Reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation to improve photovoltaic power generation efficiency

Abstract

The present invention relates to the field of reactive power compensation, and specifically to a reactive power compensation method for a photovoltaic power generation system with energy storage and grid-connected power generation for improving the efficiency of photovoltaic power generation. The method includes a photovoltaic power generation system, an energy storage system, a photovoltaic power generation system with energy storage and grid-connected power generation, and a reactive power control unit for the photovoltaic power generation system with energy storage and grid-connected power generation. The control method can utilize the reactive power control unit of the photovoltaic power generation system with energy storage and grid-connected power generation to control the photovoltaic power generation system with energy storage and grid-connected power generation according to the power generation state of the photovoltaic power generation system and the SOC state of the energy storage system, according to the instructions of the superior dispatch, to emit reactive power according to the required reactive power setting value, and during the reactive power compensation period, the photovoltaic power generation system can generate electricity normally and store electric energy in the energy storage system, thereby avoiding the "abandonment of light" phenomenon and improving the power generation efficiency of photovoltaic power generation.

Description

Technical Field

[0001] The present invention relates to the technical field of reactive power compensation, and in particular to a reactive power compensation method for a photovoltaic storage grid-connected power generation system to improve the efficiency of photovoltaic power generation. Background Art

[0002] In recent years, my country has vigorously developed new energy power generation to replace traditional thermal power stations. Among them, photovoltaic power generation has attracted much attention due to its advantages such as less geographical restrictions, short construction period, and small footprint. Affected by changes in light intensity, photovoltaic power generation power shows intermittent, volatile, and random characteristics. With the large-scale access of photovoltaic power generation to the power grid, this fluctuating photovoltaic power generation power has posed a huge challenge to the frequency stability and voltage stability of the power grid. In order to ensure the stability of the power system and improve the absorption rate of new energy power generation, it is required to improve the new energy storage standard management system, combined with the needs of new power system construction, according to the needs of new energy power generation grid connection configuration and source-grid-load-storage integration. Therefore, in the future, it may become a mandatory requirement for new energy power generation to be equipped with energy storage, and the development of integrated photovoltaic storage units may become a future trend.

[0003] In addition, the national power department stipulates that reactive power compensation devices should be installed in places where low-voltage transformers are installed and next to large power-consuming equipment. However, the voltage level of photovoltaic power generation is usually low, and it needs to be connected to the power grid using a low-voltage transformer. Therefore, current photovoltaic power stations are generally equipped with reactive power compensation devices, which can optimize the power factor of the power grid and reduce the transmission loss of the power grid. On the other hand, it can help stabilize the voltage of the power grid and reduce the voltage fluctuation caused by the access of photovoltaic power stations.

[0004] Since the current photovoltaic grid-connected converter uses a switchable device, the active power and reactive power output by the photovoltaic grid-connected converter can be independently controlled by adjusting the amplitude of the photovoltaic grid-connected converter output voltage and the power angle difference between the system voltage. Based on the above principle, the photovoltaic grid-connected converter can be used to provide reactive power support for the system to save the capacity investment of the reactive power compensation equipment of the photovoltaic power station. However, due to the capacity constraints of the photovoltaic grid-connected converter, the photovoltaic grid-connected converter can only output less reactive power while outputting active power, such as Figure 1 shown.

[0005] Therefore, in order to increase the available reactive power compensation capacity of photovoltaic grid-connected converters, avoid the active power output loss of photovoltaic power stations, and improve the utilization rate of photovoltaic power generation, a reactive power compensation method is particularly needed that can increase the available reactive power compensation capacity of photovoltaic grid-connected converters while avoiding the active power output loss of photovoltaic power stations, so as to save the capacity investment of reactive power compensation equipment of photovoltaic power stations. Summary of the invention

[0006] In view of the above-mentioned prior art, the present invention provides a reactive power compensation method for a photovoltaic energy storage grid-connected power generation system for improving the efficiency of photovoltaic power generation, mainly to solve the technical problems existing in the above-mentioned background technology.

[0007] To achieve the above object, the technical solution of the embodiment of the present invention is implemented as follows:

[0008] A reactive power compensation method for a photovoltaic storage grid-connected power generation system for improving photovoltaic power generation efficiency, wherein the photovoltaic storage grid-connected power generation system comprises a photovoltaic power generation system, an energy storage system, a photovoltaic storage grid-connected converter and a reactive power control unit of the photovoltaic storage grid-connected power generation system, and the method comprises: when the photovoltaic storage grid-connected power generation system is required to output according to a reactive power reference value, the reactive power reference value is compared with a reactive power capacity value that can be currently emitted, and if the reactive power reference value is less than the reactive power capacity value, the photovoltaic storage grid-connected converter is controlled to emit reactive power according to the reactive power reference value;

[0009] If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is less than 90%, executing the first adjustment strategy;

[0010] If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is greater than 90%, the photovoltaic storage grid-connected converter is controlled not to generate additional reactive power;

[0011] When the photovoltaic storage grid-connected power generation system is required not to output reactive power reference value, the photovoltaic storage grid-connected converter is controlled not to output reactive power, and the energy storage system is controlled not to absorb the current photovoltaic power generation system output power.

[0012] Optionally, the reactive power capacity value that can be currently emitted is calculated, specifically including: obtaining the active power value output by the photovoltaic power generation system when it is in a normal power generation state, and the aforementioned reactive power control unit calculates the reactive power capacity value that can be emitted by the photovoltaic storage grid-connected converter based on the active power value using the power triangle method.

[0013] Optionally, the first regulation strategy includes: first allowing the energy storage system to absorb the active power generated by the current photovoltaic power generation system, and then controlling the photovoltaic storage grid-connected converter to generate reactive power according to the reactive power reference value.

[0014] Optionally, the energy storage system is composed of an energy storage battery, a Buck / Boost circuit, and an energy storage power controller. The control algorithm in the energy storage power controller absorbs excess output power by controlling the duty cycle of the electronic switching device. The control algorithm in the energy storage power controller is expressed as:

[0015]

[0016] in is the duty cycle of the power electronic switching device in the Buck / Boost circuit, is the reference value of energy storage power, is the output current of the Buck / Boost circuit, is the proportional coefficient of the PI controller of the energy storage power control algorithm, is the integral coefficient of the PI controller of the energy storage power control algorithm, represents the DC side voltage of the photovoltaic energy storage grid-connected converter, and s represents the Laplace operator.

[0017] Optionally, the photovoltaic energy storage grid-connected converter is composed of a DC / AC converter circuit and a constant DC voltage controller, and the control algorithm in the constant DC voltage controller realizes the regulation of reactive power through the control algorithm in the constant DC voltage controller, wherein the control algorithm in the constant DC voltage controller is expressed as:

[0018]

[0019] in, is the proportional coefficient of the outer loop PI controller, is the integral coefficient of the outer loop control PI controller, Indicates the DC side voltage reference value of the photovoltaic and energy storage grid-connected converter. is the proportional coefficient of the inner loop PI controller, is the integral coefficient of the inner loop control PI controller, is the component of the grid-connected point voltage of the DC / AC converter on the d-axis, is the q-axis component of the grid-connected point voltage of the DC / AC converter, It is expressed as the output angular velocity of the phase-locked loop of the photovoltaic power storage grid-connected converter, It is represented by the phase angle of the phase-locked loop output of the photovoltaic and energy storage grid-connected converter. It is represented by the LC filter inductance of the photovoltaic grid-connected converter. is the grid-connected current of the DC / AC converter, is the component of the grid-connected current of the DC / AC converter on the d-axis, is the component of the grid-connected current of the DC / AC converter on the q axis, is the transfer function of the variable from the abc coordinate system to the dq coordinate system, It is expressed as the reactive power reference value of the photovoltaic and energy storage grid-connected converter. It is expressed as the reactive power measurement value of the photovoltaic energy storage grid-connected converter. is the duty cycle of the power electronic switching device in the DC / AC converter circuit, is the d-axis component of the duty cycle of the power electronic switching device in the DC / AC converter circuit, is the component of the duty cycle of the power electronic switching device in the DC / AC converter circuit on the q axis, is the grid connection point voltage of the DC / AC converter.

[0020] Optionally, the photovoltaic power generation system is composed of a photovoltaic array, a Boost circuit and a photovoltaic power generation controller. The control algorithm in the photovoltaic power generation controller includes an MPPT control algorithm and a photovoltaic array outlet voltage control algorithm. The photovoltaic array outlet voltage control algorithm is used to adjust the active power value, wherein the photovoltaic array outlet voltage control algorithm is expressed as:

[0021]

[0022] in, is the duty cycle of the power electronic switching device in the Boost circuit, is the reference value of the PV array outlet voltage, is the measured value of the PV array outlet voltage, is the proportional coefficient of the PI controller of the photovoltaic array output voltage control algorithm, is the integral coefficient of the PI controller of the photovoltaic array outlet voltage control algorithm, This is the value calculated by the MPPT control algorithm.

[0023] The MPPT control algorithm adopts the disturbance observation method.

[0024] The beneficial effect of the present invention is that a reactive power compensation method for a photovoltaic energy storage grid-connected power generation system for improving photovoltaic power generation efficiency provided by an embodiment of the present invention can improve the available reactive power compensation capacity of the photovoltaic grid-connected inverter while avoiding the active power output loss of the photovoltaic power station, thereby saving the capacity investment of the reactive power compensation equipment of the photovoltaic power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a graph showing the relationship between the capacity of the photovoltaic grid-connected converter of the present invention and the active power and reactive power;

[0026] Figure 2 This is a structural diagram of the photovoltaic and energy storage integrated unit of the present invention;

[0027] Figure 3 It is the circuit topology and control algorithm of the photovoltaic power generation system of the present invention;

[0028] Figure 4 It is a circuit topology and control algorithm diagram of the energy storage system of the present invention;

[0029] Figure 5 It is a diagram of the photovoltaic energy storage grid-connected converter system and control algorithm of the present invention;

[0030] Figure 6The grid-connected voltage and current waveforms of the reactive power compensation method of the photovoltaic energy storage grid-connected power generation system proposed to improve the efficiency of photovoltaic power generation;

[0031] Figure 7 The grid-connected voltage and current waveforms of the reactive power compensation method of the traditional photovoltaic energy storage grid-connected power generation system. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further elaborated in detail below in conjunction with the drawings and specific embodiments of the specification. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In the following description, the expression "some embodiments" is related to a subset of all possible embodiments, but it should be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0033] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0034] It should be understood that the present invention can be implemented in different forms and should not be interpreted as being limited to the embodiments proposed herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and the scope of the present invention will be fully conveyed to those skilled in the art. And the purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present invention. When used herein, the singular forms of "one", "one" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. It should also be understood that the terms "compose" and / or "include" when used in this specification determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0035] It should also be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "inside", "outside", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0036] In order to fully understand the present invention, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0037] This application provides a method for reactive power compensation of a photovoltaic storage grid-connected power generation system to improve photovoltaic power generation efficiency. Figure 2 , wherein the photovoltaic storage grid-connected power generation system includes a photovoltaic power generation system, an energy storage system, a photovoltaic storage grid-connected converter and a photovoltaic storage grid-connected power generation system reactive power control unit, and the method includes: when the photovoltaic storage grid-connected power generation system is required to output according to a reactive power reference value, the reactive power reference value is compared with the reactive power capacity value that can be currently emitted, and if the reactive power reference value is less than the reactive power capacity value, the photovoltaic storage grid-connected converter is controlled to emit reactive power according to the reactive power reference value;

[0038] If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is less than 90%, executing the first adjustment strategy;

[0039] If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is greater than 90%, the photovoltaic storage grid-connected converter is controlled not to generate additional reactive power;

[0040] When the photovoltaic storage grid-connected power generation system is required not to output reactive power reference value, the photovoltaic storage grid-connected converter is controlled not to output reactive power, and the energy storage system is controlled not to absorb the current photovoltaic power generation system output power.

[0041] Among them, the photovoltaic power generation system and the energy storage system are connected through a DC circuit, and after being gathered together, they are connected to the DC side of the photovoltaic storage grid-connected inverter. The AC side of the photovoltaic storage grid-connected inverter is connected to the power grid. On the one hand, the reactive power control unit of the photovoltaic storage grid-connected power generation system can collect information from the photovoltaic power generation system, the energy storage system and the photovoltaic storage grid-connected inverter system. On the other hand, the reactive power control unit of the photovoltaic storage grid-connected power generation system can send control instructions to the photovoltaic power generation system, the energy storage system and the photovoltaic storage grid-connected inverter system to control the power output of the photovoltaic power generation system, the energy storage system and the photovoltaic storage grid-connected inverter system.

[0042] In an optional implementation, the reactive power capacity value that can be currently generated is calculated, specifically including: obtaining the active power value output by the photovoltaic power generation system when it is in a normal power generation state, and the reactive power control unit calculates the reactive power capacity value that can be generated by the photovoltaic storage grid-connected converter based on the active power value using the power triangle method.

[0043] In an AC power system, total power (also called apparent power) is the vector sum of active power and reactive power. These three quantities form a right triangle, called the power triangle, where active power represents the power actually consumed, reactive power represents the power that flows back and forth between inductive and capacitive elements without being consumed, and total power is the product of current and voltage.

[0044] In the power triangle, the relationship between active power P, reactive power Q, and total power S follows the Pythagorean theorem:

[0045]

[0046] In actual calculation, the total power usually adopts the rated power of the equipment. In this way, the reactive power control unit can calculate the reactive power capacity value that the photovoltaic storage grid-connected converter can generate based on the real-time active power output of the photovoltaic power generation system and the maximum rated power capacity of the photovoltaic storage grid-connected converter. This value will then be used in the subsequent reactive power control strategy to ensure that the system can respond to the superior dispatching instructions and provide sufficient reactive power support when necessary.

[0047] In an optional embodiment, the first regulation strategy includes: first allowing the energy storage system to absorb the active power generated by the current photovoltaic power generation system, that is, absorbing and storing excess electric energy through the energy storage system, and then controlling the photovoltaic storage grid-connected converter to generate reactive power according to the reactive power reference value.

[0048] In an optional implementation, the energy storage system is composed of an energy storage battery, a Buck / Boost circuit, and an energy storage power controller. The control algorithm in the energy storage power controller absorbs excess output power by controlling the duty cycle of the electronic switching device. The control algorithm in the energy storage power controller is expressed as:

[0049]

[0050] in is the duty cycle of the power electronic switching device in the Buck / Boost circuit, is the reference value of energy storage power, is the output current of the Buck / Boost circuit, is the proportional coefficient of the PI controller of the energy storage power control algorithm, is the integral coefficient of the PI controller of the energy storage power control algorithm, represents the DC side voltage of the photovoltaic energy storage grid-connected converter, and s represents the Laplace operator.

[0051] Specifically, the output current and the outlet voltage of the Buck / Boost circuit are collected, the output power reference value of the energy storage battery is divided by the outlet voltage of the Buck / Boost circuit to obtain the output current reference value of the Buck / Boost circuit, the difference between the output current reference value of the Buck / Boost circuit and the output current measurement value of the Buck / Boost circuit is compared and sent to the energy storage power control algorithm PI controller to obtain the duty cycle of the power electronic switching device of the Buck / Boost circuit, and the power electronic switching device of the Buck / Boost circuit is controlled by using the duty cycle of the power electronic switching device of the Buck / Boost circuit to achieve the purpose of controlling the output power of the energy storage battery.

[0052] In an optional implementation, the photovoltaic energy storage grid-connected converter is composed of a DC / AC converter circuit and a constant DC voltage controller, and the control algorithm in the constant DC voltage controller realizes the regulation of reactive power through the control algorithm in the constant DC voltage controller, wherein the control algorithm in the constant DC voltage controller is expressed as:

[0053]

[0054] in, is the proportional coefficient of the outer loop PI controller, is the integral coefficient of the outer loop control PI controller, Indicates the DC side voltage reference value of the photovoltaic and energy storage grid-connected converter. is the proportional coefficient of the inner loop PI controller, is the integral coefficient of the inner loop control PI controller, is the component of the grid-connected point voltage of the DC / AC converter on the d-axis, is the q-axis component of the grid-connected point voltage of the DC / AC converter, It is expressed as the output angular velocity of the phase-locked loop of the photovoltaic power storage grid-connected converter, It is represented by the phase angle of the phase-locked loop output of the photovoltaic and energy storage grid-connected converter. It is represented by the LC filter inductance of the photovoltaic grid-connected converter. is the grid-connected current of the DC / AC converter, is the component of the grid-connected current of the DC / AC converter on the d-axis, is the component of the grid-connected current of the DC / AC converter on the q axis, is the transfer function of the variable from the abc coordinate system to the dq coordinate system, It is expressed as the reactive power reference value of the photovoltaic and energy storage grid-connected converter. It is expressed as the reactive power measurement value of the photovoltaic energy storage grid-connected converter. is the duty cycle of the power electronic switching device in the DC / AC converter circuit, is the component of the duty cycle of the power electronic switching device in the DC / AC converter circuit on the d-axis, is the component of the duty cycle of the power electronic switching device in the DC / AC converter circuit on the q axis, is the grid connection point voltage of the DC / AC converter.

[0055] Specifically, by collecting the DC side voltage of the DC / AC converter, the grid connection point voltage of the DC / AC converter and the grid connection current of the DC / AC converter, the grid connection point voltage of the DC / AC converter and the grid connection current of the DC / AC converter are converted from the abc coordinate system to the dq coordinate system, and the DC side voltage measurement value of the DC / AC converter is compared with the DC side voltage reference value of the DC / AC converter and sent to the outer loop control PI controller to obtain the d-axis component of the inner loop current reference value. The reactive power measurement value of the DC / AC converter is calculated by the grid connection point voltage of the DC / AC converter and the grid connection current of the DC / AC converter, and the reactive power measurement value of the DC / AC converter is compared with the reactive power reference value of the DC / AC converter and sent to the outer loop control PI controller to obtain the q-axis component of the inner loop current reference value. The d-axis component and q-axis component of the inner loop current reference value are compared with the d-axis component and q-axis component of the grid-connected current of the DC / AC converter, and then sent to the inner loop control PI controller to obtain the d-axis and q-axis components of the duty cycle of the power electronic switch device of the DC / AC converter circuit. The DC / AC converter is controlled by the duty cycle of the power electronic switch device of the DC / AC converter circuit to achieve the purpose of controlling the DC side voltage stability of the DC / AC converter and the grid-connected power generation of the DC / AC converter, and to achieve the purpose of output regulation of reactive power regulation.

[0056] In an optional embodiment, the photovoltaic power generation system is composed of a photovoltaic array, a Boost circuit and a photovoltaic power generation controller. The control algorithm in the photovoltaic power generation controller includes an MPPT control algorithm and a photovoltaic array outlet voltage control algorithm. The active power value is adjusted by the photovoltaic array outlet voltage control algorithm, wherein the photovoltaic array outlet voltage control algorithm is expressed as:

[0057]

[0058] in, is the duty cycle of the power electronic switching device in the Boost circuit, is the reference value of the PV array outlet voltage, is the measured value of the PV array outlet voltage, is the proportional coefficient of the PI controller of the photovoltaic array output voltage control algorithm, is the integral coefficient of the PI controller of the photovoltaic array outlet voltage control algorithm, This is the value calculated by the MPPT control algorithm.

[0059] Specifically, the outlet voltage of the photovoltaic array is collected, and the difference between the measured value of the photovoltaic array outlet voltage and the reference value of the photovoltaic array outlet voltage is compared and sent to the photovoltaic array outlet voltage control algorithm PI controller to obtain the duty cycle of the power electronic switching device of the Boost boost circuit. The power electronic switching device of the Boost boost circuit is controlled by the duty cycle of the power electronic switching device of the Boost boost circuit to achieve control of the photovoltaic array outlet voltage regulation, and ultimately achieve the purpose of regulating the active power value of the photovoltaic power generation system through outlet voltage regulation.

[0060] Furthermore, the MPPT control algorithm adopts the disturbance observation method.

[0061] In order to further demonstrate the implementation effect of the present invention, a comparative simulation is conducted on the reactive power compensation method for a photovoltaic grid-connected power generation system with photovoltaic storage that improves photovoltaic power generation efficiency and the reactive power compensation method for a traditional photovoltaic grid-connected power generation system with photovoltaic storage. When photovoltaic power generation is normal, the superior dispatcher requires the photovoltaic output reactive power to be 1 (pu).

[0062] Figure 6-Figure 7 The grid-connected voltage and current waveforms of the proposed reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation system to improve photovoltaic power generation efficiency are compared with those of the traditional reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation system. Figure 6 The grid-connected voltage and current waveforms of the reactive power compensation method of the photovoltaic energy storage grid-connected power generation system proposed to improve the efficiency of photovoltaic power generation. Figure 7 The grid-connected voltage and current waveforms of the reactive power compensation method of the traditional photovoltaic storage grid-connected power generation system are shown in Figure 2. By comparison, it can be seen that the proposed reactive power compensation method for the photovoltaic storage grid-connected power generation system to improve the efficiency of photovoltaic power generation can transfer active power to energy storage when photovoltaic power generation is normal, so that the photovoltaic storage grid-connected converter system can output reactive power according to the maximum reactive power value, thus saving the capacity investment of the reactive power compensation equipment of the photovoltaic power station. In contrast, the reactive power compensation method of the traditional photovoltaic storage grid-connected power generation system makes the output current of the photovoltaic storage grid-connected converter system exceed 1.1 (pu), which will damage the power electronic switching devices in the photovoltaic storage grid-connected converter system.

[0063] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. The protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A reactive power compensation method for a photovoltaic energy storage grid-connected power generation system for improving photovoltaic power generation efficiency, characterized in that: The photovoltaic storage grid-connected power generation system comprises a photovoltaic power generation system, an energy storage system, a photovoltaic storage grid-connected converter and a photovoltaic storage grid-connected power generation system reactive power control unit, and the method comprises: when the photovoltaic storage grid-connected power generation system is required to output according to a reactive power reference value, the reactive power reference value is compared with a reactive power capacity value that can be currently emitted, and if the reactive power reference value is less than the reactive power capacity value, the photovoltaic storage grid-connected converter is controlled to emit reactive power according to the reactive power reference value; If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is less than 90%, executing a first regulation strategy; If the reactive power reference value is greater than the reactive power capacity value and the SOC value of the energy storage system is greater than 90%, the photovoltaic storage grid-connected converter is controlled not to generate additional reactive power; When the photovoltaic storage grid-connected power generation system is required not to output reactive power reference value, the photovoltaic storage grid-connected converter is controlled not to output reactive power, and the energy storage system is controlled not to absorb the current photovoltaic power generation system output power; The first regulation strategy includes: firstly allowing the energy storage system to absorb the active power generated by the current photovoltaic power generation system, and then controlling the photovoltaic storage grid-connected converter to generate reactive power according to the reactive power reference value; The energy storage system is composed of an energy storage battery, a Buck / Boost circuit and an energy storage power controller. The control algorithm in the energy storage power controller absorbs the excess output power by controlling the duty cycle of the electronic switching device. The control algorithm in the energy storage power controller is expressed as: where d bat is the duty cycle of the power electronic switching device in the Buck / Boost circuit, P bat_ref is the energy storage power reference value, i bat is the output current of the Buck / Boost circuit, K pbat is the proportional coefficient of the PI controller of the energy storage power control algorithm, K ibat is the integral coefficient of the PI controller of the energy storage power control algorithm, u dc represents the DC side voltage of the photovoltaic power storage grid-connected converter, and s represents the Laplace operator; The photovoltaic energy storage grid-connected converter is composed of a DC / AC converter circuit and a constant DC voltage controller. The control algorithm in the constant DC voltage controller is used to adjust the reactive power. The control algorithm in the constant DC voltage controller is expressed as: Among them, K po is the proportional coefficient of the outer loop control PI controller, K io is the integral coefficient of the outer loop control PI controller, u dc_ref Indicates the DC side voltage reference value of the photovoltaic and energy storage grid-connected converter, K pi is the proportional coefficient of the inner loop PI controller, K ii is the integral coefficient of the inner loop control PI controller, u pd is the d-axis component of the grid-connected point voltage of the DC / AC converter, u pq is the component of the grid-connected point voltage of the DC / AC converter on the q axis, ω PLL It is expressed as the output angular velocity of the phase-locked loop of the photovoltaic power storage grid-connected converter, θ PLL It is represented by the phase angle of the phase-locked loop output of the photovoltaic power storage grid-connected converter, L f Represents the LC filter inductance of the photovoltaic power storage grid-connected converter, i abc is the grid-connected current of the DC / AC converter, i d is the component of the grid-connected current of the DC / AC converter on the d-axis, i q is the component of the grid-connected current of the DC / AC converter on the q axis, T abc / dq (θ PLL ) is the transfer function of the variable from the abc coordinate system to the dq coordinate system, Q ref It represents the reactive power reference value of the photovoltaic and energy storage grid-connected converter, Q represents the reactive power measurement value of the photovoltaic and energy storage grid-connected converter, and d abc is the duty cycle of the power electronic switching device in the DC / AC converter circuit, d d is the component of the duty cycle of the power electronic switching device in the DC / AC converter circuit on the d-axis, d q is the q-axis component of the duty cycle of the power electronic switching device in the DC / AC converter circuit, u pabc is the grid connection point voltage of the DC / AC converter.

2. The reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation system for improving photovoltaic power generation efficiency according to claim 1 is characterized in that: Calculating the reactive power capacity value that can be currently generated specifically includes: obtaining the active power value output by the photovoltaic power generation system when it is in a normal power generation state, and the reactive power control unit uses the power triangle method to calculate the reactive power capacity value that can be generated by the photovoltaic storage grid-connected converter based on the active power value.

3. The reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation system for improving photovoltaic power generation efficiency according to claim 2 is characterized in that: The photovoltaic power generation system is composed of a photovoltaic array, a Boost circuit and a photovoltaic power generation controller. The control algorithm in the photovoltaic power generation controller includes an MPPT control algorithm and a photovoltaic array outlet voltage control algorithm. The photovoltaic array outlet voltage control algorithm is used to adjust the active power value. The photovoltaic array outlet voltage control algorithm is expressed as: Among them, d PV is the duty cycle of the power electronic switch device in the Boost circuit, u PV_ref is the reference value of the photovoltaic array outlet voltage, u PV is the measured value of the PV array outlet voltage, K pPV is the proportional coefficient of the PI controller of the photovoltaic array output voltage control algorithm, K iPV is the integral coefficient of the PI controller of the photovoltaic array output voltage control algorithm, u PV_ref This is the value calculated by the MPPT control algorithm.

4. The reactive power compensation method for photovoltaic power generation system with energy storage and grid-connected power generation system for improving photovoltaic power generation efficiency according to claim 3 is characterized in that: The MPPT control algorithm adopts the disturbance observation method.

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