cases, assistance from adjustable loads or distributed power sources connected to the distribution system 119 or the like is required. Therefore, the power supply command server 115 needs to vary the power adjustment amount for each power system to be controlled.

[0086] The reasons for varying the power adjustment amount for each power system to be controlled are as follows: (1) limitations due to the transmission capacity of the system, (2) limitations due to the types, time zones, and weather conditions of adjustable power sources and loads, (3) the sum of adjustable power for each system (generally different values in the increasing and decreasing directions), etc.

[0087] As an example of the limitation due to the transmission capacity of the system in reason (1), there is an upper limit to the amount of power that can be increased or decreased due to the constraints of the power flow of each distribution line, the substations that bundle them, and the transmission lines connecting the substations (thermal constraints, stability constraints, frequency constraints, etc.). For this reason, in a certain system, there may be a situation where there is a large margin for increasing output, while there is a small margin for decreasing output, or vice versa. The locations that loop in the upper-level system are managed by, for example, fences.

[0088] As an example of the limitation due to the types, time zones, and weather conditions of adjustable power sources and loads in reason (2), a solar power plant that is not in an output suppression state is difficult to respond to an increase in output (it is slightly possible by changing the power factor), and when an adjustable load is not consuming power, it cannot respond to an increase in output (load reduction), etc. The adjustable power in a system battery changes depending on the value of the SOC (charge amount), charge direction, discharge direction, and temperature. In a solar power plant, during bad weather such as thunderstorms or at night when there is no sunlight, there are limitations in responding to an increase in output.

[0089] As an example of the influence by the sum of adjustable power for each system in reason (3), for a system with a large sum of adjustable power values, a control command for increasing the output by about 10% is issued so as not to exceed the system capacity, while for a system with a small sum of adjustable power values under the same situation, a control command for increasing the output by 80% may be issued.

[0090] Therefore, the output adjustment necessity determination unit 502 determines which area needs the assistance of distributed power sources based on external information (S3). As the area that needs the assistance of distributed power sources, for example, it may target the entire area under the jurisdiction of the power supply command center server 115, or the target area may be determined after taking into account various constraints such as transmission capacity.

[0091] Next, the output adjustment target distribution system determination unit 503 determines a distribution system 119 including an adjustable load or distributed power source 217 that is the target of output adjustment as the supply-demand adjustment area (S4). Next, the control command destination setting unit 505 sets the destination of the control command for instructing output adjustment (S5).

[0092] Next, the external destination command transmission unit (communication) 504 transmits a control command to the adjustable load or distributed power source 217 in the supply-demand adjustment area via the communication path 116. The LRT214 or the SVR215 with a communication function to which the control command is transmitted is installed in the target area for power adjustment by the load or distributed power source. Also, the external destination command transmission unit (communication) 504 retransmits the control command by an appropriate timer (S6). The reason for retransmitting the control command is to prevent the LRT214 or the SVR215 with a communication function from timing out and resetting the output adjustment command (the output adjustment amount becomes 0).

[0093] In addition, in order to indicate that the output adjustment is still in progress, the power supply command center server 115 retransmits the control command. The retransmission of the control command is used for keepalive between the power supply command center server 115 and the LRT214 or the SVR215 with communication function. By receiving the control command, the LRT214 or the SVR215 with communication function can confirm that the communication with the power supply command center server 115 is being carried out normally.

[0094] However, if the communication for long-time output adjustment does not reach the power supply command center server 115, the LRT214 or the SVR215 with communication function sets a timeout for the output adjustment as a safety measure. The power supply command center server 115 may also be configured to periodically transmit the current output adjustment value to the LRT214 or the SVR215 with communication function via a timer.

[0095] In addition, even when the power adjustment becomes unnecessary, the power supply command center server 115 may explicitly transmit a control command with the output adjustment amount set to 0 to the LRT214 or the SVR215 with communication function. Also, when the number of one-to-many connections increases in the communication via the communication path 116 from the power supply command center server 115 to the LRT214 or the SVR215 with communication function in the target area, it is also possible to adopt a method of redistributing the control command via a relay server as appropriate in the middle.

[0096] Next, an example of the internal configuration and an example of the processing of the LRT214 or the SVR215 with communication function will be described with reference to FIGS. 8 and 9. FIG. 8 is a block diagram showing an example of the internal configuration of the LRT214 or the SVR215 with communication function. The LRT214 or the SVR215 with communication function includes a command reception unit (communication) 601, a time slot generation and holding unit 602, a tap operation timing generation unit 603, a tap control I / F 604, a command interpretation unit 605, a tap operation deviation amount calculation unit 606, a general control unit 607, a timeout processing unit 608, and a tap drive unit 609.

[0097] The command reception unit (communication) 601 receives a command from the power supply command center server 115 via the communication path 116. The time slot generation and holding unit 602 generates and holds time slots. The time slot generation and holding unit 602 has a clock with sufficient accuracy and a time alignment mechanism (not shown).

[0098] The time slot generation and holding unit 602 operates at a timing synchronized with the time slots. Note that the required sufficient accuracy of the clock of the time slot generation and holding unit 602 is such that it does not exceed the guard times in FIG. 4 during the time alignment interval. Time alignment can mainly be by a time synchronization protocol via communication, but can also be by a method that does not use communication. The time slot generation and holding unit 602 can also assist in time synchronization of the SVR216 without a communication function on the terminal side, for example, by accurately moving some taps at 1:00 am.

[0099] The tap operation timing generation unit 603 receives the tap operation deviation amount from the tap operation deviation amount calculation unit 606. Thereafter, the tap operation timing generation unit 603 calculates the timing deviation amount from the reference point 405 of the virtual time slot after correcting the mechanical and electrical time lag of its own tap operation.

[0100] The tap control I / F 604 is an I / O that outputs a signal for controlling the tap operation to the tap drive unit 609. Here, the tap drive unit 609 will be described. Generally, an LRT or SVR is integrally configured with a measurement unit, a control unit, an I / F to the tap drive unit 609, the tap drive unit 609, a winding, a core, cooling oil, a cooling device, a casing, insulators, and terminals, etc.

[0101] The tap drive unit 609 is composed of a control unit and a mechanism unit (not shown). Also, the SVR215 with a communication function further includes a communication unit. When the control board and the tap drive board are configured as separate boards, some electrical signal exchanges occur, so a signal is transmitted from the tap control I / F 604 to the tap drive unit 609. When the control board and the tap drive board are integrally configured and are a single software execution entity, the I / O is simply an exchange of variables and signals on the board.

[0102] The command interpretation unit 605 interprets the control command by decoding the control command acquired by the command reception unit 601 through communication. The tap operation deviation amount calculation unit 606 calculates the tap operation deviation amount corresponding to the output adjustment amount interpreted by the command interpretation unit 605. Then, the tap operation deviation amount calculation unit 606 sends the tap operation deviation amount to the tap operation timing generation unit 603. The overall control unit 607 comprehensively controls the above-described operations in each block within the LRT214 or the SVR215 with a communication function. Further, the overall control unit 607 controls the execution of the logic of the flowchart shown in FIG. 9.

[0103] FIG. 9 is a flowchart showing an operation example of the LRT214 or the SVR215 with a communication function. First, the command reception unit 601 receives, from the power supply command station server 115 via the communication path 116, a control command including control content to be transmitted to the adjustable load or the distributed power source 217 (S11). Then, the command interpretation unit 605 interprets the control command received by the command reception unit 601. If the command reception unit 601 has not received a control command in the first loop, the control content is set without power adjustment. If the command reception unit 601 has not received a control command in the second and subsequent loops, the previous value is held for the control content (S11).

[0104] Next, when the commandless continuous time exceeds a predetermined value, the timeout processing unit 608 performs a timeout process of resetting the output adjustment target value for the distributed power source (S12). For example, when the command reception unit 601 has not communicated with the power supply command station server 115 for a predetermined time, the timeout processing unit 608 resets the output adjustment amount to 0. Note that the overall control unit 607 described later may execute control such as the timeout process performed by the timeout processing unit 608.

[0105] Next, the tap operation deviation amount calculation unit 606 calculates the temporal deviation amount from the reference point of the virtual time slot of the tap operation according to the output adjustment amount (S13). The calculation of the tap operation deviation amount corresponds to an operation of converting the values on the vertical axis (deltaPa, deltaPd) shown in FIG. 4 into the values Ta or Td on the horizontal axis.

[0106] Next, the overall control unit 607 determines whether a tap operation is necessary (S14). The determination of whether a tap operation is necessary determines whether a tap operation is necessary to perform the voltage adjustment function, which is the original function of the LRT214 or the SVR215 with a communication function. For this reason, the overall control unit 607 determines whether it is necessary to operate the tap of the transformer so that it falls within an appropriate voltage range in consideration of the power flow active power P and reactive power Q measured at its own end and the voltage drop amount in the voltage adjustment target range.

[0107] Also, the overall control unit 607 adjusts the transformation ratio by tap switching. By this adjustment, it is possible to correct the voltage drop caused by an increase or decrease in the load or the like in the power distribution system 119 and adjust the voltage of the power distribution system 119 within an appropriate range. When it is determined in step S14 that the tap operation is unnecessary, the process returns to step S11.

[0108] The characteristic function according to the present embodiment in step S14 is a function of preventing a timeout for the load or distributed power source 217. As will be described later, when the load or distributed power source 217 does not receive a command for long-time output adjustment, it also has functions such as determining to execute a tap operation to reset the output adjustment amount to 0 as a timeout process for safety.

[0109] If the transmission of the control command from the power supply command center server 115 continues and there is no decision on the tap change operation in step S14, in order to prevent a timeout in the load or distributed power source 217, the overall control unit 607 determines a tap operation in step S14. At this time, the overall control unit 607 selects, by means of the tap operation, a direction in which voltage deviation is less likely to occur, that is, the direction of tap up or tap down. That is, when there is a possibility of voltage deviation occurring, the overall control unit 607 determines a tap operation to return in the reverse direction in a short time. LRT or SVR is generally composed of multiple stages. For this reason, when a tap operation is performed on the upstream side of the distribution line 120, the tap operation on the downstream side of the distribution line 120 becomes unnecessary.

[0110] When it is determined in step S14 that a tap operation is necessary, the tap operation timing generation unit 603 controls the tap operation at a timing shifted by the tap operation deviation amount from the reference point of the virtual time slot as a characteristic operation according to this embodiment (S15). Specifically, for the tap operation determined in step S14, the tap operation timing generation unit 603 generates, as the tap operation timing, a timing shifted in time by the above-mentioned times Ta and Td with respect to the reference point 405 of the virtual time slot. The generated tap operation timing is output to the tap drive unit 609 through the tap control I / F 604.

[0111] Next, an internal configuration example and an example of processing of the SVR 216 without a communication function will be described with reference to FIGS. 10 and 11. FIG. 10 is a block diagram showing an internal configuration example of the SVR 216 without a communication function. The SVR 216 without a communication function includes a voltage measurement unit 701, a time slot generation and holding unit 702, a tap operation timing generation unit 703, a tap control I / F 704, a voltage change edge detection unit 705, a command interpretation unit 706, a tap operation deviation amount calculation unit 707, an overall control unit 708, and a tap drive unit 709.

[0112] Many parts of the SVR216 without communication function are similar to the blocks of the SVR215 with communication function shown in FIG. 8. The difference from the blocks of the SVR215 with communication function is that the input of the control command is via the power distribution line 120, which is a strong current electric wire, rather than via the communication path 116. For this reason, the SVR216 without communication function is provided with a voltage change edge detection unit 705. The voltage change edge detection unit 705 detects the voltage change edge derived from the control command input from the power distribution line 120.

[0113] The time slot generation and holding unit 702 is different from the SVR215 with communication function in that it does not depend on the time synchronization protocol. As a time synchronization method without using communication, there is a method of using a GPS receiver. Alternatively, power frequency synchronization may be used. The time slot generation and holding unit 702 measures the time only during a power outage using a self-running timer such as a real-time clock, and uses a crystal oscillator or the like to ensure sufficient accuracy.

[0114] Since the other functional blocks have the same functions as the corresponding named blocks of the LRT214 or the SVR215 with communication function shown in FIG. 8, detailed descriptions thereof are omitted. The overall control unit 708 overall controls the above-described operations in each block within the SVR216 without communication function. Also, it controls the execution of the logic of the flowchart shown in FIG. 11.

[0115] FIG. 11 is a flowchart showing an operation example of the SVR216 without communication function. The difference in operation from the LRT214 or the SVR215 with communication function shown in FIG. 9 is that the control command is transmitted via the power distribution line 120, which is a strong current electric wire. As described above, the information transmission path is in the order of the power supply command center server 115, the communication path 116, the LRT214 (a substation with communication function), the SVR215 with communication function, the power distribution line 120, the SVR216 without communication function, the adjustable load or distributed power source 217.

[0116] As shown in FIG. 1, LRT214, SVR215 with a communication function, and SVR216 without a communication function are electrically connected to the distribution line 120. LRT214 and SVR215 with a communication function prioritize communication from the perspective of ensuring information transmission and receive the output increase / decrease command 117 from the power supply command center server 115. On the other hand, SVR216 without a communication function and the adjustable load or distributed power source 217 read the output increase / decrease command 117 based on the timing of the voltage change obtained through the distribution line 120, which is a power line.

[0117] Note that when the method according to this embodiment is applied to SVR215 with a communication function and the LRT214 on the power supply side, the output increase / decrease command 117 can be read based on the timing of the voltage change of the distribution line 120, which is a power line. Also, the adjustable load or distributed power source 217 associated with the distribution line 120 between LRT214 and SVR215 can also read the output increase / decrease command 117 based on the timing of the voltage change by LRT214.

[0118] In the present invention, for the sake of simplicity, the discrete voltage fluctuations due to tap switching of the LRT or SVR are assumed to propagate to the end side as seen from the relevant LRT or SVR. The fact that voltage fluctuations propagate only to the end side is an example when the power source associated with the power distribution system 119 operates at the set active power and power factor (conventional grid-following converters, GFL, etc.). On the other hand, when the power source associated with the power distribution system 119 operates at the set active power and voltage, it propagates to the upper system side, which is the opposite direction to the end side, as seen from the LRT or SVR that has executed tap switching. The degree of propagation of voltage fluctuations to the upper system side depends on the impedance of the high-current wire between the secondary side of the SVR of interest and the power source operating at the set active power and voltage, and the capacity of the power source. The smaller the impedance and the larger the capacity of the power source, the greater the voltage fluctuations to the upper system side. Therefore, by actively using these properties, it is possible to transmit the output adjustment command to the adjustable load or distributed power source 217 connected to the upper system side via the high-current wire even from the SVR of interest.

[0119] In addition, in order to transmit information at the timing of discrete changes in voltage, unlike communication, it is necessary to separate from voltage fluctuations caused by factors such as load fluctuations. Also, generally, SVRs may be installed in multiple stages in series in the distribution system 119. For this reason, when viewed from the SVR of interest, if there are a plurality of SVRs on the power supply side (substation side), these SVRs may cause voltage changes like conflicting control commands within a relatively short period of time. For example, if the SVR that transmitted a command to increase the output is different from the SVR that transmitted a command to decrease the output, the downstream SVR may receive a command to decrease the output a few seconds after receiving the command to increase the output.

[0120] These conflicting control commands from the plurality of SVRs are caused by the difference in the reception time of the control commands received by each SVR, or an error may occur when the SVR216 without a communication function interprets the control command from the voltage change. Also, in the downstream SVR that has received conflicting control commands, the tap operation becomes frequent. Therefore, with reference to the flowchart shown in FIG. 11, the process for suppressing the influence of conflicting control commands will be described.

[0121] First, the voltage measurement unit 701 monitors the voltage change on the primary side of the associated distribution system 119 and performs noise removal such as those in which the voltage change width is in a range independent of the SVR or LRT (S21). Note that the voltage on the primary side of the distribution system 119 is the voltage when the primary side of the radial system is the power supply side.

[0122] Next, the voltage change edge detection unit 705 receives a control command addressed to the adjustable load or distributed power source 217 via the high-current electric wire, and detects an edge of a voltage change that can be interpreted as a control command. The command interpretation unit 706 interprets the control command based on the voltage change after noise removal. Thereafter, the command interpretation unit 706 holds the control command as an output adjustment specified value for the adjustable load or distributed power source 217. If the voltage change edge detection unit 705 does not receive a control command addressed to the adjustable load or distributed power source 217 in this process, the command interpretation unit 706 holds the previous value for the control content (S22).

[0123] After step S22, steps S23 to S25 are performed. Steps S23 to S25 are all processes of the command interpretation unit 706 in FIG. 10. In the figure, the control command is abbreviated as "command".

[0124] First, the command interpretation unit 706 determines whether a control command conflicting with the previously received control command has been received (S23). Examples of conflicting commands include control commands with opposite power adjustment directions such that the output is commanded to decrease from an increase in output within a short period of time.

[0125] Conflicting commands may occur when the SVR on the power supply side, particularly the SVR216 without a communication function, makes an error during command interpretation as described above. In addition, conflicting commands may also occur due to an error in command interpretation by the local SVR. For example, conflicting commands may occur when the synchronization of virtual time slots is shifted. If it is determined in step S23 that a conflicting control command has been received (YES in S23), the command interpretation unit 706 determines whether a plurality of conflicting control commands have been received within a predetermined time (S24).

[0126] When a plurality of conflicting control commands are received within a predetermined time (YES in S24), the command interpretation unit 706 holds the previous value that was held as the output adjustment specified value before receiving the conflicting commands as it is, as long as it is within a predetermined time such as, for example, 10 seconds (S25). Then, the process proceeds to step S28.

[0127] When a plurality of conflicting control commands are received after exceeding the predetermined time (NO in S24), the command interpretation unit 706 resets the output adjustment value for the adjustable load or the distributed power source 217 (S26), and proceeds to step S28. For example, when the reception time difference of a plurality of conflicting control commands is equal to or longer than a predetermined time such as 10 minutes, the command interpretation unit 706 resets the value held as the output adjustment specified value to 0. Resetting the output adjustment value in this way is a case where an error continuously occurs in an SVR or the like installed on the power supply side, and it is to prevent the local SVR from transmitting error information to the SVR, load, or distributed power source at the end side of the power distribution system 119.

[0128] Examples of the cause of the error include, in addition to the causes described above, a plurality of cases where the time synchronization deviation of the SVR216 without a communication function is being measured. Another example is a case where a load that causes a voltage change similar to the tap adjustment of the SVR216 without a communication function is installed close to the primary side of the SVR216 without a communication function.

[0129] Also, for the output adjustment of the load or the distributed power source 217 according to the present embodiment, it is not necessarily required to perform the control of the output adjustment in all of the power distribution systems 119. If the output adjustment can be performed in a power distribution system 119 at a certain ratio or more, the supply-demand adjustment considering the entire upper-level system is possible. Therefore, the application in a power distribution system 119 that constantly causes voltage fluctuations such as an arc furnace may be excluded.

[0130] In addition, in the method according to the present embodiment, even when the interpretation of the control command is normal and the polarity of the output adjustment is switched normally, including the upper-level SVR, after taking a step where the output adjustment amount once becomes zero, the operation is to perform output adjustment with the reverse polarity. Therefore, there are advantages such as preventing rapid fluctuations in the power flow and leading to stable operation of the converters.

[0131] Also, in the above-described method, the SVR216 without a communication function can receive the same control command at least twice, so that after resetting the adjustment amount from the reverse polarity to zero, it can be changed to the target polarity. Therefore, hunting such as repeated polarity inversion due to a single reception of a control command can be prevented, and the certainty of control can be enhanced.

[0132] Although not shown, a determination routine for increasing the number of confirmations when inverting the polarity may be added to the flowchart of FIG. 11. The number of confirmations may be determined by making a trade-off between certainty, response delay in output increase or decrease, and the operating frequency of the SVR.

[0133] In step S23, when the command interpretation unit 706 determines that it has not received a conflicting control command (NO in S23), it determines whether the command-free duration has exceeded a predetermined time (S27). Step S27 is a process when no control command is received for a predetermined time.

[0134] The LRT214 on the power supply side from the local SVR, the SVR215 with a communication function, and the SVR216 without a communication function always perform retransmission processing of the control command at intervals of a certain time or less so that other stations can know the current value of the control command. Specifically, the timeout prevention process in step S6 in the power supply command server 115, the timeout prevention process in step S14 in the LRT214 or the SVR215 with a communication function, and the timeout prevention process in step S29 (described later) in the SVR216 without a communication function correspond to the retransmission process of the command.

[0135] Therefore, when the command interpretation unit 706 detects that the duration without a control command has exceeded a predetermined time (YES in S27), there may be some kind of malfunction. For this reason, the command interpretation unit 706 resets the value held as the output adjustment specified value to 0 (S26).

[0136] In step S27, when there is no reception of a conflicting command or no timeout of the control command (NO in S27), the tap operation deviation amount calculation unit 707 calculates the tap operation deviation amount based on the relationship between the output adjustment specified value shown in FIG. 4 and the tap operation timing (S28). At this time, the tap operation deviation amount calculation unit 707 sets the deviation amount from the reference point 405 of the virtual time slot of the timing when the tap is actually operated at the local SVR.

[0137] Next, the overall control unit 708 determines whether a tap operation is necessary (S29). The process of step S29 is basically the same as the process of step S14 shown in FIG. 9. For example, as the original function of the SVR, based on the active power P and reactive power Q measured at the local end, or the voltage, it is considered the voltage drop amount in the voltage adjustment target range, etc., and determines whether it is necessary to operate the tap of the transformer so that it falls within an appropriate voltage range.

[0138] Also, the overall control unit 708 determines the tap operation for information transmission purposes so as not to cause a timeout in the SVR located on the end side of the distribution line 120 and the load or distributed power source 217, in the same way as step S14 shown in FIG. 9. At this time, the overall control unit 708 selects the direction (the direction of raising or lowering the tap) in which voltage deviation is less likely to occur by the tap operation. If there is a possibility of voltage deviation, it returns in the reverse direction in a short time.

[0139] In step S29, when it is determined that a tap operation is necessary, the tap operation timing generation unit 703 controls the tap operation at a timing shifted by the tap operation deviation amount from the reference point of the virtual time slot as a characteristic operation according to this embodiment (S30). Specifically, for the tap operation determined in step S29, the tap operation timing generation unit 703 generates, as the tap operation timing, a timing that is temporally shifted by the above-mentioned times Ta and Td with respect to the reference point 405 of the virtual time slot.

[0140] The tap operation timing is output to the tap drive unit through the tap control I / F 704. Then, the process returns to step S21 and the process is performed. Also, when it is determined in step S29 that the tap operation is unnecessary, the process returns to step S21 and the process is performed.

[0141] Next, an internal configuration example of the adjustable load or distributed power source 217 and an example of processing will be described with reference to FIGS. 12 and 13. FIG. 12 is a block diagram of the adjustable load or distributed power source 217. The adjustable load or distributed power source 217 includes a voltage measurement unit 801, a time slot generation and holding unit 802, a command execution unit 803, a converter control I / F 804, a voltage change edge detection unit 805, a command interpretation unit 806, a power adjustment amount determination unit 807, a general control unit 808, and a converter drive unit 809.

[0142] The voltage measurement unit 801, the time slot generation and holding unit 802, the command execution unit 803, the voltage change edge detection unit 805, and the command interpretation unit 806 shown in FIG. 12 have functions similar to the blocks of the SVR216 without a communication function shown in FIG. 10. However, due to the resistance and inductance of the distribution line, the discrete voltage variation range during the tap switching of the SVR decreases according to the distance from the SVR on the system. Therefore, the threshold value in the adjustable load or distributed power source 217 connected to a location far from the SVR may be decreased. For the same reason, even in the SVR without communication located at a far distance from the SVR with communication on the distribution line, the threshold value in the adjustable load or distributed power source 217 may be decreased.

[0143] Also, the converter control I / F 704 is an I / O that transmits commands to the power adjustment function of a converter (not shown). Similar to the tap control I / F 604 in FIG. 8, when the control board on which the adjustable load or distributed power source 217 is configured and the converter are configured on separate boards, some electrical signal exchange occurs, so a signal is transmitted from the converter control I / F 704 to the converter drive unit 809. The converter drive unit 809 drives the converter according to the received signal. When the control board and the converter drive board are integrally configured and form a single software execution entity, the I / O is simply the exchange of variables and signals on the board.

[0144] The power adjustment amount determination unit 807 determines the power adjustment amount at its own station according to the ratio of deltaPa and deltaPd obtained from the control command, based on the change range of the adjustable power at its own station or the power adjustment range agreed in advance with the organization that manages the power distribution system 119. The overall control unit 808 comprehensively controls the aforementioned operations in each block within the adjustable load or distributed power source 217. Also, the overall control unit 808 controls the execution of the logic in the flowchart shown in FIG. 13.

[0145] FIG. 13 is a flowchart showing an operation example of the adjustable load or distributed power source 217. In the figure, the control command is abbreviated as "command". The control command is sent to the adjustable load or distributed power source 217 via the power distribution line 120, which is a high-current electric wire. Therefore, the error processing and conflict determination of the control command are performed in a process similar to that of the SVR216 without a communication function shown in FIG. 11.

[0146] Specifically, steps S31, S32, S33, S34, S35, S36, and S37 in FIG. 13 are processes similar to steps S21, S22, S23, S24, S25, S26, and S27 in FIG. 11. Step S31 is a process performed by the voltage measurement unit 801. Step S32 is a process performed by the voltage change edge detection unit 805 and the command interpretation unit 806. Steps S33, S34, S35, S36, and S37 are all processes performed by the command interpretation unit 806.

[0147] After the NO determination in step S35 or step S37, the command interpretation unit 806 determines whether the same control command has been received multiple times (S38). The command interpretation unit 806 strictly checks the confirmation of the control command executed by the adjustable load or distributed power source 217, and checks multiple times whether the received control commands are the same. The reason for the command interpretation unit 806 to perform the process of step S38 is that the control command sent to the adjustable load or distributed power source 217 is directly related to the operation of actually inputting and outputting power to the power distribution system 119. For example, when power adjustment is performed due to an error, it may affect the quality maintenance of the power distribution system 119.

[0148] On the other hand, even if the above-mentioned LRT214, SVR215 with a communication function, or SVR216 without a communication function receive the same control command multiple times, only a slight deviation occurs in the timing of the tap change that should originally be performed. Therefore, it rarely affects the power distribution system 119 immediately.

[0149] Furthermore, as an inherent operation of the adjustable load or distributed power source 217, the power adjustment amount determination unit 807 performs conversion processing of the adjustment amount (S39). Note that the input / output polarity of adjustable power, the maximum power value that can be adjusted, the method of adjustment (change in the operation schedule), etc. vary depending on the adjustable load or distributed power source 217. For example, a distributed power source equipped with a system battery can perform both power input and output. However, the amount of power depends on the SOC of the battery, etc. Also, the maximum power is limited by the rating of the converter.

[0150] Also, for PV, the power adjustment direction mainly has a negative polarity of output reduction. However, at times when it is limited to the active power smaller than the current value of the panel output due to power factor constraints, it is possible to increase the active power output to the distribution system 119 by changing the power factor. Regarding this, since changes in associated requirements, etc. are necessary, there are currently constraints. An EV that can perform power input and output can, in principle, be applied to both input and output directions, similar to the system battery.

[0151] Also, an electric water heater can be ostensibly used for power adjustment by changing the operation schedule. Regarding an EV charger, ostensible power adjustment by changing the schedule is also possible. Regarding the adjustable load or distributed power source 217 as described above, the power adjustment amount determination unit 807 performs conversion of the output value for adjusting the adjustable amount of its own station according to the ratio of deltaPa and deltaPd shown in FIG. 4.

[0152] For example, when the power adjustment amount determination unit 807 of PV receives a command with deltaPd = -0.7 in a PV with an output of 10 kW, it changes the output from 10 kW to 3 kW. Note that the power adjustment amount determination unit 807 may determine in advance that the adjustable range is, for example, 30% of the reference value and change it from 10 kW to 7.9 kW. Here, the reference value may be the rated value of the PCS or the currently output value.

[0153] In addition, in a system battery whose adjustable range is set to 40% of the rated value in the discharge direction, when the power adjustment amount determination unit 807 of the system battery receives a control command of deltaPa = +0.5, it increases the power corresponding to 20% of the rated value in the discharge direction and outputs it to the system. In the case of a storage battery, the outputtable range changes depending on the SOC, temperature, or the deterioration state of the storage battery. Therefore, the power adjustment amount determination unit 807 of the system battery does not necessarily have to be designed to strictly follow the control command for output adjustment. As long as the adjustable load or distributed power source 217 can perform an operation to increase the output, for example, in response to a command to increase the output, within at least the range of each limit, a large power adjustment amount can be obtained in the entire power system.

[0154] Even if a distribution system 119 where transmission of control information via a high-current electric wire is difficult, such as the presence of an arc furnace in the previous example, is excluded from the control target, the power supply command station server 115 can perform control on other distribution systems 119 to adjust the supply and demand in the entire upper-level power system. For example, when the power supply command station server 115 detects a situation where the cumulative increase in output is insufficient, it can also increase the output change amount of the control command.

[0155] After step S36 or S39, the adjustable load or distributed power source 217 determines the input / output power adjustment amount for each station. Then, the command execution unit 803 actually performs the adjustment of the input / output power (S40).

[0156] <Example of the hardware configuration of a computer> Next, the hardware configuration of a computer 900 that constitutes each device of the distributed power source control system 1 will be described. FIG. 14 is a block diagram showing an example of the hardware configuration of the computer 900. The computer 900 is an example of the hardware used as a computer that can operate as a power system control device according to the present embodiment.

[0157] The power supply command center server 115, LRT 214, SVR 215 with communication function, SVR 216 without communication function, and adjustable load or distributed power source 217 according to this embodiment are each configured with each functional block by a computer 900 (computer) executing a program. Further, each functional block cooperates to realize the power system control methods shown in FIGS. 7, 9, 11, and 13.

[0158] The computer 900 includes a CPU (Central Processing Unit) 901, a ROM (Read Only Memory) 902, and a RAM (Random Access Memory) 903, which are respectively connected to a bus 904. Further, the computer 900 includes a non-volatile storage 905 and a network interface 906 (only for the power supply command center server 115, LRT 214, and SVR 215 with communication function).

[0159] The CPU 901 reads the program code of the software that realizes each function according to this embodiment from the ROM 902, loads it into the RAM 903, and executes it. In the RAM 903, variables, parameters, etc. generated during the arithmetic processing of the CPU 901 are temporarily written, and these variables, parameters, etc. are appropriately read by the CPU 901.

[0160] As the non-volatile storage 905, for example, an HDD (Hard Disk Drive), an SSD (Solid State Drive), a non-volatile memory, or the like is used. In this non-volatile storage 905, in addition to the OS (Operating System) and various parameters, a program for operating the computer 900 is recorded. In the ROM 902 and the non-volatile storage 907, programs, data, etc. necessary for the operation of the CPU 901 are recorded. That is, the ROM 902 and the non-volatile storage 905 are used as an example of a computer-readable non-transitory storage medium storing programs executed by the computer 900. The operations of the functional blocks shown in FIGS. 6, 8, 10, and 12 are realized by the CPU 901, the ROM 902, the RAM 903, and the non-volatile storage 905.

[0161] As the network interface 906, for example, a NIC (Network Interface Card) or the like is used. The network interface 906 can transmit and receive various data between devices via a LAN (Local Area Network), a dedicated line, or the like connected to the terminals of the NIC. Note that the communication functionless SVR 216 is not provided with the network interface 906. Also, the adjustable load or the distributed power source 217 does not necessarily have the network interface 906.

[0162] In the distributed power source control system 1 according to the above-described embodiment, by simultaneously and collectively remotely controlling a plurality of adjustable loads or distributed power sources 217 connected to the power distribution line 120 of the power distribution system 119, the adjustment force can be increased and the power system can be stabilized. For this reason, in the distributed power source control system 1, a synchronized time slot is shared between a device that discretely adjusts the voltage, such as an SVR, which is the transmission source of control information including a control command, and a controlled device, such as a PCS, which is the recipient of the control information.

[0163] Voltage regulating devices such as SVR modulate the timing of the transformer ratio adjustment operation during a time slot in response to information to be transmitted, such as an output increase / decrease command 117 for the device to be controlled. Further, the device to be controlled detects a voltage fluctuation corresponding to the timing of the transformer ratio adjustment operation, and demodulates at which position in the time slot the detected voltage fluctuation is located. Then, the device to be controlled performs a corresponding operation based on the demodulated information.

[0164] By modulating the voltage adjustment timing of a voltage regulator that performs voltage adjustment with discrete values in this way, information on the devices on the terminal side can be transmitted, and the power system can be controlled. Therefore, it becomes possible to transmit information including control commands to the devices to be controlled, such as PCS, connected to the terminal side as viewed from devices that perform discrete voltage adjustment such as SVR. Conventionally, a large amount of power has been required to adjust the frequency of the distribution system. On the other hand, in the distributed power source control system 1 according to the present embodiment, even if there are a large number of adjustable loads or distributed power sources 217, they can be controlled all at once. Therefore, it becomes possible to aggregate distributed power sources to such an extent that the frequency of the distribution system 119 can be adjusted.

[0165] Since the control command according to the present embodiment is transmitted via the distribution line 120, which is a power line, it is not necessary to newly lay a wireless or wired communication path. Further, since the control command is transmitted using the existing power line, there is no need to pay a usage fee to a communication company, and the communication cost is reduced. Also, according to the method of transmitting the control command via the distribution line 120 according to the present embodiment, it is not necessary to replace the modem or the like due to the frequent change of communication standards on the communication company side. Further, in a communication path laid by a communication company, it is easily affected by congestion caused by concentration of communication due to concerts, sports events, obstacles, disasters, etc., but the distribution line 120 is less likely to be affected by congestion.

[0166] In the power distribution system 119, operations that cause discrete voltage changes include, in addition to adjusting the transformation ratio by the SVR, adjusting the reactive power. For example, the power distribution system 119 performs operations such as parallel disconnection of the system static condenser SC (Static Condenser) or shunt reactor (Shunt Reactor). Furthermore, the load on the large customer side also becomes a factor in voltage changes in the system. Therefore, the power supply command center server 115 can use the increase in the load of the customer as a trigger for an increase in the output to the adjacent converter by controlling the output at an appropriate timing.

[0167] In addition, the configuration and operation of the distributed power control system 1 can be applied not only to the GFM shown as an example of converters and the conventional GFL, but also to loads that can be controlled via the xEMS.

[0168] Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various other application examples and modification examples can be adopted without departing from the gist of the present invention described in the claims. For example, the above-described embodiments have described the configuration of the system in detail and specifically for the purpose of easily explaining the present invention, and are not necessarily limited to those having all the configurations described. Also, it is possible to add, delete, or replace a part of the configuration of this embodiment with other configurations. In addition, the control lines and information lines show those considered necessary for explanation, and do not necessarily show all the control lines and information lines on the product. In reality, it may be considered that almost all the components are interconnected.

Explanation of Reference Numerals

[0169] 1…Distributed power control system, 115…Power supply command center server, 116…Communication path, 117…Output increase / decrease command, 118…Power system with voltage class of extra-high voltage or above, 119…Power distribution system, 120…Distribution line, 214…LRT, 215…SVR with communication function, 216…SVR without communication function, 217…Adjustable load or distributed power source, 404…Time slot, 405…Reference point, 407…Timing, 501…External information acquisition unit, 502…Output adjustment necessity determination unit, 503…Power distribution system to be output-adjusted determination unit, 504…External destination command transmission unit (communication), 505…Control command destination setting unit, 506…Overall control unit

Claims

1. An external information acquisition unit that acquires external information; An output adjustment necessity determination unit that is distributed and connected to a power system and determines the necessity of output adjustment for an output adjustable device capable of adjusting at least one of input or output power based on the external information; An output adjustment target determination unit that determines the output adjustable device to be the target of output adjustment when it is determined that output adjustment is necessary; A destination setting unit that sets a destination of control information for instructing output adjustment for the output adjustable device for a voltage ratio adjustment unit connected to the power system; A control information transmission unit that has time slots in which a plurality of the voltage ratio adjustment units connected to the power system are each synchronized in time, and transmits the control information that temporally shifts the timing of discrete voltage adjustment of the voltage ratio by the voltage ratio adjustment unit to which the destination is set, based on the time slots, to the output adjustable device connected to the end side of the voltage ratio adjustment unit. A power system control device.

2. The voltage ratio adjustment unit instructs the output adjustable device with a first command by advancing the timing of changing from the original voltage with respect to the reference point of the time slot, and instructs the output adjustable device with a second command by delaying the timing of changing from the original voltage with respect to the reference point of the time slot. The power system control device according to Claim 1.

3. The output adjustment target determination unit determines different output adjustment amounts for different power systems, The destination setting unit sets the destination of the control information for different power systems, The control information transmission unit transmits the control information with different output adjustment amounts for each set destination. The power system control device according to Claim 2.

4. The external information includes the current value of power supply and demand, measurement information of the power system, and weather information in the power system. The power system control device according to Claim 3.

5. A step of acquiring external information; A step of determining the necessity of output adjustment for an output adjustable device that is distributed and connected to a power system and capable of adjusting at least one of input or output power based on the external information; A step of determining the output adjustable device to be the target of output adjustment when it is determined that output adjustment is necessary; A step of setting a destination of control information for instructing output adjustment for the output adjustable device for a voltage ratio adjustment unit connected to the power system; A step of transmitting control information that shifts the timing of discrete voltage adjustment of the transformation ratio by the transformation ratio adjustment unit to which the destination is set in time with reference to the time slot, where the plurality of transformation ratio adjustment units connected to the power system each have a time slot synchronized in time, to the output adjustable device connected to the end side of the transformation ratio adjustment unit. Power system control method.

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