On-load capacity-regulating distribution network cooperative control method considering harmonic resonance and voltage out-of-limit

Abstract

The invention discloses an on-load capacity-regulating distribution network cooperative control method considering harmonic resonance and voltage out-of-limit, and belongs to the technical field of distribution network control, and the method comprises the following steps: S1, an on-load capacity-regulating distribution network topology and micro-source identification technology; s2, constructing harmonic resonance and voltage out-of-limit evaluation indexes of the on-load capacity regulating distribution network; s3, calculating the optimal loss in the autonomous operation scene of the distribution network; and S4, realizing source-network-load autonomous cooperative control with optimal loss and cost in the distribution network interactive operation scene. According to the energy flow distribution method, by considering the new energy permeability of the transformer area, the lower power flow, the line capacity, the harmonic resonance and the voltage out-of-limit constraint are improved, and comprehensive optimization energy flow distribution of the distribution network operation cost, the load participation willingness and the energy flow loss is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network control, and particularly relates to a coordinated control method for a distribution network with load-adjustable capacitance considering harmonic resonance and voltage over-limit. Background Technique

[0002] Under the background of carbon peaking and carbon neutrality, distributed power sources represented by solar energy have the advantages of small investment, environmental protection, high flexibility, etc., and the development scale has expanded rapidly. However, the randomness and volatility of distributed power sources are uncontrollable, and large-scale application and access also bring huge challenges and impacts to the traditional power grid. Regional autonomous microgrids provide an effective way to solve the problems of flexible, large-scale, and diverse grid connection of distributed power sources and reliable load supply, enabling the traditional end substations to transition to smart power grids.

[0003] The coordinated control of multiple micro-sources in a microgrid is the most important technology in the field of microgrid research. In terms of the control of the power electronic converter interface, in the literature "Defining control strategies for microgrids islanded operation", it is proposed that when the microgrid is in the islanded and grid-connected operation modes, different control methods are adopted for the micro-sources. When the microgrid is grid-connected, the PQ control is adopted for the micro-sources, and when the microgrid is in islanded operation, the V / f control method is adopted for the micro-sources. However, using this method is likely to cause the system to generate transient oscillations when the microgrid switches operation modes; in the literature "Design of comprehensive control strategy for low-voltage microgrid", different control methods are adopted for different micro-sources. The V / f control method is adopted for the micro-sources with stable output power, and the PQ control is adopted for the micro-sources affected by the natural environment and with unstable output. Although this method improves the operating characteristics of the microgrid, it will have a certain impact on the operating stability and flexibility of the system; in the literature "Control strategy for microgrid containing synchronous generator and voltage source inverter interface", it is proposed that when the microgrid operates independently, both types of micro-sources of the voltage source inverter interface and the synchronous generator set interface adopt the droop control method. At the same time, the active power of the load in the microgrid is distributed through the droop coefficients of their respective controls; in the literature "Research on coordinated control strategy of multiple micro-sources in microgrid", taking the hybrid energy storage system composed of batteries and supercapacitors as the basic research object, the coordinated output control strategy of the hybrid energy storage system composed of batteries and supercapacitors is studied, and on the basis of the research on the control strategy of the hybrid energy storage system, the overall coordinated control strategy of the multi-source DC microgrid is carried out.

[0004] In terms of the autonomous collaborative control optimization of multi-source energy flow in microgrids, in the literature "Research on the Cooperative and Optimization Method of Active Energy Management in Community Microgrids", the energy consumption characteristics of community microgrids are deeply analyzed, the concept of generalized users including photovoltaic and dispatchable loads is defined, and an optimization scheduling model of microgrids that simultaneously considers operation economy and user comfort is constructed, which not only reduces the operation cost but also improves the system's consumption of new energy power generation. In the literature "Research on the Multi-objective Configuration Optimization of Multi-energy Microgrids in Intelligent Parks Based on a Set of Typical Scenarios", the optimization configuration problem of multi-energy microgrids in intelligent park types is studied, a multi-objective optimization model architecture for multi-energy microgrid configuration is proposed, and the effectiveness of the proposed method in reducing construction costs and carbon emissions is verified using the energy consumption data and energy consumption distribution of the park. In the literature "Multi-objective Coordinated Control Strategy for Photovoltaic-storage Microgrid Systems", a new cooperative optimization scheduling strategy considering multiple objectives is proposed for energy storage and electrical and thermal loads. The solution process is simplified by methods such as introducing monotonicity analysis, which improves the energy control efficiency and engineering applicability of photovoltaic-storage microgrids.

[0005] In the patent with the publication number CN117374999A, a two-layer optimal configuration method and system for voltage regulation resources in a distribution network are provided, including obtaining a key fault set through spatio-temporal domain scanning; constructing a node importance index model based on power flow balance and power quality; establishing a reactive power optimization objective function by analyzing the tolerance of the distribution network; using a two-layer reactive power compensation optimal configuration model to consider multi-objective optimal configuration and operation; using a multi-objective particle swarm algorithm to obtain the optimal solution set, and selecting the best connection position, power, and capacity from it through the TOPSIS algorithm; outputting an optimal configuration plan for voltage regulation resources considering the key fault set and the tolerance of the distribution network.

[0006] In the patent with the publication number CN113890057A, a control method, device, and storage medium based on multi-microgrid cooperative optimization are provided. The control method includes the following steps: S1. Analyze the droop principle, structure, and system power distribution mechanism of traditional microgrid control; S2. Establish a distributed system control framework based on MAS; S3. Design a controller based on the Q-learning algorithm for the energy management of micro-sources; S4. Study the impact of new energy access on the stable operation of islanded microgrids; S5. Propose a microgrid frequency cooperative control method based on reinforcement learning for microgrid frequency deviation; S6. Adjust the droop parameters, change the output power of the islanded microgrid, and determine the optimal control method and strategy to achieve multi-source active power cooperation in the islanded microgrid.

[0007] The loads in the microgrid may vary over time and demand. The on-load tap-changing transformer can adjust the transformation ratio of the transformer in real time according to the load demand to adapt to different working conditions. However, with the continuous increase in the penetration rate of new energy, the problems of derivative voltage over-limit and harmonic resonance are becoming increasingly serious. The above-mentioned literature and patents cannot perform autonomous collaborative control on the distribution network containing on-load tap-changing transformers in a multi-scenario and multi-micro-source environment. Summary of the Invention

[0008] To solve the problem that the existing technology cannot perform autonomous collaborative control on the distribution network containing on-load tap-changing transformers in a multi-scenario and multi-micro-source environment. The present invention provides a collaborative control method for on-load tap-changing distribution networks considering harmonic resonance and voltage over-limit, which solves the multi-scenario and multi-micro-source optimal control problem of harmonic resonance and voltage over-limit constraints of on-load tap-changing distribution network photovoltaic inverters.

[0009] The technical solution adopted by the collaborative control method for on-load tap-changing distribution networks considering harmonic resonance and voltage over-limit of the present invention is as follows:

[0010] The collaborative control method for on-load tap-changing distribution networks considering harmonic resonance and voltage over-limit is characterized in that it includes the following steps

[0011] S1. Detect relevant electrical quantities of the micro-sources connected to each node by using the line detection terminal at the access node of the distribution network, including node voltage V, current I, frequency f, active power P, and reactive power Q;

[0012] S2. Construct an evaluation index for harmonic resonance and voltage over-limit of the on-load tap-changing distribution network;

[0013] S3. Calculate the optimal loss under the autonomous operation scenario of the distribution network;

[0014] S4. Calculate the cost-optimal source-network-load power reference value according to the loss under the interactive operation scenario of the distribution network, and send it to the control modules of each power generation / consumption unit to achieve the on-demand collaborative output of source-network-load power.

[0015] A further improvement of the technical solution of the present invention is that the step S1 includes the following steps

[0016] S1.1. Send a topology recognition signal to the i-th node in the distribution network through the detection terminal, and predict and record the line impedance in the distribution network according to the attenuation of the recognition signal;

[0017] Taking the node line detection terminal device as the leading, repeat the above steps for each node in the distribution network in turn until the distribution of all nodes and the relevant line impedance are all detected. According to the detection data, identify the topology information in the distribution network and update the topology file;

[0018] S1.2. Obtain the micro-source form and type according to the marketing 2.0 platform and the basic user information, inject small-signal disturbances of voltage and current at the micro-source access node, compare the key characteristics of the obtained micro-source port impedance characteristics with the impedance characteristic library, and identify the micro-source port characteristics;

[0019] Among them, the external characteristic impedance of the micro-source port is as follows:

[0020]

[0021] In the formula: Z s (s) is the micro-source impedance model, u s is the injected voltage disturbance, and i s is the injected current disturbance.

[0022] A further improvement of the above technical solution of the present invention is that: in step S2, according to the micro-source port characteristic identification method in S1.2, obtain the micro-source impedance model, and apply the bode diagram impedance stability criterion and the system harmonic resonance evaluation index PM, and its calculation formula is as follows:

[0023]

[0024] In the formula: Re represents the real part of the micro-source impedance model, Im represents the imaginary part of the micro-source impedance model, and arctan represents the arctangent calculation.

[0025] A further improvement of the technical solution of the present invention is that: in step S2, according to the topology file in S1.1 and the micro-source port characteristics in S1.2, obtain the real-time detection data of the node micro-source, and combine the voltage over-limit probability and the over-limit severity to construct a micro-source voltage over-limit index, which is expressed as follows:

[0026] R VV,t,i = P VV,t,i × S VV,t,i

[0027]

[0028] In the formula: R VV,t,i is the voltage over-limit index of node i at time t, P VV,t,i is the working voltage characteristic quantity of node i at time t, S VV,t,i is the voltage over-limit probability of node i at time t, V t,i is the voltage amplitude of node i at time t, f(V t,i ) is its probability density, and V max V min are the upper and lower limits of the node voltage.

[0029] A further improvement of the technical solution of the present invention lies in that: in step S3, according to the distribution network topology file and the characteristics of the micro-source ports in S1, with the goal of optimizing the loss of the distribution network micro-source, the following objective function is established:

[0030] F = minK

[0031] In the formula, the expression for solving the system loss factor K is:

[0032]

[0033] In the formula: W s is the energy efficiency loss of the distribution network micro-source, W c is the power loss of the internal converter of the micro-source, W ij is the line loss between nodes i and j;

[0034] The corresponding loss calculation formulas are as follows:

[0035] W s = (1 - η s )·P s

[0036] W C = (1 - η C )P C

[0037]

[0038] In the formula: P S , P C , P i,j are the power of the distribution network micro-source, the power of the internal converter of the micro-source, and the power consumed between nodes i and j respectively, η s , η C are the efficiency of the distribution network micro-source and the efficiency of the internal converter of the micro-source, R i , V i are the resistance and voltage corresponding to node i.

[0039] A further improvement of the technical solution of the present invention lies in that: in step S3, the load cluster power flow constraint of the distribution network micro-source with load regulation capacity is as follows:

[0040]

[0041] In the formula: P a and Q L,i are the active and reactive powers injected at node a; V a and V b are the voltages of nodes a and b; G ab and B ab are the real and imaginary parts of the node admittance matrix; δ ab is the phase angle difference between nodes a and b.

[0042] A further improvement of the technical solution of the present invention lies in that: in the step S3, there are line capacity constraints for the load-adjustable and capacitance-matching distribution network micro-sources as follows:

[0043]

[0044] In the formula: and are the upper and lower limits allowed for the line capacity respectively.

[0045] A further improvement of the technical solution of the present invention lies in that: in the step S3, there are harmonic resonance constraints for the load-adjustable and capacitance-matching distribution network micro-sources as follows:

[0046] PM>0

[0047] In the formula: PM is the stability margin index of the obtained distribution network system.

[0048] A further improvement of the technical solution of the present invention lies in that: in the step S3, there are voltage over-limit constraints for the load-adjustable and capacitance-matching distribution network micro-sources as follows:

[0049] -1<R VV,t,i <1

[0050] In the formula: R VV,t,i is the voltage over-limit evaluation index of the obtained distribution network system.

[0051] A further improvement of the technical solution of the present invention lies in that: in step S4, when there is an imbalance between supply and demand in the upper-level distribution network and reverse power supply is required in the low-voltage power grid area and non-critical load power consumption is reduced, in the scenario of interactive operation of the distribution network, a comprehensive optimal goal considering the operation cost of the distribution network, the participation willingness of the load, and the energy flow loss is formulated. At the same time, combined with the resonance and voltage over-limit constraints of the distribution network, the objective function at this time is:

[0052]

[0053] In the formula: C is the comprehensive operation cost of the distribution network; PMV t is the participation willingness function of the load equipment; a 1 represents the weight of the economic cost, a 2 represents the weight of the satisfaction degree, a 3 represents the weight of the energy flow loss of the distribution network;

[0054] Among them, the expression of the comprehensive operation cost of the distribution network is as follows:

[0055] C=(C 1 +C 2 )P work-c -C 3

[0056] In the formula: C 1Indicates the operating cost of each device in the distribution network, C 2 Indicates the maintenance cost of each device in the distribution network, C 3 Indicates the time-of-use subsidy, P work-c Indicates the working power of the c-th device.

[0057] Due to the adoption of the above technical solution, the technical progress achieved by the present invention includes:

[0058] The present invention obtains the form and type of micro-sources according to the marketing 2.0 platform and user basic information; injects small signal disturbance quantities of voltage and current at the micro-source access nodes, compares the key characteristics of the obtained micro-source port impedance characteristics with the impedance characteristic library, and conducts micro-source port characteristic identification; based on the obtained micro-source impedance model, applies the bode diagram impedance stability criterion to construct a harmonic resonance evaluation index for the distribution network with on-load tap-changing transformers and micro-sources.

[0059] The present invention defines a voltage over-limit evaluation index for the distribution network with on-load tap-changing transformers according to the real-time detection data of node micro-sources, comprehensively considering the probability of voltage over-limit and the severity of over-limit.

[0060] The present invention takes power flow, line capacity, harmonic resonance, and voltage over-limit as multiple constraints, and realizes the optimal energy flow optimization of the energy efficiency loss of distribution network micro-sources, the power loss of the internal converters of micro-sources, and the losses of lines and transformers.

[0061] The present invention takes into account the constraints of power flow, line capacity, harmonic resonance, and voltage over-limit under the condition of increasing the new energy penetration rate in the substation area, and realizes the comprehensive optimization of energy flow distribution of the operating cost of the distribution network, the willingness of the load to participate, and the energy flow loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a schematic diagram of the overall process of the coordinated control method for the distribution network with on-load tap-changing transformers considering harmonic resonance and voltage over-limit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0063] To make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. In the following description, the description of known structures and technologies is omitted to avoid unnecessarily confusing the concepts of the present invention.

[0064] The present invention provides a coordinated control method for a distribution network with on-load tap-changing transformers considering harmonic resonance and voltage over-limit, as Figure 1 shown, including the following steps:

[0065] S1. Use the line detection terminal at the distribution network access node to detect the relevant electrical quantities of the micro-sources connected to each node, including node voltage V, current I, frequency f, active power P, and reactive power Q.

[0066] The above-mentioned step S1 includes the following steps:

[0067] S1.1. The detection terminal sends a topology recognition signal to the i-th node in the distribution network. If no corresponding recognition signal is detected by other nodes in the distribution network, this node is considered an end node and recorded; if other nodes in the distribution network can detect the corresponding recognition signal, it is considered that there is a known loop between this node and other nodes and recorded. At the same time, according to the attenuation of the recognition signal, the line impedance in the distribution network is predicted and recorded.

[0068] Taking the node line detection terminal device as the leading, the above steps are sequentially repeated for each node in the distribution network until the distribution of all nodes and the relevant line impedance are all detected. According to the detection data, the topology information in the distribution network is identified and the topology file is updated.

[0069] S1.2. Obtain the form and type of the micro-source according to the marketing 2.0 platform and the basic information of the user, and inject a small signal disturbance of voltage and current at the micro-source access node. Compare the key characteristics of the obtained micro-source port impedance characteristics with the impedance characteristic library to identify the micro-source port characteristics.

[0070] Among them, the external characteristic impedance of the micro-source port is as follows:

[0071]

[0072] In the formula: Z s (s) is the micro-source impedance model, u s is the injected voltage disturbance, i s is the injected current disturbance.

[0073] S2. Construct an evaluation index containing harmonic resonance and voltage over-limit of the load regulating capacitor distribution network.

[0074] The above-mentioned step S2 includes the following steps:

[0075] S2.1. Construction of the harmonic resonance evaluation index of the distribution network micro-source.

[0076] The harmonic resonance problem of the distribution network system mainly depends on its stability characteristics. Based on the micro-source impedance model obtained in S1, applying the bode diagram impedance stability criterion, the following harmonic resonance index of the distribution network micro-source is constructed:

[0077] The calculation formula of the amplitude-frequency characteristic curve of the distribution network micro-source impedance is as follows:

[0078]

[0079] In the formula: Re and Im respectively represent the real part and the imaginary part of the micro-source impedance model.

[0080] The intersection point of the impedance amplitude-frequency characteristic curve shown in Equation (2) and the 0 dB line is the system shear frequency f c , and its calculation formula is as follows:

[0081] |Z(f c )|=20lgZ fc =0 (3)

[0082] According to the shear frequency f c obtained from Equation (3), substituting it into the phase-frequency characteristic curve of the distribution network micro-source can obtain the system harmonic resonance evaluation index PM, and its calculation formula is as follows:

[0083]

[0084] In the formula: Re and Im respectively represent the real part and the imaginary part of the micro-source impedance model, and arctan represents the arctangent calculation.

[0085] S2.2. Construct the evaluation index for the voltage over-limit of the distribution network micro-source.

[0086] Due to the change of the micro-source load, too many electrical equipment or the fluctuation of the distribution network system, the voltage over-limit situation is likely to occur. Based on the real-time detection data of the node micro-source in S1, considering the voltage over-limit probability and the severity of the over-limit comprehensively, the micro-source voltage over-limit index is constructed as

[0087]

[0088] In the formula: R VV,t,i is the voltage over-limit index of node i at time t, P VV,t,i is the working voltage characteristic quantity of node i at time t, S VV,t,i is the voltage over-limit probability of node i at time t, V t,i is the voltage amplitude of node i at time t, f(V t,i ) is its probability density, V max V min are the upper and lower limits of the node voltage, and 1.05 and 0.95 times the rated voltage are taken respectively here.

[0089] S3. Calculate the optimal loss in the autonomous operation scenario of the distribution network.

[0090] The above step S3 includes the following steps:

[0091] S3.1. In the autonomous operation scenario of the distribution network, with the change of the energy demand of the distribution area, the capacity of the on-load tap-changing transformer will switch accordingly, the system operation scenario will change, the power flow direction of the distribution network micro-source has various forms, and the system has different efficiency and performance characteristics. Based on the distribution network topology information and micro-source identification data obtained in S1, with the goal of minimizing the loss of the distribution network micro-source, the objective function and constraints are established as follows:

[0092] F = minK (6)

[0093] In the formula, the expression for solving the system loss factor K is as follows:

[0094]

[0095] In the formula: W s is the energy efficiency loss of the distribution network micro-source, W c is the power loss of the internal converter of the micro-source, W ij is the line loss between nodes i and j.

[0096] The corresponding loss calculation formula is as follows:

[0097]

[0098] In the formula: P S , P C , P i,j are the power of the distribution network micro-source, the power of the internal converter of the micro-source, and the power consumed between nodes i and j respectively, η s , η C are the efficiency of the distribution network micro-source and the efficiency of the internal converter of the micro-source, R i , V i are the resistance and voltage corresponding to node i.

[0099] S3.2. There are the following load cluster power flow constraints for the distribution network micro-source with load regulation capacity:

[0100]

[0101] In the formula: P a and Q L,i are the active and reactive powers injected at node a; V a and V b are the voltages of nodes a and b; G ab and B ab are the real and imaginary parts of the node admittance matrix; δ ab is the phase angle difference between nodes a and b.

[0102] S3.3. There are the following line capacity constraints for the distribution network micro-source with load regulation capacity:

[0103]

[0104] In the formula: and are the upper and lower limits allowed for the line capacity respectively.

[0105] S3.4. There are the following harmonic resonance constraints for the distribution network micro-source with load regulation capacity:

[0106] PM > 0 (11)

[0107] In the formula: PM is the system stability margin index obtained in S2.1.

[0108] S4.4. For the distribution network micro-source with load regulation and capacitance, there are voltage over-limit constraints as follows:

[0109] -1 < R VV,t,i < 1 (12)

[0110] In the formula: is the system voltage over-limit evaluation index obtained in S2.2.

[0111] S4. Calculate the cost-optimal source-network-load power reference value according to the losses in the distribution network interactive operation scenario, and send it to the control modules of each power generation / consumption unit to achieve the on-demand collaborative output of source-network-load power.

[0112] The above step S4 includes the following steps:

[0113] S4.1. When the supply and demand of the superior power grid are unbalanced, reverse power supply is required in the low-voltage substation area and the power consumption of non-critical loads is reduced. In this distribution network interactive operation scenario, a comprehensive optimal goal considering the distribution network operation cost, load participation willingness, and energy flow loss is formulated, and the resonance and voltage over-limit constraints of the distribution network are also considered. The objective function is:

[0114]

[0115] In the formula: C is the comprehensive operation cost of the distribution network; PMV t is the participation willingness function of the load equipment; a 1 represents the weight of the economic cost, a 2 represents the weight of the satisfaction degree, a 3 represents the weight of the distribution network energy flow loss.

[0116] Among them, the expression of the comprehensive operation cost of the distribution network is as follows:

[0117] C = (C 1 + C 2 )P work-c - C 3 (14)

[0118] In the formula: C 1 represents the operation cost of each device in the distribution network, C 2 represents the maintenance cost of each device in the distribution network, C 3 represents the time-of-use subsidy, P work-c represents the working power of the c-th device.

[0119] S4.2. The above objective function includes the power flow constraints, line capacity constraints, harmonic resonance constraints, and voltage over-limit constraints shown in S3.2 - S3.5.

[0120] For the optimization problems shown in S4.3, S3.1, and S4.1, mature algorithms such as particle swarm algorithm and ant colony algorithm can be used to solve the optimization problems to obtain the regulation power of each load.

[0121] In the above embodiments, the present invention provides a collaborative control method for a distribution network with on-load tap-changing and capacitor banks, taking into account harmonic resonance and voltage over-limit. By identifying the topological information in the distribution network and the impedance characteristics of the micro-source ports, the present invention constructs an evaluation index for harmonic resonance of the distribution network micro-source and an evaluation index for voltage over-limit of the distribution network micro-source. For the autonomous distribution network scenario, with power flow, line capacity, harmonic resonance, and voltage over-limit as multiple constraints, an energy flow optimization method with optimal energy efficiency loss of the distribution network micro-source, power loss of the internal converter of the micro-source, and line and transformer losses is designed. Furthermore, considering the scenario of the distribution network participating in grid interaction after the imbalance between supply and demand in the upper-level grid, a comprehensive optimization energy flow distribution scheme considering power flow, line capacity, harmonic resonance, and voltage over-limit constraints for the operating cost of the distribution network, the willingness of the load to participate, and the energy flow loss is designed. This multi-scenario and multi-micro-source autonomous collaborative control method for the distribution network with on-load tap-changing and capacitor banks can achieve the autonomy of the distribution network under the optimal loss target in the dynamic scenario of the distribution network with on-load tap-changing and capacitor banks, and at the same time can achieve multi-objective energy flow optimization in the scenario of the distribution network participating in grid interaction, which helps to improve the active and flexible interaction ability between the multi-degree-of-freedom characteristic converter module and the local grid, and provides a load-side means for improving the quality and efficiency of the distribution network park and saving energy and reducing emissions.

[0122] The above-described embodiments are only used to describe the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope of the present invention. The technical content claimed by the present invention has been fully recorded in the claims.

Claims

1. A coordinated control method for load-distribution capacity distribution network taking into account harmonic resonance and voltage over-limit, characterized by: The following steps are included: S1. Use the distribution network access node line detection terminal to detect the electrical quantities related to the micro-source access at each node, including node voltage V, current I, frequency f, active power P, and reactive power Q; S2. Construct evaluation indicators including harmonic resonance and voltage over-limit of load regulation and capacity distribution network; S3, calculate the optimal loss in the distribution network autonomous operation scenario; S4. According to the losses in the distribution network interactive operation scenario, the cost-optimal source-grid-load power reference value is calculated and sent to the control module of each power generation / power consumption unit to achieve on-demand coordinated output of source-grid-load power.

2. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The step S1 comprises the following steps: S1.

1. Send a topology identification signal to the i-th node in the distribution network through the detection terminal, and predict and record the line impedance in the distribution network according to the attenuation of the identification signal; With the node line detection terminal device as the main device, repeat the above steps for each node in the distribution network in turn until all node distribution conditions and related line impedances are detected. Based on the detection data, identify the topology information in the distribution network and update the topology file; S1.

2. Obtain the form and type of micro-source based on the Marketing 2.0 platform and basic user information, inject voltage and current small signal disturbances at the micro-source access node, compare the key features of the micro-source port impedance characteristics obtained with the impedance feature library, and identify the micro-source port characteristics; Among them, the external characteristic impedance of the micro source port is as follows: Where: Z s (s) is the micro source impedance model, u s is the injected voltage disturbance, i s is the injected current disturbance.

3. The method for coordinated control of load-distribution capacity and distribution network taking into account harmonic resonance and voltage over-limit according to claim 2 is characterized in that: The step S2 obtains the micro-source impedance model according to the micro-source port characteristic identification method in S1.2, applies the bode diagram impedance stability criterion, and the system harmonic resonance evaluation index PM, which is calculated as follows: Wherein: Re represents the real part of the micro-source impedance model, Im represents the imaginary part of the micro-source impedance model, and arctan represents the inverse tangent calculation.

4. The method for coordinated control of load-distribution capacity and distribution network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The step S2 obtains the real-time detection data of the node micro-source according to the distribution network topology file and the micro-source port characteristics in S1, and constructs the micro-source voltage over-limit index in combination with the voltage over-limit probability and over-limit severity, which is expressed as follows: R VV,t,i =P VV,t,i ×S VV,t,i Where: R VV,t,i is the voltage limit indicator of node i in period t, P VV,t,i is the characteristic value of the working voltage of node i in period t, S VV,t,i is the voltage limit-exceeding probability of node i in period t, V t,i is the voltage amplitude of node i at time t, f(V t,i ) is its probability density, V max V min are the upper and lower limits of the node voltage.

5. The method for coordinated control of load-modulation capacity-distribution network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: In step S3, based on the distribution network topology file and micro-source port characteristics in S1, the objective function is established with the goal of optimizing the distribution network micro-source loss as follows: F=minK In the formula, the expression for solving the system loss factor K is: Where: W s is the energy efficiency loss of the micro-source in the distribution network, W c is the power loss of the micro-source internal converter, W ij is the line loss between nodes i and j; The corresponding loss calculation formula is as follows: W s =(1-th s )·P s W C =(1-th C )P C Where: P S , P C , P i,j are the power of the micro-source in the distribution network, the power of the converter in the micro-source, and the power consumed between nodes i and j, respectively. s , η C is the efficiency of the micro-source in the distribution network and the efficiency of the converter in the micro-source, R i 、V i is the resistance and voltage corresponding to node i.

6. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The load cluster flow constraints of the micro-sources in the load regulation capacity distribution network in step S3 are as follows: Where: P a and Q L,i Active and reactive power injected into node a; V a and V b is the voltage at nodes a and b; G ab and B ab are the real and imaginary parts of the node admittance matrix; δ ab is the phase angle difference between nodes a and b.

7. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The line capacity constraints of the micro-source in the load regulation and distribution network in step S3 are as follows: Where: and They are the upper and lower limits of line capacity respectively.

8. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The step S3 contains the following constraints on the existence of harmonic resonance of the micro-source in the load regulation and capacity distribution network: PM>0 Where: PM is the obtained distribution network system stability margin indicator.

9. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: The voltage over-limit constraint of the micro-source in the load regulation and capacity distribution network in step S3 is as follows: -1＜R VV,t,i ＜1 Where: R VV,t,i is the voltage over-limit evaluation index of the distribution network system.

10. The method for coordinated control of load regulation, capacity distribution and network taking into account harmonic resonance and voltage over-limit according to claim 1 is characterized in that: In step S4, when the supply and demand of the upper distribution network is unbalanced, the low-voltage substation needs to reverse power transmission and reduce the power consumption of non-critical loads. In the interactive operation scenario of the distribution network, a comprehensive optimal goal considering the distribution network operation cost, load participation willingness, and energy flow loss is formulated. At the same time, the resonance and voltage limit constraints of the distribution network are combined. At this time, the objective function is: Where: C is the comprehensive operation cost of the distribution network; PMV t is the participation willingness function of the load equipment; a1 represents the weight of economic cost, a2 represents the weight of satisfaction, and a3 represents the weight of distribution network energy flow loss; Among them, the comprehensive operation cost expression of the distribution network is as follows: C=(C1+C2)P work-c -C3 Where: C1 represents the operating cost of each distribution network device, C2 represents the maintenance cost of each distribution network device, C3 represents the staggered subsidy, P work-c Indicates the operating power of the cth device.

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