Method for comprehensive treatment of power quality of multi-port converter device containing three-layer control strategy

Abstract

The application provides a kind of multi-port converter device power quality comprehensive treatment method containing three-layer control strategy, can prevent system from happening oscillation instability and other major risk challenges.The application considers renewable energy grid-connected active power, power quality treatment, investment compensation capacity three aspects, and designs three-layer control strategy of multi-port converter device.Compared with traditional converter device, while considering power quality treatment of multi-port converter device, it also considers renewable energy grid-connected active power and investment compensation capacity.When distributed power supply is accessed, by minimizing renewable energy grid-connected active power reduction, minimizing current harmonic total distortion rate, voltage deviation and three-phase unbalance degree, minimizing investment compensation capacity, the problems of sudden drop of renewable energy grid-connected active power, unsatisfactory power quality and excessive investment compensation capacity of distribution network are solved, which provides reference for multi-port converter device control strategy and distribution network multi-feed line power quality treatment.

Description

Technical Field

[0001] The present invention belongs to the field of converter control strategy and power quality management, and in particular relates to a comprehensive power quality management method for a multi-port converter device containing a three-layer control strategy. Background Art

[0002] Since the beginning of the new century, my country's new energy industry has experienced rapid development. Distribution networks have gradually adopted characteristics such as a high proportion of renewable energy and power electronic devices, as well as a diversified load structure. This has led to an increasing emphasis on the weak grid characteristics of distribution networks. Among these, rising total harmonic distortion (THD) of current, exceeding voltage limits, and three-phase imbalance caused by insufficient harmonics and reactive power can severely impact the power quality of multiple ports within distribution network feeders, potentially leading to significant risks such as system oscillation and instability. Therefore, multi-port power quality issues within distribution network feeders pose a significant challenge to power system stability and power supply security.

[0003] Extensive and in-depth scientific research and engineering exploration have been carried out on multi-port power quality management in distribution network feeders. The existing methods mainly use multi-port grid-connected converters. Figure 1 The schematic diagram of the multi-port grid-connected converter is shown in Figure 1. The renewable energy and the front-stage converter are usually equivalent to a DC power supply U dc , an inverter circuit consisting of 6 insulated gate bipolar transistors and an L-type filter is connected to the grid through the common connection point. Among them, the factors affecting the power quality of the common connection point are simulated by nonlinear and unbalanced loads. First, based on the grid active power instruction P * Calculate the grid-connected active current i P * and the capacity margin S of the multi-port converter m Secondly, a multi-objective optimization algorithm is used to calculate the load current i L , grid-side voltage u ga and the capacity margin S of the multi-port converter m Calculate the compensation current i c * , and combined with the grid active current to obtain the reference current i1 * Finally, the grid-connected power generation and compensation functions of the multi-port converter are realized through the current controller.

[0004] The proposed harmonic and reactive load capacity droop control based on the shared control strategy for multi-port grid-connected converters can effectively improve the power quality of the distribution network. However, due to the oversimplification of the designed compensation current, sufficient control accuracy cannot be guaranteed. A control strategy for multi-port grid-connected converters based on comprehensive power quality assessment is proposed. However, the control strategy cannot maximize the grid-connected active power and minimize the input compensation capacity, resulting in a significant reduction in economic benefits. A droop control strategy for multi-port grid-connected converters is proposed based on a combination of linear active disturbance rejection control and repetitive control. However, the adopted current inner loop structure cannot take into account both response speed and tracking accuracy. Summary of the Invention

[0005] In response to the above problems, the present invention aims to provide a comprehensive power quality management method for a multi-port converter device containing a three-layer control strategy, which is suitable for comprehensive power quality management of multiple ports in distribution network feeders.

[0006] In order to achieve the technical objectives of the present invention, the following technical solutions are adopted:

[0007] A method for comprehensive power quality management of a multi-port converter device with a three-layer control strategy, characterized by comprising the following steps:

[0008] Step S1: performing load current detection on multiple feeders of the distribution network taking into account nonlinear and unbalanced loads, and calculating reactive current components, negative sequence current components, and harmonic current components based on the detected load currents on multiple feeders of the distribution network;

[0009] Step S2: Based on the load current detection of multiple feeders in the distribution network, a three-layer control strategy for a multi-port converter device is designed, which takes into account the active power of renewable energy grid connection, power quality management, and input compensation capacity;

[0010] Step S3: Based on the objective function and constraints of the three-layer control strategy, a quantum genetic algorithm is used to solve the compensation current of the multi-port converter device to achieve comprehensive power quality management of multiple feeders in the distribution network.

[0011] Furthermore, step S1 includes the following sub-steps:

[0012] Step S11: The load current i L Expressed as:

[0013] i L =i h +i p +i q +i n

[0014] Where i L is the load current, i h is the harmonic current component, i pis the positive sequence active current component, i q is the positive sequence reactive current component, i n is the negative sequence current component;

[0015] Step S12: Load current i L The fundamental positive sequence active current component i p (i pa 、i pb 、i pc ) is represented by:

[0016]

[0017] Where G p is the DC component of the three-phase instantaneous positive sequence active equivalent conductance; Step S13: load current i L The fundamental positive sequence reactive current component i q (i qa 、i qb 、i qc ) is represented by:

[0018]

[0019] Where G q is the DC component of the three-phase instantaneous positive sequence reactive equivalent conductance; i q for i qa 、i qb 、i qc A general term for

[0020] Step S14: Based on the detected load current i of the multiple feeders in the distribution network L , solve for the negative sequence current component i n Specifically, the load current i L The negative sequence current component i is obtained by Park transformation, center frequency 2ω filtering and inverse Park transformation. n ;

[0021] Step S15: Based on the load current i of the multiple feeders in the distribution network detected L , positive sequence active current component i p , positive sequence reactive current component i q And the negative sequence current component i n , solve for the harmonic current component i h ;

[0022] i h =i L -i p -i q -i n .

[0023] Furthermore, step S2 includes the following sub-steps:

[0024] Step S21: Design an upper control strategy for the multi-port converter. The upper control strategy formulates an objective function based on the principle of minimizing the reduction in active power of renewable energy grid-connected. The objective function F of the upper control strategy for the multi-port converter is U Expressed as:

[0025]

[0026] Where N is the amount of renewable energy, ΔP k Reduction in active power of renewable energy grid-connected;

[0027] Reduction in active power of renewable energy grid-connected ΔP k Expressed as:

[0028] ΔP k =P k max -P k

[0029] Where, P k max is the active power of renewable energy connected to the grid, P k To compensate for the active power of renewable energy connected to the grid;

[0030] The total capacity of the multi-port converter is S M Satisfy the following constraints:

[0031]

[0032] Where S P is the active power capacity of renewable energy grid-connected, S H is the harmonic control capacity, S R is the reactive compensation capacity, S U There are three unbalanced capacities;

[0033] At the same time, the output power of the multi-port converter device meets the power flow constraints:

[0034]

[0035] Where, P Mi and Q Mi are the active power and reactive power of node i, P Mj is the active power of node j, P Li and Q Li are the active power and reactive power consumed by the load at node i, V i and V i are the voltages at nodes i and j, Gij and B ij are the conductance and susceptance of line ij respectively;

[0036] In addition, the output power of the multi-port converter device meets the upper limit constraint:

[0037] 0≤P k ≤P k max

[0038] The above constraints indicate that the output power of the multi-port converter device is not allowed to exceed the maximum power generated by the renewable energy source;

[0039] Step S22: Design a middle-level control strategy for the multi-port converter. The middle-level control strategy formulates an objective function based on the principle of minimizing the total current harmonic distortion rate, voltage deviation, and three-phase imbalance. The objective function F of the middle-level control strategy for the multi-port converter is M Expressed as:

[0040] min F M =min(F M1 +F M2 +F M3 )

[0041] Where, F M1 is the total harmonic distortion rate objective function of current, F M2 is the voltage deviation objective function, F M3 is the three-phase unbalance objective function;

[0042] Current harmonic total distortion rate objective function F M1 Expressed as:

[0043]

[0044] Where, δ i is the current harmonic distortion rate of node i, δ N is the current harmonic distortion rate limit, n i The number of nodes where the current harmonic distortion rate or voltage deviation does not meet the standards;

[0045] Current harmonic distortion rate δ at node i i Expressed as:

[0046]

[0047] Where, I hi is the harmonic current component of node i, I 1i is the fundamental current component of node i;

[0048] Harmonic current component I at node i hi Expressed as:

[0049]

[0050] Where, I Hi is the hth harmonic current component of node i, M is the highest frequency of the harmonic;

[0051] Voltage deviation objective function F U2 Expressed as:

[0052]

[0053] Where, γ qi is the reactive power coefficient of node i;

[0054] Reactive power coefficient γ of node i qi Expressed as:

[0055]

[0056] Where, I qi is the reactive current component of node i;

[0057] Three-phase unbalance objective function F M3 Expressed as:

[0058]

[0059] Where, I ni is the negative sequence current component of node i;

[0060] The harmonic control, reactive power compensation and three-phase balance of the multi-port converter meet the capacity constraints:

[0061] S i ≤k i S Ni

[0062] Where S i is the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter at node i, k i is the capacity margin safety factor of node i, S Ni is the rated capacity of the multi-port converter device at node i;

[0063] The above constraints indicate that the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter device is not allowed to exceed the total capacity of the multi-port converter device;

[0064] Step S23: Design the lower-level control strategy of the multi-port converter. The lower-level control strategy formulates the objective function based on the principle of minimizing the input compensation capacity. The objective function F of the lower-level control strategy of the multi-port converter is L Expressed as:

[0065]

[0066] Where S c To invest in compensation capacity;

[0067] The compensation capacity of the multi-port converter device meets the capacity constraint:

[0068]

[0069] Where S m is the capacity margin of the multi-port converter, S N is the rated capacity of the multi-port converter, S P The active power capacity of renewable energy grid-connected to the multi-port converter device;

[0070] The above constraints indicate that the compensation capacity of the multi-port converter device is not allowed to exceed the capacity margin of the multi-port converter device.

[0071] Furthermore, step S3 includes the following sub-steps:

[0072] Step S31: encoding the chromosome based on the quantum state, initializing the population, and setting the parameters of the multi-port converter device;

[0073] Step S32: measuring all individuals in the population and converting the measurement results into binary bit strings;

[0074] Step S33: Calculate the objective function of all individuals in the population based on the binary bit string;

[0075] Step S34: Record the best individual in the population according to the objective function calculation result;

[0076] Step S35: Determine whether the objective function of the optimal individual in the population meets the convergence accuracy or whether the maximum number of iterations has been reached. If so, output the compensation current and end the quantum genetic algorithm; if not, proceed to step S36, and the population will continue to evolve;

[0077] Step S36: updating the population based on the quantum rotation gate;

[0078] Step S37: Perform a quantum mutation operation on the population based on the quantum NOT gate, and the updated iterative population enters step S32.

[0079] Compared with traditional converters, the present invention not only considers the power quality management of multi-port converters, but also takes into account the active power of renewable energy grid connection and the input compensation capacity. When distributed power sources are connected, the present invention solves the problems of sudden drop in active power of renewable energy grid connection, unsatisfactory power quality and excessive input compensation capacity in the distribution network by minimizing the reduction in active power of renewable energy grid connection, minimizing the total current harmonic distortion rate, voltage deviation and three-phase imbalance, and minimizing the input compensation capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 This is the schematic diagram of a multi-port grid-connected converter;

[0081] Figure 2 A three-layer control strategy for multi-port grid-connected converters;

[0082] Figure 3 This is a flow chart for solving the output compensation current of a multi-port grid-connected converter using a quantum genetic algorithm.

[0083] Figure 4 It is the node voltage 12 hours before and after treatment.

[0084] Figure 5 It is the 24-hour reactive power output of the converter.

[0085] Figure 6 To control the time when harmonics exceed the standard before and after. DETAILED DESCRIPTION

[0086] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments may help developers in related fields to further understand the technical solutions of the present invention. It should be noted that the embodiments are intended to explain the present invention rather than to limit the present invention.

[0087] The embodiment of the present invention discloses a method for comprehensive power quality management of a multi-port converter device including a three-layer control strategy, which includes the following steps:

[0088] Step S1: performing load current detection on multiple feeders of the distribution network taking into account nonlinear and unbalanced loads, and calculating reactive current components, negative sequence current components, and harmonic current components based on the detected load currents on multiple feeders of the distribution network;

[0089] Step S2: Based on the load current detection of multiple feeders in the distribution network, a three-layer control strategy for a multi-port converter device is designed, which takes into account the active power of renewable energy grid connection, power quality management, and input compensation capacity;

[0090] Step S3: Based on the objective function and constraints of the three-layer control strategy, a quantum genetic algorithm is used to solve the compensation current of the multi-port converter device to achieve comprehensive power quality management of multiple feeders in the distribution network.

[0091] The step S1 includes the following sub-steps:

[0092] Step S11: Detect the load current i of multiple feeders in the distribution network L , solve for the reactive current component i q . Load current i L The fundamental positive sequence active current component i pa 、i pb 、i pc It can be expressed as:

[0093]

[0094] Where G p It is the DC component of the three-phase instantaneous positive sequence active equivalent conductance.

[0095] Load current i L The fundamental positive sequence reactive current component i qa 、i qb 、i qc It can be expressed as:

[0096]

[0097] Where G q is the DC component of the three-phase instantaneous positive-sequence reactive equivalent conductance.

[0098] Step S12: Detect the load current i of multiple feeders in the distribution network. L , solve for the negative sequence current component i n . The load current i L The negative sequence current component i is obtained by Park transformation, center frequency 2ω filtering and inverse Park transformation. n .

[0099] Step S13: Detect the load current i of multiple feeders in the distribution network. L And the negative sequence current component i n , solve for the harmonic current component i n .

[0100] i h =i L -i p -i q -i n

[0101] The step S2 includes the following sub-steps:

[0102] Step S21: Design the upper control strategy of the multi-port converter device, and formulate the objective function based on the principle of minimizing the reduction in active power of renewable energy grid-connected. The objective function F of the upper control strategy of the multi-port converter device is U It can be expressed as:

[0103]

[0104] Where N is the amount of renewable energy, ΔP k It is the reduction in active power of renewable energy grid-connected.

[0105] Reduction in active power of renewable energy grid-connected ΔP k It can be expressed as:

[0106] ΔP k =P k max -P k

[0107] Where, P k max is the active power of renewable energy connected to the grid, P k To compensate for the active power of renewable energy connected to the grid.

[0108] The total capacity of the multi-port converter is S M Satisfy the following constraints:

[0109]

[0110] Where S P is the active power capacity of renewable energy grid-connected, S H is the harmonic control capacity, S R is the reactive compensation capacity, S U There are three unbalanced capacities.

[0111] At the same time, the output power of the multi-port converter device meets the power flow constraints:

[0112]

[0113] Where, P Mi and Q Mi are the active power and reactive power of node i, P Mj is the active power of node j, P Li and Q Li are the active power and reactive power consumed by the load at node i, V i and V i are the voltages at nodes i and j, G ij and B ij are the conductance and susceptance of line ij respectively.

[0114] In addition, the output power of the multi-port converter device meets the upper limit constraint:

[0115] 0≤P k ≤P k max

[0116] The above constraints indicate that the output power of the multi-port converter device is not allowed to exceed the maximum power generated by the renewable energy source.

[0117] Step S22: The middle-level control strategy of the multi-port converter sets an objective function based on the principle of minimizing the total current harmonic distortion rate, voltage deviation and three-phase imbalance. The objective function F of the middle-level control strategy of the multi-port converter is: M It can be expressed as:

[0118] minF M =min(F M1 +F M2 +F M3 )

[0119] Where, F M1 is the total harmonic distortion rate objective function of current, F M2 is the voltage deviation objective function, F M3 is the three-phase imbalance objective function.

[0120] Current harmonic total distortion rate objective function F M1 It can be expressed as:

[0121]

[0122] Where, δ i is the current harmonic distortion rate of node i, δ N is the current harmonic distortion rate limit, n i The number of nodes where the current harmonic distortion rate or voltage deviation does not meet the standards.

[0123] Current harmonic distortion rate δ at node i i It can be expressed as:

[0124]

[0125] Where, I hi is the harmonic current component of node i, I 1i is the fundamental current component of node i.

[0126] Harmonic current component I at node i hi It can be expressed as:

[0127]

[0128] Where, IHi is the hth harmonic current component of node i, and M is the highest frequency of the harmonic.

[0129] Voltage deviation objective function F U2 It can be expressed as

[0130]

[0131] Where, γ qi is the reactive power coefficient of node i.

[0132] Reactive power coefficient γ of node i qi It can be expressed as:

[0133]

[0134] Where, I qi is the reactive current component of node i.

[0135] Three-phase unbalance objective function F M3 It can be expressed as:

[0136]

[0137] Where, I ni is the negative sequence current component of node i.

[0138] The harmonic control, reactive power compensation and three-phase balance of the multi-port converter meet the capacity constraints:

[0139] S i ≤k i S Ni

[0140] Where S i is the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter at node i, k i is the capacity margin safety factor of node i, S Ni is the rated capacity of the multi-port converter at node i.

[0141] The above constraints indicate that the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter device is not allowed to exceed the total capacity of the multi-port converter device.

[0142] Step S23: The lower-level control strategy of the multi-port converter sets an objective function based on the principle of minimizing the input compensation capacity. The objective function F of the lower-level control strategy of the multi-port converter is: L It can be expressed as:

[0143]

[0144] Where S cTo input compensation capacity.

[0145] The compensation capacity of the multi-port converter device meets the capacity constraint:

[0146]

[0147] Where S m is the capacity margin of the multi-port converter, S N is the rated capacity of the multi-port converter, S P It is the active power capacity of renewable energy grid-connected with multi-port converter.

[0148] The above constraints indicate that the compensation capacity of the multi-port converter device is not allowed to exceed the capacity margin of the multi-port converter device.

[0149] Figure 2 This is a three-layer control strategy for a multi-port grid-connected converter. The upper-layer strategy minimizes the active power reduction of renewable energy grid-connected devices; the middle-layer strategy minimizes total current harmonic distortion, voltage deviation, and three-phase imbalance; and the lower-layer strategy minimizes the input compensation capacity. It should be noted that the three-layer control strategies are in a progressive relationship.

[0150] The step S3 includes the following sub-steps:

[0151] Step S31: encoding the chromosome based on the quantum state, initializing the population, and setting the parameters of the multi-port converter device;

[0152] Step S32: measuring all individuals in the population and converting the measurement results into binary bit strings;

[0153] Step S33: Calculate the objective function of all individuals in the population based on the binary bit string;

[0154] Step S34: Record the best individual in the population according to the objective function calculation result;

[0155] Step S35: Determine whether the objective function of the optimal individual in the population meets the convergence accuracy or whether the maximum number of iterations has been reached. If so, output the compensation current and end the quantum genetic algorithm; if not, proceed to step S36, and the population will continue to evolve;

[0156] Step S36: updating the population based on the quantum rotation gate;

[0157] Step S37: Perform a quantum mutation operation on the population based on the quantum NOT gate, and the updated iterative population enters step S32.

[0158] Figure 3 This is a flow chart for solving the output compensation current of a multi-port grid-connected converter using a quantum genetic algorithm.

[0159] A quantum genetic algorithm (QGA) is used to solve the compensation current output by a multi-port grid-connected converter based on the objective function and constraints of a three-layer control strategy. The solution involves encoding chromosomes based on quantum states, updating the population using quantum rotation gates, and performing quantum mutation operations on the population using quantum NOT gates.

[0160] The present invention will be further described below with reference to specific examples.

[0161] Assuming the voltage amplitude qualified range is [0.95.1.05] pu, the system voltage offset was 22.23 before treatment and 11.69 after treatment, a decrease of 10.54 compared to before treatment, thus improving the overall voltage quality of the distribution network.

[0162] In order to compare the voltage amplitude before and after treatment in detail, the changes of node voltage are analyzed by taking the 12th hour as an example. The node voltage amplitude is as follows: Figure 4 As shown. Figure 4 It can be seen that before the treatment, the voltage of four nodes in the system exceeded the upper limit. After the treatment, the voltage amplitude of each node was within the qualified range, meeting its power quality requirements.

[0163] The 24-hour reactive power output of the converter is as follows: Figure 5 As shown in Figure 2, during nighttime when voltage is low, the multi-port converter with the three-layer control strategy generates reactive power to increase system voltage. During daytime when voltage is high, the multi-port converter with the three-layer control strategy does not absorb reactive power to reduce system voltage.

[0164] During the period when harmonics exceed the standard (1:00-8:00), a multi-port converter device with a three-layer control strategy controls the harmonics of the entire network. Figure 6 THD before and after harmonic control at the node where the harmonic source is located U As shown in the comparison chart, after being controlled by a multi-port converter device with a three-layer control strategy, the harmonic distortion rate is reduced to within the acceptable limit.

[0165] The disclosed multi-port converter device with a three-layer control strategy implements a comprehensive method for managing power quality across multiple feeders in a distribution network, preventing significant risks and challenges such as system oscillation and instability. Furthermore, the invention provides an important reference for multi-port converter device control strategies and power quality management across multiple feeders in distribution networks.

[0166] The above describes specific embodiments of the present invention. It should be noted that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes and modifications within the scope of the claims without affecting the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A comprehensive power quality management method for a multi-port converter device with a three-layer control strategy, characterized in that: The following steps are involved: Step S1: performing load current detection on multiple feeders of the distribution network taking into account nonlinear and unbalanced loads, and calculating reactive current components, negative sequence current components, and harmonic current components based on the detected load currents on multiple feeders of the distribution network; Step S2: Based on the load current detection of multiple feeders in the distribution network, a three-layer control strategy for a multi-port converter device is designed, which takes into account the active power of renewable energy grid connection, power quality management, and input compensation capacity; Step S3: Based on the objective function and constraints of the three-layer control strategy, a quantum genetic algorithm is used to solve the compensation current of the multi-port converter device to achieve comprehensive power quality management of multiple feeders in the distribution network; The step S2 includes the following sub-steps: Step S21: Design an upper control strategy for the multi-port converter. The upper control strategy formulates an objective function based on the principle of minimizing the reduction in active power of renewable energy grid-connected. The objective function F of the upper control strategy for the multi-port converter is U Expressed as: ； Where N is the amount of renewable energy, ΔP k Reduction in active power of renewable energy grid-connected; Reduction in active power of renewable energy grid-connected ΔP k Expressed as: ； Where, P k max is the active power of renewable energy connected to the grid, P k To compensate for the active power of renewable energy connected to the grid; Step S22: Design a middle-level control strategy for the multi-port converter. The middle-level control strategy formulates an objective function based on the principle of minimizing the total current harmonic distortion rate, voltage deviation, and three-phase imbalance. The objective function F of the middle-level control strategy for the multi-port converter is M Expressed as: ； Where, F M1 is the total harmonic distortion rate objective function of current, F M2 is the voltage deviation objective function, F M3 is the three-phase unbalance objective function; Current harmonic total distortion rate objective function F M1 Expressed as: ； Where, δ i is the current harmonic distortion rate of node i, δ N is the current harmonic distortion rate limit, n i The number of nodes where the current harmonic distortion rate or voltage deviation does not meet the standards; Current harmonic distortion rate δ at node i i Expressed as: ； Where, I hi is the harmonic current component of node i, I 1i is the fundamental current component of node i; Harmonic current component I at node i hi Expressed as: ； Where, I Hi is the hth harmonic current component of node i, M is the highest frequency of the harmonic; Voltage deviation objective function F M2 Expressed as: ； Where, γ qi is the reactive power coefficient of node i; Reactive power coefficient γ of node i qi Expressed as: ； Where, I qi is the reactive current component of node i; Three-phase unbalance objective function F M3 Expressed as: ； Where, I ni is the negative sequence current component of node i; Step S23: Design the lower-level control strategy of the multi-port converter. The lower-level control strategy formulates the objective function based on the principle of minimizing the input compensation capacity. The objective function F of the lower-level control strategy of the multi-port converter is L Expressed as: ； Where S c is the input compensation capacity, I h is the harmonic current component, I q is the reactive current component, I n is the negative sequence current component.

2. The method for comprehensive power quality management of a multi-port converter device with a three-layer control strategy according to claim 1 is characterized in that: The step S1 includes the following sub-steps: Step S11: The load current i L Expressed as: ； Where i L is the load current, i h is the harmonic current component, i p is the positive sequence active current component, i q is the positive sequence reactive current component, i n is the negative sequence current component; Step S12: Load current i L The fundamental positive sequence active current component i p Expressed as: ； Where G p is the DC component of the three-phase instantaneous positive sequence active equivalent conductance; i p for i pa 、i pb 、i pc A general term for Step S13: Load current i L The fundamental positive sequence reactive current component i q Expressed as: ； Where G q is the DC component of the three-phase instantaneous positive sequence reactive equivalent conductance; i q for i qa 、i qb 、i qc A general term for Step S14: Based on the detected load current i of the multiple feeders in the distribution network L , solve for the negative sequence current component i n Specifically, the load current i L The negative sequence current component i is obtained by Park transformation, center frequency 2ω filtering and inverse Park transformation. n ; Step S15: Based on the load current i of the multiple feeders in the distribution network detected L , positive sequence active current component i p , positive sequence reactive current component i q And the negative sequence current component i n , solve for the harmonic current component i h ; 。 3. The comprehensive power quality management method for a multi-port converter device with a three-layer control strategy according to claim 1 is characterized in that: In step S21, The total capacity of the multi-port converter is S M Satisfy the following constraints: ； Where S P is the active power capacity of renewable energy grid-connected, S H is the harmonic control capacity, S R is the reactive compensation capacity, S U There are three unbalanced capacities; At the same time, the output power of the multi-port converter device meets the power flow constraints: ； i=1, 2, …, N; Where, P Mi and Q Mi are the active power and reactive power of node i, P Mj is the active power of node j, P Li and Q Li are the active power and reactive power consumed by the load at node i, V i and V i are the voltages at nodes i and j, G ij and B ij are the conductance and susceptance of line ij respectively; In addition, the output power of the multi-port converter device meets the upper limit constraint: ； The above constraints indicate that the output power of the multi-port converter device is not allowed to exceed the maximum power generated by the renewable energy source; In step S22, The harmonic control, reactive power compensation and three-phase balance of the multi-port converter meet the capacity constraints: ； Where S i is the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter at node i, k i is the capacity margin safety factor of node i, S Ni is the rated capacity of the multi-port converter device at node i; The above constraints indicate that the total capacity of harmonic control, reactive power compensation and three-phase balance of the multi-port converter device is not allowed to exceed the total capacity of the multi-port converter device; In step S23, The compensation capacity of the multi-port converter device meets the capacity constraint: ； Where S m is the capacity margin of the multi-port converter, S N is the rated capacity of the multi-port converter, S P The active power capacity of renewable energy grid-connected to the multi-port converter device; The above constraints indicate that the compensation capacity of the multi-port converter device is not allowed to exceed the capacity margin of the multi-port converter device.

4. The method for comprehensive power quality management of a multi-port converter device with a three-layer control strategy according to claim 1 is characterized in that: The step S3 includes the following sub-steps: Step S31: encoding the chromosome based on the quantum state, initializing the population, and setting the parameters of the multi-port converter device; Step S32: measuring all individuals in the population and converting the measurement results into binary bit strings; Step S33: Calculate the objective function of all individuals in the population based on the binary bit string; Step S34: Record the best individual in the population according to the objective function calculation result; Step S35: Determine whether the objective function of the optimal individual in the population meets the convergence accuracy or whether the maximum number of iterations has been reached. If so, output the compensation current and end the quantum genetic algorithm; if not, proceed to step S36, and the population will continue to evolve; Step S36: updating the population based on the quantum rotation gate; Step S37: Perform a quantum mutation operation on the population based on the quantum NOT gate, and the updated iterative population enters step S32.

Images