Reactive power regulation method and system for new energy station based on distributed energy storage

Abstract

The application relates to a new energy station reactive power regulation method and system based on distributed energy storage, which adjusts the active or reactive power output of the energy storage unit by using the four-quadrant operation function of the energy storage converter PCS according to the real-time active power, real-time reactive power, power prediction curve, working state of each box transformer, working state of each photovoltaic inverter and working state of each energy storage unit of the new energy station, so that the reactive power balance of the new energy station or the response of the reactive power regulation of the power grid is realized. Compared with the prior art, the application has the advantages of solving the reactive power demand problem of the new energy station under the participation of the distributed energy storage, improving the power factor and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to new energy technology, in particular to a new energy station reactive power regulation method and system based on distributed energy storage. BACKGROUND

[0002] With the increasing proportion of new energy power such as photovoltaic and wind power, in order to ensure the safe and stable operation of the power grid, energy storage has been fully developed. The current energy storage is usually arranged in the form of centralized access, and the distributed arrangement of energy storage in multiple points in a photovoltaic power station or a wind farm is still rare. The distributed arrangement of energy storage system can solve the problem of land acquisition difficulty of the built new energy station, and has the characteristics of flexible arrangement location and convenient expansion. The key equipment of the energy storage system, the energy storage converter (PCS), has four-quadrant operation function, which can adjust the phase difference of current and voltage according to the needs, and realize the emission and absorption of reactive power. However, how to solve the problem of reactive power demand of new energy station under the participation of distributed energy storage becomes a technical problem to be solved. SUMMARY

[0003] The purpose of the present application is to overcome the defects of the prior art and provide a new energy station reactive power regulation method and system based on distributed energy storage.

[0004] The purpose of the present application can be achieved by the following technical solutions:

[0005] According to one aspect of the present application, a new energy station reactive power regulation method based on distributed energy storage is provided. According to the real-time active power, real-time reactive power, power prediction curve, working state of each box transformer, working state of each photovoltaic inverter and working state of each energy storage unit data of the new energy station, the four-quadrant operation function of the energy storage converter (PCS) is used to adjust the active or reactive power output of the energy storage unit, so as to realize the reactive power balance of the new energy station or respond to the reactive power regulation of the power grid.

[0006] As a preferred technical solution, the method specifically includes the following steps:

[0007] Step 1, establishing a distributed energy storage system applied to a new energy station;

[0008] Step 2, the energy storage controller collects new energy station power parameters, power prediction parameters and energy storage unit parameters;

[0009] Step 3, the energy storage controller calculates according to the collected parameters to determine the total reactive power deviation, the reactive power imbalance of each power collection line and the reactive power regulation capacity of each energy storage unit;

[0010] Step 4, the energy storage controller judges whether the total reactive power regulation is needed, if not, step 5) is executed, otherwise step 6) is executed.

[0011] Step 5, the energy storage converter PCS maintains the status quo and sends the current energy storage unit parameters to the energy storage controller;

[0012] Step 6, further determine whether the reactive power needs to be adjusted between the collection lines, if not, execute step 7), otherwise execute step 8);

[0013] Step 7, the energy storage controller allocates reactive power according to the average between the lines, and determines whether the involved energy storage unit has the implementation condition, if the condition is met, the energy storage converter PCS executes the adjustment instruction; if the condition is not met, the energy storage converter PCS maintains the status quo, whether the energy storage converter PCS executes the adjustment instruction or not, the current energy storage unit parameters are sent to the energy storage controller;

[0014] Step 8, the energy storage controller allocates reactive power according to the proportion of the reactive power deviation between the lines, and determines whether the involved energy storage unit has the implementation condition, if the condition is met, the energy storage converter PCS executes the adjustment instruction; if the condition is not met, the energy storage converter PCS maintains the status quo, whether the energy storage converter PCS executes the adjustment instruction or not, the current energy storage unit parameters are sent to the energy storage controller.

[0015] As a preferred technical solution, the total field reactive power deviation Q in step 3 is calculated as follows:

[0016]

[0017] Where S is the total field apparent power, is the current total field power factor, is the set total field power factor.

[0018] As a preferred technical solution, the reactive power imbalance of each collection line in step 3 is calculated as follows:

[0019]

[0020] Where Q i is the reactive power deviation of the i-th collection line, is the apparent power of the i-th collection line, P j is the active output of the j-th transformer on the i-th collection line, Q j is the reactive output of the j-th transformer on the i-th collection line, is the average power factor of the i-th collection line, is the set total field power factor, and n is the number of energy storage units.

[0021] As a preferred technical solution, the reactive power regulation capacity of each energy storage unit in step 3 is calculated as follows: kQ kable Q kable = S k -P k -Q k , P k is the active output of the PCS where the energy storage unit is located, and Q k is the reactive output of the PCS where the energy storage unit is located.

[0022] As a preferred technical solution, the judgment in step 4 is specifically: when the current overall field power factor is equal to the set overall field power factor , no overall field reactive power adjustment is performed; otherwise, overall field reactive power adjustment is performed.

[0023] As a preferred technical solution, the judgment in step 6 is specifically:

[0024] When , no reactive power adjustment is needed between the collector lines, where is the average power factor on the i-th collector line; otherwise, reactive power adjustment is needed.

[0025] As a preferred technical solution, the judgment in step 7 as to whether the energy storage unit has implementation conditions is specifically:

[0026] When , the energy storage unit reactive power adjustment capability meets the overall field reactive power adjustment demand, and has complete implementation conditions; when , it has partial implementation conditions; when Q able = 0, the energy storage unit has no implementation conditions.

[0027] n is the number of energy storage units, Q able is the energy storage unit reactive power adjustable amount, and Q is the overall field reactive power adjustment demand.

[0028] As a preferred technical solution, the judgment in step 8 as to whether the energy storage unit has implementation conditions is specifically:

[0029] When , the energy storage unit reactive power adjustment capability meets the overall field reactive power adjustment demand, and has complete implementation conditions; when , it has partial implementation conditions; when Q kable = 0, the energy storage unit has no implementation conditions.

[0030] n i is the number of energy storage units on the i-th collector line, Q i is the reactive power deviation of the i-th collector line, and Q kable is the reactive power adjustment capability of each energy storage unit, which is the difference between the capacity S k of the PCS where the energy storage unit is located and the current power.

[0031] According to another aspect of the present application, a system for the reactive power regulation method of the new energy station based on the distributed energy storage is provided, the system comprises an energy storage unit and an energy storage controller, the energy storage unit is connected to the low-voltage side of the new energy station transformer substation in a distributed manner, a plurality of energy storage units are in communication with the energy storage controller through optical fibers, the energy storage controller controls the active or reactive power output of each energy storage unit, and a distributed energy storage system applied to the new energy station is established.

[0032] The energy storage controller calculates and allocates the required active or reactive power output of each energy storage unit according to the real-time operation data and the power prediction curve of the new energy station, realizes the reactive power balance between a plurality of transformer substations and energy storage units on the same power collection line, or the reactive power balance between a plurality of power collection lines, or the reactive power response demand of the new energy station to the power grid.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] 1) The present application provides a method for the reactive power regulation of the new energy station under the participation of the distributed energy storage by using the energy storage converter (PCS), solves the problem of the reactive power demand of the new energy station under the participation of the distributed energy storage, and improves the power factor.

[0035] 2) The present application improves the reactive power regulation response capability of the new energy station under the participation of the distributed energy storage to the power grid.

[0036] 3) The distributed arrangement of the energy storage has the advantages of saving land resources, not requiring additional land acquisition, flexible arrangement, convenient expansion, low fire risk level, and being particularly suitable for the existing new energy station.

[0037] 4) The energy storage system of the present application can serve as a continuous adjustable reactive power source through the energy storage converter (PCS), and can balance the active power and the reactive power in real time.

[0038] 5) The present application can realize the reactive power balance within a single power collection line, and reduce the large line loss of the new energy station caused by the long line during the regulation process. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 FIG. 1 is a structural schematic diagram of the system of the present application;

[0040] Figure 2 FIG. 2 is a detailed structural schematic diagram of part of the system of the present application;

[0041] Figure 3 FIG. 3 is a flowchart of the method of the present application. DETAILED DESCRIPTION

[0042] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the present application.

[0043] As shown in the drawings, Figure 1 The system for reactive power regulation of the new energy station under the participation of the distributed energy storage of the present application is connected with the energy storage unit in the form of distributed arrangement on the low-voltage side of the box transformer of the photovoltaic power station on the basis of the existing photovoltaic power generation system, and the energy storage unit comprises energy storage isolation transformer, energy storage converter (PCS), energy management system (EMS), battery management system (BMS), battery and other main components. Each energy storage unit communicates with the energy storage control system through optical fiber, and the energy storage control system controls each energy storage unit to absorb / output active / reactive power.

[0044] According to the real-time active power, real-time reactive power, power prediction curve, working state of each box transformer, working state of each photovoltaic inverter and working state of each energy storage unit and other data of the new energy station, the four-quadrant operation function of the energy storage converter (PCS) is used to adjust the active / reactive power absorption / output of the energy storage unit, so as to realize the reactive power balance of the new energy station or the reactive power regulation response to the power grid.

[0045] As shown in the drawings, Figure 2 The energy storage unit is connected in the form of distributed arrangement on the low-voltage side of the box transformer of the new energy station, a plurality of energy storage units communicate with the energy storage controller through optical fiber, the energy storage controller comprehensively controls the active / reactive power absorption / output of each energy storage unit, and a distributed energy storage system applied to the new energy station is established. The energy storage controller calculates and distributes the required active / reactive power output of each energy storage unit according to the real-time operation data and the power prediction curve of the new energy station, so as to realize the reactive power balance between a plurality of box transformers and energy storage units on the same power collection line, the reactive power balance between a plurality of power collection lines, or the reactive power response demand of the new energy station to the power grid.

[0046] As shown in the drawings, Figure 3 The specific process of the method of the present application is as follows:

[0047] Step 1, establishing a distributed energy storage system applied to the new energy station;

[0048] Step 2, the energy storage controller collects power parameters, power prediction parameters and energy storage unit parameters of the new energy station;

[0049] Step 3, the energy storage controller calculates and determines the overall reactive power deviation, reactive power imbalance of each power collection line and reactive power regulation capacity of each energy storage unit according to the collected parameters;

[0050] Step 4, the energy storage controller determines whether to perform the full field reactive power adjustment, if not, step 5) is executed, otherwise step 6) is executed;

[0051] Step 5, the energy storage converter PCS maintains the status and sends the current energy storage unit parameters to the energy storage controller;

[0052] Step 6, further determine whether the reactive power adjustment is needed between the collection lines, if not, step 7) is executed, otherwise step 8) is executed;

[0053] Step 7, the energy storage controller distributes the reactive power according to the average between the lines, and determines whether the involved energy storage unit has the implementation condition, if the condition is met, the energy storage converter PCS executes the adjustment instruction; if the condition is not met, the energy storage converter PCS maintains the status, whether the energy storage converter PCS executes the adjustment instruction or not, the current energy storage unit parameters are sent to the energy storage controller;

[0054] Step 8, the energy storage controller distributes the reactive power according to the proportion of the line-to-line reactive power deviation, and determines whether the involved energy storage unit has the implementation condition, if the condition is met, the energy storage converter PCS executes the adjustment instruction; if the condition is not met, the energy storage converter PCS maintains the status, whether the energy storage converter PCS executes the adjustment instruction or not, the current energy storage unit parameters are sent to the energy storage controller.

[0055] The full field reactive power deviation Q in step 3 is calculated as follows:

[0056]

[0057] Wherein, S is the full field apparent power, is the current full field power factor, is the set full field power factor.

[0058] The reactive power imbalance of each collection line in step 3 is calculated as follows:

[0059]

[0060] Wherein Q i is the reactive power deviation of the i-th collection line, is the apparent power of the i-th collection line, P j is the active output of the j-th transformer on the i-th collection line, Q j is the reactive output of the j-th transformer on the i-th collection line, is the average power factor of the i-th collection line, is the set full field power factor, and n is the number of energy storage units.

[0061] The reactive power adjustment capacity of each energy storage unit in step 3 is the capacity S of the PCS where it is located.k Q kable represents Q kable = S k -P k -Q k , P k is the active output of the PCS in which the energy storage unit is located, and Q k is the reactive output of the PCS in which the energy storage unit is located.

[0062] The judgment in step 4 is specifically: when the current overall power factor is equal to the set overall power factor , no overall reactive adjustment is performed; otherwise, overall reactive adjustment is performed.

[0063] The judgment in step 6 is specifically:

[0064] When , no reactive adjustment is needed between the collector lines, wherein is the average power factor on the i-th collector line; otherwise, reactive adjustment is needed.

[0065] As a preferred technical solution, the judgment in step 7 as to whether the energy storage unit has an implementation condition is specifically:

[0066] When , the reactive adjustment capability of the energy storage unit meets the overall reactive adjustment demand, and has a complete implementation condition; when , it has a partial implementation condition; and when Q able = 0, the energy storage unit has no implementation condition.

[0067] n is the number of energy storage units, Q able is the reactive adjustable amount of the energy storage unit, and Q is the overall reactive adjustment demand.

[0068] The judgment in step 8 as to whether the energy storage unit has an implementation condition is specifically:

[0069] When , the reactive adjustment capability of the energy storage unit meets the overall reactive adjustment demand, and has a complete implementation condition; when , it has a partial implementation condition; and when Q kable = 0, the energy storage unit has no implementation condition.

[0070] n i is the number of energy storage units on the i-th collector line, Q i is the reactive deviation of the i-th collector line, and Q kable is the reactive adjustment capability of each energy storage unit, which is the capacity S k of the PCS in which the energy storage unit is located and the difference from the current power.

[0071] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A reactive power regulation method for new energy power plants based on distributed energy storage, characterized in that, This method uses the four-quadrant operation function of the energy storage converter PCS to adjust the active or reactive power output of the energy storage unit based on the real-time active power, real-time reactive power, power prediction curves, working status of each transformer, working status of each photovoltaic inverter and working status of each energy storage unit of the new energy power station, thereby achieving reactive power balance of the new energy power station or responding to the reactive power regulation of the power grid. The method specifically includes the following steps: Step 1: Establish a distributed energy storage system for new energy power plants; Step 2: The energy storage controller collects power parameters, power prediction parameters, and energy storage unit parameters of the new energy power station; Step 3: The energy storage controller calculates based on the collected parameters to determine the overall reactive power deviation, the reactive power imbalance of each collector line, and the reactive power regulation capability of each energy storage unit. Step 4: The energy storage controller determines whether full-field reactive power regulation is required. If not, proceed to step 5); otherwise, proceed to step 6. Step 5: The energy storage converter PCS maintains its current state and sends the current parameters of the energy storage unit to the energy storage controller. Step 6: Further determine whether reactive power regulation is required between the collector lines. If not, proceed to step 7); otherwise, proceed to step 8. Step 7: The energy storage controller distributes reactive power evenly between lines and determines whether the energy storage units involved meet the implementation conditions. If the conditions are met, the energy storage converter PCS executes the adjustment command; if the conditions are not met, the energy storage converter PCS maintains the status quo. Regardless of whether the energy storage converter PCS executes the adjustment command, it sends the parameters of the current energy storage unit to the energy storage controller. Step 8: The energy storage controller allocates reactive power according to the ratio of inter-line reactive power deviation and determines whether the energy storage unit involved meets the implementation conditions. If the conditions are met, the energy storage converter PCS executes the adjustment command; if the conditions are not met, the energy storage converter PCS maintains the status quo. Regardless of whether the energy storage converter PCS executes the adjustment command, it sends the current parameters of the energy storage unit to the energy storage controller.

2. The reactive power regulation method for new energy power plants based on distributed energy storage according to claim 1, characterized in that, The full-field reactive power deviation Q in step 3 is calculated as follows: Where S is the apparent power across the entire field. The current overall power factor, The set power factor for the entire field.

3. The reactive power regulation method for new energy power plants based on distributed energy storage according to claim 1, characterized in that, The reactive power imbalance of each collector line in step 3 is calculated as follows: Q i Let i be the reactive power deviation of the i-th collector line. Let P be the apparent power of the i-th collector line. j Q is the active power output of the j-th transformer on the i-th circuit. j For the reactive power output of the j-th transformer on the i-th circuit, Let be the average power factor on the i-th set of wires. Here, n represents the set power factor for the entire field, and n represents the number of energy storage units.

4. The reactive power regulation method for new energy power plants based on distributed energy storage according to claim 1, characterized in that, The reactive power regulation capability of each energy storage unit in step 3 is represented by the capacity S of its respective PCS. k The difference Q from the current power kable It means that Q kable =S k -P k -Q k P k Q is the active power output of the PCS. k This refers to the reactive power output of the PCS.

5. The reactive power regulation method for new energy power stations based on distributed energy storage according to claim 1, characterized in that, The judgment in step 4 specifically refers to: when the current overall power factor... With the set overall power factor If they are equal, no full-field reactive power adjustment is performed; otherwise, full-field reactive power adjustment is performed.

6. The reactive power regulation method for new energy power stations based on distributed energy storage according to claim 1, characterized in that, The judgment in step 6 is specifically as follows: when At this time, reactive power regulation is not required between collector lines, among which Let be the average power factor on the i-th set of wires; Otherwise, it needs to be done.

7. The reactive power regulation method for new energy power plants based on distributed energy storage according to claim 1, characterized in that, Step 7, determining whether the energy storage unit involved meets the implementation conditions, specifically involves: when At that time, the reactive power regulation capability of the energy storage unit meets the reactive power regulation needs of the entire field, and it is fully capable of implementation; when At that time, some implementation conditions were met; when Q able When the value is 0, the energy storage unit is not ready for implementation; n is the number of energy storage units, Q able Q represents the reactive power adjustable quantity of the energy storage unit, and Q represents the reactive power adjustment requirement of the entire field.

8. The reactive power regulation method for new energy power plants based on distributed energy storage according to claim 1, characterized in that, Step 8, determining whether the energy storage unit involved meets the implementation conditions, specifically involves: when At that time, the reactive power regulation capability of the energy storage unit meets the reactive power regulation needs of the entire field, and it is fully capable of implementation; when At that time, some implementation conditions were met; when Q kable When the value is 0, the energy storage unit is not ready for implementation; n i Let Q be the number of energy storage units on the i-th set of wires. i Let Q be the reactive power deviation of the i-th collector line. kable The reactive power regulation capability of each energy storage unit is represented by the capacity S of its respective PCS. k The difference between the current power and the current power.

9. A system for reactive power regulation in a new energy power station based on distributed energy storage as described in claim 1, characterized in that, The system includes energy storage units and energy storage controllers. The energy storage units are connected to the low-voltage side of the transformer substation in a distributed manner. Multiple energy storage units communicate with the energy storage controller through optical fiber. The energy storage controller coordinates and controls the active or reactive power output of each energy storage unit, thus establishing a distributed energy storage system for new energy power stations. The energy storage controller calculates and allocates the active or reactive power required by each energy storage unit based on the real-time operation data and power prediction curve of the new energy power station, so as to achieve reactive power balance between multiple transformers and energy storage units on the same collector line, or reactive power balance between multiple collector lines, or reactive power response requirements of the new energy power station to the power grid.

Images