Transformer area power mutual aid method and system

Abstract

The invention belongs to the technical field of AC / DC power distribution networks and micro-grids, and discloses a transformer area power mutual aid method and system, and the method comprises the steps: calculating the load rate of a distribution transformer according to the active power of the distribution transformer, setting the flow direction of the active power of the distribution transformer, and obtaining the load condition of each transformer area; calculating the total out-of-limit power of all forward heavy overload transformer areas and the total out-of-limit power of all reverse heavy overload transformer areas to obtain the out-of-limit power condition of each transformer area, and establishing a preliminary power distribution strategy; distributing the out-of-limit power of the heavy overload transformer area, and distributing the remaining out-of-limit power to the adjacent transformer area based on an electrical distance proximity principle; and based on the threshold condition that the load rates of all the transformer areas reach, setting the charging and discharging power of the direct-current energy storage device, and adjusting the active power of the alternating-current transformer area through the charging and discharging operation of the direct-current energy storage device. According to the invention, the problem of reverse heavy overload of the distribution transformer caused by power returning of the distributed power supply is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of AC / DC distribution networks and microgrids, and in particular to a method and system for mutual assistance of power in substations. Background Art

[0002] With the rapid development of renewable energy, distributed photovoltaic power generation has been widely used in rural areas of my country. Rural areas are rich in distributed photovoltaic resources. According to statistics, more than 95% of distributed photovoltaics are connected through rural low-voltage distribution networks, providing clean and sustainable energy supply for rural areas. However, the electricity load of rural residents is generally low, and the photovoltaic power generation often exceeds the local electricity demand during the day, resulting in a large amount of power being sent back to the distribution network, causing the distribution transformer to be reversely overloaded or overloaded. At the same time, some rural areas also have small factories, irrigation wells and other power loads, which consume a lot of electricity during certain periods, further exacerbating the imbalance of the distribution network load. To solve these problems, power mutual assistance technology in substations, especially low-voltage flexible DC interconnection technology, has gradually attracted attention. It establishes a DC interconnection network on the low-voltage side to achieve flexible power allocation between multiple distribution substations, providing a new idea for solving the problems of photovoltaic reverse transmission and load imbalance.

[0003] However, the existing power mutual assistance technology in substations still has some shortcomings: first, most methods lack real-time and accurate calculation of the load rate of distribution transformers and timely judgment of heavy overload conditions, resulting in insufficient targeted power allocation; second, the existing power allocation strategies are often too simple and fail to fully consider the priority of forward and reverse heavy overloads, as well as the impact of electrical distance on power allocation, making it difficult to achieve the optimal power mutual assistance effect; in addition, the existing methods generally lack an integrated intelligent decision-making system and cannot automatically execute the optimal power mutual assistance strategy according to real-time conditions.

[0004] Therefore, how to provide a solution to the reverse overload of the distribution transformer caused by the power return of the distributed power source has become an urgent problem to be solved. Summary of the invention

[0005] The embodiment of the present invention provides a method and system for mutual assistance of power in substation areas, which redistributes the power of low-voltage distribution substation areas through an AC / DC conversion device to solve the problem of reverse heavy overload of distribution transformers caused by power return of distributed power sources in the prior art.

[0006] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0007] According to a first aspect of an embodiment of the present invention, a method for mutual assistance of power in a metropolitan area is provided.

[0008] In one embodiment, the area power mutual assistance method includes:

[0009] According to the active power of the distribution transformer and the capacity of the distribution transformer, the load rate of the distribution transformer is calculated, and the active power flow direction of the distribution transformer is set to obtain the load situation of each substation;

[0010] Based on the load conditions of each substation, determine whether there is a heavily overloaded substation, and calculate the total over-limit power of all forward heavily overloaded substations and the total over-limit power of reverse heavily overloaded substations, obtain the over-limit power situation of each substation, and establish a preliminary power allocation strategy;

[0011] According to the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is allocated to the adjacent areas based on the principle of electrical proximity, until there are no heavily overloaded areas or the load rates of all areas reach the threshold conditions;

[0012] Based on the threshold condition that the load rate of all substations is reached, the charging and discharging power of the DC energy storage device is set, and the active power of the AC substation is adjusted through the charging and discharging operation of the DC energy storage device.

[0013] In one embodiment, the load rate of the distribution transformer is calculated based on the active power of the distribution transformer and the capacity of the distribution transformer, the load condition of each substation is obtained, and the active power flow direction of the distribution transformer is set to include:

[0014] Based on all substations, real-time data of distribution transformers are collected to obtain the active power of distribution transformers;

[0015] The load factor of the distribution transformer is calculated by using the active power of the distribution transformer and combining the capacity of the distribution transformer;

[0016] According to the load rate of the distribution transformer, the active power flow direction of the distribution transformer is set to determine the power flow direction of each substation.

[0017] In one embodiment, the calculation expression of the distribution transformer load rate is:

[0018]

[0019] In the formula, λ i represents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i;

[0020] The active power flow direction of the distribution transformer is set as follows: the active power of the distribution transformer flows from the medium-voltage distribution network to the low-voltage distribution network in the positive direction.

[0021] In one embodiment, the total over-limit power of all forward heavily overloaded stations is calculated as follows:

[0022]

[0023] Where P Σ+ Represents the sum of the over-limit powers of all forward heavily overloaded stations, λ max Indicates the positive heavy load rate threshold of the station area;

[0024] The calculation expression of the total over-limit power of all reverse heavy overload stations is:

[0025]

[0026] Where P Σ- Represents the sum of the over-limit power of all reverse overload areas, λ min Indicates the reverse heavy load rate threshold of the station area.

[0027] In one embodiment, according to the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is allocated to the adjacent area based on the principle of electrical distance proximity until there is no heavily overloaded area or the load rate of all areas reaches the threshold. The conditions include:

[0028] Based on the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is reserved;

[0029] When there is no reverse heavy overload area, the remaining over-limit power of the forward heavy overload area is distributed to the adjacent areas according to the principle of electrical distance proximity, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold;

[0030] When there is no forward heavily overloaded area, the remaining over-limit power of the reverse heavily overloaded area is distributed to the adjacent areas according to the principle of electrical distance proximity until there is no reverse heavily overloaded area or the load rate of all areas reaches the reverse heavy load rate threshold.

[0031] In one embodiment, based on the preliminary power allocation strategy, allocating the over-limit power of the heavily overloaded area and retaining the remaining over-limit power includes:

[0032] Compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area;

[0033] When the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, the over-limit power of the forward over-limited area is preferentially allocated to the reverse over-limited area until there is no reverse heavily overloaded area, and the remaining over-limit power is retained;

[0034] When the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, the over-limit power of the reverse over-limit area is preferentially allocated to the forward over-limit area until there is no forward heavily overloaded area and the remaining over-limit power is retained.

[0035] In one embodiment, the condition that all the load rates of the substations reach the threshold includes two situations: all the load rates of the substations reach the forward heavy load rate threshold and all the load rates of the substations reach the reverse heavy load rate threshold.

[0036] In one embodiment, based on the threshold condition that the load rates of all substations are reached, setting the charging and discharging power of the DC energy storage device, and adjusting the active power of the AC substation through the charging and discharging operation of the DC energy storage device includes:

[0037] When the load rates of all substations reach the forward heavy load rate threshold, the total over-limit power of the forward heavy overload substation is compared with the maximum discharge power of the DC energy storage device, and the discharge power of the DC energy storage device is determined based on the comparison result. The active power of the AC substation is supplied through the discharge operation of the DC energy storage device;

[0038] When the load rates of all substations reach the reverse heavy load rate threshold, the total over-limit power of the reverse heavy overload substation is compared with the maximum charging power of the DC energy storage device, and the charging power of the DC energy storage device is determined based on the comparison result. The active power of the AC substation is absorbed through the charging operation of the DC energy storage device.

[0039] According to a second aspect of the embodiments of the present invention, a substation power mutual assistance system is provided.

[0040] In one embodiment, the substation power mutual assistance system includes an AC / DC conversion device, a DC interconnection line, a DC energy storage device and a fusion terminal;

[0041] Among them, an AC / DC conversion device is configured in each substation, and the AC side of the AC / DC conversion device is connected to the low-voltage busbar of the corresponding substation;

[0042] DC interconnection line, used to connect the DC side of the AC / DC conversion device in each substation;

[0043] DC energy storage device, used to regulate the active power of the AC station area through charging and discharging operations;

[0044] The fusion terminal is used to collect the active power of the distribution transformer, analyze the load conditions and over-limit power conditions of each substation, establish a preliminary power allocation strategy, and generate corresponding control instructions, and send the corresponding control instructions to the AC / DC conversion device.

[0045] In one embodiment, the fusion terminal includes a load rate analysis unit, an over-limit power judgment unit, a power allocation and optimization unit, and an energy storage adjustment unit;

[0046] The load factor analysis unit is used to calculate the load factor of the distribution transformer according to the active power of the distribution transformer and the capacity of the distribution transformer, and to set the active power flow direction of the distribution transformer to obtain the load situation of each substation;

[0047] The over-limit power judgment unit is used to judge whether there is a heavily overloaded area based on the load conditions of each area, and calculate the total over-limit power of all forward heavily overloaded areas and the total over-limit power of reverse heavily overloaded areas, obtain the over-limit power conditions of each area, and establish a preliminary power allocation strategy;

[0048] The power allocation and optimization unit is used to allocate the over-limit power of the heavily overloaded area according to the preliminary power allocation strategy, and allocate the remaining over-limit power to the adjacent areas based on the principle of electrical distance proximity, until there is no heavily overloaded area or the load rate of all areas reaches the threshold condition;

[0049] The energy storage regulating unit is used to set the charging and discharging power of the DC energy storage device based on the threshold condition that the load rate of all substations is reached, and to regulate the active power of the AC substation through the charging and discharging operation of the DC energy storage device.

[0050] In one embodiment, the load rate analysis unit includes an active power acquisition module, a load rate calculation module and a power flow module;

[0051] Among them, the active power acquisition module is used to collect real-time data of distribution transformers based on all substations to obtain the active power of distribution transformers;

[0052] A load factor calculation module is used to calculate the load factor of the distribution transformer by using the active power of the distribution transformer and combining the capacity of the distribution transformer;

[0053] The power flow module is used to set the active power flow of the distribution transformer according to the load rate of the distribution transformer and determine the power flow direction of each substation.

[0054] In one embodiment, the calculation expression of the distribution transformer load rate is:

[0055]

[0056] In the formula, λ irepresents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i;

[0057] The active power flow direction of the distribution transformer is set as follows: the active power of the distribution transformer flows from the medium-voltage distribution network to the low-voltage distribution network in the positive direction.

[0058] In one embodiment, the power allocation and optimization unit includes a preliminary power allocation module, a forward heavy overload optimization module, and a reverse heavy overload optimization module;

[0059] The preliminary power allocation module is used to allocate the over-limit power of the heavily overloaded area based on the preliminary power allocation strategy and retain the remaining over-limit power;

[0060] The forward heavy overload optimization module is used to distribute the remaining over-limit power of the forward heavy overload area to the adjacent areas according to the principle of electrical proximity when there is no reverse heavy overload area, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold;

[0061] The reverse heavy overload optimization module is used to distribute the remaining over-limit power of the reverse heavy overload area to the adjacent areas according to the principle of electrical distance proximity when there is no forward heavy overload area, until there is no reverse heavy overload area, or the load rate of all areas reaches the reverse heavy load rate threshold.

[0062] In one embodiment, the preliminary power allocation module includes an over-limit power comparison module, a forward priority allocation module, and a reverse priority allocation module;

[0063] The over-limit power comparison module is used to compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area;

[0064] A forward priority allocation module is used to allocate the over-limit power of the forward over-limit area to the reverse over-limit area in priority when the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, until there is no reverse heavily overloaded area, and retain the remaining over-limit power;

[0065] The reverse priority allocation module is used to allocate the over-limit power of the reverse over-limit area to the forward over-limit area in priority when the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, until there is no forward heavily overloaded area, and retain the remaining over-limit power.

[0066] In one embodiment, the condition that all the load rates of the substations reach the threshold includes two situations: all the load rates of the substations reach the forward heavy load rate threshold and all the load rates of the substations reach the reverse heavy load rate threshold.

[0067] In one embodiment, the energy storage regulation unit includes a forward heavy load control module and a reverse heavy load control module;

[0068] Among them, the forward overload control module is used to compare the total over-limit power of the forward heavy overload area with the maximum discharge power of the DC energy storage device when the load rate of all areas reaches the forward overload load rate threshold, and determine the discharge power of the DC energy storage device based on the comparison result, and supply active power to the AC area through the discharge operation of the DC energy storage device;

[0069] The reverse heavy load control module is used to compare the total over-limit power of the reverse heavy overload area with the maximum charging power of the DC energy storage device when the load rate of all areas reaches the reverse heavy load rate threshold, and determine the charging power of the DC energy storage device based on the comparison result, and absorb the active power of the AC area through the charging operation of the DC energy storage device.

[0070] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0071] In one embodiment, the computer device includes a memory and a processor, wherein a computer program is stored in the memory, and the steps of the above method are implemented when the processor executes the computer program.

[0072] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0073] In one embodiment, the computer-readable storage medium stores a computer program, which implements the steps of the above method when executed by a processor.

[0074] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0075] (1) The present invention redistributes the power of low-voltage distribution stations through an AC-DC conversion device, effectively solving the problem of reverse overload and overload of distribution transformers caused by the power return of distributed power sources, which not only improves the operating safety of the distribution network, but also provides technical support for the large-scale access of distributed energy. At the same time, the present invention accurately calculates the load rate of each substation through real-time monitoring and analysis of the active power data of the distribution transformer, and judges the heavy overload situation according to the preset threshold, providing an accurate data basis for power mutual assistance. By establishing a preliminary power allocation strategy, intelligent power allocation between heavily overloaded substations is realized, and the principle of electrical distance proximity is used to reasonably allocate the remaining power, effectively alleviating the load imbalance problem between substations.

[0076] (2) The present invention introduces a DC energy storage device. When there is still over-limit power after power distribution, the active power of the AC substation is further adjusted by intelligently controlling the charging and discharging operations of the energy storage device, thereby achieving a more refined and flexible load balance. In addition, the introduction of the fusion terminal enables the entire system to have intelligent analysis and decision-making capabilities, and can automatically execute the optimal power mutual assistance strategy according to real-time conditions, which not only improves the operating efficiency and reliability of the distribution network, but also provides an innovative solution for the flexible access and efficient consumption of distributed energy. It has important practical significance and promotion value for building a more intelligent, flexible and safe modern distribution network.

[0077] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0079] Figure 1 is a flow chart of a method for mutual assistance of power in a substation area according to an exemplary embodiment;

[0080] Figure 2 is a schematic diagram of basic elements of a power mutual assistance system in an area according to an exemplary embodiment;

[0081] Figure 3 is a specific implementation diagram of a method for mutual assistance of power in a substation area according to an exemplary embodiment;

[0082] Figure 4 This is a diagram showing an application example of a substation power mutual assistance system in a village in a certain place according to an exemplary embodiment;

[0083] Figure 5 It is a transmission power curve diagram of three AC / DC conversion devices on a certain day after a power mutual assistance system of a substation area is applied in a village in a certain place according to an exemplary embodiment;

[0084] Figure 6 is a structural block diagram of a substation power mutual assistance system according to an exemplary embodiment;

[0085] Figure 7 The diagram is a schematic structural diagram of a computer device according to an exemplary embodiment. DETAILED DESCRIPTION

[0086] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0087] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0088] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0089] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0090] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0091] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0092] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0093] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0094] Figure 1 and Figure 3 An embodiment of a power mutual assistance method for a substation of the present invention is shown.

[0095] In this optional embodiment, the area power mutual assistance method includes:

[0096] Step S101: Calculate the load rate of the distribution transformer according to the active power of the distribution transformer and the capacity of the distribution transformer, and set the active power flow direction of the distribution transformer to obtain the load condition of each substation;

[0097] Specifically, Figure 3 As shown in the figure, the specific implementation process of the power mutual assistance method of the substation based on low-voltage flexible DC interconnection described in the present invention is as follows: ① collecting the active power of the distribution transformer; ② calculating the load rate of the distribution transformer.

[0098] It should be noted that in the power system, when the load of the substation is close to its rated capacity, it is called heavy load; when the load of the substation exceeds its rated capacity, it is called overload. In this embodiment, the substation is divided into three types according to the load conditions of each substation: heavy overload substation, normal load substation and no-load substation; among them, heavy overload substation includes heavy load substation and overload substation, heavy load substation refers to the substation whose load rate exceeds the rated range (set to 80% in this embodiment), overload substation refers to the substation whose load rate exceeds 100%, normal load substation refers to the substation whose load rate is within the rated range, and no-load substation refers to the substation whose load rate is 0; normal load substation and no-load substation are in normal working state or non-working state, which does not belong to the situation to be discussed in this invention. This invention mainly focuses on the heavy overload substation where safety accidents are most likely to occur.

[0099] Step S103: Based on the load conditions of each substation, determine whether there is a heavily overloaded substation, and calculate the total over-limit power of all forward heavily overloaded substations and the total over-limit power of all reverse heavily overloaded substations, obtain the over-limit power conditions of each substation, and establish a preliminary power allocation strategy;

[0100] Specifically, ③ determines whether there is a forward or reverse heavy overload area. If there is a forward or reverse heavy overload area, enter ④, otherwise the area power mutual assistance is not performed. In this embodiment, the heavy overload area where the active power flow of the distribution transformer is in the forward direction is called the forward heavy overload area, and the heavy overload area where the active power flow of the distribution transformer is in the reverse direction is called the reverse heavy overload area; the forward heavy load rate threshold of the area is preset to 80%, and the reverse heavy load rate threshold is preset to -80%, which can also be manually specified according to the actual on-site control needs. For example, if you do not want the distribution transformer to have power reverse transmission, you can specify the reverse heavy load rate threshold of the area as 0%.

[0101] Specifically, ④ calculate the sum of the over-limit power of all forward heavily overloaded stations, and obtain the total over-limit power P of the forward heavily overloaded stations Σ+ ⑤ Calculate the sum of the over-limit power of all reverse overload areas to obtain the total over-limit power P of the reverse overload area. Σ- .

[0102] Step S105: allocate the over-limit power of the heavily overloaded area according to the preliminary power allocation strategy, and allocate the remaining over-limit power to the adjacent areas based on the principle of electrical proximity, until there is no heavily overloaded area or the load rate of all areas reaches the threshold condition;

[0103] Step S107: based on the threshold condition that the load rates of all substations have reached, the charging and discharging power of the DC energy storage device is set, and the active power of the AC substation is adjusted through the charging and discharging operation of the DC energy storage device.

[0104] Specifically, ⑥ if P Σ+ >PΣ- :

[0105] 1) The over-limit power of the forward heavy overload area is preferentially allocated to the reverse heavy overload area until there is no reverse heavy overload area. At this time, P Σ+ =P Σ+ -P Σ- , P Σ- =0;

[0106] 2) According to the principle of electrical proximity, the over-limit power of the forward heavy overload area is distributed to the adjacent areas until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold. At this time, P Σ+ =0 or λ i ≥λ max (i=1,2,3,...,n, n represents the number of substations connected to the low voltage flexible DC interconnection system);

[0107] 3) If the load rate of all stations reaches the positive heavy load rate threshold, that is, λ i≥ λ max (i=1,2,3,...,n), the DC energy storage device discharges and supplies active power to the AC station area; if the maximum discharge power of the DC energy storage device is greater than P Σ+ , then the discharge power of the DC energy storage device is set to P Σ+ , otherwise the DC energy storage device discharges at maximum power.

[0108] Specifically, ⑦ if P Σ+ ≤P Σ— :

[0109] 1) The over-limit power of the reverse heavy overload area is preferentially allocated to the forward heavy overload area until there is no forward heavy overload area. At this time, P Σ- =P Σ- -P Σ+ , P Σ+ =0;

[0110] 2) According to the principle of electrical proximity, the over-limit power of the reverse heavy overload area is distributed to the adjacent areas until there is no reverse heavy overload area, or the load rate of all areas reaches the reverse heavy load rate threshold. At this time, P Σ- =0 or λ i ≤λ min (i=1,2,3,...,n, n represents the number of substations connected to the low voltage flexible DC interconnection system).

[0111] 3) If the load rate of all stations reaches the reverse heavy load rate threshold, that is, λ i ≤λ min(i=1,2,3,...,n), the DC energy storage device is charged and absorbs active power from the AC station area; if the maximum charging power of the DC energy storage device is greater than P Σ- , then the charging power of the DC energy storage device is set to P Σ- , otherwise the DC energy storage device is charged at maximum power.

[0112] In this optional embodiment, the load rate of the distribution transformer is calculated according to the active power of the distribution transformer and the capacity of the distribution transformer, the load condition of each substation is obtained, and the active power flow direction of the distribution transformer is set to include:

[0113] Step S1011: Based on all substations, real-time data of distribution transformers are collected respectively to obtain active power of distribution transformers;

[0114] Step S1013, using the active power of the distribution transformer and the capacity of the distribution transformer to calculate the load rate of the distribution transformer;

[0115] Step S1015: according to the load rate of the distribution transformer, set the active power flow direction of the distribution transformer and determine the power flow direction of each substation.

[0116] In this optional embodiment, the calculation expression of the distribution transformer load rate is:

[0117]

[0118] In the formula, λ i represents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i;

[0119] The active power flow direction of the distribution transformer is set as follows: the active power of the distribution transformer flows from the medium-voltage distribution network to the low-voltage distribution network in the positive direction.

[0120] Specifically, since each distribution substation has distributed power sources and power loads, bidirectional power flow may occur in the distribution transformer; in this embodiment, the power flow from 10kV to 380V is defined as forward, and the power flow from 380V to 10kV is defined as reverse.

[0121] In this optional embodiment, the total over-limit power of all forward heavily overloaded stations is calculated as follows:

[0122]

[0123] Where P Σ+ Represents the sum of the over-limit powers of all forward heavily overloaded stations, λ maxIndicates the positive heavy load rate threshold of the station area;

[0124] The calculation expression of the total over-limit power of all reverse heavy overload stations is:

[0125]

[0126] Where P Σ- Represents the sum of the over-limit power of all reverse overload areas, λ min Indicates the reverse heavy load rate threshold of the station area.

[0127] In this optional embodiment, according to the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is allocated to the adjacent area based on the principle of electrical distance proximity until there is no heavily overloaded area or the load rate of all areas reaches the threshold. The conditions include:

[0128] Step S1051: Based on the preliminary power allocation strategy, allocate the over-limit power of the heavily overloaded area and retain the remaining over-limit power;

[0129] Step S1053: when there is no reverse heavy overload area, the remaining over-limit power of the forward heavy overload area is distributed to the adjacent areas according to the principle of electrical proximity, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold;

[0130] Step S1055: When there is no forward heavily overloaded area, the remaining over-limit power of the reverse heavily overloaded area is distributed to adjacent areas according to the principle of electrical proximity until there is no reverse heavily overloaded area or the load rates of all areas reach the reverse heavy load rate threshold.

[0131] Specifically, the preliminary power allocation strategy includes: if there is no reverse heavily overloaded area, the remaining over-limit power of the forward heavily overloaded area will be allocated to the adjacent areas according to the principle of electrical distance proximity, until there is no forward heavily overloaded area, or the load rate of all areas reaches the forward heavy load rate threshold; if there is no forward heavily overloaded area, the remaining over-limit power of the reverse heavily overloaded area will be allocated to the adjacent areas according to the principle of electrical distance proximity, until there is no reverse heavily overloaded area, or the load rate of all areas reaches the reverse heavy load rate threshold.

[0132] In this optional embodiment, based on the preliminary power allocation strategy, allocating the over-limit power of the heavily overloaded area and retaining the remaining over-limit power includes:

[0133] Compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area;

[0134] When the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, the over-limit power of the forward over-limited area is preferentially allocated to the reverse over-limited area until there is no reverse heavily overloaded area, and the remaining over-limit power is retained;

[0135] When the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, the over-limit power of the reverse over-limit area is preferentially allocated to the forward over-limit area until there is no forward heavily overloaded area and the remaining over-limit power is retained.

[0136] In this optional embodiment, the condition that all the substation load rates reach the threshold includes two situations: all the substation load rates reach the forward heavy load rate threshold and all the substation load rates reach the reverse heavy load rate threshold.

[0137] In this optional embodiment, based on the threshold condition that the load rates of all substations are reached, setting the charging and discharging power of the DC energy storage device, and adjusting the active power of the AC substation through the charging and discharging operation of the DC energy storage device includes:

[0138] Step S1071: When the load rates of all the substations reach the forward heavy load rate threshold, compare the total over-limit power of the forward heavy overload substation with the maximum discharge power of the DC energy storage device, and determine the discharge power of the DC energy storage device based on the comparison result, and supply active power to the AC substation through the discharge operation of the DC energy storage device;

[0139] Step S1073: When the load rates of all substations reach the reverse heavy load rate threshold, compare the total over-limit power of the reverse heavy overload substation with the maximum charging power of the DC energy storage device, and determine the charging power of the DC energy storage device based on the comparison result, and absorb the active power of the AC substation through the charging operation of the DC energy storage device.

[0140] Figure 2 , Figure 4 and Figure 6 An embodiment of a substation power mutual assistance system of the present invention is shown.

[0141] In this optional embodiment, the substation power mutual assistance system includes an AC / DC conversion device, a DC interconnection line, a DC energy storage device and a fusion terminal;

[0142] Among them, an AC / DC conversion device is configured in each substation, and the AC side of the AC / DC conversion device is connected to the low-voltage busbar of the corresponding substation;

[0143] DC interconnection line, used to connect the DC side of the AC / DC conversion device in each substation;

[0144] DC energy storage device, used to regulate the active power of the AC station area through charging and discharging operations;

[0145] The fusion terminal is used to collect the active power of the distribution transformer, analyze the load conditions and over-limit power conditions of each substation, establish a preliminary power allocation strategy, and generate corresponding control instructions, and send the corresponding control instructions to the AC / DC conversion device.

[0146] Specifically, Figure 2 As shown, in this embodiment, a substation power mutual assistance system involves n distribution substations, each of which is equipped with an AC / DC conversion device C i (i=1,2,...,n), C i The AC side is connected to the low voltage busbar of the distribution station area i, C1, C2...C n The DC side is connected through a DC interconnection line, and the DC energy storage device is directly connected to the DC interconnection line or connected to the DC distribution cabinet. i , power load L i , so the distribution transformer T i Power may flow in both directions. In this embodiment, the power flowing from 10 kV to 380 V is defined as the forward direction, and the power flowing from 380 V to 10 kV is defined as the reverse direction.

[0147] Specifically, in the above embodiment, the AC-DC conversion device C i It adopts a three-level topology structure and has the function of flexible switching between DC voltage regulation mode / fixed active and reactive modes; the DC interconnection line voltage level can be selected as 750V or ±375V.

[0148] Specifically, Figure 4 As shown in the figure, the solid line represents the power line, and the dotted line represents the data flow. In this embodiment, the fusion terminal is responsible for collecting the active power of the distribution transformer and the operating status of the AC / DC conversion device, solving the power mutual assistance method of the substation (including analyzing the load situation and over-limit power situation of each substation, establishing a preliminary power allocation strategy, and generating corresponding control instructions), and sending the control instructions to the AC / DC conversion device. If multiple substations covered by the power mutual assistance system are equipped with fusion terminals, only the fusion terminal of a certain substation is assigned the task of solving and executing the power mutual assistance method of the substation. The fusion terminal summarizes the active power of the distribution transformer, the operating status of the AC / DC conversion device, the control instructions that have been issued, and uploads it to the cloud master station. The fusion terminal communicates with the AC / DC conversion device of this substation through RS-485, and communicates with the AC / DC conversion devices and DC energy storage devices of other substations through LoRa.

[0149] In this optional embodiment, the fusion terminal includes a load rate analysis unit 201, an over-limit power determination unit 203, a power allocation and optimization unit 205, and an energy storage adjustment unit 207;

[0150] The load factor analysis unit 201 is used to calculate the load factor of the distribution transformer according to the active power of the distribution transformer and the capacity of the distribution transformer, and to set the active power flow direction of the distribution transformer to obtain the load condition of each substation;

[0151] The over-limit power judgment unit 203 is used to judge whether there is a heavily overloaded area based on the load conditions of each area, and calculate the total over-limit power of all forward heavily overloaded areas and the total over-limit power of reverse heavily overloaded areas, obtain the over-limit power conditions of each area, and establish a preliminary power allocation strategy;

[0152] The power allocation and optimization unit 205 is used to allocate the over-limit power of the heavily overloaded area according to the preliminary power allocation strategy, and allocate the remaining over-limit power to the adjacent areas based on the principle of electrical distance proximity, until there is no heavily overloaded area or the load rate of all areas reaches the threshold condition;

[0153] The energy storage regulating unit 207 is used to set the charging and discharging power of the DC energy storage device based on the threshold condition that the load rates of all substations have reached, and regulate the active power of the AC substation through the charging and discharging operations of the DC energy storage device.

[0154] In this optional embodiment, the load rate analysis unit 201 includes an active power acquisition module, a load rate calculation module and a power flow module;

[0155] Among them, the active power acquisition module (not shown in the figure) is used to collect real-time data of distribution transformers based on all substations to obtain the active power of distribution transformers;

[0156] A load factor calculation module (not shown in the figure) is used to calculate the load factor of the distribution transformer by using the active power of the distribution transformer and combining the capacity of the distribution transformer;

[0157] The power flow module (not shown in the figure) is used to set the active power flow of the distribution transformer according to the load rate of the distribution transformer and determine the power flow direction of each substation.

[0158] In this optional embodiment, the calculation expression of the distribution transformer load rate is:

[0159]

[0160] In the formula, λ i represents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i;

[0161] The active power flow direction of the distribution transformer is set as follows: the active power of the distribution transformer flows from the medium-voltage distribution network to the low-voltage distribution network in the positive direction.

[0162] In this optional embodiment, the power allocation and optimization unit 205 includes a preliminary power allocation module, a forward heavy overload optimization module, and a reverse heavy overload optimization module;

[0163] The preliminary power allocation module (not shown in the figure) is used to allocate the over-limit power of the heavily overloaded area based on the preliminary power allocation strategy and retain the remaining over-limit power;

[0164] The forward heavy overload optimization module (not shown in the figure) is used to distribute the remaining over-limit power of the forward heavy overload area to the adjacent areas according to the principle of electrical proximity when there is no reverse heavy overload area, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold;

[0165] The reverse heavy overload optimization module (not shown in the figure) is used to distribute the remaining over-limit power of the reverse heavy overload area to the adjacent areas according to the principle of electrical distance when there is no forward heavy overload area, until there is no reverse heavy overload area, or the load rate of all areas reaches the reverse heavy load rate threshold.

[0166] In this optional embodiment, the preliminary power allocation module includes an over-limit power comparison module, a forward priority allocation module, and a reverse priority allocation module;

[0167] Among them, the over-limit power comparison module (not shown in the figure) is used to compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area;

[0168] A forward priority allocation module (not shown in the figure) is used to allocate the over-limit power of the forward over-limit area to the reverse over-limit area in priority when the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, until there is no reverse heavily overloaded area, and retain the remaining over-limit power;

[0169] The reverse priority allocation module (not shown in the figure) is used to preferentially allocate the over-limit power of the reverse over-limit area to the forward over-limit area when the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, until there is no forward heavily overloaded area and the remaining over-limit power is retained.

[0170] In this optional embodiment, the condition that all the substation load rates reach the threshold includes two situations: all the substation load rates reach the forward heavy load rate threshold and all the substation load rates reach the reverse heavy load rate threshold.

[0171] In this optional embodiment, the energy storage adjustment unit 207 includes a forward heavy load control module and a reverse heavy load control module;

[0172] Among them, the forward overload control module (not shown in the figure) is used to compare the total over-limit power of the forward heavy overload area with the maximum discharge power of the DC energy storage device when the load rate of all areas reaches the forward overload load rate threshold, and determine the discharge power of the DC energy storage device based on the comparison result, and supply the active power of the AC area through the discharge operation of the DC energy storage device;

[0173] The reverse overload control module (not shown in the figure) is used to compare the total over-limit power of the reverse overload area with the maximum charging power of the DC energy storage device when the load rate of all areas reaches the reverse overload load rate threshold, and determine the charging power of the DC energy storage device based on the comparison result, and absorb the active power of the AC area through the charging operation of the DC energy storage device.

[0174] In order to facilitate understanding of the above technical solution of the present invention, the actual application of the present invention in a certain village in a certain place is taken as an example for specific description as follows:

[0175] like Figure 4 As shown in the figure, it is an application example of the power mutual assistance system of the substation area based on low-voltage flexible DC interconnection of the present invention in a certain village in a certain place. The power load of the two substation areas in the village is mainly residential load, which is connected to distributed photovoltaics. The power load is low and the photovoltaic power generation power is large, which easily causes the distribution transformer to be reversely overloaded; the power load of substation area 1 and substation area 3 is mainly the village-run cement processing plant, which has a high power load and easily causes the distribution transformer to be forwardly overloaded. After the system described in the present invention is deployed, the three distribution substation areas are interconnected on the low-voltage side through an AC-DC conversion device, and the substation areas are interconnected through a DC750V DC line; and energy is transferred according to the operating conditions of the substation area, and the photovoltaic power generation is transferred to the nearest cement processing plant for consumption, or transferred to a DC energy storage device for storage, thereby solving the problem of reverse overload of the distribution transformer caused by the return of distributed photovoltaic power.

[0176] like Figure 5 As shown in the figure, in the above application example, the power transmission situation of the three AC / DC conversion devices in the village during 7:00-17:40 on a certain day, among which, the power of the AC / DC conversion device in area 2 is positive, indicating that the flexible DC system absorbs power from area 2; the power of the AC / DC conversion device in areas 1 and 3 is negative, indicating that the flexible DC system provides power to areas 1 and 3; the sum of the PCS power of areas 1, 2, and 3 is approximately 0, indicating that the power of area 2 is transferred to areas 1 and 3, proving that the on-site consumption of distributed photovoltaics during the day is completed through the present invention, avoiding the occurrence of reverse heavy overload of the distribution transformer caused by the return of distributed photovoltaic power.

[0177] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 7 As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0178] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0179] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0180] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0181] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0182] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for mutual assistance of power in substations, characterized in that: The power mutual assistance method of the substation area includes: According to the active power of the distribution transformer and the capacity of the distribution transformer, the load rate of the distribution transformer is calculated, and the active power flow direction of the distribution transformer is set to obtain the load situation of each substation; Based on the load conditions of each substation, determine whether there is a heavily overloaded substation, and calculate the total over-limit power of all forward heavily overloaded substations and the total over-limit power of reverse heavily overloaded substations, obtain the over-limit power situation of each substation, and establish a preliminary power allocation strategy; According to the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is allocated to the adjacent areas based on the principle of electrical proximity, until there are no heavily overloaded areas or the load rates of all areas reach the threshold conditions; Based on the threshold condition that the load rate of all substations is reached, the charging and discharging power of the DC energy storage device is set, and the active power of the AC substation is adjusted through the charging and discharging operation of the DC energy storage device.

2. A method for mutual assistance of power in substations according to claim 1, characterized in that: The method of calculating the load rate of the distribution transformer according to the active power of the distribution transformer and the capacity of the distribution transformer, obtaining the load condition of each substation, and setting the active power flow direction of the distribution transformer includes: Based on all substations, real-time data of distribution transformers are collected to obtain the active power of distribution transformers; The load factor of the distribution transformer is calculated by using the active power of the distribution transformer and combining the capacity of the distribution transformer; According to the load rate of the distribution transformer, the active power flow direction of the distribution transformer is set to determine the power flow direction of each substation.

3. A method for mutual assistance of power in substations according to claim 2, characterized in that: The calculation expression of the distribution transformer load rate is: In the formula, λ i represents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i; The setting of the active power flow direction of the distribution transformer is as follows: the active power of the distribution transformer flows from the medium voltage distribution network to the low voltage distribution network in a positive direction.

4. A method for mutual assistance of power in substations according to claim 3, characterized in that: The calculation expression of the total over-limit power of all forward heavily overloaded stations is: Where P Σ+ Represents the sum of the over-limit powers of all forward heavily overloaded stations, λ max Indicates the positive heavy load rate threshold of the station area; The calculation expression of the total over-limit power of all reverse heavy overload stations is: Where P Σ- Represents the sum of the over-limit power of all reverse overload areas, λ min Indicates the reverse heavy load rate threshold of the station area.

5. The method for mutual assistance of power in substations according to claim 1, characterized in that: The above-mentioned allocation of over-limit power to the heavily overloaded area according to the preliminary power allocation strategy and the allocation of the remaining over-limit power to the adjacent area based on the principle of electrical proximity until there is no heavily overloaded area or the load rate of all areas reaches the threshold conditions include: Based on the preliminary power allocation strategy, the over-limit power of the heavily overloaded area is allocated, and the remaining over-limit power is reserved; When there is no reverse heavy overload area, the remaining over-limit power of the forward heavy overload area is distributed to the adjacent areas according to the principle of electrical distance proximity, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold; When there is no forward heavily overloaded area, the remaining over-limit power of the reverse heavily overloaded area is distributed to the adjacent areas according to the principle of electrical distance proximity until there is no reverse heavily overloaded area or the load rate of all areas reaches the reverse heavy load rate threshold.

6. A method for mutual assistance of power in substations according to claim 5, characterized in that: The method of allocating the over-limit power of the heavily overloaded area based on the preliminary power allocation strategy and retaining the remaining over-limit power includes: Compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area; When the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, the over-limit power of the forward over-limited area is preferentially allocated to the reverse over-limited area until there is no reverse heavily overloaded area, and the remaining over-limit power is retained; When the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, the over-limit power of the reverse over-limit area is preferentially allocated to the forward over-limit area until there is no forward heavily overloaded area and the remaining over-limit power is retained.

7. The method for mutual assistance of power in substations according to claim 1, characterized in that: The condition that the load rates of all substations reach the threshold value includes two situations: the load rates of all substations reach the forward heavy load rate threshold value and the load rates of all substations reach the reverse heavy load rate threshold value.

8. The method for mutual assistance of power in substations according to claim 1, characterized in that: The setting of the charge and discharge power of the DC energy storage device based on the threshold condition that the load rates of all the substations are reached, and adjusting the active power of the AC substation through the charge and discharge operation of the DC energy storage device includes: When the load rates of all substations reach the forward heavy load rate threshold, the total over-limit power of the forward heavy overload substation is compared with the maximum discharge power of the DC energy storage device, and the discharge power of the DC energy storage device is determined based on the comparison result. The active power of the AC substation is supplied through the discharge operation of the DC energy storage device; When the load rates of all substations reach the reverse heavy load rate threshold, the total over-limit power of the reverse heavy overload substation is compared with the maximum charging power of the DC energy storage device, and the charging power of the DC energy storage device is determined based on the comparison result. The active power of the AC substation is absorbed through the charging operation of the DC energy storage device.

9. A power mutual assistance system for a substation area, characterized in that: The power mutual assistance system of the substation area includes AC / DC conversion device, DC interconnection line, DC energy storage device and fusion terminal; Wherein, the AC / DC conversion device is configured in each substation, and the AC side of the AC / DC conversion device is connected to the low-voltage busbar of the corresponding substation; The DC interconnection line is used to connect the DC side of the AC / DC conversion device in each substation; The DC energy storage device is used to adjust the active power of the AC station area through charging and discharging operations; The fusion terminal is used to collect the active power of the distribution transformer, analyze the load condition and over-limit power condition of each substation, establish a preliminary power allocation strategy, and generate corresponding control instructions, and send the corresponding control instructions to the AC / DC conversion device.

10. The area power mutual assistance system according to claim 9, characterized in that: The fusion terminal includes a load rate analysis unit, an over-limit power judgment unit, a power allocation and optimization unit, and an energy storage adjustment unit; The load factor analysis unit is used to calculate the load factor of the distribution transformer according to the active power of the distribution transformer and the capacity of the distribution transformer, and to set the active power flow direction of the distribution transformer to obtain the load condition of each substation; The over-limit power judgment unit is used to judge whether there is a heavily overloaded area based on the load conditions of each area, and calculate the total over-limit power of all forward heavily overloaded areas and the total over-limit power of reverse heavily overloaded areas, obtain the over-limit power conditions of each area, and establish a preliminary power allocation strategy; The power allocation and optimization unit is used to allocate the over-limit power of the heavily overloaded area according to the preliminary power allocation strategy, and allocate the remaining over-limit power to the adjacent areas based on the principle of electrical distance proximity, until there is no heavily overloaded area or the load rate of all areas reaches the threshold condition; The energy storage regulating unit is used to set the charging and discharging power of the DC energy storage device based on the threshold condition that the load rates of all substations are reached, and to regulate the active power of the AC substation through the charging and discharging operations of the DC energy storage device.

11. A power mutual assistance system for substations according to claim 10, characterized in that: The load rate analysis unit includes an active power acquisition module, a load rate calculation module and a power flow module; The active power acquisition module is used to collect real-time data of distribution transformers based on all substations to obtain the active power of distribution transformers; The load rate calculation module is used to calculate the load rate of the distribution transformer by using the active power of the distribution transformer in combination with the capacity of the distribution transformer; The power flow module is used to set the active power flow of the distribution transformer according to the load rate of the distribution transformer and determine the power flow direction of each substation.

12. A power mutual assistance system for substations according to claim 11, characterized in that: The calculation expression of the distribution transformer load rate is: In the formula, λ i represents the load factor of the distribution transformer in area i, P i represents the active power of the distribution transformer in area i, S i represents the capacity of the distribution transformer in area i; The setting of the active power flow direction of the distribution transformer is as follows: the active power of the distribution transformer flows from the medium voltage distribution network to the low voltage distribution network in a positive direction.

13. The area power mutual assistance system according to claim 10, characterized in that: The power distribution and optimization unit includes a preliminary power distribution module, a forward heavy overload optimization module and a reverse heavy overload optimization module; The preliminary power allocation module is used to allocate the over-limit power of the heavily overloaded area based on the preliminary power allocation strategy, and retain the remaining over-limit power; The forward heavy overload optimization module is used to distribute the remaining over-limit power of the forward heavy overload area to the adjacent areas according to the principle of electrical proximity when there is no reverse heavy overload area, until there is no forward heavy overload area, or the load rate of all areas reaches the forward heavy load rate threshold; The reverse heavy overload optimization module is used to distribute the remaining over-limit power of the reverse heavy overload area to the adjacent areas according to the principle of electrical distance proximity when there is no forward heavy overload area, until there is no reverse heavy overload area, or the load rate of all areas reaches the reverse heavy load rate threshold.

14. A power mutual assistance system for substations according to claim 13, characterized in that: The preliminary power allocation module includes an over-limit power comparison module, a forward priority allocation module and a reverse priority allocation module; The over-limit power comparison module is used to compare the total over-limit power of the forward heavy overload area with the total over-limit power of the reverse heavy overload area; The forward priority allocation module is used to allocate the over-limit power of the forward over-limit area to the reverse over-limit area preferentially when the total over-limit power of the forward heavily overloaded area is greater than the total over-limit power of the reverse heavily overloaded area, until there is no reverse heavily overloaded area, and retain the remaining over-limit power; The reverse priority allocation module is used to preferentially allocate the over-limit power of the reverse over-limit area to the forward over-limit area when the total over-limit power of the forward heavily overloaded area is less than or equal to the total over-limit power of the reverse heavily overloaded area, until there is no forward heavily overloaded area, and retain the remaining over-limit power.

15. The area power mutual assistance system according to claim 10, characterized in that: The condition that the load rates of all substations reach the threshold value includes two situations: the load rates of all substations reach the forward heavy load rate threshold value and the load rates of all substations reach the reverse heavy load rate threshold value.

16. The area power mutual assistance system according to claim 10, characterized in that: The energy storage adjustment unit includes a forward heavy load control module and a reverse heavy load control module; The forward overload control module is used to compare the total over-limit power of the forward heavy overload area with the maximum discharge power of the DC energy storage device when the load rates of all areas reach the forward overload load rate threshold, and determine the discharge power of the DC energy storage device based on the comparison result, and supply active power to the AC area through the discharge operation of the DC energy storage device; The reverse heavy load control module is used to compare the total over-limit power of the reverse heavy overload area with the maximum charging power of the DC energy storage device when the load rates of all areas reach the reverse heavy load rate threshold, and determine the charging power of the DC energy storage device based on the comparison result, and absorb the active power of the AC area through the charging operation of the DC energy storage device.

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