Substation load balancing control method based on intelligent fusion terminal and shared energy storage system

Abstract

The present invention proposes a method for controlling the load balance of a power distribution area based on an intelligent fusion terminal and a shared energy storage system: Step S1: Select a fusion terminal in a certain power distribution area as the master fusion terminal according to the one-master-multiple-slave mode and in combination with the preset fusion terminal priority, and establish a communication connection with the fusion terminals in other power distribution areas; Step S2: Determine whether the communication between the slave fusion terminals in each power distribution area asking the master fusion terminal is normal; Step S3: Determine whether there is a power distribution area in the emergency power supply mode; Step S4: The master fusion terminal obtains the information of the interconnected and mutually supported power distribution areas, and takes the goal of balancing the load rates of each power distribution area to solve the required transfer power of each power distribution area; Step S5: Determine whether the surplus power on the DC side bus meets the energy storage power constraint conditions; Step S6: The master fusion terminal issues a power command to the PCS current conversion devices in each power distribution area and forwards it to the fusion terminals in each power distribution area. The shared energy storage system is realized to participate in the load rate balance of the power distribution transformers in the power distribution area, improve the utilization rate of energy storage resources, and reduce the operation loss of the overloaded power distribution transformers.

Description

Technical Field

[0001] The present invention relates to the technical field of low-voltage substation area energy storage control, and particularly relates to a method for controlling the load balance of a substation area based on an intelligent fusion terminal and a shared energy storage system. Background Art

[0002] With the rapid development of new energy power generation technology, as the end of the distribution network, the low-voltage distribution substation area needs to absorb a large amount of electric energy brought by the access of distributed power sources. In addition, with the rapid growth of the load, the peak-valley difference is intensifying, and problems such as overloading and low voltage in the substation area are gradually becoming prominent. By introducing energy storage technology, it is possible to support the efficient absorption of distributed power sources and the load balance of the substation area. However, at present, the problems of low resource utilization rate, poor comprehensive benefits, and inability of the main station of the distribution network to control the area independently in the energy storage configured independently for each substation area are gradually emerging, and the optimal control of the shared energy storage system has gradually become an important issue to be faced in the economic operation of the low-voltage substation area. Summary of the Invention

[0003] In view of the defects and deficiencies existing in the prior art, the present invention proposes a method for controlling the load balance of a substation area based on an intelligent fusion terminal and a shared energy storage system to solve the technical problems of increased operation loss caused by overloading in the substation area, the problem that independent energy storage cannot control overloading in different substation areas, and the absorption of electric energy from distributed power sources.

[0004] It mainly includes the following steps: Step S1: When the shared energy storage system based on the fusion terminal starts to operate, according to the number of fusion terminals, select the fusion terminal of a certain substation area as the main control fusion terminal in the one-master-multi-slave mode and in combination with the preset priority of the fusion terminal, and establish a communication connection with the fusion terminals of other substation areas; Step S2: Determine whether the communication between the slave fusion terminals of each substation area and the main control fusion terminal is normal by querying; Step S3: Determine whether there is a substation area in the emergency power supply mode; Step S4: The main control fusion terminal obtains the information of the interconnected substation areas, and takes the balance of the load rates of each substation area as the goal to solve the transfer power required for each substation area; Step S5: Determine whether the surplus power on the DC side bus meets the energy storage power constraint conditions; Step S6: The main control fusion terminal issues a power command to the PCS converter device of each substation area and forwards it to the fusion terminal of each substation area.

[0005] The present invention realizes the balance of the load rates of the distribution transformers in the substation area by the main control fusion terminal uniformly calculating the power commands for the power interconnection and mutual assistance of each fusion terminal, comprehensively considering the energy storage power constraints, improves the utilization rate of energy storage resources, and reduces the operation loss of the distribution transformer under overloading.

[0006] The present invention specifically adopts the following technical solutions:

[0007] A method for controlling the load balance of a power distribution area based on an intelligent fusion terminal and a shared energy storage system, characterized in that, based on a power distribution area model composed of multiple interconnected shared energy storage systems, the shared energy storage system is composed of a fusion terminal, a communication gateway, an energy storage communication middle computer, an energy storage PCS converter device, and an energy storage BMS device connected in sequence;

[0008] It includes the following steps:

[0009] Step S1: When the shared energy storage system starts to operate, according to the number of fusion terminals, select a fusion terminal in a certain power distribution area as the main control fusion terminal in a one-master-multiple-slave mode and in combination with a preset fusion terminal priority, and establish a communication connection with the fusion terminals in other power distribution areas;

[0010] Step S2: Judge whether the communication between the slave fusion terminals in each power distribution area and the main control fusion terminal is normal;

[0011] Step S3: Judge whether there is a power distribution area in the emergency power supply mode;

[0012] Step S4: The main control fusion terminal obtains the information of the interconnected and mutual-aid power distribution areas, and takes the goal of balancing the load rates of each power distribution area to solve the transfer power required for each power distribution area;

[0013] Step S5: Judge whether the surplus power on the DC side bus meets the energy storage power constraint conditions;

[0014] Step S6: The main control fusion terminal issues a power command to the energy storage PCS converter devices in each power distribution area and forwards it to the fusion terminals in each power distribution area.

[0015] [[ID=2,4]]Further, step S2 is specifically as follows:

[0016] The slave fusion terminals communicate with the main control fusion terminal respectively and inquire about the working status bit of the main control fusion terminal multiple times; if the main control fusion terminal is still in an abnormal communication state after being inquired multiple times, the main control fusion terminal is transferred to the fusion terminal of the next priority according to the preset fusion terminal priority, and the master-slave relationship communication is re-established, and step S2 is judged again; if all the fusion terminal priority sequences are polled and the belonging of the main control fusion terminal still cannot be determined, a warning signal of abnormal shared energy storage work is fed back, and the power interconnection and mutual-aid function is stopped;

[0017] The slave fusion terminals communicate with the main control fusion terminal respectively and inquire about the working status bit of the main control fusion terminal multiple times; if the main control fusion terminal feedbacks that the communication is normal, the main control fusion terminal collects the operation modes of the energy storage communication middle computers in each power distribution area to confirm the number n of power distribution areas that can participate in the power interconnection and mutual-aid.

[0018] [[ID=3,33]]Further, step S3 is specifically as follows:

[0019] Assume that all integrated terminals are in normal working mode. The integrated terminals belonging to the same power distribution area collect the operation data of the energy storage system connected to the lower-level energy storage communication master unit multiple times at fixed time intervals through the communication gateway and calculate the average electrical quantity; the master integrated terminal obtains the average electrical quantity data of the integrated terminals of n power distribution areas participating in power interconnection and mutual assistance once at fixed time intervals through the subscription mechanism;

[0020] If there is an integrated terminal in an emergency power supply mode in a certain power distribution area, after the master integrated terminal obtains the emergency power supply status word of the slave integrated terminal, the master integrated terminal takes over the control right of the integrated terminal in the emergency power supply area and reduces the number n of power distribution areas participating in power interconnection and mutual assistance obtained in step S2 by 1; the master integrated terminal collects the operation data of the energy storage PCS current conversion device connected to the lower-level energy storage communication master unit of the emergency power supply area multiple times at fixed time intervals and calculates the average value; the average load power of the emergency power supply area obtained by calculation is evenly distributed to the remaining n - 1 power distribution areas participating in power interconnection and mutual assistance.

[0021] Further, the master integrated terminal obtaining the average electrical quantity data of other integrated terminals includes: the distribution transformer capacity of each power distribution area: S i 、the distribution transformer load rate: RoL i 、phase voltage, current, active power, reactive power and power factor, energy storage PCS capacity S pcs_i 、PCS operation mode, PCS operation power: P pcs_i 、energy storage system SOC: SOC i 、electrical quantities such as the real-time power of the energy storage system and the working status bits of the integrated terminal.

[0022] Further, step S4 is specifically as follows:

[0023] Step S41: Based on the load rate RoL of each power distribution area i , calculate the average load rate of n power distribution areas participating in power interconnection and mutual assistance according to the following formula:

[0024]

[0025] Step S42: Calculate the mutual assistance power P participated by the energy storage PCS of each power distribution area T_i ; Define P T_i <0 indicates that electrical energy is fed from AC to DC, and P T_i >0 indicates that electrical energy is fed from DC to AC; Define RoL lim as the upper limit value of the distribution transformer load rate; calculate according to the following formula:

[0026]

[0027] Further, step S5 is specifically as follows:

[0028] Step S51: Calculate the surplus DC bus power P without considering the absorption of the energy storage battery according to the following formula bus0 :

[0029]

[0030] where P bus0 <0 indicates that there is surplus power in the DC bus, the energy storage battery participates in the absorption of the surplus power in the substation area, and the energy storage battery is in the charging state; P bus0 >0 indicates the power gap of the DC bus, the energy storage battery participates in the supplement of the power gap in the substation area, and the energy storage battery is in the discharging state;

[0031] Step S52: The master control fusion terminal obtains the charge and discharge power limits of the energy storage batteries in each substation area. The charging power limit is P charge_lim_i , and the discharging power limit is P discharge_lim_i . Calculate the total charge and discharge power limits P charge_lim and P discharge_lim respectively according to the following formula:

[0032]

[0033] Step S53: According to the positive and negative relationship of the surplus DC bus power P bus0 calculated in Step S4, judge whether P bus0 meets the charge and discharge power limits of the energy storage battery;

[0034] If P bus0 <0, and the energy storage battery participates in the absorption of the surplus power of the DC bus, then the surplus DC bus power P bus considering the absorption of the energy storage battery needs to meet:

[0035] -P charge_lim ≤P bus ≤0(1.6)

[0036] If P bus0 >0, and the energy storage battery participates in the supplement of the power gap of the DC bus, then the surplus DC bus power P bus considering the absorption of the energy storage battery needs to meet:

[0037] 0≤P bus ≤P discharge_lim (1.7)

[0038] Step S54: If there is DC bus power that does not meet equations (1.6) and (1.7) and cannot be absorbed by the common energy storage battery, reduce the required transfer power of each substation area according to the following formula:

[0039]

[0040] Further, step S6 is specifically as follows:

[0041] All fusion terminals set the power interconnection and mutual assistance function enable bit FlagA and the overload threshold RoL th Trigger bit FlagB; where FlagA = 1 indicates that the power interconnection and mutual assistance function is enabled, and FlagA = 0 indicates that the power interconnection and mutual assistance function is disabled; the load rate RoL of any substation area i >= RoL th , making FlagB = 1, otherwise FlagB = 0; according to the power to be transferred by each substation area energy storage PCS obtained by calculating steps S1 - S5, combined with the flag bits FlagA and FlagB, the master control fusion terminal issues the power transfer command for each substation area energy storage PCS to the communication median machine of each substation area energy storage according to the following formula, and forwards it to each substation area fusion terminal:

[0042] P T_i = P T_i ·FlagA·FlagB(1.9).

[0043] Further, the communication gateway should include at least 2 RJ45 interfaces and 2 fiber optic interfaces; the fusion terminal is connected to the first RJ45 interface of gateway 1 through a network port, the second RJ45 interface of gateway 1 is connected to the RJ45 interface of the energy storage communication median machine 1, the first fiber optic interface of gateway 1 is connected to the second fiber optic interface of gateway 2, the first fiber optic interface of gateway 2 is connected to the second interface of gateway 3, and so on, until the first fiber optic interface of gateway n is connected to the second fiber optic interface of gateway 1, forming a fiber optic ring network communication; the energy storage communication median machine includes at least 3 RJ45 interfaces, the first RJ45 interface of the energy storage communication median machine 1 is connected to the second RJ45 interface of gateway 1, the second RJ45 interface of the energy storage communication median machine 1 is connected to the RJ45 interface of the energy storage PCS converter device, and the third RJ45 interface of the energy storage communication median machine 1 is connected to the RJ45 interface of the energy storage BMS device.

[0044] Further, the AC - side electrical connection port of the energy storage PCS converter device is connected to the substation area AC, and the DC - side electrical connection port is connected to the DC - side electrical connection ports of other energy storage PCS converter devices, forming a cross - substation area DC - side bus - shared energy storage connection structure. The electrical connection port 1 of the energy storage BMS device is connected to the energy storage battery, and the electrical connection port 2 of the energy storage BMS device is connected to the DC - side bus.

[0045] Further, the communication gateway is powered by an uninterruptible power supply (UPS) device of the energy storage system, serving as a backup power supply under the condition of power outage in the transformer area; the fusion terminal receives electrical quantity data sent by a number of intelligent fusion terminals and a number of energy storage communication medium machines; the intelligent fusion terminal is connected to other devices through one or more of wireless public network, RS485, and HPLC; the energy storage communication medium machine receives the power regulation command sent by the fusion terminal through the RJ45 interface and forwards it to the energy storage PCS converter device.

[0046] The present invention and its preferred solutions have the following advantages or beneficial effects: By the master control fusion terminal, the power commands for each fusion terminal to participate in power interconnection and mutual assistance are uniformly calculated, and the power constraints of the energy storage are comprehensively considered, so as to realize the sharing of the energy storage system to participate in the balance of the load rate of the distribution transformer in the transformer area, improve the utilization rate of energy storage resources, and reduce the operation loss of the overloaded distribution transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The following further details the present invention in conjunction with the drawings and specific embodiments:

[0048] Figure 1 It is a schematic diagram of the overall process of the embodiment of the present invention.

[0049] Figure 2 It is a schematic diagram of the communication connection mode and electrical connection of the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] In the following, specific embodiments of the present application will be described in detail with reference to the drawings. According to these detailed descriptions, those skilled in the art can clearly understand the present application and can implement the present application. Without departing from the principle of the present application, the features in different embodiments can be combined to obtain new implementation manners, or some features in certain embodiments can be replaced to obtain other preferred implementation manners.

[0051] To make the features and advantages of the present invention more obvious and understandable, the following specific embodiments are given and described in detail in conjunction with the drawings:

[0052] As Figure 1 shown, the load balancing control method for the transformer area based on the intelligent fusion terminal and the shared energy storage system provided in this embodiment is based on the system as Figure 2 shown, including an intelligent fusion terminal, a communication gateway, an energy storage communication medium machine, an energy storage PCS converter device, and an energy storage BMS device; and is composed of multiple interconnected transformer areas.

[0053] The intelligent fusion terminal is used to collect the operation information of the energy storage system sent by the energy storage communication middle machine connected under this substation area, to collect the substation area load rate and the three-phase active power and reactive power information of the low-voltage distribution network, to collect the operation information of the energy storage system, the substation area load rate and the three-phase active power and reactive power information sent by other substation area intelligent fusion terminals, and to perform edge computing on the substation area balanced load rate and generate the power command for the energy storage PCS converter required for load balancing;

[0054] The communication gateway is used to provide communication conversion between the network interface and the optical fiber interface, and to form a communication ring network by connecting with other communication gateways through optical fibers to improve communication reliability;

[0055] The energy storage communication middle machine is used to collect the operation information of the connected energy storage BMS device, to collect the operation information of the connected energy storage PCS converter device, and to receive the power command issued by the intelligent fusion terminal and forward it to the energy storage PCS converter device;

[0056] The energy storage PCS converter device is used to realize the power conversion between DC and AC, to respond to and execute the power command sent by the energy storage communication middle machine through the RJ45 interface, and to send up the operation information of the energy storage PCS converter;

[0057] The energy storage BMS device is used to manage the charging and discharging of energy storage batteries, and to stably share the DC bus voltage of the energy storage and compensate for the power gap;

[0058] The uninterruptible power supply UPS device is used to supply power to the communication gateway and to supply power to the communication gateway in case of power outage in the substation area to maintain communication stability.

[0059] The method solution as the main body specifically includes the following steps:

[0060] Step S1: When the shared energy storage system based on the fusion terminal starts to run, according to the number of fusion terminals, select a fusion terminal in a certain substation area as the master fusion terminal and establish a communication connection with the fusion terminals in other substation areas in a one-master-multiple-slaves mode combined with the preset fusion terminal priority;

[0061] Step S2: Judge whether the communication between the slave fusion terminals in each substation area and the master fusion terminal is normal;

[0062] The slave fusion terminals communicate with the master fusion terminal respectively and inquire about the working status bit of the master fusion terminal multiple times. If the master fusion terminal is still in an abnormal communication state after being inquired multiple times, the master fusion terminal will be transferred to the fusion terminal of the next priority according to the preset fusion terminal priority, the master-slave relationship communication will be re-established, and step S2 will be judged again; if the ownership of the master fusion terminal still cannot be determined after polling all the fusion terminal priority sequences, a shared energy storage working abnormal alarm signal will be fed back and the subsequent power interconnection and mutual assistance function will be stopped.

[0063] The fusion terminal communicates with the master fusion terminal respectively, and repeatedly queries the working status bit of the master fusion terminal. If the master fusion terminal feedbacks that the communication is normal, the master fusion terminal collects the operation mode of the middle machine of the energy storage communication in each substation area to confirm the number n of substation areas that can participate in power interconnection and mutual assistance.

[0064] Step S3: Determine whether there is a substation area in the emergency power supply mode;

[0065] All fusion terminals are in the normal working mode. The fusion terminals belonging to the same substation area collect the operation data of the energy storage system connected to the lower part of the middle machine of the energy storage communication at fixed time intervals through the communication gateway and calculate the average value of the electrical quantities. The master fusion terminal obtains the average value data of the electrical quantities of the fusion terminals of n substation areas participating in power interconnection and mutual assistance at fixed time intervals through the subscription mechanism.

[0066] If there is a fusion terminal of a certain substation area in the emergency power supply mode, after the master fusion terminal obtains the emergency power protection status word of the slave fusion terminal, the master fusion terminal takes over the control right of the fusion terminal of the emergency power supply substation area, and reduces the number n of substation areas participating in power interconnection and mutual assistance obtained in step S2 by 1. The master fusion terminal collects the operation data of the energy storage PCS converter device connected to the lower part of the middle machine of the energy storage communication in the emergency power protection substation area at fixed time intervals and calculates the average value. The average value of the load power of the emergency power supply substation area obtained by calculation is evenly distributed to the remaining n-1 substation areas participating in power interconnection and mutual assistance.

[0067] The master fusion terminal obtains the average value data of the electrical quantities of other fusion terminals including but not limited to: the distribution transformer capacity of each substation area: S i 、the distribution transformer load rate: RoL i 、phase voltage, current, active power, reactive power and power factor, energy storage PCS capacity S pcs_i 、PCS operation mode, PCS operation power: P pcs_i 、energy storage system SOC: SOC i 、electrical quantities such as the real-time power of the energy storage system and the working status bit of the fusion terminal.

[0068] Step S4: The master fusion terminal obtains the information of the interconnected and mutually assisted substation areas, and solves the required transfer power of each substation area with the goal of balancing the load rate of each substation area; specifically including:

[0069] 1. Based on the load rate RoL of each substation area i , calculate the average load rate of n substation areas participating in power interconnection and mutual assistance according to the following formula.

[0070]

[0071] 2. Calculate the mutual assistance power P participated by the energy storage PCS of each substation area T_i . Define PT_i <0 indicates that AC power is fed into DC power, P T_i >0 indicates that DC power is fed out to AC power. Define RoL lim as the upper limit value of the distribution transformer load rate. Calculate according to the following formula:

[0072]

[0073] Step S5: Determine whether the surplus power of the DC side bus meets the energy storage power constraint conditions; specifically include:

[0074] 1. Calculate the surplus power P of the DC bus without considering the absorption of the energy storage battery according to the following formula bus0 .

[0075]

[0076] Among them, P bus0 <0 indicates that there is surplus power on the DC bus, the energy storage battery participates in the absorption of the surplus power in the distribution area, and the energy storage battery will be in the charging state. P bus0 >0 indicates the shortage power of the DC bus, the energy storage battery participates in the supplement of the shortage power in the distribution area, and the energy storage battery will be in the discharging state.

[0077] 2. The master control fusion terminal obtains the charge and discharge power limit values of the energy storage batteries in each distribution area, where the charging power limit value is P charge_lim_i , and the discharge power limit value P discharge_lim_i . Calculate the total charge and discharge power limit values P charge_lim and P discharge_lim respectively according to the following formula.

[0078]

[0079]

[0080] 3. According to the positive and negative relationship of the surplus power P of the DC bus without considering the absorption of the energy storage battery obtained in step S4 bus0 , judge whether P bus0 meets the charge and discharge power limit values of the energy storage battery.

[0081] If P bus0 <0, the energy storage battery participates in the absorption of the surplus power of the DC bus, then the surplus power P of the DC bus considering the absorption of the energy storage battery bus needs to meet:

[0082] -P charge_lim ≤P bus ≤0(1.6)

[0083] If P bus0> 0, if the energy storage battery participates in supplementing the DC bus gap power, then the surplus power P of the DC bus absorbed by the energy storage battery is considered bus It is necessary to satisfy:

[0084] 0 ≤ P bus ≤ P discharge_lim (1.7)

[0085] 4. If there is DC bus power that does not satisfy equations (1.6) and (1.7) and cannot be absorbed by the common energy storage battery, it is necessary to reduce the transfer power required for each substation area according to the following formula:

[0086]

[0087] Step S6: The master control fusion terminal sends power commands to the PCS converters in each substation area and forwards them to the fusion terminals in each substation area.

[0088] All fusion terminals set the power interconnection and mutual assistance function enable bit FlagA and the heavy load threshold RoL th Trigger bit FlagB. The cloud master station can directly modify FlagA and RoL th . Among them, FlagA = 1 indicates that the power interconnection and mutual assistance function is enabled, FlagA = 0 indicates that the power interconnection and mutual assistance function is disabled, and the initial value of FlagA can be configured as 1. The load rate RoL of any substation area i > = RoL th , making FlagB = 1, otherwise FlagB = 0, and the initial value of RoL th can be configured as 65%. According to the transfer power required for the energy storage PCS in each substation area calculated in steps S1 - S5, combined with the flag bits FlagA and FlagB, the master control fusion terminal issues the transfer power command required for the energy storage PCS in each substation area to the energy storage communication middle machine in each substation area according to the following formula and forwards it to the fusion terminals in each substation area:

[0089] P T_i = P T_i ·FlagA·FlagB (1.9)

[0090] For example Figure 2As shown in the figure, in this embodiment, the communication gateway should include at least two RJ45 interfaces and two fiber optic interfaces. The intelligent fusion terminal is connected to the first RJ45 interface of gateway 1 through a network port. The second RJ45 interface of gateway 1 is connected to the RJ45 interface of the medium-level energy storage communication device 1. The first fiber optic interface of gateway 1 is connected to the second fiber optic interface of gateway 2. The first fiber optic interface of gateway 2 is connected to the second interface of gateway 3, and so on, until the first fiber optic interface of gateway n is connected to the second fiber optic interface of gateway 1, forming a fiber optic ring network communication. The medium-level energy storage communication device should include at least three RJ45 interfaces. The first RJ45 interface of the medium-level energy storage communication device 1 is connected to the second RJ45 interface of gateway 1. The second RJ45 interface of the medium-level energy storage communication device 1 is connected to the RJ45 interface of the energy storage PCS conversion device. The third RJ45 interface of the medium-level energy storage communication device 1 is connected to the RJ45 interface of the energy storage BMS device.

[0091] In this embodiment, the AC side electrical connection port of the energy storage PCS device is connected to the distribution transformer area AC, and the DC side electrical connection port is connected to the DC side electrical connection ports of other energy storage PCS devices, forming a cross-distribution transformer area DC side bus shared energy storage connection structure. The electrical connection port 1 of the energy storage BMS device is connected to the energy storage battery, and the electrical connection port 2 of the energy storage BMS device is connected to the DC side bus.

[0092] In this embodiment, the communication gateway is powered by the uninterruptible power supply (UPS) device of the energy storage system, serving as a backup power supply under the condition of power outage in the distribution transformer area to support the normal communication of the communication gateway.

[0093] In this embodiment, the intelligent fusion terminal is capable of receiving electrical quantity data sent by several intelligent fusion terminals and several medium-level energy storage communication devices.

[0094] In this embodiment, the intelligent fusion terminal is connected to other devices through the wireless public network, RS485, and HPLC methods.

[0095] In this embodiment, the medium-level energy storage communication device has the data forwarding function of receiving the power regulation instructions sent by the intelligent fusion terminal through the RJ45 interface and forwarding them to the energy storage PCS converter.

[0096] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also regarded as the protection scope of the present invention.

[0097] The present invention is not limited to the above-mentioned optimal implementation manners. Anyone can derive various other forms of area load balancing control methods based on intelligent fusion terminals and shared energy storage systems under the inspiration of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for controlling the load balance of a power distribution area based on an intelligent fusion terminal and a shared energy storage system, characterized in that, A substation area model composed of multiple interconnected shared energy storage systems, where each shared energy storage system is composed of a fusion terminal, a communication gateway, an energy storage communication middle unit, an energy storage PCS current conversion device, and an energy storage BMS device connected in sequence; Including the following steps: Step S1: When the shared energy storage system starts to operate, according to the number of fusion terminals, select a fusion terminal in a certain substation area as the master fusion terminal and establish communication connections with the fusion terminals in other substation areas in a one-master-multiple-slaves mode combined with a preset fusion terminal priority; Step S2: Determine whether the communication between the slave fusion terminals in each substation area and the master fusion terminal is normal by querying the master fusion terminal; Step S3: Determine whether there is a substation area in the emergency power supply mode; Step S4: The master control fusion terminal obtains the information of the interconnected and mutual-aid power supply areas to balance the load rate RoL of each power supply area i as the goal, and calculates the average load rate of the n power supply areas participating in the power interconnection and mutual aid: And calculate the mutual assistance power P participated by the energy storage PCS in each substation area T_i : Among them, P T_i <0 indicates that AC power is fed into DC power, and P T_i >0 indicates that DC power is fed out to AC power; RoL lim is the upper limit value of the distribution transformer load rate, S pcs_i is the energy storage PCS capacity, S i is the distribution transformer capacity of each substation area; Step S5: Determine whether the surplus power of the DC side bus meets the energy storage power constraint conditions, specifically including: calculating the surplus power P of the DC bus without considering the absorption of the energy storage battery bus0 : Obtain the total charge-discharge power limit P of the energy storage batteries in each substation area charge_lim and P discharge_lim : where the charging power limit is P charge_lim_i , the discharging power limit P discharge_lim_i ; Determine P bus0 to see if it meets the charge and discharge power limit of the energy storage battery; If P bus0 < 0, then considering the surplus DC bus power P bus absorbed by the energy storage battery, it is necessary to satisfy: -P charge_lim ≤P bus ≤0 If P bus0 > 0, then considering the surplus DC bus power P bus absorbed by the energy storage battery, it is necessary to satisfy: 0 ≤ P bus ≤ P discharge_lim If not satisfied, reduce the transfer power required for each substation area; Step S6: The master fusion terminal issues a power command to the energy storage PCS current conversion devices in each substation area and forwards it to the fusion terminals in each substation area.

2. The substation area load balancing control method based on an intelligent fusion terminal and a shared energy storage system according to claim 1, characterized in that: Step S2 is specifically: The slave fusion terminals communicate with the master fusion terminal respectively and query the working status bit of the master fusion terminal multiple times; if the master fusion terminal is still in an abnormal communication state after being queried multiple times, transfer the master fusion terminal to the fusion terminal with the next priority according to the preset fusion terminal priority, re-establish the master-slave relationship communication, and perform the judgment of step S2 again; If it is still impossible to determine the ownership of the master fusion terminal after polling all the fusion terminal priority sequences, feedback a shared energy storage working abnormal alarm signal and stop the power interconnection and mutual assistance function; The slave fusion terminals communicate with the master fusion terminal respectively and query the working status bit of the master fusion terminal multiple times; if the master fusion terminal feedbacks that the communication is normal, the master fusion terminal collects the operation modes of the energy storage communication middle units in each substation area to confirm the number n of substation areas that can participate in power interconnection and mutual assistance.

3. The substation area load balancing control method based on an intelligent fusion terminal and a shared energy storage system according to claim 2, characterized in that: Step S3 is specifically: Assume that all fusion terminals are in the normal working mode. The fusion terminals belonging to the same substation area collect the operation data of the energy storage system connected to the energy storage communication middle unit multiple times at fixed time intervals through the communication gateway and calculate the average electrical quantity; the master fusion terminal obtains the average electrical quantity data of the n fusion terminals in the substation areas participating in power interconnection and mutual assistance once at fixed time intervals through the subscription mechanism; If there is a fusion terminal in a certain substation area in the emergency power supply mode, after the master fusion terminal obtains the emergency power protection status word of the slave fusion terminal, the master fusion terminal takes over the control right of the fusion terminal in the emergency power supply substation area and reduces the number n of substation areas participating in power interconnection and mutual assistance obtained in step S2 by 1; the master fusion terminal collects the operation data of the energy storage PCS current conversion device connected to the energy storage communication middle unit in the emergency power supply substation area multiple times at fixed time intervals and calculates the average value; the calculated average load power of the emergency power supply substation area is evenly distributed to the remaining n - 1 substation areas participating in power interconnection and mutual assistance.

4. The method for controlling the load balance of a transformer substation area based on an intelligent fusion terminal and a shared energy storage system according to claim 3, wherein: The main control fusion terminal obtains the average electrical quantity data of other fusion terminals, including: the distribution transformer capacity of each district: S i , the distribution transformer load rate: RoL i , the phase voltage, current, active power, reactive power and power factor, the energy storage PCS capacity S pcs_i , the PCS operation mode, the PCS operation power: P pcs_i , the energy storage system SOC: SOC i , the electrical quantity of the real-time power of the energy storage system and the working status bit of the fusion terminal.

5. The method for controlling the load balance of the substation area based on the intelligent fusion terminal and the shared energy storage system according to claim 4, wherein: The power to be transferred required for each substation area is reduced according to the following formula:

6. The method for controlling the load balance of the substation area based on the intelligent fusion terminal and the shared energy storage system according to claim 5, wherein: Step S6 is specifically as follows: All fusion terminals set the power interconnection and mutual assistance function enable bit FlagA and the overload threshold RoL th Trigger bit FlagB; among them, FlagA = 1 indicates that the power interconnection and mutual assistance function is enabled, and FlagA = 0 indicates that the power interconnection and mutual assistance function is disabled; the load rate RoL of any substation area i >= RoL th , making FlagB = 1, otherwise FlagB = 0; according to the power that each substation area energy storage PCS needs to transfer obtained by calculating Steps S1 - S5, combined with the flag bits FlagA and FlagB, the master control fusion terminal issues the power transfer command that each substation area energy storage PCS needs to transfer to the middle communication machine of each substation area energy storage according to the following formula, and forwards it to each substation area fusion terminal: P T_i = P T_i ·FlagA·FlagB 7. The method for controlling the load balance of a transformer substation area based on an intelligent fusion terminal and a shared energy storage system according to claim 1, characterized in that: The communication gateway should include at least 2 RJ45 interfaces and 2 fiber optic interfaces; the fusion terminal is connected to the first RJ45 interface of gateway 1 through a network port, the second RJ45 interface of gateway 1 is connected to the RJ45 interface of the energy storage communication middle computer 1, the first fiber optic interface of gateway 1 is connected to the second fiber optic interface of gateway 2, the first fiber optic interface of gateway 2 is connected to the second interface of gateway 3, and so on, until the first fiber optic interface of gateway n is connected to the second fiber optic interface of gateway 1 to form a fiber optic ring network communication; the energy storage communication middle computer includes at least 3 RJ45 interfaces, the first RJ45 interface of the energy storage communication middle computer 1 is connected to the second RJ45 interface of gateway 1, the second RJ45 interface of the energy storage communication middle computer 1 is connected to the RJ45 interface of the energy storage PCS converter device, and the third RJ45 interface of the energy storage communication middle computer 1 is connected to the RJ45 interface of the energy storage BMS device.

8. The method for controlling load balancing in a substation area based on an intelligent fusion terminal and a shared energy storage system according to claim 7, characterized in that: The AC side electrical connection port of the energy storage PCS converter device is connected to the substation area AC, and the DC side electrical connection port is connected to the DC side electrical connection ports of other energy storage PCS converter devices to form a cross-substation area DC side bus shared energy storage connection structure. The electrical connection port 1 of the energy storage BMS device is connected to the energy storage battery, and the electrical connection port 2 of the energy storage BMS device is connected to the DC side bus.

9. The method for controlling the load balance of a substation area based on an intelligent fusion terminal and a shared energy storage system according to claim 7, wherein: The communication gateway is powered by the uninterruptible power supply UPS device of the energy storage system as a backup power supply under the condition of substation area power outage; the fusion terminal receives the electrical quantity data sent by a number of intelligent fusion terminals and a number of energy storage communication middle computers; the intelligent fusion terminal is connected to other devices through one or more of the wireless public network, RS485, and HPLC methods; the energy storage communication middle computer receives the power regulation command sent by the fusion terminal through the RJ45 interface and forwards it to the energy storage PCS converter device.

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