Electric energy quality treatment method and device, computer equipment, readable storage medium and program product

Abstract

The invention relates to an electric energy quality treatment method and device, computer equipment, a computer readable storage medium and a computer program product. The method comprises the following steps: analyzing the voltage of a common coupling point during a fault period, and determining a positive and negative sequence current expression for voltage support; when the voltage drops below a preset value, calculating positive and negative sequence current required by voltage support based on the current expression, and comparing the positive and negative sequence current with rated current of a slave inverter; if the positive and negative sequence current is greater than the rated current of the slave inverter, determining that the slave inverter cannot independently realize voltage support, and controlling the master inverter and the slave inverter to jointly realize voltage support; and if the current capacity of the main inverter remains after the voltage support is realized, the remaining capacity of the main inverter is used for transmitting active power. By adopting the method, voltage support can be carried out in a fault scene, reactive power injection is realized, and the quality of power output by a power grid during a fault period is improved.

Description

Technical Field

[0001] The present application relates to the field of electric power engineering technology, and in particular to a method, device, computer equipment, computer-readable storage medium and computer program product for power quality management. Background Art

[0002] With the widespread application of distributed power sources, power quality management under fault conditions has become a very meaningful research topic. Common fault types are roughly divided into two categories: symmetrical faults and asymmetrical faults, of which asymmetrical faults account for 89%. When an asymmetrical fault occurs in the power grid, since the grid voltage and current usually contain positive and negative sequence components, the use of traditional grid-connected control strategies often leads to a sharp increase in inverter current; the interaction between positive and negative sequence voltages and currents will produce active power double frequency fluctuations, which in turn leads to DC bus voltage fluctuations and third harmonic currents, which may cause DC bus overvoltage or grid pollution in severe cases. Therefore, it is necessary to study the power quality management strategy during grid voltage drop faults.

[0003] In most current studies, a fixed control target is used for mathematical derivation to obtain the reference value of the grid-connected current. For example, the negative sequence component of the current is set to zero to obtain a three-phase symmetrical grid-connected current. However, once a certain target is selected, it corresponds to a unique current reference value. At this time, the remaining targets cannot be achieved and the goal of high power quality output cannot be met. Therefore, new strategies are needed to achieve reactive power injection and transmit active power to improve the power quality of the grid output during faults. Summary of the invention

[0004] Based on this, it is necessary to provide a power quality management method, device, computer equipment, computer-readable storage medium and computer program product that can take into account both reactive power injection and active power transmission in order to address the above technical problems.

[0005] In a first aspect, the present application provides a method for power quality management, comprising:

[0006] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0007] When the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0008] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0009] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0010] In one embodiment, determining a current expression for voltage support includes:

[0011] Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during a fault;

[0012] Determine positive and negative sequence voltage expressions based on the voltage condition and the maximum and minimum voltage expressions;

[0013] Based on the positive and negative sequence voltage expressions and the rated voltage of the power grid, the positive and negative sequence current expressions for voltage support are determined.

[0014] In one embodiment, controlling the master inverter and the slave inverter to jointly implement voltage support includes:

[0015] Determining a minimum voltage support coefficient according to the current required for the voltage support and the rated current of the slave inverter;

[0016] Determining a current reference value of a slave inverter according to the minimum voltage support coefficient and the current expression;

[0017] The current reference value of the master inverter is determined according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, the master inverter and the slave inverter are controlled to jointly achieve voltage support.

[0018] In one of the embodiments, determining a minimum voltage support coefficient according to the positive and negative sequence currents required for the voltage support and the rated current, and determining a current reference value of a slave inverter according to the minimum voltage support coefficient and the current expression, comprises:

[0019] Determine an initial voltage support coefficient, and use the initial voltage support coefficient as the current voltage support coefficient;

[0020] Determine a current current reference value according to the current voltage support coefficient and the current expression;

[0021] If the current reference value is not greater than the rated current of the slave inverter, the voltage support coefficient is not equal to the first preset value, and the current reference value is not less than the rated current of the slave inverter at a preset multiple, the current reference value is used as the current reference value of the slave inverter.

[0022] In one embodiment, the method further comprises:

[0023] If the current positive and negative sequence current is greater than the rated current of the slave inverter, subtract the second preset value from the current voltage support coefficient, and return to determine the current current reference value according to the current voltage support coefficient and the current expression;

[0024] If the current positive and negative sequence currents are not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter;

[0025] If the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, then the current voltage support coefficient is added to the third preset value, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0026] In one embodiment, the method further comprises:

[0027] If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

[0028] In a second aspect, the present application also provides a power quality management device, comprising:

[0029] An analysis module for analyzing the voltage at the common coupling point during a fault and determining the positive and negative sequence current expressions for voltage support;

[0030] A comparison module, configured to calculate the positive and negative sequence currents required for voltage support based on the current expression when the voltage drops to a preset value, and compare the positive and negative sequence currents with the rated current of the slave inverter;

[0031] A support module, configured to determine that the slave inverter cannot independently achieve voltage support if the positive and negative sequence currents are greater than the rated current of the slave inverter, and control the master inverter and the slave inverter to jointly achieve voltage support;

[0032] The transmission module is used to use the remaining capacity of the main inverter to transmit active power if the current capacity of the main inverter is still remaining after achieving voltage support.

[0033] In a third aspect, the present application further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0034] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0035] When the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0036] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0037] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0038] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0039] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0040] When the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0041] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0042] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0043] In a fifth aspect, the present application further provides a computer program product, including a computer program, which implements the following steps when executed by a processor:

[0044] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0045] When the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0046] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0047] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0048] The above-mentioned power quality management method, device, computer equipment, computer-readable storage medium and computer program product first analyze the voltage at the common coupling point during the fault period and determine the positive and negative sequence current expressions for voltage support; when the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter; if the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the main inverter and the slave inverter are controlled to jointly achieve voltage support; if the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power. By limiting the inverter current and quantitatively describing the compensation of the main inverter and the slave inverter in the fault scenario, reactive power injection and active power transmission are achieved to improve the power quality of the power grid output during the fault period. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0050] Figure 1 An application environment diagram of a power quality management method in an embodiment;

[0051] Figure 2 A schematic diagram of a flow chart for determining a minimum voltage support coefficient in one embodiment;

[0052] Figure 3 A schematic diagram of a process for determining a residual flow of a main inverter in one embodiment;

[0053] Figure 4 is a structural block diagram of a power quality management device in one embodiment;

[0054] Figure 5 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0056] In one embodiment, Figure 1 As shown, a power quality management method is provided. This embodiment uses the method applied to a terminal as an example. It can be understood that the method can also be applied to a server, and can also be applied to a system including a terminal and a server, and is implemented through the interaction between the terminal and the server.

[0057] In this embodiment, the method includes the following steps:

[0058] Step 102: Analyze the voltage at the common coupling point during the fault period and determine the positive and negative sequence current expressions for voltage support.

[0059] Among them, the common coupling point, also known as the Point of Common Coupling (PCC), is the connection point of more than one user load in the power system.

[0060] Exemplarily, the voltage at the common coupling point during the fault is analyzed, and the positive sequence current expression and the negative sequence current expression for voltage support are determined respectively.

[0061] Step 104: when the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter.

[0062] Among them, voltage support refers to ensuring that the voltage of key nodes in the power system remains within the specified range through certain technical means, thereby ensuring the stable operation of the power system and maintaining the quality of power energy.

[0063] Among them, positive sequence current and negative sequence current are concepts in power system analysis, which are used to describe the asymmetry phenomenon in three-phase power systems. In a symmetrical three-phase system, the phase relationship of current or voltage is the same as the system benchmark, which is called positive sequence current. When the three-phase currents have the same phase angle and equal magnitude, but are arranged in reverse order according to CBA, it is called negative sequence current.

[0064] Optionally, the preset value is determined by the rated voltage of the common coupling point.

[0065] Exemplarily, when the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the sum of the positive and negative sequence currents is compared with the rated current of the slave inverter.

[0066] Step 106: If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support.

[0067] Exemplarily, if the sum of the positive and negative sequence currents is greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support.

[0068] Step 108: If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0069] For example, if the current capacity of the main inverter still has residual capacity after achieving the voltage support function, the expression of output power obtained by analysis is:

[0070]

[0071] Among them I d2 + The d-axis positive sequence current outputted by the main inverter, i.e. the current used to output active power, C is:

[0072]

[0073] in is the maximum active power fluctuation.

[0074] The above-mentioned power quality management method, device, computer equipment, computer-readable storage medium and computer program product first analyze the voltage at the common coupling point during the fault period and determine the positive and negative sequence current expressions for voltage support; when the voltage drops to a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter; if the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the main inverter and the slave inverter are controlled to jointly achieve voltage support; if the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power. By limiting the inverter current and quantitatively describing the compensation of the main inverter and the slave inverter in the fault scenario, reactive power injection and active power transmission are achieved to improve the power quality of the power grid output during the fault period.

[0075] In an exemplary embodiment, determining a current expression for voltage support includes: analyzing voltage conditions and maximum and minimum voltage expressions that need to be satisfied at a common coupling point during a fault; determining positive and negative sequence voltage expressions based on the voltage conditions and maximum and minimum voltage expressions; and determining positive and negative sequence current expressions for voltage support based on the positive and negative sequence voltage expressions and the rated voltage of the grid.

[0076] Among them, positive sequence voltage refers to the voltage in the three-phase AC power system, where the phases of the voltages differ by 120 degrees and conform to the ABC phase sequence. In this phase sequence, the voltage of phase A leads that of phase B, the voltage of phase B leads that of phase C, and the voltage of phase C leads that of phase A. Negative sequence voltage refers to the voltage of the three-phase voltage, where the phases of the voltages differ by 120 degrees, but the phase sequence is opposite to the positive sequence, that is, the voltage of phase A lags behind that of phase B, the voltage of phase B lags behind that of phase C, and the voltage of phase C lags behind that of phase A. Negative sequence voltage usually occurs when an asymmetric fault occurs in the system.

[0077] Exemplarily, based on the analysis of the PCC point voltage during the fault period, the principle of voltage support is obtained, and the calculation formula is as follows:

[0078] U PCC + =U g + +ωL g I q +

[0079] U PCC - =U g - -ωL g I q -

[0080] Among them, + represents the positive sequence component, - represents the negative sequence component, U PCC + Indicates the positive sequence voltage at PCC point, U PCC - Indicates the negative sequence voltage at the PCC point. The conditions that the PCC voltage needs to meet are:

[0081]

[0082] Among them U a , U b , U c They are the three-phase voltages at PCC points abc respectively. Further analysis shows that the grid connection point voltage can be expressed as:

[0083]

[0084] Among them U + , U - are the positive and negative sequence voltage amplitudes at the PCC point respectively; where σ and η are:

[0085]

[0086] in is the initial phase difference between the positive and negative sequence voltages at the PCC point. Combined with the conditions that the PCC voltage needs to meet, the expression of the positive and negative sequence voltage is determined as:

[0087]

[0088] Where A and B are:

[0089]

[0090] Among them U N is the rated voltage of the power grid, so the current expression for voltage support is:

[0091]

[0092] Among them U + , U - are the positive and negative sequence voltages of the power grid respectively; I q + , I q - are respectively the positive and negative sequence components of the inverter output current on the q axis; ωL g is the grid impedance.

[0093] In this embodiment, by analyzing and obtaining the current expression for voltage support, the current required to maintain voltage stability can be easily obtained, so that the corresponding current can be accurately used to achieve voltage support.

[0094] In an exemplary embodiment, a master inverter and a slave inverter are controlled to jointly achieve voltage support, including: determining a minimum voltage support coefficient based on a current required for voltage support and a rated current of the slave inverter; determining a current reference value of the slave inverter based on the minimum voltage support coefficient and a current expression; determining a current reference value of the master inverter based on the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, controlling the master inverter and the slave inverter to jointly achieve voltage support.

[0095] Exemplarily, the minimum voltage support coefficient m is determined according to the current required for voltage support and the rated current of the inverter, and new A and B are obtained according to m as follows:

[0096]

[0097] Determine the positive and negative sequence current reference value I from the inverter based on the new A, B and current expressions q + and I q - , that is, the q-axis current that needs to be provided by the inverter.

[0098] The current reference value of the master inverter is determined according to the current reference value of the slave inverter and the current required for voltage support. The formula is as follows:

[0099]

[0100] Among them I q +* , I q -* To support the voltage to [0.85U N ,1.1U N ]Required q-axis current, I q2 + , I q2 - The q-axis current that needs to be provided by the main inverter.

[0101] Based on the q-axis current that the slave inverter needs to provide and the q-axis current that the master inverter needs to provide, the master inverter and the slave inverter are controlled to output corresponding currents to jointly achieve voltage support.

[0102] In this embodiment, the voltage drop problem under severe faults is solved by controlling the master and slave inverters to jointly implement voltage support, thereby effectively protecting the safety of the system.

[0103] In an exemplary embodiment, Figure 2 As shown, the minimum voltage support coefficient is determined according to the positive and negative sequence currents and the rated current required for voltage support, and the current reference value of the slave inverter is determined according to the minimum voltage support coefficient and the current expression, including: determining the initial voltage support coefficient, and taking the initial voltage support coefficient as the current voltage support coefficient; determining the current current reference value according to the current voltage support coefficient and the current expression; if the current current reference value is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current current reference value is not less than the rated current of the slave inverter with a preset multiple, then the current current reference value is used as the current reference value of the slave inverter.

[0104] Optionally, the initial voltage support coefficient may be 0.1, the first preset value may be 1, and the preset ratio may be 0.99.

[0105] For example, the initial voltage support coefficient 0.1 is determined as the current voltage support coefficient, and the current positive and negative sequence current reference value I corresponding to the current voltage support coefficient is calculated according to the current voltage support coefficient and the current expression. q + and I q - If the sum of the current positive and negative sequence current reference values ​​is not greater than the rated current I rate, and the current voltage support coefficient is not equal to 1, and the sum of the current positive and negative sequence current reference values ​​is not less than 0.99 times the rated current of the slave inverter, the current positive and negative sequence current reference value is used as the current reference value of the slave inverter, that is, the q-axis current used for voltage support in the slave inverter.

[0106] In this embodiment, when the master and slave inverters work together, the voltage support coefficient is used to determine the current size used for voltage support in the slave inverter, and then the current value used for voltage support in the master inverter can be obtained, and the current that can be used to output active power in the master inverter can be accurately obtained.

[0107] In an exemplary embodiment, Figure 2 As shown, the method also includes: if the current positive and negative sequence current is greater than the rated current of the slave inverter, the current voltage support coefficient is subtracted from the second preset value, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, the current voltage support coefficient is added to the third preset value, and the current current reference value is returned according to the current voltage support coefficient and the current expression.

[0108] Optionally, the second preset value may be 0.01, and the third preset value may be 0.1.

[0109] Exemplarily, if the sum of the current positive and negative sequence currents is greater than the rated current of the slave inverter, the current voltage support coefficient is subtracted by 0.01, and the current positive and negative sequence current reference value determined according to the current voltage support coefficient and the current expression is returned; if the sum of the current positive and negative sequence current reference values ​​is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to 1, the current positive and negative sequence current reference value is used as the current reference value of the slave inverter; if the sum of the current positive and negative sequence current reference values ​​is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to 1, and the sum of the current positive and negative sequence current reference values ​​is less than 0.99 times the rated current of the slave inverter, then the current voltage support coefficient is added by 0.1, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0110] In this embodiment, by maximizing the q-axis positive and negative sequence currents of the slave inverter for voltage support, the current of the master inverter for voltage support can be reduced as much as possible, so that more current capacity of the master inverter can be used to transmit active power.

[0111] In an exemplary embodiment, the method further includes: if the positive and negative sequence currents are not greater than the rated current of the slave inverter, determining that the slave inverter can independently achieve voltage support, controlling the use of the slave inverter to achieve voltage support, and using the master inverter to transmit active power.

[0112] Exemplarily, if the positive and negative sequence currents required for voltage support are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, the slave inverter is controlled to independently achieve voltage support, and then the master inverter is used to transmit active power.

[0113] In this embodiment, when the slave inverter can independently realize voltage support, the master inverter is controlled to transmit active power, which can effectively suppress the fluctuation of active power.

[0114] In an exemplary embodiment, Figure 3 As shown, if the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power, including: The expression of output power obtained by analysis is:

[0115]

[0116] Among them I d2 + The d-axis positive sequence current outputted by the main inverter, i.e. the current used to output active power, C is:

[0117]

[0118] in is the maximum active power fluctuation.

[0119] First, let Determine whether k is greater than 0. When k is greater than 0, determine the maximum current I of the main inverter max Is it in the interval (I rate1 , 1.2I rate1 ), where I rate1 is the rated current of the main inverter; if I max Not in the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + +1, then return to determine the maximum current I of the main inverter max Is it in the interval (I rate1 , 1.2I rate1 ); if I max Belong to the interval (I rate1 , 1.2I rate1 ), then let Id2 + =I d2 + -1, then judge I max Is it in the interval (I rate1 , 1.2I rate1 ), if I max Belong to the interval (I rate1 , 1.2I rate1 ), then return to I d2 + =I d2 + -1; if I max Not in the interval (I rate1 , 1.2I rate1 ), then the output I d2 + When k is not greater than 0, the maximum current I of the main inverter is determined. max Is it in the interval (I rate1 , 1.2I rate1 ), where I rate1 is the rated current of the main inverter; if I max Not in the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + -1, and then return to determine the maximum current I of the main inverter max Is it in the interval (I rate1 , 1.2I rate1 ); if I max Belong to the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + +1, then judge I max Is it in the interval (I rate1 , 1.2I rate1 ), if I max Belong to the interval (I rate1 , 1.2I rate1 ), then return to I d2 + =I d2 + +1; if I max Not in the interval (I rate1 , 1.2I rate1 ), then the output I d2 + Among them, the maximum current of the main inverter I maxIt is composed of the q-axis positive and negative sequence current and the d-axis positive and negative sequence current of the main inverter.

[0120] In an exemplary embodiment, Figure 4 As shown in the figure, based on the analysis of the PCC point voltage during the fault period, the principle of voltage support is obtained, and the calculation formula is as follows:

[0121] U PCC + =U g + +ωL g I q +

[0122] U PCC - =U g - -ωL g I q -

[0123] Among them, + represents the positive sequence component, - represents the negative sequence component, U PCC + Indicates the positive sequence voltage at PCC point, U PCC - indicates the negative sequence voltage at the PCC point. The conditions that the PCC voltage needs to meet are:

[0124]

[0125] Among them U a , U b , U c They are the three-phase voltages at PCC points abc respectively. Further analysis shows that the grid connection point voltage can be expressed as:

[0126]

[0127] Among them U + , U - are the positive and negative sequence voltage amplitudes at the PCC point respectively; where σ and η are:

[0128]

[0129] in is the initial phase difference between the positive and negative sequence voltages at the PCC point. Combined with the conditions that the PCC voltage needs to meet, the expression of the positive and negative sequence voltage is determined as:

[0130]

[0131] Where A and B are:

[0132]

[0133] Among them U N is the rated voltage of the power grid, so the current expression for voltage support is:

[0134]

[0135] Among them U + , U - are the positive and negative sequence voltages of the power grid respectively; I q + , I q - are respectively the positive and negative sequence components of the inverter output current on the q axis; ωL g is the grid impedance.

[0136] When the voltage drops to 0.88U N The following is based on the current expression:

[0137]

[0138] Calculate the positive and negative sequence currents required for voltage support, and compare the sum of the positive and negative sequence currents with the rated current of the slave inverter.

[0139] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and then the initial voltage support coefficient of 0.1 is determined as the current voltage support coefficient. The current current reference value corresponding to the current voltage support coefficient is calculated according to the current voltage support coefficient and the current expression. If the current current reference value is not greater than the rated current of the inverter, and the current voltage support coefficient is not equal to 1, and the current current reference value is not less than 0.99 times the rated current of the slave inverter, the current current reference value is used as the current reference value of the slave inverter, that is, the q-axis current used for voltage support in the slave inverter. If the current positive and negative sequence current is greater than the rated current of the slave inverter, the current voltage support coefficient is subtracted by 0.01, and the current current reference value determined by the current voltage support coefficient and current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to 1, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to 1, and the current positive and negative sequence current is less than 0.99 times the rated current of the slave inverter, the current voltage support coefficient is added by 0.1, and the current current reference value determined by the current voltage support coefficient and current expression is returned. The new A and B are determined according to the minimum voltage support coefficient:

[0140]

[0141] Substituting the new A and B into the current expression, the positive and negative sequence current reference values ​​of the slave inverter can be obtained. The calculation formula for the positive and negative sequence current reference values ​​of the master inverter is:

[0142]

[0143] Among them I q +* , I q -* To support the voltage to [0.85U N , 1.1U N ]Required q-axis current, I q2 + , I q2 - The q-axis current that the master inverter needs to provide. Based on the q-axis current that the slave inverter needs to provide and the q-axis current that the master inverter needs to provide, the master inverter and the slave inverter are controlled to output corresponding currents to jointly achieve voltage support. If the current capacity of the master inverter is still remaining after achieving voltage support, the remaining capacity of the master inverter is used to transmit active power, including: The expression of output power obtained by analysis is:

[0144]

[0145] Among them I d2 + The d-axis positive sequence current outputted by the main inverter, i.e. the current used to output active power, C is:

[0146]

[0147] in is the maximum active power fluctuation. First, let Determine whether k is greater than 0. When k is greater than 0, determine the maximum current I of the main inverter max Is it in the interval (I rate1 , 1.2I rate1 ), where I rate1 is the rated current of the main inverter; if I max Not in the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + +1, then return to determine the maximum current I of the main inverter max Is it in the interval (I rate1 , 1.2I rate1 ); if I max Belong to the interval (I rate1 , 1.2I rate1 ), then let Id2 + =I d2 + -1, then judge I max Is it in the interval (I rate1 , 1.2I rate1 ), if I max Belong to the interval (I rate1 , 1.2I rate1 ), then return to I d2 + =I d2 + -1; if I max Not in the interval (I rate1 , 1.2I rate1 ), then the output I d2 + When k is not greater than 0, the maximum current I of the main inverter is determined. max Is it in the interval (I rate1 , 1.2I rate1 ), where I rate1 is the rated current of the main inverter; if I max Not in the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + -1, and then return to determine the maximum current I of the main inverter max Is it in the interval (I rate1 , ); if I max Belong to the interval (I rate1 , 1.2I rate1 ), then let I d2 + =I d2 + +1, then judge I max Is it in the interval (I rate1 , 1.2I rate1 ), if I max Belong to the interval (I rate1 , 1.2I rate1 ), then return to I d2 + =I d2 + +1; if I max Not in the interval (I rate1 , 1.2I rate1 ), then the output I d2 + Among them, the maximum current of the main inverter I maxIt is composed of the q-axis positive and negative sequence current and the d-axis positive and negative sequence current of the main inverter.

[0148] If the positive and negative sequence currents required for voltage support are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, the slave inverter is controlled to independently achieve voltage support, and then the master inverter is used to transmit active power.

[0149] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0150] In an exemplary embodiment, Figure 4 As shown, a power quality management device is provided, including: an analysis module, a comparison module, a support module and a transmission module, wherein:

[0151] An analysis module for analyzing the voltage at the common coupling point during a fault and determining the positive and negative sequence current expressions for voltage support;

[0152] A comparison module, used for calculating the positive and negative sequence currents required for voltage support based on the current expression when the voltage drops to a preset value, and comparing the positive and negative sequence currents with the rated current of the slave inverter;

[0153] A support module is used to determine that the slave inverter cannot independently achieve voltage support if the positive and negative sequence currents are greater than the rated current of the slave inverter, and control the master inverter and the slave inverter to jointly achieve voltage support;

[0154] The transmission module is used to use the remaining capacity of the main inverter to transmit active power if the current capacity of the main inverter is still remaining after achieving voltage support.

[0155] In one embodiment, the analysis module is further configured to:

[0156] Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during the fault; determine the positive and negative sequence voltage expressions based on the voltage conditions and maximum and minimum voltage expressions; determine the positive and negative sequence current expressions used for voltage support based on the positive and negative sequence voltage expressions and the rated voltage of the grid.

[0157] In one embodiment, the support module is further used to:

[0158] Determine the minimum voltage support coefficient according to the current required for voltage support and the rated current of the slave inverter; determine the current reference value of the slave inverter according to the minimum voltage support coefficient and the current expression; determine the current reference value of the master inverter according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, control the master inverter and the slave inverter to jointly achieve voltage support.

[0159] In one embodiment, the support module is further used to:

[0160] Determine an initial voltage support coefficient and use the initial voltage support coefficient as the current voltage support coefficient; determine a current current reference value based on the current voltage support coefficient and the current expression; if the current current reference value is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current current reference value is not less than the rated current of the slave inverter at a preset multiple, use the current current reference value as the current reference value of the slave inverter.

[0161] In one embodiment, the support module is further used to:

[0162] If the current positive and negative sequence current is greater than the rated current of the slave inverter, the second preset value is subtracted from the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, the third preset value is added to the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0163] In one embodiment, the power quality management device is further used for:

[0164] If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

[0165] Each module in the above-mentioned power quality management device can be implemented in whole or in part by software, hardware and their combination. Each of the above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the above modules.

[0166] In an exemplary embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as shown in FIG. Figure 5 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store voltage data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for power quality management is implemented.

[0167] Those skilled in the art will understand that Figure 5 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0168] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0169] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0170] When the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0171] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0172] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0173] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0174] Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during the fault; determine the positive and negative sequence voltage expressions based on the voltage conditions and maximum and minimum voltage expressions; determine the positive and negative sequence current expressions used for voltage support based on the positive and negative sequence voltage expressions and the rated voltage of the grid.

[0175] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0176] Determine the minimum voltage support coefficient according to the current required for voltage support and the rated current of the slave inverter; determine the current reference value of the slave inverter according to the minimum voltage support coefficient and the current expression; determine the current reference value of the master inverter according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, control the master inverter and the slave inverter to jointly achieve voltage support.

[0177] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0178] Determine an initial voltage support coefficient and use the initial voltage support coefficient as the current voltage support coefficient; determine a current current reference value based on the current voltage support coefficient and the current expression; if the current current reference value is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current current reference value is not less than the rated current of the slave inverter at a preset multiple, use the current current reference value as the current reference value of the slave inverter.

[0179] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0180] If the current positive and negative sequence current is greater than the rated current of the slave inverter, the second preset value is subtracted from the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, the third preset value is added to the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0181] In one embodiment, when the processor executes the computer program, the processor further implements the following steps:

[0182] If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

[0183] In one embodiment, a computer readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

[0184] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0185] When the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0186] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0187] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0188] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0189] Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during the fault; determine the positive and negative sequence voltage expressions based on the voltage conditions and maximum and minimum voltage expressions; determine the positive and negative sequence current expressions used for voltage support based on the positive and negative sequence voltage expressions and the rated voltage of the grid.

[0190] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0191] Determine the minimum voltage support coefficient according to the current required for voltage support and the rated current of the slave inverter; determine the current reference value of the slave inverter according to the minimum voltage support coefficient and the current expression; determine the current reference value of the master inverter according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, control the master inverter and the slave inverter to jointly achieve voltage support.

[0192] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0193] Determine an initial voltage support coefficient and use the initial voltage support coefficient as the current voltage support coefficient; determine a current current reference value based on the current voltage support coefficient and the current expression; if the current current reference value is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current current reference value is not less than the rated current of the slave inverter at a preset multiple, use the current current reference value as the current reference value of the slave inverter.

[0194] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0195] If the current positive and negative sequence current is greater than the rated current of the slave inverter, the second preset value is subtracted from the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, the third preset value is added to the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0196] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0197] If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

[0198] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0199] Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support;

[0200] When the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter;

[0201] If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support;

[0202] If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

[0203] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0204] Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during the fault; determine the positive and negative sequence voltage expressions based on the voltage conditions and maximum and minimum voltage expressions; determine the positive and negative sequence current expressions used for voltage support based on the positive and negative sequence voltage expressions and the rated voltage of the grid.

[0205] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0206] Determine the minimum voltage support coefficient according to the current required for voltage support and the rated current of the slave inverter; determine the current reference value of the slave inverter according to the minimum voltage support coefficient and the current expression; determine the current reference value of the master inverter according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, control the master inverter and the slave inverter to jointly achieve voltage support.

[0207] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0208] Determine an initial voltage support coefficient and use the initial voltage support coefficient as the current voltage support coefficient; determine a current current reference value based on the current voltage support coefficient and the current expression; if the current current reference value is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current current reference value is not less than the rated current of the slave inverter at a preset multiple, use the current current reference value as the current reference value of the slave inverter.

[0209] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0210] If the current positive and negative sequence current is greater than the rated current of the slave inverter, the second preset value is subtracted from the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; if the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, the third preset value is added to the current voltage support coefficient, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

[0211] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0212] If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

[0213] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0214] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0215] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for controlling power quality, characterized in that: The method comprises: Analyze the voltage at the common coupling point during the fault and determine the positive and negative sequence current expressions for voltage support; When the voltage drops below a preset value, the positive and negative sequence currents required for voltage support are calculated based on the current expression, and the positive and negative sequence currents are compared with the rated current of the slave inverter; If the positive and negative sequence currents are greater than the rated current of the slave inverter, it is determined that the slave inverter cannot independently achieve voltage support, and the master inverter and the slave inverter are controlled to jointly achieve voltage support; If the current capacity of the main inverter is still remaining after achieving voltage support, the remaining capacity of the main inverter is used to transmit active power.

2. The method according to claim 1, characterized in that The determining of the current expression for voltage support comprises: Analyze the voltage conditions and maximum and minimum voltage expressions that need to be met at the common coupling point during a fault; Determine positive and negative sequence voltage expressions based on the voltage condition and the maximum and minimum voltage expressions; Based on the positive and negative sequence voltage expressions and the rated voltage of the power grid, the positive and negative sequence current expressions for voltage support are determined.

3. The method according to claim 1, characterized in that The controlling the master inverter and the slave inverter to jointly realize voltage support includes: Determining a minimum voltage support coefficient according to the current required for the voltage support and the rated current of the slave inverter; Determining a current reference value of a slave inverter according to the minimum voltage support coefficient and the current expression; The current reference value of the master inverter is determined according to the current reference value of the slave inverter and the current required for voltage support; based on the current reference value of the slave inverter and the current reference value of the master inverter, the master inverter and the slave inverter are controlled to jointly achieve voltage support.

4. The method according to claim 3, characterized in that The step of determining a minimum voltage support coefficient according to the positive and negative sequence currents required for the voltage support and the rated current, and determining a current reference value of a slave inverter according to the minimum voltage support coefficient and the current expression comprises: Determine an initial voltage support coefficient, and use the initial voltage support coefficient as the current voltage support coefficient; Determine a current current reference value according to the current voltage support coefficient and the current expression; If the current reference value is not greater than the rated current of the slave inverter, the voltage support coefficient is not equal to the first preset value, and the current reference value is not less than the rated current of the slave inverter at a preset multiple, the current reference value is used as the current reference value of the slave inverter.

5. The method according to claim 4, characterized in that The method further comprises: If the current positive and negative sequence current is greater than the rated current of the slave inverter, subtract the second preset value from the current voltage support coefficient, and return to determine the current current reference value according to the current voltage support coefficient and the current expression; If the current positive and negative sequence currents are not greater than the rated current of the slave inverter, and the voltage support coefficient is equal to the first preset value, the current current reference value is used as the current reference value of the slave inverter; If the current positive and negative sequence current is not greater than the rated current of the slave inverter, and the voltage support coefficient is not equal to the first preset value, and the current positive and negative sequence current is less than the rated current of the slave inverter at a preset multiple, then the current voltage support coefficient is added to the third preset value, and the current current reference value determined according to the current voltage support coefficient and the current expression is returned.

6. The method according to claim 1, characterized in that The method further comprises: If the positive and negative sequence currents are not greater than the rated current of the slave inverter, it is determined that the slave inverter can independently achieve voltage support, and the slave inverter is controlled to achieve voltage support, and the master inverter is used to transmit active power.

7. A power quality control device, characterized in that: The device comprises: An analysis module for analyzing the voltage at the common coupling point during a fault and determining the positive and negative sequence current expressions for voltage support; A comparison module, configured to calculate the positive and negative sequence currents required for voltage support based on the current expression when the voltage drops to a preset value, and compare the positive and negative sequence currents with the rated current of the slave inverter; A support module, configured to determine that the slave inverter cannot independently achieve voltage support if the positive and negative sequence currents are greater than the rated current of the slave inverter, and control the master inverter and the slave inverter to jointly achieve voltage support; The transmission module is used to use the remaining capacity of the main inverter to transmit active power if the current capacity of the main inverter is still remaining after achieving voltage support.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

Images