A comprehensive compensation control method for power supply network voltage based on chain-type power electronic converter

Abstract

The present invention provides a comprehensive compensation control method for power supply network voltage based on a three-phase chain power electronic converter, which is implemented by a random load current detection module, a power supply network voltage variation closed-loop control module and a power supply network access point reactive power closed-loop control module. The random load current detection module calculates the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid, and the output value of the power supply network voltage variation control module and the output value of the power supply network access point reactive power closed-loop control module are superimposed on the calculation of the reactive current component. Finally, the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid are added, and output as a total current reference value to the converter current control module, so as to achieve the purpose of compensating the power supply network voltage. The power quality problem caused by the load is effectively controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply quality control of power supply networks, and in particular to a power supply network voltage comprehensive compensation control method based on a three-phase chain-type power electronic converter. Background Art

[0002] In the current power electronic system applications, H-bridge cascade-based power electronic converters have the advantages of modular structure design, high stability and small footprint, and occupy the vast majority of the high-voltage power electronic converter market share.

[0003] In the current national production equipment, the continuous emergence of new production equipment has greatly improved the production efficiency, but at the same time, the complex production process has also caused a greater impact on the power grid. Among them, the representative random loads are arc furnace loads and rolling mills. Especially in the modern steel industry, a large number of arc furnace steelmaking processes are adopted, and the arc furnace load is a typical random load, which will bring a large number of reactive power, harmonics, voltage flicker, negative sequence and other problems to the power grid. These random loads have an increasing impact on the power grid. The present invention uses a mature H-bridge cascade power electronic converter as a basis, and proposes a multi-angular velocity coordinate transformation method, which avoids the AC phase detection error of the traditional current detection method, achieves a high-precision control effect, and stabilizes the power supply quality of the power grid. Summary of the invention

[0004] In order to solve the technical problems raised by the background technology, the present invention provides a load compensation control method suitable for an H-bridge cascade power electronic converter. Based on the mature three-phase H-bridge unit cascade converter, a comprehensive compensation control method for voltage flicker, power factor and harmonic current is proposed, which can effectively control the power quality problems caused by the load, and at the same time ensure the power quality control accuracy of the power supply network, speed up the response speed of the system and improve the power supply quality of the power grid.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A power supply network voltage comprehensive compensation control method based on a three-phase chain-type power electronic converter, wherein the method is implemented by a random load current detection module, a power supply network voltage variation closed-loop control module and a power supply network access point reactive power closed-loop control module.

[0007] The random load current detection module calculates the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid, and superimposes the output value of the power supply network voltage change control module and the output value of the reactive power closed-loop control module of the power supply network access point into the calculation of the reactive current component. Finally, the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid are added together and output as the total current reference value to the H-bridge cascade power electronic converter current control module to achieve the purpose of compensating the power supply network voltage.

[0008] Furthermore, the control method in the random load current detection module includes the following:

[0009] 1) First, the line current sampling value of the random load I load_A ,I load_B ,I load_C Perform per-unit processing to obtain the per-unit value of the load current I load_Apu ,I load_Bpu ,I load_Cpu The base value of the unit is the rated line current effective value Isn of the H-bridge cascade power electronic converter device; Clark transformation is performed on the three-phase line current unit value of the load, and the current value under the ABC coordinate is transformed into the αβ coordinate system to obtain the α-axis component I of the load current. load_Alfa and the β-axis component I load_Beta ;

[0010] 2) For the detection of reactive current components, the phase voltage phase (50Hz AC component) of the random load power supply is used to perform Park transformation on the line current, and the current value under the αβ coordinate is converted into the current value I under the DQ coordinate. load_D1 and I load_Q1 Since the H-bridge cascade converter has no active power generation device, it does not affect the active current component I load_D1 To compensate for the reactive current component I under the DQ coordinate load_Q1 Filter to remove the AC component and obtain the reactive current component I after filtering load_Q1P , plus the output value I of the closed-loop control module of the power supply network voltage change Ref_U and the current reference value I output by the reactive power closed-loop control module at the access point ref_Q Finally, the phase voltage phase (50Hz AC component) of the random load power supply is used to perform an inverse Park transform, and the result obtained is I load_DS1 and I load_QS1 , which is the reactive component in the random load line current;

[0011] 3) For the detection of harmonic current components injected by the load into the power grid, the phase of the multiple angular velocity calculated by the phase voltage phase of the random load, that is, the integer multiple component of 50Hz, is used for Park transformation to convert the current value under the αβ coordinate into the current value under the DQ coordinate, and obtain I load_D2 ~I load_D4 and I load_Q2 ~I load_Q4 , and then filter the D and Q current components respectively to remove the AC components, and finally use the phase of the multiple angular velocity calculated by the phase voltage phase of the random load to perform inverse Park transformation, and the result I load_DS2 ~I load_DS4 and I load_QS2 ~I load_QS4 , which is the harmonic component in the random load line current;

[0012] 4) For the detection of the current component causing voltage flicker, the subsynchronous phase, i.e., the 25Hz AC component, is calculated from the phase voltage phase of the random load power supply. Park transformation is performed on the line current to convert the current value under the αβ coordinates into the current value under the DQ coordinates to obtain I load_Ds and I load_Qs ; Then to I load_Ds and I load_Qs The current components are filtered separately to remove the AC components and obtain I load_DsP and I load_QsP Finally, the subsynchronous phase calculated by the phase voltage phase of the random load power supply is used to perform an inverse Park transformation on the line current to obtain I load_DSs and I load_QSs , get the flicker component in the random load line current;

[0013] After the above calculations, add the results of 2), 3) and 4) to obtain the component I of the total load current in the αβ coordinate system. load_Alfa_s and I load_Beta_s , and perform an inverse Clark transformation to obtain the total load current calculation value I fref_A ,I fref_B ,I fref_C , which is output as the total current reference value to the H-bridge cascade power electronic converter current control module to achieve the purpose of compensating the power supply network voltage.

[0014] Furthermore, the phase of the multiple angular velocity and the subsynchronous phase of the random load are obtained by obtaining the phase of the 50Hz AC component of the three-phase power supply voltage of the random load through a phase-locked loop PLL, and then calculating the phase of the multiple angular velocity and the subsynchronous phase through trigonometric functions.

[0015] Furthermore, the control method of the power supply network voltage variation closed-loop control module includes the following:

[0016] Collect the power supply network bus voltage U HV , and then calculate its effective value U HV_rms , and then use the rated voltage RMS value U n After per-unit processing, the per-unit value of the power supply network bus voltage U is obtained. HV_pu , after filtering out its DC component through a high-pass filter, the voltage error value U is obtained HV_err Finally, after passing through a proportional differential regulator, the output value I of the current reference value is obtained. Ref_U .

[0017] Furthermore, the control method of the reactive power closed-loop control module of the power supply network access point includes the following:

[0018] Collect the current I at the bus access point HV , and then calculate its effective value I HV_rms , and according to the current value I of the rated capacity of the access point n Perform per-unit processing to obtain the per-unit value of the current I HV_pu At the same time, the voltage per unit value U obtained in the voltage change closed-loop control is used HV_pu Calculate the reactive power Q at the system access point HV_pu , and then pass it through a proportional integral regulator to obtain the system reactive current reference value I ref_Q .

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The present invention uses a mature H-bridge cascade power electronic converter as a basis and proposes a multi-angular velocity coordinate transformation method, which avoids the AC phase detection error of the traditional current detection method, achieves a high-precision control effect, and stabilizes the power supply quality of the power grid.

[0021] 2) Based on the mature three-phase H-bridge unit cascade converter, the present invention proposes a comprehensive compensation control method for voltage flicker, power factor and harmonic current, which effectively controls the power quality problems caused by the load and improves the power supply quality of the power grid.

[0022] 3) The present invention not only compensates for high-order harmonic currents, but also takes into account the compensation of reactive current of 50 Hz of the industrial frequency and flicker current in the frequency range below 50 Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a topological diagram of a three-phase H-bridge cascade power electronic converter system and its controller of the present invention;

[0024] Figure 2It is a topology diagram (star connection) of a three-phase H-bridge power unit cascade power electronic converter of the present invention;

[0025] Figure 3 This is the topology diagram of the three-phase H-bridge power unit cascade power electronic converter of the present invention (delta connection)

[0026] Figure 4 It is a block diagram of voltage flicker, reactive power and harmonic comprehensive compensation control of the present invention;

[0027] Figure 5 It is a block diagram of multi-angular velocity voltage rotation vector calculation of the present invention. DETAILED DESCRIPTION

[0028] The specific implementation modes provided by the present invention are described in detail below with reference to the accompanying drawings.

[0029] The present invention refers to a three-phase H-bridge unit cascade structure power electronic converter topology such as Figure 1 As shown, in order to illustrate the content of the present invention, it is assumed that a random load is connected to the power grid through a step-up transformer, and a power electronic converter is connected in parallel to the random load for compensation. For the power grid, load compensation means using corresponding equipment to compensate for the power quality problems caused by the load, including voltage flicker, reactive power, harmonics and other problems of the power grid.

[0030] The topology diagram of the three-phase H-bridge power unit cascade power electronic converter is divided into star topology (such as Figure 2 ) and angular topology (such as Figure 3 )

[0031] like Figure 4 As shown, a power supply network voltage comprehensive compensation control method based on a three-phase chain power electronic converter is implemented by a random load current detection module, a power supply network voltage variation closed-loop control module and a power supply network access point reactive power closed-loop control module.

[0032] The random load current detection module calculates the harmonic current component I injected by the load into the power grid load_DS2 ~I load_DS4 and I load_QS2 ~I load_QS4 , reactive current component I load_DS1 and I load_QS1 And the current component I that causes voltage flicker load_DSs and I load_QSs , the power supply network voltage change control module output value I Ref_U and the current reference value I output by the reactive power closed-loop control module at the access point ref_Q Superimposed on the reactive current component I load_DS1 and I load_QS1In the calculation, the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid are finally added together as the total current reference value I fref_A ,I fref_B ,I fref_C The output is sent to the H-bridge cascade power electronic converter current control module to achieve the purpose of compensating the power supply network voltage.

[0033] 1) Detection of harmonic current components

[0034] In the harmonic component detection module of the random load, the control method detects the second, third and fourth harmonic components in the random load current component. The main idea of ​​the method is to multiply the power supply voltage of the load, thereby obtaining a multiplied frequency rotating vector higher than the power frequency, and then orient the load current according to the multiplied frequency vector of the power supply voltage of the random load, thereby obtaining the amplitude of each harmonic and performing load compensation. The traditional harmonic detection method has a phase lag of the detection component after filtering the harmonic component. The present invention mainly converts each component into a DC quantity, thereby avoiding the possibility of phase error.

[0035] 2) Detection of flicker current components

[0036] The definition of flicker component refers to the AC component below 50Hz power frequency, which is mainly concentrated around 25Hz. This method proposes a method to convert the power frequency vector of the voltage into a subsynchronous 25Hz rotating vector, and at the same time orient the current of the random load using this subsynchronous 25Hz rotating vector, and detect the DC component as a given value for compensation, thereby avoiding the phase error caused by low-pass filtering.

[0037] 3) Detection of reactive current component

[0038] For the 50Hz reactive component of the power frequency, this method orients the random load current according to the load supply voltage rotation vector, thereby obtaining the reactive current component of the load.

[0039] The method of the present invention also includes a power supply network voltage variation closed-loop control module and a power supply network access point reactive power closed-loop control module. Compared with the traditional load compensation control strategy, it fundamentally solves the phase lag problem caused by current detection.

[0040] like Figure 4 As shown, the control method in the random load current detection module includes the following:

[0041] 1) First, the line current sampling value of the random load I load_A ,I load_B ,I load_C Perform per-unit processing to obtain the per-unit value of the load current I load_Apu ,Iload_Bpu ,I load_Cpu The base value of the unit is the rated line current effective value Isn of the H-bridge cascade power electronic converter device; Clark transformation is performed on the three-phase line current unit value of the load, and the current value under the ABC coordinate is transformed into the αβ coordinate system to obtain the α-axis component I of the load current. load_Alfa and the β-axis component I load_Beta ;

[0042] 2) For the detection of reactive current components, the phase voltage phase (50Hz AC component) of the random load power supply is used to perform Park transformation on the line current, and the current value under the αβ coordinate is converted into the current value I under the DQ coordinate. load_D1 and I load_Q1 Since the H-bridge cascade converter has no active power generation device, it does not affect the active current component I load_D1 To compensate for the reactive current component I under the DQ coordinate load_Q1 Filter to remove the AC component and obtain the reactive current component I after filtering load_Q1P , plus the output value I of the closed-loop control module of the power supply network voltage change Ref_U and the current reference value I output by the reactive power closed-loop control module at the access point ref_Q Finally, the phase voltage phase (50Hz AC component) of the random load power supply is used to perform an inverse Park transform, and the result obtained is I load_DS1 and I load_QS1 , which is the reactive component in the random load line current;

[0043] 3) For the detection of harmonic current components injected by the load into the power grid, the phase of the multiple angular velocity calculated by the phase voltage phase of the random load, that is, the integer multiple component of 50Hz, is used for Park transformation to convert the current value under the αβ coordinate into the current value under the DQ coordinate, and obtain I load_D2 ~I load_D4 and I load_Q2 ~I load_Q4 , and then filter the D and Q current components respectively to remove the AC components, and finally use the phase of the multiple angular velocity calculated by the phase voltage phase of the random load to perform inverse Park transformation, and the result I load_DS2 ~I load_DS4 and I load_QS2 ~I load_QS4 , which is the harmonic component in the random load line current;

[0044] 4) For the detection of the current component causing voltage flicker, the subsynchronous phase, i.e., the 25Hz AC component, is calculated from the phase voltage phase of the random load power supply. Park transformation is performed on the line current to convert the current value under the αβ coordinates into the current value under the DQ coordinates to obtain Iload_Ds and I load_Qs ; Then to I load_Ds and I load_Qs The current components are filtered separately to remove the AC components and obtain I load_DsP and I load_QsP Finally, the subsynchronous phase calculated by the phase voltage phase of the random load power supply is used to perform an inverse Park transformation on the line current to obtain I load_DSs and I load_QSs , get the flicker component in the random load line current;

[0045] After the above calculations, add the results of 2), 3) and 4) to obtain the component I of the total load current in the αβ coordinate system. load_Alfa_s and I load_Beta_s , and perform an inverse Clark transformation to obtain the total load current calculation value I fref_A ,I fref_B ,I fref_C , which is output as the total current reference value to the H-bridge cascade power electronic converter current control module to achieve the purpose of compensating the power supply network voltage.

[0046] The formulas for the Clark transform, inverse Clark transform, Park transform, and inverse Park transform used in this section are as follows:

[0047] Clark Transformation:

[0048]

[0049] The meanings of the variables in this section are as follows:

[0050] U α : The component of the α axis after transformation;

[0051] U β : The component of the β axis after transformation;

[0052] U a : A-phase component before transformation;

[0053] U b : B phase component before transformation;

[0054] U c : C-phase component before transformation;

[0055] Inverse Clark transform:

[0056]

[0057] The meanings of the variables in this section are as follows:

[0058] U α: The component of the α axis before transformation;

[0059] U β : The component of the β axis before transformation;

[0060] U a : A-phase component after transformation;

[0061] U b : B phase component after transformation;

[0062] U c : C-phase component after transformation;

[0063] Park Transform:

[0064]

[0065] The meanings of the variables in this section are as follows:

[0066] U α : The component of the α axis before transformation;

[0067] U β : The component of the β axis before transformation;

[0068] U d : D-axis component after transformation;

[0069] U q : Q-axis component after transformation;

[0070] cosθ: the phase adopted by the transformation;

[0071] sinθ: the quadrature phase used in the transformation;

[0072] Inverse Park transform:

[0073]

[0074] The meanings of the variables in this section are as follows:

[0075] U α : The component of the α axis after transformation;

[0076] U β : The component of the β axis after transformation;

[0077] U d : D-axis component before transformation;

[0078] U q : Q-axis component before transformation;

[0079] cosθ: the phase adopted by the transformation;

[0080] sinθ: the quadrature phase used in the transformation;

[0081] The low-pass filter (LPF) transfer function used is:

[0082]

[0083] The meanings of the variables in this section are as follows:

[0084] S: transfer function frequency domain operator;

[0085] A n : filter passband gain;

[0086] ω n : transfer function shear frequency;

[0087] ζ: filter damping coefficient.

[0088] The calculation method of multi-angular speed voltage rotation vector is as follows Figure 5 As shown, the phase of the multiple angular velocity and the sub-synchronous phase of the random load are obtained by obtaining the phase of the 50Hz AC component of the three-phase power supply voltage of the random load through a phase-locked loop PLL, and then the phase of the multiple angular velocity and the sub-synchronous phase are calculated through trigonometric functions.

[0089] like Figure 4 As shown, the control method of the power supply network voltage variation closed-loop control module includes the following:

[0090] Collect the power supply network bus voltage U HV , and then calculate its effective value U HV_rms , and then use the rated voltage RMS value U n After per-unit processing, the per-unit value of the power supply network bus voltage U is obtained. HV_pu , after filtering out its DC component through a high-pass filter, the voltage error value U is obtained HV_err Finally, after passing through a proportional differential regulator, the output value I of the current reference value is obtained. Ref_U .

[0091] The high-pass filter transfer function and proportional differential regulator transfer function used in this part are as follows:

[0092] The transfer function of the high-pass filter is:

[0093] The meanings of the variables in this section are as follows:

[0094] S: transfer function frequency domain operator;

[0095] A n : filter passband gain;

[0096] ω n: transfer function shear frequency;

[0097] ζ: filter damping coefficient;

[0098] The transfer function of the high-pass filter is: G(S) = K p +K d S

[0099] S: transfer function frequency domain operator;

[0100] K p : Regulator proportional coefficient;

[0101] K d : Regulator differential coefficient.

[0102] like Figure 4 As shown, the control method of the reactive power closed-loop control module of the power supply network access point includes the following:

[0103] Collect the current I at the bus access point HV , and then calculate its effective value I HV_rms , and according to the current value I of the rated capacity of the access point n Perform per-unit processing to obtain the per-unit value of the current I HV_pu At the same time, the voltage per unit value U obtained in the voltage change closed-loop control is used HV_pu Calculate the reactive power Q at the system access point HV_pu , and then pass it through a proportional integral regulator to obtain the system reactive current reference value I ref_Q .

[0104] The PI regulator transfer function used in this part is as follows:

[0105] PI regulator transfer function:

[0106]

[0107] S: transfer function frequency domain operator;

[0108] K p : Regulator proportional coefficient;

[0109] K I : Regulator integral coefficient.

[0110] The above embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A power supply network voltage comprehensive compensation control method based on a three-phase chain-type power electronic converter, characterized in that: The method is implemented by a random load current detection module, a power supply network voltage variation closed-loop control module and a power supply network access point reactive power closed-loop control module; The random load current detection module calculates the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid, and superimposes the output value of the power grid voltage variation control module and the output value of the reactive power closed-loop control module of the power grid access point into the calculation of the reactive current component. Finally, the harmonic current component, reactive current component and current component causing voltage flicker injected by the load into the power grid are added together and output as the total current reference value to the H-bridge cascade power electronic converter current control module, so as to achieve the purpose of compensating the power grid voltage. The control method in the random load current detection module includes the following: 1) First, the line current sampling value of the random load I load_A ,I load_B ,I load_C Perform per-unit processing to obtain the per-unit value of the load current I load_Apu ,I load_Bpu ,I load_Cpu The base value of the unit is the rated line current effective value Isn of the H-bridge cascade power electronic converter device; Clark transformation is performed on the three-phase line current unit value of the load, and the current value under the ABC coordinate is transformed into the αβ coordinate system to obtain the α-axis component I of the load current. load_Alfa and the β-axis component I load_Beta ; 2) For the detection of reactive current components, the phase voltage phase of the random load power supply is used to perform Park transformation on the line current, and the current value under the αβ coordinate is converted into the current value I under the DQ coordinate. load_D1 and I load_Q1 Since the H-bridge cascade converter has no active power generation device, it does not affect the active current component I load_D1 To compensate for the reactive current component I under the DQ coordinate load_Q1 Filter to remove the AC component and obtain the reactive current component I after filtering load_Q1P , plus the output value I of the closed-loop control module of the power supply network voltage change Ref_U and the current reference value I output by the reactive power closed-loop control module at the access point ref_Q Finally, the phase voltage phase of the random load power supply is used to perform an inverse Park transformation, and the result obtained is I load_DS1 and I load_QS1 , which is the reactive component in the random load line current; 3) For the detection of harmonic current components injected by the load into the power grid, the phase of the multiple angular velocity calculated by the phase voltage phase of the random load, that is, the integer multiple component of 50Hz, is used for Park transformation to convert the current value under the αβ coordinate into the current value under the DQ coordinate, and obtain I load_D2 ~I load_D4 and I load_Q2 ~I load_Q4 , and then filter the D and Q current components respectively to remove the AC components, and finally use the phase of the multiple angular velocity calculated by the phase voltage phase of the random load to perform inverse Park transformation, and the result I load_DS2 ~I load_DS4 and I load_QS2 ~I load_QS4 , which is the harmonic component in the random load line current; The detection of the harmonic current component is to perform frequency multiplication processing on the load supply voltage, thereby obtaining a frequency multiplication rotating vector higher than the power frequency, and then orient the load current according to the frequency multiplication vector of the random load supply voltage, thereby obtaining the amplitude of each harmonic and performing load compensation; 4) For the detection of the current component causing voltage flicker, the subsynchronous phase, i.e., the 25Hz AC component, is calculated from the phase voltage phase of the random load power supply. Park transformation is performed on the line current to convert the current value under the αβ coordinates into the current value under the DQ coordinates to obtain I load_Ds and I load_Qs ; Then to I load_Ds and I load_Qs The current components are filtered separately to remove the AC components and obtain I load_DsP and I load_QsP Finally, the subsynchronous phase calculated by the phase voltage phase of the random load power supply is used to perform an inverse Park transformation on the line current to obtain I load_DSs and I load_QSs , get the flicker component in the random load line current; The detection of the current component causing voltage flicker proposes a method of converting the power frequency vector of the voltage into a subsynchronous 25Hz rotating vector, and orienting the current of the random load using this subsynchronous 25Hz rotating vector, detecting the DC component therein as a given value for compensation, thereby avoiding the phase error caused by low-pass filtering; After the above calculations, add the results of 2), 3) and 4) to obtain the component I of the total load current in the αβ coordinate system. load_Alfa_s and I load_Beta_s , and perform an inverse Clark transformation to obtain the total load current calculation value I fref_A ,I fref_B ,I fref_C , which is output as the total current reference value to the H-bridge cascade power electronic converter current control module to achieve the purpose of compensating the power supply network voltage.

2. A power supply network voltage comprehensive compensation control method based on a three-phase chain-type power electronic converter according to claim 1, characterized in that: The phase and sub-synchronous phase of the multiple angular velocity of the random load are obtained by passing the three-phase power supply voltage of the random load through a phase-locked loop PLL to obtain the phase of the 50Hz AC component, and then the phase and sub-synchronous phase of the multiple angular velocity are calculated through trigonometric functions.

3. The method for comprehensive compensation control of power supply network voltage based on three-phase chain-type power electronic converter according to claim 1 is characterized in that: The control method of the power supply network voltage variation closed-loop control module includes the following steps: Collect the power supply network bus voltage U HV , and then calculate its effective value U HV_rms , and then use the rated voltage RMS value U n After per-unit processing, the per-unit value of the power supply network bus voltage U is obtained. HV_pu , after filtering out its DC component through a high-pass filter, the voltage error value U is obtained HV_err Finally, after passing through a proportional differential regulator, the output value of the current reference value I is obtained. Ref_U .

4. The method for comprehensive compensation control of power supply network voltage based on three-phase chain-type power electronic converter according to claim 1 is characterized in that: The control method of the reactive power closed-loop control module of the power supply network access point includes the following: Collect the current I at the bus access point HV , and then calculate its effective value I HV_rms , and according to the current value I of the rated capacity of the access point n Perform per-unit processing to obtain the per-unit value of the current I HV_pu At the same time, the voltage per unit value U obtained in the voltage change closed-loop control is used HV_pu Calculate the reactive power Q at the system access point HV_pu , and then pass it through a proportional integral regulator to obtain the system reactive current reference value I ref_Q .

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