CN-121984003-A - Harmonic suppression method of energy storage grid-connected system and energy storage grid-connected system

CN121984003ACN 121984003 ACN121984003 ACN 121984003ACN-121984003-A

Abstract

The application provides a harmonic suppression method of an energy storage grid-connected system and the energy storage grid-connected system, and belongs to the technical field of harmonic suppression. The method comprises the steps of collecting three-phase electric energy information of grid connection points of an energy storage grid connection system in real time, determining harmonic current content according to the three-phase electric energy information, collecting three-phase current output by each energy storage converter in the energy storage grid connection system in real time if the harmonic current content of the grid connection points of the energy storage grid connection system does not meet a preset grid harmonic standard, determining n-time harmonic current corresponding to each energy storage converter based on the three-phase current output by each energy storage converter, generating a target driving signal based on the n-time harmonic current corresponding to each energy storage converter, and sending the target driving signal to each energy storage converter to control each energy storage converter to cooperatively execute harmonic suppression. The application can achieve the effect of dynamically adjusting the harmonic suppression strategy based on the real-time total harmonic distortion rate of the energy storage grid-connected system and the harmonic difference states of the plurality of energy storage converters so as to improve the harmonic suppression capability of the energy storage grid-connected system.

Inventors

FENG HONGYU
Ma Dongmao
YU JIAN
DAN CHEN

Assignees

宁夏宝丰昱能科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260206

Claims (10)

1. A method for harmonic suppression in an energy storage grid-connected system, the method being applied to a control module in the energy storage grid-connected system, the method comprising: Acquiring three-phase electric energy information of a grid-connected point of the energy storage grid-connected system in real time, and determining harmonic current content of the grid-connected point of the energy storage grid-connected system according to the three-phase electric energy information, wherein the three-phase electric energy information comprises three-phase current and three-phase voltage; If the harmonic current content of the grid connection point of the energy storage grid-connected system does not meet the preset power grid harmonic standard, acquiring three-phase current output by each energy storage converter in the energy storage grid-connected system in real time, and determining n times of harmonic current corresponding to each energy storage converter based on the three-phase current output by each energy storage converter, wherein n is a positive integer greater than zero; Generating a target driving signal based on the n-order harmonic current corresponding to each energy storage converter, and sending the target driving signal to each energy storage converter so as to control each energy storage converter to cooperatively execute harmonic suppression.
2. The method for suppressing harmonics of an energy storage grid-connected system according to claim 1, wherein the harmonic current content includes a total harmonic current content and an n-th harmonic current content, the collecting three-phase electric energy information of a grid-connected point of the energy storage grid-connected system in real time, and determining the harmonic current content of the grid-connected point of the energy storage grid-connected system according to the three-phase electric energy information includes: and carrying out harmonic analysis on the three-phase current and the three-phase voltage to determine the total harmonic current content and the n-order harmonic current content of the grid-connected point of the energy storage grid-connected system.
3. The method for harmonic suppression of an energy storage grid-connected system according to claim 1, wherein determining the n-th harmonic current corresponding to each energy storage converter based on the three-phase current of each energy storage converter comprises: respectively carrying out fundamental frequency filtering treatment on the three-phase currents of each energy storage converter so as to obtain total harmonic current components corresponding to each energy storage converter; Performing fundamental frequency phase locking processing on the three-phase current of each energy storage converter to obtain a baseband current phase corresponding to each energy storage converter; Based on the baseband current phase corresponding to each energy storage converter, carrying out coordinate transformation on the total harmonic current component corresponding to each energy storage converter so as to obtain the total harmonic current component corresponding to each energy storage converter after coordinate transformation; And carrying out harmonic extraction on the total harmonic current component after the coordinate transformation to obtain n-order harmonic current corresponding to each energy storage converter.
4. The method for suppressing harmonics of an energy storage grid-connected system according to claim 1, wherein said transmitting a target driving signal to each energy storage converter based on the n-th harmonic current corresponding to each energy storage converter comprises: Determining the reference harmonic current corresponding to each energy storage converter according to the n-order harmonic current corresponding to each energy storage converter; Generating harmonic compensation voltages corresponding to the energy storage converters according to the n-order harmonic currents and the reference harmonic currents corresponding to the energy storage converters, and carrying out coordinate inverse transformation on the harmonic compensation voltages to obtain three-phase compensation voltages corresponding to the energy storage converters; According to the three-phase current output by each energy storage converter, determining the corresponding three-phase reference voltage of each energy storage converter; And generating target driving signals corresponding to the energy storage converters according to the three-phase reference voltages and the three-phase compensation voltages corresponding to the energy storage converters, and sending the target driving signals to the corresponding energy storage converters.
5. The method for harmonic suppression of an energy storage grid-connected system according to claim 4, wherein the n-th harmonic current comprises an active harmonic current and a reactive harmonic current, the reference harmonic current comprises an active reference harmonic current and a reactive reference harmonic current, the harmonic compensation voltage comprises an active harmonic compensation voltage and a reactive harmonic compensation voltage, and the generating of the harmonic compensation voltage corresponding to each energy storage converter according to the n-th harmonic current and the reference harmonic current corresponding to each energy storage converter comprises: According to the active harmonic current and the active reference harmonic current corresponding to each energy storage converter, determining an active harmonic current difference value corresponding to each energy storage converter, and generating an active harmonic compensation voltage corresponding to each energy storage converter based on the active harmonic current difference value; And determining reactive harmonic current difference values corresponding to the energy storage converters according to reactive harmonic currents and reactive reference harmonic currents corresponding to the energy storage converters, and generating reactive harmonic compensation voltages corresponding to the energy storage converters based on the reactive harmonic current difference values.
6. The method for harmonic suppression of an energy storage grid-connected system according to claim 4, wherein generating the target driving signal corresponding to each energy storage converter according to the three-phase reference voltage and the three-phase compensation voltage corresponding to each energy storage converter comprises: Adding each phase of reference voltage contained in the three-phase reference voltage corresponding to the energy storage converter with each phase of compensation voltage contained in the three-phase compensation voltage corresponding to the energy storage converter respectively to obtain each phase of target voltage corresponding to the energy storage converter; and inputting the target voltages of the phases corresponding to the energy storage converters into the pulse width modulator to obtain target driving signals corresponding to the energy storage converters.
7. The method of harmonic rejection of an energy storage grid-tie system of claim 1, further comprising: and if the n-order harmonic current of the target energy storage converter is greater than or equal to a first preset threshold value, regulating down the reference harmonic current of at least one energy storage converter except the target energy storage converter according to a preset regulation strategy.
8. The method of harmonic rejection of an energy storage grid tie system according to claim 7, further comprising: if the n-order harmonic current of the target energy storage converter is greater than or equal to a second preset threshold value, generating a turn-off driving signal, and sending the turn-off driving signal to a switch corresponding to the target energy storage converter, so that the target energy storage converter is forced to be turned off, wherein the second preset threshold value is greater than the first preset threshold value.
9. The energy storage grid-connected system is characterized by comprising a plurality of energy storage converters, a control module, a plurality of switches and a plurality of energy storage batteries, wherein the switches and the energy storage batteries are in one-to-one correspondence with the energy storage converters; One end of each energy storage converter is connected with an external alternating current power grid through a switch, the other end of each energy storage converter is connected with an energy storage battery, and the control module is connected with a grid connection point, an output end of each energy storage converter, a control end of each energy storage converter and a control end of each switch; The control module is configured to perform the steps of the method for harmonic rejection of an energy storage grid-tie system as claimed in any one of claims 1 to 8.
10. The energy storage grid-tie system of claim 9, wherein the control module comprises a centralized controller, a judgment unit, a band reject filter, a coordinate transformer, a subtracter, an integral controller, an inverse coordinate transformer, an adder, a pulse width modulator, a power control unit, and a phase-locked loop; the first input end of the centralized controller is connected with grid connection points commonly connected with the energy storage converters, the second input end of the centralized controller, the input end of the phase-locked loop and the input end of the power control unit are all connected with the output end of each energy storage converter, the first output end of the centralized controller is connected with the input end of the judging unit, and the second output end of the centralized controller is connected with the control end of each switch; The output end of the judging unit is connected with the input end of the band-stop filter, the output end of the band-stop filter is connected with the first input end of the coordinate converter, and the second input end of the coordinate converter and the second input end of the coordinate inverse converter are both connected with the output end of the phase-locked loop; The first output end of the coordinate transformer and the third output end of the centralized controller are connected with the input end of one subtracter, the second output end of the coordinate transformer and the fourth output end of the centralized controller are connected with the input end of the other subtracter, the output end of each subtracter is respectively connected with the input end of one integral controller, the output end of each integral controller is connected with the first input end of the coordinate inverse transformer, the output end of the coordinate inverse transformer is connected with the first input end of the adder through the first input end of the adder, the output end of the power control unit is connected with the second input end of the adder, the output end of the adder is connected with the input end of the pulse width modulator, and the output end of the pulse width modulator is connected with the control end of each energy accumulator.

Description

Harmonic suppression method of energy storage grid-connected system and energy storage grid-connected system Technical Field The application relates to the technical field of harmonic suppression, in particular to a harmonic suppression method of an energy storage grid-connected system and the energy storage grid-connected system. Background With the increasing demands of renewable energy source large-scale grid connection and power systems for flexible regulation capability, electrochemical energy storage systems are widely applied to power generation sides, power grid sides and user sides due to the advantages of quick response and flexible configuration. The energy storage converter is used as core power conversion and control equipment of an electrochemical energy storage system, and the electric energy quality, particularly harmonic characteristic, of grid-connected operation directly influences the safe and stable operation of a power grid and the service life and efficiency of access equipment. However, under the operation condition that a plurality of energy storage converters are connected in parallel to the same common connection point, the energy storage converters have non-uniform superposition of amplitude and phase of current harmonic waves output by the energy storage converters due to factors such as power device parameter dispersion, battery charge difference, environment difference and the like, so that the total harmonic distortion rate of the grid-connected point is raised, and the electric energy quality and the safety of power electronic equipment are threatened. In the related art, the current harmonics of the parallel energy storage converters are usually suppressed in three ways, namely, a passive filter, an active filter or a hybrid filter is additionally arranged to filter or compensate specific times of harmonics, the current harmonics are suppressed in a software control method such as a virtual impedance method and droop control, and the higher harmonics generated in the inversion process of the multi-circuit topology circulation device are suppressed in a third way by injecting harmonic currents with specific frequencies into the circuit. However, when harmonic suppression is performed on the parallel energy storage converters in a plurality of modes disclosed in the related art, the modes are mainly focused on harmonic optimization of a single energy storage converter, and lack of cooperative observation and global control on the whole harmonic state of the grid-connected system leads to poor suppression effect in a parallel scenario of a plurality of energy storage converters. In addition, due to factors such as manufacturing process differences, inconsistent ageing degrees of devices, different charge states of batteries and the like, harmonic suppression requirements of a plurality of converters running in parallel are different, and differential harmonic suppression is difficult to realize by related technical schemes. Further, the related art solution cannot dynamically adjust the control strategy according to the actual total harmonic distortion rate of the grid-connected point, so that the harmonic suppression effect is poor. Disclosure of Invention The application aims to provide a harmonic suppression method of an energy storage grid-connected system and the energy storage grid-connected system, which can achieve the effect of dynamically adjusting a harmonic suppression strategy based on the real-time total harmonic distortion rate of the energy storage grid-connected system and the harmonic difference states of a plurality of energy storage converters so as to improve the harmonic suppression capability of the energy storage grid-connected system. Embodiments of the present application are implemented as follows: in a first aspect of the embodiment of the present application, a method for suppressing harmonics of an energy storage grid-connected system is provided, where the method is applied to a control module in the energy storage grid-connected system, and the method includes: Acquiring three-phase electric energy information of a grid-connected point of the energy storage grid-connected system in real time, and determining harmonic current content of the grid-connected point of the energy storage grid-connected system according to the three-phase electric energy information, wherein the three-phase electric energy information comprises three-phase current and three-phase voltage; if the harmonic current content of the grid-connected point of the energy storage grid-connected system does not meet the preset power grid harmonic standard, acquiring three-phase current output by each energy storage converter in the energy storage grid-connected system in real time, and determining n-th harmonic current corresponding to each energy storage converter based on the three-phase current output by each energy storage converter, wherein n is a positive integer greater tha