An active power control method for a multi - microgrid sharing its own energy storage to participate in AGC frequency regulation

Abstract

The present invention discloses an active power control method for multiple microgrids to share their own energy storage for AGC frequency regulation, belonging to the field of power system control, which includes the following steps: building a multi-microgrid system MMG composed of several microgrids, and implementing internal and external sharing control for the multi-microgrid's own energy storage to participate in AGC frequency regulation; based on the coupling relationship of the internal and external sharing of the microgrid's own energy storage, when regulating the internal sharing of the energy storage for the multi-microgrid system to preferentially meet the basic peak shaving requirements of the MMG, the external sharing of the MMG responds to the AGC frequency regulation command. The present invention can effectively alleviate the problem of shortage of frequency regulation resources in the new power system. At the same time, the present invention explores the adjustable potential of the own energy storage within the MMG, and provides a method for sharing the microgrid's own energy storage to participate in the AGC frequency regulation auxiliary service of the power grid.

Description

Technical Field

[0001] The present invention relates to the field of power system control, and in particular, to an active power control method for multi-microgrid sharing its own energy storage to participate in AGC frequency modulation. Background Art

[0002] Affected by the intermittency and volatility of new energy output, microgrids, as good carriers of distributed new energy, have problems such as poor voltage quality and power fluctuations. Microgrids usually configure energy storage to suppress new energy fluctuations. However, due to the obvious peak-valley characteristics of the load curve of a single microgrid and the uncertainty of the annual change of the microgrid load, the configured energy storage capacity does not fully match the actual utilization capacity, and the actual utilization rate of the user-side energy storage is relatively low. In addition, with the continuous improvement of the new energy penetration rate, the frequency modulation demand of the new power system is also gradually increasing, and it is urgent to further explore the user-side frequency modulation resources; the regulation performance and regulation stability of the aggregated user-side distributed energy storage are higher than those of other flexible loads. Therefore, the present invention proposes that multi-microgrids share their own energy storage to participate in the AGC frequency modulation of the power grid, providing strong support for the frequency modulation of the new power system.

[0003] At present, some research has proposed to maximize the utilization of energy storage resources by reasonably sharing energy storage, but it mainly focuses on the "incremental investment" of centralized energy storage, ignoring the potential for external sharing of the microgrid's own distributed energy storage; existing research on exploring the sharing potential of the microgrid's own distributed energy storage also elaborates on relevant business models and operation mechanisms from the perspective of market transactions, without involving the control mode of the microgrid's own energy storage, and even less able to give relevant control strategies for the external sharing of the microgrid's own energy storage on the premise of meeting the needs of the microgrid users themselves. In addition, current domestic and foreign research on the use of user-side resources to assist the power grid in frequency modulation mostly focuses on flexible loads such as temperature control loads and electric vehicle chargers, without considering the possibility of using the idle capacity of user-side energy storage for external sharing and participating in grid ancillary services, especially participating in the AGC frequency modulation ancillary service of the power grid. Therefore, it is urgent to propose an AGC frequency modulation control technology for multi-microgrids to share their own energy storage, aiming to clarify the control principle of the external sharing of the multi-microgrid's own energy storage to respond to the AGC frequency modulation command on the premise of meeting the basic peak shaving demand of the MMG through internal sharing, and to give an energy storage peak shaving and frequency modulation command allocation model and a rolling calculation method for the frequency modulation declaration capacity considering the coupling relationship between internal and external sharing of energy storage, which is of great practical significance for improving the utilization rate and income of the microgrid's own energy storage and alleviating the shortage of frequency modulation resources in the new power system. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide an active power control technology for multi-microgrids to share their own energy storage to participate in AGC frequency modulation, aiming to solve the problems of low utilization rate of existing distributed energy storage and shortage of frequency modulation resources in the new power system.

[0005] To achieve the above technical objectives, the present application provides an active power control method for a multi-microgrid sharing its own energy storage to participate in AGC frequency modulation, including the following steps:

[0006] Build a multi-microgrid system MMG composed of several microgrids, and perform internal and external sharing control for the multi-microgrid's own energy storage to participate in AGC frequency modulation;

[0007] Based on the coupling relationship of internal and external sharing of the microgrid's own energy storage, when regulating the energy storage to preferentially meet the basic peak shaving demand of the MMG for internal sharing of the multi-microgrid system, the external sharing of the MMG responds to the AGC frequency modulation command.

[0008] Preferably, when performing internal sharing, based on the energy storage regulation cost and future frequency modulation margin, allocate the MMG peak shaving command, control the energy storage to respond to the peak shaving command while considering the economy of peak shaving response, and reserve an adjustable margin for subsequent frequency modulation.

[0009] Preferably, when performing external sharing, based on the current energy storage peak shaving plan and future MMG peak shaving demand, roll-calculate the real-time frequency modulation declarable capacity of the energy storage, and after receiving the AGC frequency modulation command, optimize the allocation of the frequency modulation command according to the reserved future peak shaving margin, so as to control the energy storage to reserve the basic response to the power grid frequency modulation for the next peak shaving margin.

[0010] Preferably, in the process of allocating the peak shaving command based on internal sharing, based on the energy storage regulation cost and future frequency modulation margin, construct an objective function and optimize the allocation of the peak shaving command, where the objective function is expressed as:

[0011] F 1 = k 1 f 1 + k 2 f 2 + k 3 f 3 ;

[0012] In the formula: f 1 is the energy storage regulation economy function; f 2 is the energy storage SOC adjustment margin function; f 3 is the energy storage power adjustment margin function; k 1 , k 2 and k 3 are the relative weights of each objective, used to emphasize the objective preference, satisfying k 1 + k 2 + k 3 = 1.

[0013] Preferably, in the process of obtaining the objective function, the energy storage regulation economy function is expressed as:

[0014]

[0015] Where: N is the number of microgrid-owned energy storages participating in sharing in the MMG; λ p,j is the energy storage regulation cost coefficient; P batt,j,t is the charging and discharging power of the j-th microgrid energy storage at time t, positive for charging and negative for discharging; α 1 is the balance coefficient of f 1 , which is used to balance the order of magnitude between different objective functions;

[0016] The energy storage SOC regulation margin function is expressed as:

[0017]

[0018] Where: E j is the rated capacity of the j-th microgrid energy storage; S j,t is the SOC of the j-th microgrid energy storage at time t, defined as the ratio of the remaining capacity of the energy storage to the rated capacity; S ref,p is the SOC reference value when each microgrid energy storage participates in peak shaving. To ensure the maximum equivalent frequency modulation margin reserved for the SOC, it is advisable to take 0.5; α 2 is the balance coefficient of f 2 ;

[0019] The energy storage power regulation margin function is expressed as:

[0020]

[0021] Where: P max,j is the rated power of the j-th microgrid energy storage; α 3 is the balance coefficient of f 3 ;

[0022] Preferably, in the process of constructing the objective function, the constraint conditions of the objective function include the MMG peak shaving instruction constraint, the microgrid energy storage charging and discharging constraint, the microgrid energy storage state of charge constraint, the microgrid energy storage power constraint, and the line power constraint; among them,

[0023] MMG peak shaving instruction constraint:

[0024]

[0025] Where: P sys,t is the peak shaving instruction capacity received by the energy storage operator at time t, obtained by summing the peak shaving demands of each microgrid user in the MMG. The upward PCC node curve is positive;

[0026] Microgrid energy storage charging and discharging constraint:

[0027]

[0028] Where: η ch,j and ηdis,j is the charging and discharging efficiency of the j-th microgrid energy storage:

[0029] Microgrid energy storage state of charge constraint:

[0030] S j,min ≤ S j,t ≤ S j,max

[0031] Where: S j,max and S j,min respectively represent the maximum and minimum state of charge allowed for the j-th microgrid energy storage;

[0032] Microgrid energy storage power constraint:

[0033]

[0034] Where: P max,j is the rated power of the j-th microgrid energy storage; Δt is the calculation step size;

[0035] Line power constraint:

[0036] -P MG,j ≤ P NE,j,t +P G,j,t -P L,j,t -P batt,j,t ≤ P MG,j

[0037] Where: P NE,j,t and P G,j,t are the outputs of the new energy unit and the traditional unit in the j-th microgrid at time t; P L,j,t represents the load of the j-th microgrid at time t; P MG,j is the interactive power limit between the j-th microgrid and the bus, determined according to the thermal limit of the tie line.

[0038] Preferably, in the process of rolling calculation of the real-time frequency modulation declarable capacity of the energy storage, the energy storage frequency modulation declarable capacity rolling calculation method is:

[0039]

[0040] Where: P ap is the frequency modulation declarable capacity; P agc is the grid AGC signal at time t, with the upward PCC node curve being positive; P ag1,j and P ag3,j are the upper limits of the charging and discharging powers of the j-th microgrid energy storage in the future Δt period considering power limitations; P ag2,j and P ag4,j$P_{j,\max}^{\Delta t}$ is the upper limit of the charging and discharging power of the microgrid energy storage $j$ in the future $\Delta t$ period; $\beta$ is the peak shaving reserve coefficient, which reflects the energy storage margin reserved for the next peak shaving; $\Delta t$ corresponds to an energy storage peak shaving cycle.

[0041] Preferably, during the rolling calculation, the microgrid energy storage can only change the charging and discharging power value when responding to the AGC frequency modulation of the power grid, and cannot change the charging and discharging state. Therefore, we have:

[0042]

[0043] In the formula: $P$ batt,j is the power sequence of the microgrid energy storage $j$ in the future $\Delta t$ period; $K$ SOC,j is the SOC sequence of the microgrid energy storage $j$ in the future $\Delta t$ period;

[0044] The peak shaving reserve coefficient $\beta$ is dynamically given according to the short-term prediction results of the overall peak shaving demand of the MMG:

[0045]

[0046] In the formula: $P$ agc,t is the current AGC frequency modulation command of the power grid; $P$ sys,t+1 is the next peak shaving command of the MMG.

[0047] Preferably, during the process of optimizing the distribution of the frequency modulation command, the objective function for optimizing the distribution of the frequency modulation command is expressed as:

[0048]

[0049] In the formula: $S$ ref,f is the SOC reference value when each microgrid energy storage participates in frequency modulation, and is obtained according to the short-term prediction of the next overall peak shaving demand of the MMG;

[0050] The constraint conditions include the AGC frequency modulation command constraint of the power grid and the energy storage operation constraint. Among them,

[0051] The AGC frequency modulation command constraint of the power grid is

[0052]

[0053] In the formula: $\Delta P$ batt,j,t is the change in the charging and discharging power of the $j$-th microgrid energy storage in response to the power grid frequency modulation at time $t$, with an increase in charging power / a decrease in discharging power being positive.

[0054] The present invention also provides an active power control system for multiple microgrids sharing their own energy storage to participate in AGC frequency modulation. This system is used to implement the above-mentioned active power control method, and this system includes:

[0055] A control module, configured to perform internal and external sharing control for the participation of the multi-microgrid's own energy storage in AGC frequency regulation according to a multi-microgrid system MMG composed of a plurality of microgrids;

[0056] A response module, configured to, based on the coupling relationship of the internal and external sharing of the microgrid's own energy storage, regulate the energy storage to preferentially meet the basic peak shaving requirements of the MMG for internal sharing of the multi-microgrid system while responding to the AGC frequency regulation command for external sharing of the MMG.

[0057] The present invention discloses the following technical effects:

[0058] The present invention can effectively alleviate the problem of shortage of frequency regulation resources in the new power system.

[0059] The present invention clarifies the control mode in which the multi-microgrid's own energy storage responds to the AGC frequency regulation command for external sharing on the premise of meeting the basic peak shaving requirements of the MMG for internal sharing, which can improve the utilization rate of the microgrid's distributed energy storage and bring additional frequency regulation benefits to microgrid users.

[0060] The present invention analyzes the coupling relationship between the internal and external sharing of the multi-microgrid's own energy storage, proposes a corresponding energy storage peak shaving and frequency regulation command allocation model and a rolling calculation method for the declared frequency regulation capacity, solves the capacity coordination problem of the microgrid's own energy storage when participating in internal peak shaving and external frequency regulation, and gives full play to the regulation potential of the microgrid's own energy storage.

[0061] Based on the unified control of the multi-microgrid's own energy storage by the shared energy storage operator, the present invention generates a scale effect, meets the access threshold for ancillary services, provides support for the power grid frequency regulation service, and avoids the problem that the surplus capacity available for external sharing of a single microgrid's own energy storage is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0063] Figure 1 It is a control architecture diagram of the multi-microgrid shared own energy storage;

[0064] Figure 2 It is a schematic diagram of the MMG shared own energy storage participating in the response;

[0065] Figure 3 It is a flowchart of the multi-microgrid's own energy storage participating in the power grid AGC frequency regulation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0066] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are only some, rather than all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein generally can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative efforts fall within the scope of protection of this application.

[0067] As Figure 1 shown, the present invention provides a logic control architecture for multiple microgrids to share their own energy storage in the grid-connected state, and the specific structure is as follows:

[0068] In the MMG composed of m microgrids, each microgrid is composed of a reference typical microgrid. In addition to its own energy storage, it may also include distributed new energy units, diesel units, and loads.

[0069] Power interaction is carried out between each microgrid in the MMG through the bus, and power interaction between the MMG and the superior power grid is carried out through the PCC node.

[0070] The shared energy storage operator uniformly regulates the own energy storage of each microgrid, and meets the peak shaving requirements of microgrid users in the MMG by reasonably regulating the operating states of each shared energy storage, and fully utilizes the idle capacity of the energy storage to respond to the AGC frequency modulation command of the superior power grid, so as to realize the safe, reliable, and economic operation of the MMG and provide stable and fast frequency modulation resources to the superior power grid.

[0071] As Figure 2 、 Figure 3 shown, the present invention proposes a method for multiple microgrids' own energy storage to participate in the AGC frequency modulation control of the power grid, and the specific steps are as follows:

[0072] Step 1: Taking the shared energy storage operator as the centralized control platform, regulating the own energy storage of the multiple microgrid system for internal and external sharing, monitoring the operating states of the energy storage of each microgrid, and evaluating the adjustable potential;

[0073] Step 2: After receiving the peak shaving command of the MMG, the shared energy storage operator calculates the command allocation scheme for the internal sharing of the own energy storage of each microgrid by solving the peak shaving command allocation model that comprehensively considers the energy storage regulation cost and the future frequency modulation margin, and issues the regulation command;

[0074] Step 3: Based on the energy storage peak shaving output plans for the current peak shaving period and combined with the short-term prediction results of future MMG peak shaving demands, the shared energy storage operator calculates the reportable capacity for energy storage frequency modulation for each unit at present in a rolling manner and submits the report;

[0075] Step 4: After receiving the AGC frequency modulation command from the power grid, the shared energy storage operator calculates the command allocation plan for the external sharing of the self-owned energy storage of each microgrid by solving the frequency modulation command allocation model that reserves the future peak shaving margin, and issues the control command;

[0076] Step 5: The self-owned energy storage of each microgrid executes the control command to fully respond to the AGC frequency modulation command on the basis of meeting the MMG peak shaving demand.

[0077] Specifically, in Step 2, the objective function of the peak shaving command allocation model that comprehensively considers the energy storage control cost and the future frequency modulation margin during internal sharing is:

[0078] F 1 =k 1 f 1 +k 2 f 2 +k 3 f 3 ;

[0079] In the formula: f 1 is the energy storage control economy function; f 2 is the energy storage SOC adjustment margin function; f 3 is the energy storage power adjustment margin function; k 1 , k 2 and k 3 are the relative weights of each objective, used to emphasize the objective preference, and satisfy k 1 +k 2 +k 3 =1.

[0080] Energy storage control economy function:

[0081] When the shared energy storage operator controls the energy storage to respond to peak shaving, it needs to consider its operating costs over the entire life cycle:

[0082]

[0083] In the formula: N is the number of self-owned energy storage of microgrids participating in sharing in the MMG; λ p,j is the energy storage control cost coefficient; P batt,j,t is the charging and discharging power of the energy storage of the jth microgrid at time t, positive for charging and negative for discharging; α 1 is the balance coefficient of f 1 used to balance the order of magnitude between different objective functions.

[0084] Energy storage SOC regulation margin function:

[0085] When the microgrid's own energy storage meets the peak shaving demand of the MMG internally, it is necessary to consider the problem of the SOC exceeding the limit during the future frequency modulation period caused by the excessive current SOC fluctuation, and enhance the sustainable dispatching ability of the energy storage:

[0086]

[0087] In the formula: E j is the rated capacity of the j-th microgrid energy storage; S j,t is the SOC of the j-th microgrid energy storage at time t, defined as the ratio of the remaining capacity of the energy storage to the rated capacity; S ref,p is the SOC reference value when each microgrid energy storage participates in peak shaving. To ensure the maximum equivalent frequency modulation margin reserved for the SOC, it is advisable to take 0.5; α 2 is the balance coefficient of f 2 of.

[0088] Energy storage power regulation margin function:

[0089] Balance the charging and discharging power of each microgrid's own energy storage, reduce the impact of charging and discharging power constraints on the energy storage's participation in future frequency modulation, and improve the subsequent upward / downward frequency modulation margin of the energy storage:

[0090]

[0091] In the formula: P max,j is the rated power of the j-th microgrid energy storage; α 3 is the balance coefficient of f 3 of.

[0092] In step 2, when sharing internally, comprehensively consider the constraint conditions of the peak shaving command allocation model for the energy storage regulation cost and the future frequency modulation margin, specifically including:

[0093] MMG peak shaving command constraint

[0094]

[0095] In the formula: P sys,t is the peak shaving command capacity received by the energy storage operator at time t, obtained by summing the peak shaving demands of each microgrid user in the MMG. The upward PCC node curve is positive.

[0096] Microgrid energy storage charging and discharging constraint:

[0097]

[0098] In the formula: η ch,j and η dis,j are the charging and discharging efficiencies of the j-th microgrid energy storage.

[0099] State of charge constraint of microgrid energy storage:

[0100] S j,min ≤S j,t ≤S j,max ;

[0101] Where: S j,max and S j,min respectively represent the maximum and minimum state of charge allowed for the j-th microgrid energy storage.

[0102] Power constraint of microgrid energy storage;

[0103]

[0104] Where: P max,j is the rated power of the j-th microgrid energy storage; Δt is the calculation step size.

[0105] Line power constraint:

[0106] When the microgrid energy storage participates in peak shaving within the microgrid and shares with others, the interactive power limit between each microgrid and the bus needs to be considered. Therefore, there is a line power constraint:

[0107] -P MG,j ≤P NE,j,t +P G,j,t -P L,j,t -P batt,j,t ≤P MG,j ;

[0108] Where: P NE,j,t and P G,j,t are the outputs of the new energy unit and the traditional unit in the j-th microgrid at time t; P L,j,t represents the load of the j-th microgrid at time t; P MG,j is the interactive power limit between the j-th microgrid and the bus, which is determined according to the thermal limit of the tie line.

[0109] In step 3, the rolling calculation method of the frequency modulation declaration capacity of the energy storage considering the current energy storage peak shaving plan and the future MMG peak shaving demand when sharing externally is:

[0110]

[0111] Where: P ap is the frequency modulation declaration capacity; P agc is the AGC signal of the power grid at time t, with the upward PCC node curve being positive; P ag1,j and P ag3,j are the upper limit values of the charge and discharge power of the j-th microgrid energy storage in the future Δt period considering power limitations; P ag2,j and P ag4,j$P_{j,\Delta t}^{max}$ is the upper limit of the charging and discharging power of the microgrid energy storage j in the future $\Delta t$ period; $\beta$ is the peak shaving reserve coefficient, which reflects the energy storage margin reserved for the next peak shaving; $\Delta t$ corresponds to an energy storage peak shaving cycle, taking 15 minutes.

[0112] In the rolling calculation method of the energy storage frequency modulation declaration capacity, when the microgrid energy storage responds to the AGC frequency modulation of the power grid, it can only change the charging and discharging power values and cannot change the charging and discharging states. Therefore, we have:

[0113]

[0114] In the formula: $P$ batt,j is the power sequence of the microgrid energy storage j in the future $\Delta t$ period; $K$ SOC,j is the SOC sequence of the microgrid energy storage j in the future $\Delta t$ period.

[0115] In the rolling calculation method of the energy storage frequency modulation declaration capacity, the peak shaving reserve coefficient $\beta$ needs to be dynamically given according to the short-term prediction results of the overall peak shaving demand of the MMG:

[0116]

[0117] In the formula: $P$ agc,t is the current AGC frequency modulation command of the power grid; $P$ sys,t+1 is the next peak shaving command of the MMG.

[0118] In step 4, the optimization objective function for optimizing the frequency modulation command by considering the reserved future peak shaving margin after receiving the AGC frequency modulation command is:

[0119]

[0120] In the formula: $S$ ref,f is the SOC reference value when each microgrid energy storage participates in frequency modulation, and it needs to be determined according to the short-term prediction of the next overall peak shaving demand of the MMG; when the next peak shaving demand is for up-regulation, it takes 0.6, otherwise it takes 0.4.

[0121] In step 4, the constraint conditions of the frequency modulation command allocation model by considering the reserved future peak shaving margin after receiving the AGC frequency modulation command specifically include:

[0122] Power grid AGC frequency modulation command constraint

[0123]

[0124] In the formula: $\Delta P$ batt,j,t is the change in the charging and discharging power of the j-th microgrid energy storage in responding to the power grid frequency modulation at time t, with an increase in charging power / decrease in discharging power being positive.

[0125] Energy storage operation constraint:

[0126] To reduce the life loss caused by frequent switching between charge and discharge states, the microgrid's own energy storage cannot change the charge and discharge state when participating in AGC frequency regulation, and can only adjust the charge and discharge power value; the operating constraints of other energy storage are similar to the peak shaving instruction allocation model of the microgrid's own energy storage, which will not be elaborated here.

[0127] The present invention clarifies the control mode in which multiple microgrid's own energy storages share externally to respond to AGC frequency regulation instructions on the premise of sharing internally to meet the basic peak shaving requirements of MMG, which can improve the utilization rate of distributed energy storage in the microgrid and bring additional frequency regulation benefits to microgrid users.

[0128] The present invention analyzes the coupling relationship between the internal and external sharing of multiple microgrid's own energy storages, proposes corresponding energy storage peak shaving and frequency regulation instruction allocation models and rolling calculation methods for frequency regulation declaration capacity, solves the capacity coordination problem of the microgrid's own energy storage when participating in internal peak shaving and external frequency regulation, and gives full play to the regulation potential of the microgrid's own energy storage.

[0129] The present invention is based on the unified control of each microgrid's own energy storage in the MMG by the shared energy storage operator, generates a scale effect, reaches the access threshold of ancillary services, provides support for the power grid frequency regulation service, and avoids the problem that the surplus capacity that can be shared externally by a single microgrid's own energy storage is small.

[0130] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one Figure 1 one process or multiple processes and / or blocks Figure 1 means for implementing the functions specified in one block or multiple blocks.

[0131] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "multiple" means two or more, unless otherwise specifically defined.

[0132] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for active power control in which multiple microgrids share their own energy storage and participate in AGC frequency modulation, characterized in that: The following steps are involved: Build a multi-microgrid system MMG consisting of several microgrids, and implement internal and external sharing control of multi-microgrid self-owned energy storage participating in AGC frequency regulation; Based on the coupling relationship between the internal and external sharing of the microgrid's own energy storage, the energy storage is regulated to prioritize the MMG basic peak-shaving needs for the internal sharing of the multi-microgrid system, while responding to the AGC frequency regulation instructions for the external sharing of the MMG; When sharing internally, MMG peak-shaving instructions are allocated based on the energy storage regulation cost and future frequency regulation margin. While considering the economic efficiency of peak-shaving response, the energy storage response peak-shaving instructions are controlled and an adjustable margin is reserved for subsequent frequency regulation. When sharing externally, the real-time frequency regulation capacity of energy storage is calculated on a rolling basis based on the current energy storage peak regulation plan and future MMG peak regulation demand. After receiving the AGC frequency regulation command, the frequency regulation command is optimized and allocated according to the reserved future peak regulation margin, which is used to control the energy storage to retain the basic response grid frequency regulation for the next peak regulation margin. In the process of allocating peak load instructions based on internal sharing, an objective function is constructed based on the energy storage regulation cost and the future frequency regulation margin to optimize the allocation of peak load instructions, wherein the objective function is expressed as: F1=k1f1+k2f2+k3f3; Where: f1 is the energy storage regulation economy function; f2 is the energy storage SOC regulation margin function; f3 is the energy storage power regulation margin function; k1, k2 and k3 are the relative weights of each target, which are used to emphasize the target preference and satisfy k1+k2+k3=1; In the process of obtaining the objective function, the energy storage regulation economic function is expressed as: Where: N is the number of microgrid-owned energy storage participating in the MMG; λ p,j is the energy storage regulation cost coefficient; P batt,j,t is the charging and discharging power of the jth microgrid energy storage at time t, which is positive when charging and negative when discharging; α1 is the balance coefficient of f1, which is used to balance the orders of magnitude between different objective functions; The energy storage SOC adjustment margin function is expressed as: Where: E j is the rated capacity of the jth microgrid energy storage; S j,t is the SOC of the jth microgrid energy storage at time t, defined as the ratio of the remaining energy storage capacity to the rated capacity; S ref,p is the SOC reference value when each microgrid energy storage participates in peak regulation. In order to ensure that the equivalent frequency regulation margin reserved by SOC is the largest, it is appropriate to take 0.5; α2 is the balance coefficient of f2; The energy storage power regulation margin function is expressed as: Where: P max,j is the rated power of the jth microgrid energy storage; α3 is the balance coefficient of f3; In the process of constructing the objective function, the constraint conditions of the objective function include MMG peak load instruction constraint, microgrid energy storage charging and discharging constraint, microgrid energy storage charge state constraint, microgrid energy storage power constraint and line power constraint; wherein, MMG peak load instruction constraints: Where: P sys,t is the peak load instruction capacity received by the energy storage operator at time t, which is obtained by summing up the peak load demands of each microgrid user in the MMG, and the upward adjustment of the PCC node curve is positive; Microgrid energy storage charging and discharging constraints: Where: η ch,j With η dis,j is the charging and discharging efficiency of the j-th microgrid energy storage: Microgrid energy storage charge state constraints: S j,min ≤S j,t ≤S j,max Where: S j,max With S j,min They represent the maximum and minimum state of charge allowed for the j-th microgrid energy storage; Microgrid energy storage power constraints: Where: P max,j is the rated power of the jth microgrid energy storage; Δt is the calculation step length; Line power constraints: -P MG,j ≤P NE,j,t +P G,j,t -P L,j,t -P batt,j,t ≤P MG,j Where: P NE,j,t With P G,j,t is the output of the new energy unit and the traditional unit in the jth microgrid at time t; P L,j,t represents the load of the jth microgrid at time t; P MG,j is the interactive power limit between the jth microgrid and the bus, which is determined according to the thermal limit of the tie line.

2. According to claim 1, a method for active power control in which multiple microgrids share their own energy storage and participate in AGC frequency modulation is characterized by: In the process of rolling calculation of the real-time frequency regulation capacity that can be reported for energy storage, the rolling calculation method for the reported capacity of energy storage frequency regulation is as follows: Where: P ap Declare capacity for frequency regulation; P agc is the grid AGC signal at time t, and the upward adjustment of the PCC node curve is positive; P ag1,j and P ag3,j P is the upper limit of the charging and discharging power of the microgrid energy storage j in the future Δt period considering power limitation; ag2,j and P ag4,j is the upper limit of the charging and discharging power of the microgrid energy storage j in the future Δt period considering the SOC limitation; β is the peak-shaving reservation coefficient, which reflects the energy storage margin reserved for the next peak-shaving; Δt corresponds to an energy storage peak-shaving cycle.

3. According to claim 2, a method for active power control in which multiple microgrids share their own energy storage and participate in AGC frequency modulation is characterized by: In the process of rolling calculation, the microgrid energy storage can only change the charging and discharging power value when responding to the grid AGC frequency modulation, but cannot change the charging and discharging state, so: Where: P batt,j K is the power sequence of the microgrid energy storage j in the future Δt period; SOC,j is the SOC sequence of the microgrid energy storage j in the future Δt period; The peak load reserve coefficient β is dynamically given based on the short-term forecast results of the overall peak load demand of MMG: Where: P agc,t P is the AGC frequency modulation instruction of this power grid; sys,t+1 This is the next MMG peak-shaving instruction.

4. According to claim 1, a method for active power control in which multiple microgrids share their own energy storage and participate in AGC frequency modulation is characterized by: In the process of optimizing the allocation of frequency modulation instructions, the objective function for optimizing the allocation of frequency modulation instructions is expressed as: Where: S ref,f It is the SOC reference value of each microgrid energy storage when participating in frequency regulation, and is determined based on the short-term forecast of the next MMG overall peak regulation demand; The constraints include the grid AGC frequency regulation instruction constraint and the energy storage operation constraint, where the grid AGC frequency regulation instruction constraint is Where: ΔP batt,j,t P is the change in charging and discharging power of the jth microgrid energy storage in response to grid frequency modulation at time t. Increasing charging power / reducing discharging power is positive. agc,t This is the AGC frequency modulation instruction of this power grid.

5. An active control system in which multiple microgrids share their own energy storage and participate in AGC frequency modulation, characterized in that: The active power control method for multiple microgrids sharing self-owned energy storage to participate in AGC frequency modulation as claimed in claim 1 comprises: A control module is used to execute internal and external sharing control of the multi-microgrid self-owned energy storage participating in AGC frequency regulation according to the multi-microgrid system MMG composed of several microgrids; The response module is used to regulate the internal sharing of energy storage in the multi-microgrid system based on the coupling relationship between the internal and external sharing of the microgrid's own energy storage, while giving priority to meeting the basic peak-shaving needs of MMG, and responding to the AGC frequency regulation instructions for the external sharing of MMG.

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