Generator access control method of energy storage power generation system

Abstract

The invention discloses a generator access control method of an energy storage power generation system. The method comprises the following steps: connecting a generator to an alternating current side of an energy storage converter through a control switch; when the energy storage converter is in an off-grid state, if the total power supply amount of the energy storage converter meets the load requirement, the generator is disconnected with the load through the control switch, and at the moment, the energy storage converter carries out loading independently; if the total power supply quantity of the energy storage converter does not meet the load requirement, judging the output power of the generator; if the output power of the generator is not overloaded relative to the load demand, the control switch is closed to enable the generator to be loaded independently, and the energy storage converter seals waves; otherwise, the control switch is closed to enable the energy storage converter and the generator to be jointly loaded. The method has the advantages that the energy storage converter is subjected to wave sealing after the generator is connected into the system, power can be prevented from being accumulated on the bus for a long time, and the overvoltage risk of the bus is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of inverters, and particularly to a method for controlling the connection of a generator in an energy storage power generation system. Background Art

[0002] The energy storage power generation system mainly includes two main functions: electric energy conversion and storage. Taking the photovoltaic energy storage power generation system as an example, first, the direct current (DC) generated by the photovoltaic modules is converted into alternating current (AC) for use by household, industrial, and commercial equipment. When the electric energy generated by the photovoltaic modules exceeds the immediate demand, the excess electric energy is stored in a battery pack, usually a lithium-ion battery or a lead-acid battery. When the light is insufficient or during peak power demand, the electric energy stored in the battery pack can be reconverted into alternating current through an inverter to meet the power demand. However, the arrangement of the energy storage converter is generally fixed for a long time, while the load power demand gradually increases, which makes it difficult for the energy storage converter to meet the load power demand. Summary of the Invention

[0003] One of the purposes of the present application is to provide a method for controlling the connection of a generator in an energy storage power generation system that can solve at least one defect in the above background art.

[0004] To achieve at least one of the above purposes, the technical solution adopted in the present application is as follows: A method for controlling the connection of a generator in an energy storage power generation system includes the following steps: Connect the generator to the AC side of the energy storage converter through a control switch; when the energy storage converter is in an off-grid state, collect the bus voltage and the SOC of the energy storage battery of the energy storage converter, and then calculate the total power supply of the energy storage converter; if the total power supply of the energy storage converter meets the load demand, the generator disconnects from the load through the control switch, and at this time, the energy storage converter executes an off-grid control loop to operate with load alone as a voltage source; if the total power supply of the energy storage converter does not meet the load demand, judge the output power of the generator; if the output power of the generator is not overloaded relative to the load demand, close the control switch so that the generator operates with load alone as a voltage source, and at this time, the energy storage converter blocks the wave; otherwise, close the control switch so that the energy storage converter executes a grid-connected control loop to operate with load together as a current source and the generator as a voltage source.

[0005] Preferably, the connection between the generator and the load includes the following process: Control the generator to start, and after the generator outputs normally, sample the output voltage of the generator, and then use it as the input of the off-grid control loop of the energy storage converter; at the same time, sample the output frequency of the generator, and then calculate the output angular velocity of the generator and assign it to the phase-locked loop as the input; after the energy storage converter completes the phase-locking of the generator output, close the control switch to connect the generator to the system and the load, and at the same time, the energy storage converter blocks the wave.

[0006] Preferably, the energy storage converter includes a power generation unit and an energy storage battery. The power generation unit and the energy storage battery are respectively connected in parallel to the DC / AC unit through a DC / DC unit and a bidirectional DC / DC unit. When the generator operates under a single load, the energy storage converter is adapted to charge the energy storage battery through the power generation unit. When the energy storage battery is charged to a preset SOC, the energy storage converter is adapted to release the wave blocking and resume loading. At this time, the control switch is disconnected and the generator is shut down.

[0007] Preferably, when the generator operates under a single load, the process of charging the energy storage battery by the power generation unit is as follows: the DC / DC unit resumes wave releasing, the bidirectional DC / DC unit executes an off-grid control loop, and the power generation unit charges the energy storage battery through the DC / DC unit and the bidirectional DC / DC unit. At this time, the DC / AC unit continues to maintain wave blocking.

[0008] Preferably, the control process for the overload of the generator output power relative to the load demand is as follows: the energy storage converter resumes wave releasing and executes a grid-connected control loop. When executing the grid-connected control loop, the output voltage of the generator is sampled and used as the input of the phase-locked loop in the grid-connected control loop of the energy storage converter. Then, the discharge power of the energy storage battery is controlled through the grid-connected control loop to be the difference between the load demand and the generator output power.

[0009] Preferably, the grid-connected control loop of the bidirectional DC / DC unit includes a battery current limiting loop, a battery current loop, and a control signal generation module. The given value of the bus voltage is used as the input of the battery current limiting loop and is subjected to error calculation with the sampled value of the bus voltage. The calculation result is sent to a PI controller. The output of the PI controller is used as the limiting value of the given value in the battery current loop. The limited given value is subjected to error calculation with the sampled value of the current of the energy storage battery. The calculation result is sent to a PI controller. The PI controller outputs a duty cycle to the control signal generation module to output a control signal corresponding to the bidirectional DC / DC unit. The off-grid control loop of the bidirectional DC / DC unit includes a bus voltage loop, a battery current loop, and a control signal generation module. The given value of the bus voltage is used as the input of the bus voltage loop and is subjected to error calculation with the sampled value of the bus voltage. The calculation result is sent to a PI controller. After the output of the PI controller is limited, it is used as the given value of the battery current loop and is subjected to error calculation with the sampled value of the current of the energy storage battery. The calculation result is sent to a PI controller. The PI controller sends the output duty cycle to the control signal generation module to output a control signal corresponding to the bidirectional DC / DC unit.

[0010] Preferably, the grid-connected control loop of the DC / AC unit includes a phase-locked loop, a bus voltage loop, an AC current loop, a dq transformation unit, and a control signal generation module; the sampled value of the grid voltage or the sampled value of the generator output voltage is used as the input of the phase-locked loop, and the corresponding phase and frequency are output; at the same time, the three-phase current and voltage on the AC side are converted into the corresponding active value, reactive value, and zero-sequence injection through the dq transformation unit; the given value of the bus voltage is used as the input of the bus voltage loop to calculate the error with the sampled value of the bus voltage, and the calculation result is sent to the PI controller to output as the active given value of the AC current loop, and then the error is calculated with the transformed current active value, and the calculation result is sent to the PI controller; the reactive given value of the AC current loop is calculated with the transformed current reactive value, and the calculation result is sent to the PI controller; the transformed voltage active value and voltage reactive value are respectively fed forward with the output result of the AC current loop; the two results after feedforward and the zero-sequence injection are converted into a duty cycle through the dq transformation unit and sent to the control signal generation module to output the control signal corresponding to the DC / AC unit.

[0011] Preferably, the off-grid control loop of the DC / AC unit includes a phase-locked loop, a voltage given value generation module, an output voltage loop, an output current loop, a dq transformation unit, and a control signal generation module; the sampled value of the generator output voltage is used as the input of the phase-locked loop, and the corresponding phase and frequency are output; at the same time, the three-phase current and voltage on the AC side are converted into the corresponding active value, reactive value, and zero-sequence through the dq transformation unit; the voltage and frequency that the energy storage converter needs to output are input to the voltage given value generation module and converted into the corresponding voltage active given value and voltage reactive given value of the output voltage loop; the output voltage loop calculates the error between the voltage active given value and the transformed voltage active value, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the active given value of the output current loop and the error is calculated with the transformed current active value, and the calculation result is sent to the PI controller; at the same time, the output voltage loop calculates the error between the voltage reactive given value and the transformed voltage reactive value, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the reactive given value of the output current loop and the error is calculated with the transformed current reactive value, and the calculation result is sent to the PI controller; the output result of the output current loop and the zero-sequence injection are converted into a duty cycle through the dq transformation unit and sent to the control signal generation module to output the control signal corresponding to the DC / AC unit.

[0012] Preferably, the control switch uses a selector switch. The AC side of the energy storage converter is connected to the generator and the grid respectively through the control switch, and the load is connected between the output port of the energy storage converter and the control switch; when the energy storage converter supplies power to the load alone, the control switch remains disconnected from the generator; when the generator supplies power to the load, the control switch connects the generator to the AC side of the energy storage converter by closing.

[0013] Preferably, both the load and the generator are connected in parallel to the AC side of the energy storage converter through branches, and the control switch is arranged on the branch corresponding to the generator; when the energy storage converter supplies power to the load alone, the control switch remains open; when the generator supplies power to the load, the control switch connects the generator to the AC side of the energy storage converter by closing.

[0014] Compared with the prior art, the beneficial effects of this application are as follows: After the generator is connected to the system, the energy storage converter is blocked, which can prevent the power from accumulating on the bus for a long time and avoid the risk of bus overvoltage. At the same time, the generator is used as a voltage source to carry the load alone, or when the power of the generator is insufficient, the energy storage converter is used as a current source to carry the load together with the generator; this avoids the uncontrollable output power of the energy storage converter caused by two voltage sources carrying the load together. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the working process of this application.

[0016] Figure 2 Based on Figure 1 shown in the working process is a schematic flow diagram.

[0017] Figure 3 It is a schematic structural diagram of one example of the hardware connection of the generator to the energy storage power generation system in this application.

[0018] Figure 4 It is a schematic structural diagram of another example of the hardware connection of the generator to the energy storage power generation system in this application.

[0019] Figure 5 It is a schematic flow diagram of the working scenario judgment of the energy storage power generation system in this application.

[0020] Figure 6 It is a schematic diagram of the power distribution when the generator carries the load alone in this application.

[0021] Figure 7 It is a schematic diagram of the power distribution when the generator and the energy storage converter carry the load together in this application.

[0022] Figure 8 It is a schematic structural diagram of the mode judgment loop in this application.

[0023] Figure 9 It is a schematic structural diagram of the control loop of the DC / DC unit in this application.

[0024] Figure 10 It is a schematic structural diagram of the control loop of the bidirectional DC / DC unit in this application.

[0025] Figure 11This is a schematic diagram of the control loop structure of the DC / AC unit in this application.

[0026] In the figure: power generation unit 101, DC / DC unit 102, DC / AC unit 103, bidirectional DC / DC unit 104, energy storage battery 105, load switch 106, grid connection switch 107, electricity meter 108, power grid 200, load 300, generator 401, control switch 402. Detailed implementation manners

[0027] Next, in combination with the detailed implementation manners, this application will be further described. It should be noted that in the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0028] In the description of this application, it should be noted that for orientation terms, if there are terms such as "center", "transverse", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation and position relationship are based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific protection scope of this application.

[0029] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence.

[0030] In this application, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0032] The terms "comprise" and "have" and any variations thereof in the description and claims of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that comprises a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these process, method, product or device.

[0033] One preferred embodiment of this application is, as Figures 1 to 4 shown, a method for controlling the connection of a generator of an energy storage power generation system, including the following steps: Connect the generator 401 to the AC side of the energy storage converter through the control switch 402, that is, first connect the generator 401 to the energy storage power generation system by means of hardware connection. When the energy storage converter is in the off-grid state, collect the bus voltage and the SOC of the energy storage battery 105 of the energy storage converter, and then calculate the total power supply of the energy storage converter. If the total power supply of the energy storage converter meets the demand of the load 300, the generator 401 disconnects from the load 300 through the control switch 402. At this time, the energy storage converter executes the off-grid control loop to supply power to the load 300 as a voltage source to achieve independent load carrying. If the total power supply of the energy storage converter does not meet the demand of the load 300, it is necessary to judge the output power of the generator 401; if the output power of the generator 401 is not overloaded relative to the demand of the load 300, that is, the generator 401 will not be overloaded during operation, the control switch 402 can be closed so that the generator 401 is connected to the load 300 to achieve independent load carrying of the generator 401 as a voltage source. At this time, the energy storage converter blocks the wave; otherwise, the control switch 402 is closed so that the energy storage converter executes the grid-connected control loop to supply power to the load 300 as a current source and the generator 401 as a voltage source simultaneously to achieve common load carrying.

[0034] It is understandable that after the generator 401 is connected to the energy storage power generation system, the energy storage converter is blocked, which can prevent power from accumulating on the bus for a long time and avoid the risk of bus overvoltage. At the same time, by using the generator 401 as a voltage source to carry the load alone, or when the power of the generator 401 is insufficient, the energy storage converter is used as a current source to carry the load together with the generator 401, which can avoid the uncontrollable output power of the energy storage converter caused by two voltage sources carrying the load together.

[0035] For the convenience of understanding this embodiment, the structure of the energy storage power generation system can be described first. As Figure 3 and Figure 4 shown, the energy storage power generation system includes a power generation unit 101, a DC / DC unit 102, a DC / AC unit 103, a bidirectional DC / DC unit 104, an energy storage battery 105, a load switch 106, a grid connection switch 107, and a load 300. The power generation unit 101 and the energy storage battery 105 are respectively connected in parallel to the DC bus of the DC / AC unit 103 through the corresponding DC / DC unit 102 and bidirectional DC / DC unit 104. The specific connection method can adopt a three-level connection, that is, they are respectively connected to the positive bus BUS+ of the DC side of the DC / AC unit 103, the bus midpoint BUSM, and the negative bus BUS-. The AC side of the DC / AC unit 103 is connected to the load 300 through the load switch 106; at the same time, the AC side of the DC / AC unit 103 is also connected to the power grid 200 through the grid connection switch 107, so that the grid connection switch 107 can be closed when the energy storage power generation system operates in parallel, and the grid connection switch 107 can be disconnected when the energy storage power generation system operates off-grid. Since the control loop for parallel operation needs to collect the voltage of the power grid 200, an ammeter 108 is also installed on the connection side of the power grid 200. The ammeter 108 can collect the voltage of the power grid 200 and transmit it to the corresponding power device through a communication protocol. Among them, the connection architecture between the power generation unit 101, the DC / DC unit 102, the DC / AC unit 103, the bidirectional DC / DC unit 104, and the energy storage battery 105 can form an energy storage converter.

[0036] It should be known that there are various specific types of energy storage power generation systems, such as photovoltaic energy storage power generation systems and wind energy storage power generation systems, etc.; for the convenience of understanding, this application will take a photovoltaic energy storage power generation system as an example, and the power generation unit 101 in the energy storage power generation system uses PV modules. There are various specific ways to connect the generator 401 hardware based on the above energy storage power generation system. For the convenience of understanding, the following will be described in detail through two specific examples.

[0037] Example 1: As Figure 3As shown, a control switch 402 is further provided between the grid-connected switch 107 and the power grid 200; the control switch 402 adopts a selector switch, so that the AC side of the energy storage converter is connected to the generator 401 and the power grid 200 respectively through the control switch 402. When the energy storage converter supplies power to the load 300 alone, the control switch 402 can remain in the off state, so that the generator 401 is not connected to the AC side of the energy storage converter. When the generator 401 supplies power to the load 300 alone, the control switch 402 can be closed to the position of the generator 401, so that the generator 401 is connected to the AC side of the energy storage converter.

[0038] Example 2: As Figure 4 shown, the generator 401 is connected in parallel to the AC side of the energy storage converter through a branch, and the control switch 402 is arranged on the branch corresponding to the generator 401. At this time, the grid-connected switch 107 is located between the connection position of the generator 401 and the power grid 200. When the energy storage converter supplies power to the load 300 alone, the control switch 402 remains off, so that the generator 401 is not connected to the AC side of the energy storage converter. When the generator 401 supplies power to the load 300, the control switch 402 connects the generator 401 to the AC side of the energy storage converter by closing.

[0039] It can be understood that the above two examples can both meet the requirements of this application, and those skilled in the art can choose according to actual needs. For the convenience of controlling the generator 401, the control switch 402 can be selected as a switch with remote control function, such as an ATS switch; or a generator 401 with remote start-stop control can be adopted.

[0040] It should be known that the working modes of a conventional energy storage power generation system are divided into a grid-connected mode (MOD = 0) and an off-grid mode (MOD = 1) according to whether the power grid 200 is incorporated; in the grid-connected mode, the power grid 200 can provide energy for the load 300 or the energy storage battery 105, while in the off-grid mode, all the power required by the load 300 is provided by the energy storage converter. From the foregoing content, it can be seen that the units of the energy storage converter capable of supplying power to the load 300 include the power generation unit 101 and the energy storage battery 105; that is, the energy storage converter can supply power to the load 300 alone through the power generation unit 101, or can supply power to the load 300 alone through the energy storage battery 105, or can also supply power to the load 300 through the power generation unit 101 and the energy storage battery 105 at the same time. And the technical solution of this application is to connect the generator 401 to realize the power supply to the load 300 when the conventional energy storage power generation system cannot meet the requirements of the load 300 in the off-grid state through the energy storage converter. For the convenience of understanding, the specific working scenarios of the energy storage power generation system of this application in the off-grid mode will be described in detail below.

[0041] AsFigure 5 As shown, when the energy storage power generation system operates in the off-grid mode, the PV module gives priority to supplying power to the load 300, and determines the control instruction that the current system should execute according to the bus voltage v bus and the SOC value of the energy storage battery 105. Among them, v ref1 represents the upper threshold value of the bus voltage, v ref2 represents the lower threshold value of the bus voltage, SOC th1 represents the upper SOC threshold value of the energy storage battery 105, SOC th2 represents the lower SOC threshold value of the energy storage battery 105.

[0042] Scenario 1: When the bus voltage v bus is greater than or equal to the upper threshold value v ref1 of the bus voltage, it indicates that the output power P pv of the PV module at this time is greater than the required power P load of the load 300; if the SOC of the energy storage battery 105 is greater than or equal to the upper SOC threshold value SOC th1 at this time, it means that the energy storage battery 105 is fully charged. Then, the output power P pv of the PV module is load-limited, and the load-limiting value is equal to the required power P load of the load 300.

[0043] Scenario 2: When the bus voltage v bus is greater than or equal to the upper threshold value v ref1 of the bus voltage, it indicates that the output power P pv of the PV module at this time is greater than the required power P load of the load 300; if the SOC of the energy storage battery 105 is less than the upper SOC threshold value SOC th1 at this time, it means that the energy storage battery 105 is not fully charged, and the PV module can be made to charge the energy storage battery 105 through the bidirectional DC / DC unit 104. The charging power P bat is the smaller value between (P pv -P load ) and P batmax ; among them, P batmax represents the maximum charging power. At this time, the output power P pv of the PV module is equal to the required power P load of the load 300 plus the charging power P bat of the energy storage battery 105; that is, the PV module is loaded and charges the energy storage battery 105 at this time.

[0044] Scenario 3: When the bus voltage v bus is less than or equal to the lower threshold value v ref2 of the bus voltage, it indicates that the output power Ppv is less than the required power P of the load 300 (at the maximum power point). load If the SOC of the energy storage battery 105 is greater than the lower threshold SOC at this time th2 , the energy storage battery 105 can be made to discharge to the load 300 through the bidirectional DC / DC unit 104, and the discharge power P bat is P load -P pv ; that is, at this time, the PV module and the energy storage battery 105 supply the load simultaneously.

[0045] Scenario 4: When the bus voltage v bus is less than or equal to the lower threshold v of the bus voltage ref2 , it indicates that the output power P of the PV module at this time pv (at the maximum power point) is less than the required power P of the load 300 load . If the SOC of the energy storage battery 105 is less than or equal to the lower threshold SOC at this time th2 , it means that the energy storage battery 105 has insufficient power and cannot guarantee the power supply to the load 300 for a long time; at this time, the system enters the generator mode (GENMOD), that is, the generator 401 is connected to the energy storage power generation system and supplies power to the load 300.

[0046] It should be noted that when the SOC of the energy storage battery 105 reaches the lower threshold SOC th2 , the energy storage battery 105 should be able to supply power to the load 300 for a period of time. Therefore, SOC th2 should be reasonably set according to the capacity of the energy storage battery 105 in the energy storage power generation system, the maximum output power P of the energy storage converter invmax , the start-up time of the generator 401, the phase-locked time and other conditions. When the bus voltage v bus is between the upper threshold v of the bus voltage ref1 and the lower threshold v ref2 , the current control strategy is maintained.

[0047] It can be understood that from the above analysis process, when the energy storage power generation system works in Scenario 1 or Scenario 2, due to the change of light or the increase of the required power P of the load 300 load , resulting in the output power P of the PV module pv being less than the required power P of the load 300 load , the energy storage power generation system will switch from Scenario 1 or Scenario 2 to Scenario 3, so that the PV module and the energy storage battery 105 jointly provide power for the load 300. When the energy storage battery 105 discharges to the lower threshold SOC th2When it is time, it will switch from Scenario 3 to Scenario 4 generator mode; that is, the technical solution of the present application mainly targets the process of switching from Scenario 3 to Scenario 4. For the convenience of understanding, the following will describe the specific process of switching from Scenario 3 to Scenario 4 in detail.

[0048] Specifically, as Figure 2 shown, when the PV module and the energy storage battery 105 supply power to the load 300 at the same time, the energy storage converter can control the generator 401 to start. At this time, the power generation power P of the energy storage battery 105 bat = P load -P pv . It should be noted that before the generator 401 starts, the energy storage converter needs to execute an off-grid control loop.

[0049] After the generator 401 outputs normally, the output voltage waveform of the energy storage converter needs to track the output voltage waveform of the generator 401. That is, the output voltage v of the generator 401 gena 、v genb 、v genc is sampled and used as the input of the voltage reference generation module in the off-grid control loop of the DC / AC unit 103 in the energy storage converter; at the same time, the output frequency f of the generator 401 gen is sampled, and the output angular velocity ω of the generator 401 is calculated gen and assigned to the input ω of the phase-locked loop in the off-grid control loop of the DC / AC unit 103 ref .

[0050] When the energy storage converter completes the phase-locking of the output of the generator 401, it controls the switch 104 to close, and connects the generator 401 hardware to the energy storage power generation system to supply power to the load 300. At the same time, the energy storage converter is blocked, that is, the DC / DC unit 102, the bidirectional DC / DC unit 104, and the DC / AC unit 103 in the energy storage converter are blocked. It should be noted that when blocking the energy storage converter, the switch action time needs to be considered to ensure that the time interval between the blocking of the energy storage converter and the access of the generator 401 is short.

[0051] If the generator 401 is in an un-overloaded state, that is, the normal output power P of the generator 401 gen is less than the maximum output power P of the generator 401 genmax , or in other words, the required power P of the load 300 load is less than or equal to the output power P of the generator 401 gen . Generally speaking, the output power of the generator 401 during normal operation can meet the requirements of the load 300. In order to meet the possible required power P of the load 300 loadIn the case of an increase, and since the power consumption of the generator 401 is relatively high, the connection time of the generator 401 should be minimized. When the generator 401 is operating under load alone, the PV module serving as the power generation unit 101 can charge the energy storage battery 105.

[0052] For the PV module to charge the energy storage battery 105, the DC side of the energy storage converter filters the ripple. At this time, the control loop of the DC / DC unit 102 comes into play, and at the same time, the control loop of the bidirectional DC / DC unit 104 executes off-grid control. Then, the PV module charges the energy storage battery 105 through the DC / DC unit 102 and the bidirectional DC / DC unit 104. At this time, the AC side of the energy storage converter remains filtered, rendering the corresponding control loop of the DC / AC unit 103 ineffective, thereby avoiding the impact of the operation of the generator 401 on the charging of the energy storage battery 105.

[0053] When the energy storage battery 105 is charged to reach the preset SOC, i.e., the SOC of the energy storage battery 105 is greater than the upper SOC threshold SOC th1 at this time, the PV module stops charging the energy storage battery 105, and at the same time, the AC side of the energy storage converter filters the ripple. As a result, the DC / AC unit 103 executes the off-grid control loop, and then the energy storage converter supplies power to the load 300; after the energy storage converter stabilizes its output, the control switch 402 can be disconnected to disconnect the generator 401 from the energy storage power generation system and perform a normal shutdown.

[0054] If the generator 401 is in an overloaded state, i.e., the required power P of the load 300 load is greater than the normal output power P of the generator 401 gen . Generally speaking, the output power of the generator 401 during normal operation cannot meet the requirements of the load 300. At this time, the generator 401 will operate in an overloaded state, and long-term overloading of the generator 401 is not allowed. At this time, the energy storage converter needs to be connected to achieve joint loading to avoid long-term overloading of the generator 401.

[0055] Specifically, the energy storage converter restarts filtering and executes the grid-connected control loop. When executing the grid-connected control loop, the output voltages v gena 、v genb 、v genc of the generator 401 are sampled and used as the input to the phase-locked loop in the grid-connected control loop of the DC / AC unit 103 in the energy storage converter. Then, through the grid-connected control loop, the discharge power of the energy storage battery 105 is controlled to be the difference between the demand of the load 300 and the output power of the generator 401. That is, the output power P of the energy storage converter at this time inv =P load -P genMeanwhile, during this process, the output power of the PV module can be identified. If the output power P of the PV module pv does not operate at the maximum power point P pvmax , then the PV module can perform MPPT tracking at this time and charge the energy storage battery 105.

[0056] To further facilitate the understanding of the operation of the generator 401 connected to the energy storage power generation system, the system power distribution in the generator mode will be described in detail below.

[0057] 1. For the scenario where the generator 401 supplies power to the load 300 alone.

[0058] As Figure 6 shown, at time t1, the required power P of the load 300 load increases, and the output power of the energy storage converter increases accordingly. At this time, the energy storage power generation system still executes the off-grid control loop (MOD = 1).

[0059] At time t2, the output power P of the PV module pv is less than the required power P of the load load , and the SOC of the energy storage battery 105 drops to the SOC lower limit threshold SOC th2 . At this time, the energy storage power generation system enters the generator mode, and the energy storage converter controls the generator 401 to start. The energy storage power generation system still executes the off-grid control loop (MOD = 1).

[0060] At time t3, the generator 401 starts successfully. The output voltage waveform of the energy storage converter tracks the output voltage waveform of the generator 401. At time t4, the energy storage converter completes the phase-locking of the output voltage waveform of the generator 401, and the energy storage converter will control the switch 402 to close, so that the generator 401 is connected to the energy storage power generation system.

[0061] At time t5, the closing action of the control switch 402 is completed, and the generator 401 is connected to the energy storage power generation system. Since the energy storage converter executes the off-grid control loop (MOD = 1) at this time and acts as a voltage source. The generator 401 is also a voltage source, and the two voltage sources are connected in parallel, so that the power output to the load 300 is redistributed. Therefore, at time t6, the energy storage converter blocks the wave, and at this time, the required power of the load 300 is all provided by the generator 401, avoiding the uncontrollable output power of the energy storage converter caused by the simultaneous operation of the two voltage sources. At the same time, the PV module charges the energy storage battery 105 through the DC / DC unit 102 and the bidirectional DC / DC unit 104.

[0062] At time t7, the SOC of the energy storage battery 105 reaches the SOC upper limit threshold SOC th1, the PV module stops charging the energy storage battery 105 and starts to supply power to the load 300 through the DC / DC unit 102 and the DC / AC unit 103. At this time, the energy storage inverter executes the off-grid control loop (MOD = 1), and the two voltage sources are connected in parallel, so that the power output to the load 300 is redistributed. Therefore, the energy storage inverter needs to disconnect the control switch 402 to disconnect the generator 401 from the energy storage power generation system, avoiding the uncontrollable output power of the energy storage inverter caused by the simultaneous operation of the two voltage sources, and at the same time reducing the overall energy consumption of the system. At the moment t8, the disconnection action of the control switch 402 is completed, and the generator 401 is disconnected from the energy storage power generation system. At this time, all the required power of the load 300 is provided by the energy storage inverter.

[0063] It should be noted that the SOC threshold for the PV module to charge the energy storage battery 105 in the generator mode may not be the SOC upper limit threshold SOC th1 , and it should be reasonably set according to the actual working conditions. In the above situation, the generator 401 can always meet the power demand of the load 300, and there is no need for the energy storage inverter to provide power for the load 300; therefore, the energy storage inverter always executes the off-grid control loop (MOD = 1).

[0064] II. For the scenario where the generator 401 and the energy storage inverter jointly supply power to the load 300.

[0065] Such as Figure 7 shown, during the time period t1 - t6, the energy storage power generation system enters the generator mode, and the process is the same as that Figure 6 when the generator 401 supplies load alone, so it will not be elaborated again.

[0066] At the moment a, the required power P load of the load 401 increases, and the increased required power P load is greater than the maximum output power P genmax of the generator 401, and the generator 401 is in an overloaded state.

[0067] At the moment b, after receiving the overload information of the generator 401, the energy storage inverter executes the grid-connected control loop (MOD = 0). The energy storage inverter is connected as a current source to supply power to the load 300, and the output power of the energy storage inverter gradually increases during this process.

[0068] It should be noted that for the reception of the overload information of the generator 401, in addition to the energy storage inverter directly obtaining the overload information of the generator 401 through communication, it is also possible to judge whether the generator 401 is overloaded by detecting the output power of the generator 401.

[0069] At the moment c, the output power of the generator 401 drops to the maximum output power P genmax, the output power of the energy storage converter stops rising. At this time, the excess power of the PV module can charge the energy storage battery 105.

[0070] At time d, the SOC of the energy storage battery 105 reaches the SOC upper limit threshold SOC th1 . The PV module stops charging the energy storage battery 105. The energy storage converter switches from the grid-connected control loop (MOD = 0) to the off-grid control loop (MOD = 1). The process at subsequent times is the same as that of the generator 401 operating alone with load, and will not be repeated here.

[0071] In this embodiment, the grid-connected and off-grid control loops of the energy storage power generation system mainly refer to the grid-connected and off-grid control loops corresponding to the DC / DC unit 102, the DC / AC unit 103, and the bidirectional DC / DC unit 104 in the energy storage converter. For the convenience of understanding, the specific working processes of the grid-connected and off-grid control loops of the DC / DC unit 102, the DC / AC unit 103, and the bidirectional DC / DC unit 104 will be elaborated in detail below.

[0072] It should be noted that the execution of the grid-connected and off-grid control loops of the above-mentioned power units needs to be judged by the mode judgment loop first. Specifically, as Figure 8 shown, the mode judgment loop judges the control mode of the energy storage power generation system by collecting information such as the SOC of the energy storage battery 105, the output power P of the energy storage converter inv , the bus voltage v bus , the grid voltage v ga , v gb , v gc , etc., and then outputs the mode selection signal MOD, the battery current set value i bat * , the bus voltage set value v bus * , etc. for use in the subsequent grid-connected and off-grid control processes of the power units.

[0073] At the same time, when the energy storage power generation system operates in the grid-connected mode, the AC side terminal voltage of the energy storage converter will be determined by the power grid 200. Therefore, the energy storage converter acts as a current source in the grid-connected mode. When the energy storage power generation system operates in the off-grid mode, the grid-connected switch 107 will be disconnected. At this time, the energy storage converter needs to stably output voltage. Therefore, the energy storage converter acts as a voltage source in the off-grid mode. Of course, when the energy storage converter and the generator 401 are loaded simultaneously, although the energy storage power generation system executes the grid-connected mode, the grid-connected switch 107 remains disconnected. At this time, the AC side terminal voltage of the energy storage converter will be determined by the generator 401. Therefore, the energy storage converter still acts as a current source in this grid-connected mode.

[0074] I. For the grid-connected and off-grid control loop of the DC / DC unit 102.

[0075] When the DC / DC unit 102 is operating, either the power generation unit 101 supplies power to the energy storage battery 105 or the power generation unit 101 supplies power to the load 300. Therefore, whether the energy storage inverter is in the grid-connected or off-grid mode, the DC / DC unit 102 performs MPPT tracking. Therefore, the control loop of the DC / DC unit 102 can also be called the PV control loop.

[0076] As Figure 9 shown, the PV control loop includes an MPPT calculation unit, a PV voltage outer loop, a PV current inner loop, and a control signal generation module. The sampled values of the output voltage v pv and output current i pv of the PV module are used as the inputs of the MPPT calculation unit. The MPPT calculation unit outputs v pv * as the set value of the PV voltage outer loop, which is used to calculate the error with the sampled value v pv of the output voltage of the PV module. The calculation result is sent to the PI controller. The current set value i pv * output by the PI controller 1 is limited. The limit value i pv-max is determined according to the specific control strategy. For example, in the anti-backflow scenario, according to the SOC of the energy storage battery 105 and the power P grid of the power grid 200, the output current of the PV module is limited to prevent excess power from being fed into the grid. The limited current set value i pv * is used as the input of the PV current inner loop, which is used to calculate the error with the sampled value i pv of the output current of the PV module. The calculation result is sent to the PI controller. The PI controller outputs the duty cycle d pv which is sent to the control signal generation module. The control signal generation module outputs the corresponding control signal PWM DC / DC for the DC / DC unit 102.

[0077] II. The grid-connected and off-grid control loop for the bidirectional DC / DC unit 104.

[0078] As Figure 10 shown, when the energy storage inverter is in the grid-connected mode, i.e., MOD = 0, the grid-connected control loop of the bidirectional DC / DC unit 104 is called the grid-connected battery control loop, which includes a battery current limiting loop, a battery current loop, and a control signal generation module. The set value v bus * of the bus voltage is used as the input of the battery current limiting loop, which is used to calculate the error with the sampled value v bus of the bus voltage. The calculation result is sent to the PI controller. The output of the PI controller is used as the current set value i bat in the battery current loop.* The limited value, and the current reference value i after limiting bat * and the current sampling value i of the energy storage battery 105 bat perform error calculation, and the calculation result is sent to the PI controller. The PI controller outputs the duty cycle d bat which is sent to the control signal generation module, and the control signal generation module outputs the control signal PWM corresponding to the bidirectional DC / DC unit 105 bat .

[0079] When the energy storage converter is in the off-grid mode, i.e., MOD = 1, the off-grid control loop of the bidirectional DC / DC unit 104 is called the off-grid battery control loop, which includes a bus voltage loop, a battery current loop, and a control signal generation module. The given value v of the bus voltage bus * is used as the input of the bus voltage loop, and performs error calculation with the bus voltage sampling value v bus , and the calculation result is sent to the PI controller. The current reference value i output by the PI controller bat * is limited and then used as the given value input of the battery current loop. The limited current reference value i bat * and the current sampling value i of the energy storage battery 105 bat perform error calculation, and the calculation result is sent to the PI controller. The PI controller outputs the duty cycle d bat which is sent to the control signal generation module, and the control signal generation module outputs the control signal PWM corresponding to the bidirectional DC / DC unit 104 bat .

[0080] III. The grid-connected and off-grid control loop for the DC / AC unit 103

[0081] As Figure 11 shown, when the energy storage converter is in the grid-connected mode, i.e., MOD = 0, the grid-connected control loop of the DC / AC unit 103 includes a phase-locked loop, a bus voltage loop, an AC current loop, a dq transformation unit, and a control signal generation module

[0082] If the grid-connected mode of the energy storage converter is to connect to the power grid 200 at this time; close the grid-connected switch 107, and the grid voltages v ga , v gb , v gc collected through the electricity meter 108 are the voltages v a , v b , v c on the AC side of the energy storage converter. The voltages v a , v b , v cAs the input of the phase-locked loop, the grid voltage frequency ω is obtained after passing through the phase-locked loop, and then the grid voltage frequency ω is integrated to obtain the phase θ g Meanwhile, the sampled values of the three-phase alternating current i a , i b , i c collected by the ammeter 108 are converted into i d , i q , i0 through the dq transformation unit, and the grid voltages v ga , v gb , v gc are converted into v d , v q , v0 through the dq transformation unit. Among them, i d and v d are the active values of the current and voltage respectively, i q and v q are the reactive values of the current and voltage respectively, and i0 and v0 are subjected to zero-sequence injection.

[0083] The given value v bus * of the bus voltage is used as the input of the bus voltage loop, and the error is calculated with the sampled value v bus of the bus voltage. The calculation result is sent to the PI controller. The output of the PI controller is used as the active given value i d * of the alternating current loop, and the error is calculated with the active value i d of the current obtained by dq transformation. The calculation result is sent to the PI controller to output the active given value v d * of the voltage. The reactive given value i q * of the alternating current loop is used to calculate the error with the reactive value i q of the current obtained by dq transformation. The calculation result is sent to the PI controller to output the reactive given value v q * of the voltage. The active value v d of the voltage and the reactive value v q obtained by dq transformation are respectively used for feedforward with the active given value v d * of the voltage output by the alternating current loop and the reactive given value v q * of the voltage. The two results after feedforward and the zero-sequence injection are converted into the duty ratio d DC / AC through the dq transformation unit and sent to the control signal generation module, and the control signal generation module outputs the control signal PWM DC / AC corresponding to the DC / AC unit 103.

[0084] If the grid - connection mode of the energy storage converter at this time is to achieve co - loading with the generator 401, then disconnect the grid - connection switch 107, and sample the output voltages v gena 、v genb 、v genc of the generator 401 as the input of the phase - locked loop. After passing through the phase - locked loop, the output frequency f gen of the generator 401 is obtained, and then the output angular velocity ω gen of the generator 401 is calculated and assigned to the input ω ref of the phase - locked loop. Then, integrate according to the frequency ω output by the phase - locked loop to obtain the corresponding phase θ g .

[0085] At the same time, sample the three - phase current sampling values i a 、i b 、i c output by the energy storage converter and convert them into i d 、i q 、i0 through the dq transformation unit. The output three - phase voltages v a 、v b 、v c are converted into v d 、v q 、v0 through the dq transformation unit. Among them, i d and v d are the active values of the current and voltage respectively, i q and v q are the reactive values of the current and voltage respectively, and i0 and v0 are used for zero - sequence injection. The subsequent control process is the same as the control process of connecting to the power grid 200, so it will not be repeated here.

[0086] When the energy storage converter is in the off - grid mode, that is, MOD = 1, the off - grid control loop of the DC / AC unit 103 includes a phase - locked loop, a voltage reference generation module, an output voltage loop, an output current loop, a dq transformation unit, and a control signal generation module.

[0087] Sample the output voltages v gena 、v genb 、v genc of the generator 401 as the input of the phase - locked loop. After passing through the phase - locked loop, the output frequency f gen of the generator 401 is obtained, and then the output angular velocity ω gen of the generator 401 is calculated and assigned to the input ω ref of the phase - locked loop. Then, integrate according to the frequency ω output by the phase - locked loop to obtain the corresponding phase θ g . At the same time, sample the three - phase current sampling values i a 、i b 、i cConverted to \(i_d\), \(i_q\), and \(i_0\) through the dq transformation unit, and the output three-phase voltages \(v_a\), \(v_b\), and \(v_c\) are converted to \(v_d\), \(v_q\), and \(v_0\) through the dq transformation unit. Among them, \(i_d\) and \(v_d\) are the active values of the current and voltage respectively, \(i_q\) and \(v_q\) are the reactive values of the current and voltage respectively, and \(i_0\) and \(v_0\) are subjected to zero-sequence injection. d \(i_d\) q \(i_q\) a \(v_a\) b \(v_b\) c \(v_c\) d \(v_d\) q \(v_q\) d \(i_d\) d and \(v_d\) q \(i_q\) q and \(v_q\) are the reactive values of the current and voltage respectively, and \(i_0\) and \(v_0\) are subjected to zero-sequence injection.

[0088] The voltages \(v_a\), \(v_b\), \(v_c\) that the energy storage converter needs to output and the frequency input voltage given generation module are converted into the voltage active given value \(v_{refd}\) and the voltage reactive given value \(v_{refq}\) corresponding to the output voltage loop. The output voltage loop calculates the error between the voltage active given value \(v_{refd}\) and the voltage active value \(v_d\) obtained by dq transformation, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the active given value \(i_{refd}\) of the output current loop, and the error is calculated with the current active value \(i_d\) obtained by transformation, and the calculation result is sent to the PI controller. The reactive given value \(v_{refq}\) of the output voltage loop calculates the error with the voltage reactive value \(v_q\) obtained by dq transformation, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the reactive given value \(i_{refq}\) of the output current loop, and the error is calculated with the current reactive value \(i_q\) obtained by dq transformation, and the calculation result is sent to the PI controller. The output result of the output current loop after passing through the PI controller and the zero-sequence injection are converted into the duty cycle \(d\) through the dq transformation unit and sent to the control signal generation module, and the control signal generation module outputs the control signal PWM corresponding to the DC / AC unit 103. a0 \(v_a\) b0 \(v_b\) c0 \(v_c\) d * \(v_{refd}\) q * \(v_{refq}\) d * The voltage active given value \(v_{refd}\) d is calculated for error with the voltage active value \(v_d\) obtained by dq transformation, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the active given value \(i_{refd}\) of the output current loop d * and the error is calculated with the current active value \(i_d\) obtained by transformation d \(i_d\) q * The reactive given value \(v_{refq}\) of the output voltage loop q is calculated for error with the voltage reactive value \(v_q\) obtained by dq transformation q * \(i_{refq}\) q \(i_q\) DC / AC and sent to the control signal generation module, and the control signal generation module outputs the control signal PWM corresponding to the DC / AC unit 103 DC / AC

[0089] The basic principles, main features and advantages of the present application have been described above. Those skilled in the art should understand that the present application is not limited by the above embodiments. What is described in the above embodiments and the specification is only the principle of the present application. Without departing from the spirit and scope of the present application, various changes and improvements will occur to the present application, and these changes and improvements all fall within the scope of the present application claimed. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the connection of a generator in an energy storage power generation system, characterized in that, The steps include: Connect the generator to the AC side of the energy storage converter through a control switch; When the energy storage converter is off-grid, the bus voltage and the SOC of the energy storage battery of the energy storage converter are collected to calculate the total power supply of the energy storage converter; If the total power supply of the energy storage converter meets the load demand, the generator is disconnected from the load through the control switch. At this time, the energy storage converter executes the off-grid control loop and acts as a voltage source to carry the load alone; If the total power supply of the energy storage converter does not meet the load demand, the output power of the generator is judged; If the generator output power is not overloaded relative to the load demand, close the control switch so that the generator can carry the load alone as a voltage source, and the energy storage inverter is blocked at this time; otherwise, close the control switch so that the energy storage inverter executes the grid-connected control loop as a current source and the generator as a voltage source to carry the load together.

2. The generator access control method of the energy storage power generation system according to claim 1, wherein The connection between the generator and the load includes the following processes: The generator is controlled to start, and the output voltage of the generator is sampled after the generator outputs normally, which is then used as the input of the off-grid control loop of the energy storage converter; at the same time, the output frequency of the generator is sampled, and the output angular velocity of the generator is calculated and assigned to the phase-locked loop as input; After the energy storage converter completes the phase locking of the generator output, the control switch is closed to connect the generator to the system and the load, and the energy storage converter is blocked at the same time.

3. The generator access control method for the energy storage power generation system according to claim 2, characterized in that The energy storage converter includes a power generation unit and an energy storage battery, and the power generation unit and the energy storage battery are connected in parallel to the DC / AC unit through a DC / DC unit and a bidirectional DC / DC unit respectively; When the generator is loaded alone, the energy storage converter is suitable for charging the energy storage battery through the power generation unit; When the energy storage battery is charged to a preset SOC, the energy storage converter is suitable for releasing the wave blocking and re-loading, at which time the control switch is disconnected and the generator is shut down.

4. The generator access control method of the energy storage power generation system according to claim 3, characterized in that When the generator is loaded alone, the process of the power generation unit charging the energy storage battery is as follows: The DC / DC unit starts to release the wave again, the bidirectional DC / DC unit executes the off-grid control loop, and the power generation unit charges the energy storage battery through the DC / DC unit and the bidirectional DC / DC unit. At this time, the DC / AC unit continues to keep the wave closed.

5. The generator access control method of the energy storage power generation system according to claim 4, characterized in that The control process when the generator output power is overloaded relative to the load demand is as follows: The energy storage converter re-discharges and executes the grid-connected control loop; When executing the grid-connected control loop, the output voltage of the generator is sampled and used as the input of the phase-locked loop in the grid-connected control loop of the energy storage inverter, and then the discharge power of the energy storage battery is controlled by the grid-connected control loop to be the difference between the load demand and the generator output power.

6. The method for controlling the connection of the generator of the energy storage power generation system according to claim 5, characterized in that, The grid-connected control loop of the bidirectional DC / DC unit includes a battery current limiting loop, a battery current loop and a control signal generating module; The given value of bus voltage is used as the input of battery current limiting loop and the error is calculated with the sampled value of bus voltage, and the calculation result is sent to PI controller; The output of the PI controller is used as the limit value of the given value in the battery current loop. The error between the given value after the limit and the current sampling value of the energy storage battery is calculated, and the calculation result is sent to the PI controller; The duty cycle output by the PI controller is sent to the control signal generation module, which outputs the control signal corresponding to the bidirectional DC / DC unit; The off-grid control loop of the bidirectional DC / DC unit includes a bus voltage loop, a battery current loop, and a control signal generation module; The given value of the bus voltage is used as the input of the bus voltage loop to calculate the error with the sampled value of the bus voltage, and the calculation result is sent to the PI controller; After limiting the output of the PI controller, it is used as the given value of the battery current loop, and the error is calculated with the sampled value of the current of the energy storage battery. The calculation result is sent to the PI controller; The PI controller sends the duty cycle output to the control signal generation module, which outputs the control signal corresponding to the bidirectional DC / DC unit.

7. The generator access control method of the energy storage power generation system according to claim 5, characterized in that The grid-connected control loop of the DC / AC unit includes a phase-locked loop, a bus voltage loop, an AC current loop, a dq transformation unit, and a control signal generation module; The sampled value of the grid voltage or the sampled value of the generator output voltage is used as the input of the phase-locked loop, and the corresponding phase and frequency are output; at the same time, the three-phase current and voltage on the AC side are converted into the corresponding active value, reactive value, and zero-sequence injection through the dq transformation unit; The given value of the bus voltage is used as the input of the bus voltage loop to calculate the error with the sampled value of the bus voltage. The calculation result is sent to the PI controller to output as the active given value of the AC current loop, and then the error is calculated with the transformed current active value. The calculation result is sent to the PI controller; The reactive given value of the AC current loop is calculated with the transformed current reactive value, and the calculation result is sent to the PI controller; The transformed voltage active value and voltage reactive value are respectively fed forward with the output result of the AC current loop; The two results after feed-forward and the zero-sequence injection are converted into a duty cycle through the dq transformation unit and sent to the control signal generation module, which outputs the control signal corresponding to the DC / AC unit.

8. The generator access control method of the energy storage power generation system according to claim 5, characterized in that, The off-grid control loop of the DC / AC unit includes a phase-locked loop, a voltage given value generation module, an output voltage loop, an output current loop, a dq transformation unit, and a control signal generation module; The sampled value of the generator output voltage is used as the input of the phase-locked loop, and the corresponding phase and frequency are output; at the same time, the three-phase current and voltage on the AC side are converted into the corresponding active value, reactive value, and zero-sequence through the dq transformation unit; The voltage and frequency that the energy storage converter needs to output are input to the voltage given value generation module, which is converted into the corresponding voltage active given value and voltage reactive given value of the output voltage loop; The output voltage loop calculates the error between the voltage active given value and the transformed voltage active value, and the calculation result is sent to the PI controller; The output result of the PI controller is used as the active given value of the output current loop, and the error is calculated with the transformed current active value. The calculation result is sent to the PI controller; At the same time, the output voltage loop calculates the error between the voltage reactive given value and the transformed voltage reactive value, and the calculation result is sent to the PI controller; the output result of the PI controller is used as the reactive given value of the output current loop, and the error is calculated with the transformed current reactive value. The calculation result is sent to the PI controller; The output result of the output current loop and the zero-sequence injection are converted into a duty cycle through the dq transformation unit and sent to the control signal generation module to output the control signal corresponding to the DC / AC unit.

9. The generator access control method for the energy storage power generation system according to any one of claims 1-8, characterized in that, The control switch adopts a selector switch. The AC side of the energy storage converter is respectively connected to the generator and the power grid through the control switch, and the load is connected between the output port of the energy storage converter and the control switch; When the energy storage converter supplies power to the load alone, the control switch keeps the connection with the generator disconnected; When the generator supplies power to the load, the control switch connects the generator to the AC side of the energy storage converter by closing.

10. The generator access control method of the energy storage power generation system according to any one of claims 1-8, characterized in that, Both the load and the generator are connected in parallel to the AC side of the energy storage converter through branches, and the control switch is arranged on the branch corresponding to the generator; When the energy storage converter supplies power to the load alone, the control switch remains open; When the generator supplies power to the load, the control switch connects the generator to the AC side of the energy storage converter by closing.

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