A current control method suitable for AC / DC microgrid converter

Abstract

This invention relates to the field of low-voltage power distribution technology and discloses a current regulation method applicable to AC / DC microgrid converters. The steps are as follows: S1, parameter setting; S2, collecting the total active power on the grid side and sending it to the converter host; the host collects and calculates the effective value of the grid voltage of phase A, and then calculates the mutual active current of each phase; S3, collecting the grid current, calculating the voltage phase vertical component corresponding to the positive sequence reactive current of each phase, the voltage phase in-phase component and vertical component corresponding to the negative sequence current of each phase, and the in-phase component and vertical component of each phase's harmonic current in the same reference phase; S4, calculating the current coefficient for energy mutual assistance and power quality management; S5, calculating the current regulation target value; jump to S2. This invention addresses the power quality problem in energy mutual assistance scenarios, effectively utilizes PCS capacity, solves the problems of heavy overload and power quality in the distribution area, enables one device to have two functions, fully utilizes the advantages of energy conversion, and saves costs.

Description

Technical Field

[0001] This invention relates to the field of low-voltage power distribution, and more particularly to a current regulation method applicable to AC / DC microgrid converters. Background Technology

[0002] With the increasing penetration of clean energy sources such as distributed photovoltaics in low-voltage distribution networks, the uncertainties of photovoltaic and wind power generation have led to significant fluctuations in the load factor of distribution areas. Power quality issues such as reactive power, harmonics, and three-phase imbalance are becoming increasingly prominent, seriously jeopardizing the safe and stable operation of low-voltage distribution networks. To alleviate these problems, AC / DC microgrid converters (PCS) have been used as an effective solution for flexible interconnection between distribution areas and for power quality management. However, most PCS in the field only consider a single operating condition and cannot be compatible with both distribution area power sharing and power quality management. Therefore, how to comprehensively manage the power quality and load imbalance problems of low-voltage distribution networks and further optimize the capacity allocation between distribution area power sharing and power quality management is currently a key research focus. Summary of the Invention

[0003] This invention addresses the shortcomings and defects of existing technologies by providing a current regulation method applicable to AC / DC microgrid converters. For operating conditions where power quality management needs to be performed simultaneously in scenarios involving energy exchange or energy storage between two units, a reasonable capacity allocation method is set up to enable the management of power quality in the transformer area while maintaining power transmission capabilities.

[0004] The objective of this invention can be achieved through the following technical solutions.

[0005] A current regulation method applicable to AC / DC microgrid converters includes the following steps.

[0006] S1 is used to set parameters for the AC / DC microgrid converter.

[0007] The settings include the transformer capacities Sn1 and Sn2 connected to each AC / DC microgrid converter master and slave, the load factor threshold λ1 for starting energy mutual assistance, the target value λ2 for load factor mutual assistance, the capacity allocation mode, the effective value limit of the three-phase output current Irms, and the effective value limit of the neutral current I0rms.

[0008] S2, the microgrid controller collects the total active power P1 and P2 of the AC / DC microgrid converter master and slave on the grid side and sends them to the AC / DC microgrid converter master.

[0009] The AC / DC microgrid converter host collects and calculates the effective value of the A-phase grid voltage UA, and then calculates the active current I1p of each phase based on the parameters set by P1, P2, and P2.

[0010] S3, the AC / DC microgrid converter locally collects the current data of the power grid, calculates the vertical component I1q of the positive sequence reactive current of each phase in the corresponding voltage phase, the in-phase component I2p[i] of the negative sequence current of each phase in the corresponding voltage phase, the vertical component I2q[i] of the negative sequence current of each phase in the corresponding voltage phase, the in-phase component I_harm_cos[i][k] of each phase's harmonic current in the same reference phase, and the vertical component I_harm_sin[i][k] of each phase's harmonic current in the same reference phase.

[0011] S4. Based on the mode setting, Irms, I0rms and the above current calculation results, the AC / DC microgrid converter calculates the current coefficient s0 for energy mutual assistance and the current coefficient s1 for power quality management.

[0012] S5. Based on the above current calculation results, s0, and s1, calculate the current regulation target value Iref, which will be used as the input value for subsequent current inner loop control.

[0013] Jump to S2.

[0014] Preferably, there are 5 capacity allocation modes.

[0015] mode=1, only considering the energy mutual assistance condition.

[0016] mode=2, only power quality management conditions are considered.

[0017] mode=3, energy mutual assistance priority, that is, the remaining current capacity will only be used for power quality management if the effective value of the three-phase output current is less than Irms when energy mutual assistance is fully implemented.

[0018] mode=4, power quality management takes priority, that is, the remaining current capacity will only be used for energy mutual assistance if the effective value of the three-phase output current is less than Irms and the effective value of the neutral current is less than or equal to I0rms when power quality management is fully implemented.

[0019] mode=5, same priority, that is, within the Irms range, s0=s1 is calculated, and then s1 is further calculated in combination with I0rms.

[0020] Preferably, I1p is calculated as follows.

[0021] S21, Energy Mutual Aid Start Flag = 0, I1p = 0.

[0022] S22, calculate the power of the two units at λ1 and λ2.

[0023] P11=λ1·Sn1; P12=λ2·Sn1; P21=λ1·Sn2; P22=λ2·Sn2.

[0024] Among them, P11 is the power of the corresponding area of the AC-DC microgrid converter main unit under λ1, P12 is the power of the corresponding area of the AC-DC microgrid converter main unit under λ2, P21 is the power of the corresponding area of the AC-DC microgrid converter slave unit under λ1, and P22 is the power of the corresponding area of the AC-DC microgrid converter slave unit under λ2.

[0025] S23. If P1 > P11 and P2 < P22, then Flag = 1, △P = min(P1 - P11, P22 - P2), and I1p = I1p + △P / (3 * UA); otherwise, proceed to S24.

[0026] Among them, △P is the power difference to be regulated in this round.

[0027] S24. If P1 < P21 and P2 > P21, then Flag = 1, △P = max(P1 - P11, P22 - P2), and I1p = I1p + △P / (3 * UA); otherwise, proceed to S25.

[0028] S25. If Flag = 0, then do not perform energy mutual assistance and I1p = 0; otherwise, proceed to S26.

[0029] S26. If I1p = 0, then Flag = 0; otherwise, proceed to S27.

[0030] S27. If I1p > 0 and P2 > P21, then △P = P21 - P2 and I1p = I1p + △P / (3 * UA).

[0031] If I1p > 0 and P1 < P12, then △P = P12 - P1 and I1p = I1p + △P / (3 * UA).

[0032] If I1p < 0 and P1 > P11, then △P = P1 - P11 and I1p = I1p + △P / (3 * UA).

[0033] If I1p < 0 and P2 < P22, then △P = P2 - P22 and I1p = I1p + △P / (3 * UA).

[0034] Otherwise, I1p remains unchanged.

[0035] Preferably, the step S21 is only performed once during initialization.

[0036] Preferably, the communication method between the microgrid controller and the AC-DC microgrid converter main unit is generally RS-485, network cable or LoRa, and the communication period is 2 minutes.

[0037] Preferably, the method for calculating s0 and s1 is as follows.

[0038] When mode = 1: s1 = 0; if I1p < Irms, then s0 = 1; otherwise, s0 = Irms / I1p.

[0039] When B.mode=2: (I_harm[i][k]) 2 =(I_harm_cos[i][k]) 2 +(I_harm_sin[i][k]) 2 .

[0040]

[0041] s0 = 0; the minimum value among k1min, k2 and 1 is s1.

[0042] Where i takes 0, 1, and 2 to represent phases A, B, and C, respectively; k is the harmonic index, generally k takes 0 to 5, representing the 3rd, 5th, 7th, 9th, 11th, and 13th harmonics, respectively; k1[i] is the coefficient of each phase satisfying the above formula, with a minimum value of k1min; k2 is the coefficient satisfying I0rms; I2p[i] and I2q[i] are the in-phase and vertical components of the negative sequence current of each phase in the corresponding voltage phase, respectively; the in-phase component I0p[i] and vertical component I0q[i] of the zero sequence current of each phase in the corresponding voltage phase; I1q is the vertical component of the positive sequence reactive current of each phase in the corresponding voltage phase; I_harm_cos[i][k] and I_harm_sin[i][k] are the in-phase and vertical components of the kth harmonic current of each phase in the same reference phase, respectively; I_harm0[k] is the effective value of the kth harmonic current on the neutral line.

[0043] When C.mode = 3: If I1p > Irms, then s0 = Irms / I1p, s1 = 0; otherwise

[0044] s0 = 1; the minimum value among k1min, k2 and 1 is s1.

[0045] D.mode=4: (I_harm[i][k]) 2 =(I_harm_cos[i][k]) 2 +(I_harm_sin[i][k]) 2 .

[0046]

[0047] s0 = 0; the minimum value among k1min, k2 and 1 is s1.

[0048] If s1 < 1, then s0 = 0; otherwise:

[0049] s1 = 1; the smaller of k1min and 1 is s0.

[0050] When E.mode=5:

[0051] The smaller of k1min and 1 is s0; the smallest of k1min, k2 and 1 is s1.

[0052] Preferably, the AC / DC microgrid converter master unit is used to receive power from the distribution area, and the AC / DC microgrid converter slave unit is used for DC voltage regulation. The corresponding relationship of their capacity allocation modes is as follows.

[0053] When the mode of the AC / DC microgrid converter master is 1, the mode of the AC / DC microgrid converter slave is preferably selected as 3, but can also be selected as 1.

[0054] When the AC / DC microgrid converter master mode=2, the AC / DC microgrid converter slave mode=2.

[0055] When the AC / DC microgrid converter master mode=3, the AC / DC microgrid converter slave mode should preferably be 3, but can also be 1.

[0056] When the AC / DC microgrid converter master mode=4, the AC / DC microgrid converter slave mode should preferably be 3, but can also be 1 or 2.

[0057] When the AC / DC microgrid converter master mode=5, the AC / DC microgrid converter slave mode should preferably be 3, but can also be 1.

[0058] The beneficial technical effects of this invention are as follows: In the case of power quality problems in the energy mutual assistance scenario of power distribution area, the capacity of PCS can be effectively utilized, and the problems of heavy overload and power quality in the power distribution area can be solved at the same time. This allows one device to have the functions of two types of devices, giving full play to the energy conversion advantages of power electronic equipment, and saving equipment and construction costs. Attached Figure Description

[0059] Figure 1 This is the overall flowchart of the present invention.

[0060] Figure 2 This is a schematic diagram of the energy mutual assistance operation between two stations in an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and do not limit the scope of the invention.

[0062] Example: Figure 1 As shown, a capacity allocation method applicable to AC / DC microgrid converters specifically includes the following steps.

[0063] S1 is used to set parameters for the AC / DC microgrid converter (PCS).

[0064] The settings include the transformer capacities Sn1 and Sn2 connected to each AC / DC microgrid converter master and slave, the load factor threshold λ1 for starting energy mutual assistance, the target value λ2 for load factor mutual assistance, the capacity allocation mode, the effective value limit of the three-phase output current Irms, and the effective value limit of the neutral current I0rms.

[0065] 1) λ1 can be set to 80%, λ2 can be set to 60%, and λ1-λ2≥10%.

[0066] 2) There are 5 modes: mode=1, only energy mutual assistance mode is considered; mode=2, only power quality management mode is considered; mode=3, energy mutual assistance priority, that is, the remaining current capacity is used for power quality management only if the effective value of the three-phase output current is less than Irms when energy mutual assistance is fully implemented; mode=4, power quality management priority, that is, the remaining current capacity is used for energy mutual assistance only if the effective value of the three-phase output current is less than Irms and the effective value of the neutral current is less than or equal to I0rms when power quality management is fully implemented; mode=5, same priority, that is, within the range of Irms, s0=s1 is calculated, and then s1 is further calculated in combination with I0rms.

[0067] 3) The working modes of PCS master and PCS slave are shown in the table below.

[0068] PCS Host PCS slave machine mode=1 mode=1 or mode=3 mode=2 mode=2 mode=3 mode=1 or mode=3 mode=4 mode=1 or mode=2 or mode=3 mode=5 mode=1 or mode=3

[0069] When the host capacity allocation mode is not equal to 2, the slave can preferentially select mode = 3.

[0070] S2, the microgrid controller collects the total active power P1 and P2 of the AC / DC microgrid converter master and slave on the grid side and sends them to the AC / DC microgrid converter master.

[0071] The AC / DC microgrid converter host collects and calculates the effective value of the A-phase grid voltage UA, and then calculates the active current I1p of each phase according to the set parameters.

[0072] The communication method between the microgrid controller and the PCS host is generally RS-485, network cable or LoRa, and the communication cycle is 2 minutes.

[0073] S3, PCS locally collects the current data of the power grid, calculates the vertical component I1q of the positive sequence reactive current of each phase in the corresponding voltage phase, the in-phase component I2p[i] of the negative sequence current of each phase in the corresponding voltage phase, the vertical component I2q[i] of the negative sequence current of each phase in the corresponding voltage phase, the in-phase component I_harm_cos[i][k] of each phase's harmonic current in the same reference phase, and the vertical component I_harm_sin[i][k] of each phase's harmonic current in the same reference phase.

[0074] S4. Based on the mode setting, Irms, I0rms and the above current calculation results, the AC / DC microgrid converter calculates the current coefficient s0 for energy mutual assistance and the current coefficient s1 for power quality management.

[0075] S5. Based on the above current calculation results, s0, and s1, calculate the current regulation target value Iref, which will be used as the input value for subsequent current inner loop control.

[0076] Jump to S2.

[0077] Figure 2 This is a schematic diagram of the energy mutual assistance operation between two transformer substations in an embodiment of the present invention. The microgrid controller is connected to the grid side of transformer substation 1, obtains the grid-side power of the two transformer substations through communication, and sends the data to the PCS host through 485 communication. The AC side of each PCS is connected to the grid side of its respective transformer substation. The CT collects the current on the grid side, and the DC side is connected through a DC line to realize energy mutual assistance.

[0078] The calculation process for the active current I1p of each mutual aid in this invention is as follows.

[0079] S21, Energy Mutual Aid Start Flag = 0, I1p = 0.

[0080] S22, calculate the power of the two units at λ1 and λ2.

[0081] P11=λ1·Sn1; P12=λ2·Sn1; P21=λ1·Sn2; P22=λ2·Sn2.

[0082] Where P11 is the power of the AC / DC microgrid converter main unit corresponding to the transformer area under λ1, P12 is the power of the AC / DC microgrid converter main unit corresponding to the transformer area under λ2, P21 is the power of the AC / DC microgrid converter slave unit corresponding to the transformer area under λ1, and P22 is the power of the AC / DC microgrid converter slave unit corresponding to the transformer area under λ2.

[0083] S23, if P1 > P11 and P2 < P22, then Flag = 1, ΔP = min(P1 - P11, P22 - P2), I1p = I1p + ΔP / (3 * UA); otherwise, go to S24.

[0084] Where ΔP is the power difference to be regulated in this round.

[0085] S24, if P1 < P21 and P2 > P21, then Flag = 1, ΔP = max(P1 - P11, P22 - P2), I1p = I1p + ΔP / (3 * UA); otherwise, go to S25.

[0086] S25, if Flag = 0, then do not perform energy mutual aid, I1p = 0; otherwise, go to S26.

[0087] S26, if I1p = 0, then Flag = 0; otherwise, go to S27.

[0088] S27, if I1p > 0 and P2 > P21, then ΔP = P21 - P2, I1p = I1p + ΔP / (3 * UA).

[0089] If I1p > 0 and P1 < P12, then ΔP = P12 - P1, I1p = I1p + ΔP / (3 * UA).

[0090] If I1p < 0 and P1 > P11, then ΔP = P1 - P11, I1p = I1p + ΔP / (3 * UA).

[0091] If I1p < 0 and P2 < P22, then ΔP = P2 - P22, I1p = I1p + ΔP / (3 * UA).

[0092] Otherwise, I1p remains unchanged.

[0093] When A.mode = 1: s1 = 0; if I1p < Irms, then s0 = 1; otherwise s0 = Irms / I1p.

[0094] B.mode = 2: (I_harm[i][k]) 2 = (I_harm_cos[i][k]) 2 + (I_harm_sin[i][k]) 2 .

[0095]

[0096] s0 = 0; the minimum value among k1min, k2, and 1 is s1.

[0097] Where i takes 0, 1, and 2 to represent phases A, B, and C, respectively; k is the harmonic index, generally k takes 0 to 5, representing the 3rd, 5th, 7th, 9th, 11th, and 13th harmonics, respectively; k1[i] is the coefficient of each phase satisfying the above formula, with a minimum value of k1min; k2 is the coefficient satisfying I0rms; I2p[i] and I2q[i] are the in-phase and vertical components of the negative sequence current of each phase in the corresponding voltage phase, respectively; the in-phase component I0p[i] and vertical component I0q[i] of the zero sequence current of each phase in the corresponding voltage phase; I1q is the vertical component of the positive sequence reactive current of each phase in the corresponding voltage phase; I_harm_cos[i][k] and I_harm_sin[i][k] are the in-phase and vertical components of the kth harmonic current of each phase in the same reference phase, respectively; I_harm0[k] is the effective value of the kth harmonic current on the neutral line.

[0098] When C.mode = 3: If I1p > Irms, then s0 = Irms / I1p, s1 = 0; otherwise:

[0099] s0 = 1; the minimum value among k1min, k2 and 1 is s1.

[0100] D.mode=4: (I_harm[i][k]) 2 =(I_harm_cos[i][k]) 2 +(I_harm_sin[i][k]) 2 .

[0101]

[0102] s0 = 0; the minimum value among k1min, k2 and 1 is s1.

[0103] If s1 < 1, then s0 = 0; otherwise:

[0104] s1 = 1; the smaller of k1min and 1 is s0.

[0105] When E.mode=5:

[0106] The smaller of k1min and 1 is s0; the smallest of k1min, k2 and 1 is s1.

[0107] The above embodiments are descriptions of specific implementations of the present invention, and not limitations thereof. Those skilled in the art can make various modifications and changes without departing from the spirit and scope of the present invention to obtain corresponding equivalent technical solutions. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A current regulation method suitable for AC / DC microgrid converters, characterized in that, It includes the following steps: S1. Set parameters for the AC / DC microgrid converter; The settings include the transformer capacities Sn1 and Sn2 connected to the master and slave of each AC / DC microgrid converter, the load rate threshold λ1 for starting energy mutual assistance, the load rate mutual assistance target value λ2, the capacity allocation mode mode, the effective value limit of the three-phase output current Irms, and the effective value limit of the neutral line current I0rms; S2. The microgrid controller collects the total grid-side active powers P1 and P2 corresponding to the master and slave of the AC / DC microgrid converter and sends them to the master of the AC / DC microgrid converter; The master of the AC / DC microgrid converter collects and calculates the effective value UA of the A-phase grid voltage, and then calculates the mutual active current I1p of each phase according to P1, P2, and the set parameters. The calculation method of I1p is as follows: S21. The energy mutual assistance start flag bit Flag = 0, I1p = 0; S22. Calculate the powers of the two regions under λ1 and λ2: P11 = λ1·Sn1; P12 = λ2·Sn1; P21 = λ1·Sn2; P22 = λ2·Sn2; Among them, P11 is the power of the area corresponding to the master of the AC / DC microgrid converter under λ1, P12 is the power of the area corresponding to the master of the AC / DC microgrid converter under λ2, P21 is the power of the area corresponding to the slave of the AC / DC microgrid converter under λ1, and P22 is the power of the area corresponding to the slave of the AC / DC microgrid converter under λ2; S23. If P1 > P11 and P2 < P22, then Flag = 1, △P = min(P1 - P11, P22 - P2), I1p = I1p + △P / (3*UA); otherwise, go to S24; Among them, △P is the power difference to be regulated in this round; S24. If P1 < P21 and P2 > P21, then Flag = 1, △P = max(P1 - P11, P22 - P2), I1p = I1p + △P / (3*UA); otherwise, go to S25; S25. If Flag = 0, do not perform energy mutual assistance, I1p = 0; otherwise, go to S26; S26. If I1p = 0, then Flag = 0; otherwise, go to S27; S27. If I1p > 0 and P2 > P21, then △P = P21 - P2, I1p = I1p + △P / (3*UA); If I1p > 0 and P1 < P12, then △P = P12 - P1, I1p = I1p + △P / (3*UA); If I1p < 0 and P1 > P11, then △P = P1 - P11, I1p = I1p + △P / (3*UA); If I1p < 0 and P2 < P22, then △P = P2 - P22, I1p = I1p + △P / (3*UA); Otherwise, I1p remains unchanged; S3, the AC / DC microgrid converter locally collects the current data of the power grid, calculates the vertical component I1q of the positive sequence reactive current of each phase in the corresponding voltage phase, the in-phase component I2p[i] of the negative sequence current of each phase in the corresponding voltage phase, the vertical component I2q[i] of the negative sequence current of each phase in the corresponding voltage phase, the in-phase component I_harm_cos[i][k] of each phase's harmonic current in the same reference phase, and the vertical component I_harm_sin[i][k] of each phase's harmonic current in the same reference phase. S4. Based on the mode setting, Irms, I0rms and the above current calculation results, the AC / DC microgrid converter calculates the current coefficient s0 for energy mutual assistance and the current coefficient s1 for power quality management. S5. Based on the above current calculation results, s0, and s1, calculate the current regulation target value Iref, which will be used as the input value for subsequent current inner loop control. Jump to S2; The method for calculating s0 and s1 is as follows: When mode = 1: s1 = 0; if I1p < Irms, then s0 = 1; otherwise, s0 = Irms / I1p; When B.mode=2: (I_harm[i][k]) 2 =(I_harm_cos[i][k]) 2 +(I_harm_sin[i][k]) 2 ; s0 = 0; the minimum value among k1min, k2, and 1 is s1; Where i takes values ​​of 0, 1, and 2 to represent phases A, B, and C, respectively; k is the harmonic index, ranging from 0 to 5, representing the 3rd, 5th, 7th, 9th, 11th, and 13th harmonics, respectively; k1[i] is the coefficient of each phase satisfying the above formula, with a minimum value of k1min; k2 is the coefficient satisfying I0rms; I2p[i] and I2q[i] are the in-phase and vertical components of the negative sequence current of each phase in the corresponding voltage phase, respectively; the in-phase component I0p[i] and vertical component I0q[i] of the zero sequence current of each phase in the corresponding voltage phase; I1q is the vertical component of the positive sequence reactive current of each phase in the corresponding voltage phase; I_harm_cos[i][k] and I_harm_sin[i][k] are the in-phase and vertical components of the kth harmonic current of each phase in the same reference phase, respectively; I_harm0[k] is the effective value of the kth harmonic current on the neutral line; I_harm[i][k] is the effective value of the kth harmonic current of each phase. When C.mode = 3: If I1p > Irms, then s0 = Irms / I1p, s1 = 0; otherwise: s0 = 1; the minimum value among k1min, k2, and 1 is s1; When D.mode=4: (I_harm[i][k]) 2 =(I_harm_cos[i][k]) 2 +(I_harm_sin[i][k]) 2 ; s0 = 0; the minimum value among k1min, k2, and 1 is s1; If s1 < 1, then s0 = 0; otherwise: s1 = 1; the smaller of k1min and 1 is s0; When E.mode=5: The smaller of k1min and 1 is s0; the smallest of k1min, k2 and 1 is s1.

2. The current regulation method for AC / DC microgrid converters according to claim 1, characterized in that, There are 5 capacity allocation modes: mode=1, only considering the energy mutual assistance condition; mode=2, only power quality management conditions are considered; mode=3, energy mutual assistance priority, that is, the remaining current capacity will be used for power quality management only if the effective value of the three-phase output current is less than Irms when energy mutual assistance is fully performed. mode=4, power quality management takes priority, that is, the remaining current capacity will be used for energy mutual assistance only if the effective value of the three-phase output current is less than Irms and the effective value of the neutral current is less than or equal to I0rms when power quality management is fully completed. mode=5, same priority, that is, within the Irms range, s0=s1 is calculated, and then s1 is further calculated in combination with I0rms.

3. The current regulation method for AC / DC microgrid converters according to claim 1, characterized in that, Step S21 is performed only once during initialization.

4. The current regulation method for AC / DC microgrid converters according to claim 1, characterized in that, The communication between the microgrid controller and the AC / DC microgrid converter host is via RS-485, network cable, or LoRa, with a communication cycle of 2 minutes.

5. A current regulation method for AC / DC microgrid converters according to claim 1, characterized in that, The AC / DC microgrid converter master unit is used to receive power from the distribution area, and the AC / DC microgrid converter slave unit is used for DC voltage regulation. The corresponding relationship of their capacity allocation modes is as follows: When the mode of the AC / DC microgrid converter master is 1, the mode of the AC / DC microgrid converter slave is preferably selected as 3, but can also be selected as 1; When the AC / DC microgrid converter master mode=2, the AC / DC microgrid converter slave mode=2; When the AC / DC microgrid converter master mode=3, the AC / DC microgrid converter slave mode should preferably be selected as 3, but can also be selected as 1; When the AC / DC microgrid converter master mode=4, the AC / DC microgrid converter slave mode should preferably be 3, but can also be 1 or 2; When the AC / DC microgrid converter master mode=5, the AC / DC microgrid converter slave mode should preferably be 3, but can also be 1.

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