A kind of light storage soft platform and off-grid switching method and switching simulation device

Abstract

The application discloses a kind of light storage soft platform and off-grid switching method, comprising the following steps: S1, parallel off-grid switching simulation device is connected with a plurality of flexible areas and a plurality of area circuit breakers respectively;S2, respectively collect the voltage, phase angle and frequency on the upper end of flexible area and area circuit breaker;S3, the data collected are calculated, whether to have parallel off-grid switching condition is judged;S4, according to the judgment result, decide whether to perform parallel off-grid switching operation.Solve the parallel off-grid switching problem in power flexible dc interconnection system, a kind of light storage soft platform and off-grid switching method and switching simulation device of the application, realize the monitoring before and after parallel off-grid switching in flexible area system, carry out the control of area circuit breaker after meeting parallel off-grid switching condition, realize area power failure support transfer supply.

Description

Technical Field

[0001] This invention relates to the field of control technology for flexible DC interconnection systems in power grids, and in particular to a method and simulation device for switching between on-grid and off-grid systems using a photovoltaic-storage flexible radiator. Background Technology

[0002] In recent years, with the increase in load on the distribution network and the connection of new energy power generation and consumption equipment to the grid, the operation and management of the original distribution network has been under tremendous pressure. By utilizing the complementary characteristics of the load rates of different transformer substations, an AC / DC interconnected low-voltage distribution network can be constructed to realize load transfer, power outage support, and efficient power supply between different load transformer substations.

[0003] Existing patents, including those related to high-frequency isolated flexible distribution transformer interconnection systems and their control methods, such as Chinese patent application number CN112600240A, propose a microgrid grid-connected / off-grid switching strategy based on a virtual synchronous machine. Although it proposes to reduce current surges and achieve seamless switching, in the power grid system, when transferring power from one distribution transformer capacity to another, in addition to considering the current surge during grid-connected / off-grid switching, it is also necessary to consider the grid-connected / off-grid switching under the flexible DC interconnection system in the power system. This invention solves the grid-connected / off-grid problem of flexible distribution transformers by using a simulation device to control the grid-connected / off-grid switching of flexible distribution transformers. Summary of the Invention

[0004] This invention solves the problem of grid-connected and off-grid switching in flexible DC interconnection systems. It proposes a method and simulation device for grid-connected and off-grid switching of flexible photovoltaic-storage transformer substations, realizes monitoring before and after grid-connected and off-grid switching in flexible transformer substation systems, controls the circuit breaker of the substation after the grid-connected and off-grid switching conditions are met, and realizes power supply support and transfer in the substation when power is lost.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for switching between on-grid and off-grid optical storage flexible radiator, comprising the following steps: S1 connects the grid-connected / off-grid switching simulation device to several flexible distribution areas and several distribution area circuit breakers respectively; S2 collects the voltage, phase angle, and frequency of the flexible distribution area and the upper end of the circuit breaker in the distribution area, respectively. S3 calculates the collected data to determine whether the conditions for switching between online and offline networks are met; S4, based on the judgment result, decides whether to execute and disconnect from the network.

[0006] In this invention, the connection between the grid-connected and off-grid switching simulation device and each flexible transformer area and each transformer area circuit breaker is first completed. The grid-connected and off-grid switching simulation device can collect the voltage, phase angle and frequency information of the flexible transformer area and the transformer area circuit breaker in real time, and determine whether the grid-connected and off-grid switching conditions are met through data algorithms. Finally, the grid-connected and off-grid switching modes of the control area are controlled.

[0007] Preferably, step S2 includes: The voltage U of several flexible transformer areas was collected in real time. fc Phase angle θ fc Frequency f fc And the voltage U at the top of several circuit breakers in the distribution area grid Phase angle θ grid Frequency f grid .

[0008] In this invention, for the voltage U of the flexible transformer area fc Phase angle θ fc Frequency f fc And the voltage U at the top of the circuit breaker in the distribution area grid Phase angle θ grid Frequency f grid Real-time monitoring is conducted to ensure data synchronization.

[0009] Preferably, step S3 includes the following steps: S31, calculate the voltage difference U between the flexible distribution area and the circuit breaker in the distribution area respectively. dv Phase angle difference θ dv and frequency difference f dv ; S32, based on the voltage difference U dv Phase angle difference θ dv and frequency difference f dv Calculate the reliability coefficients for voltage, phase angle, and frequency; S33 determines whether the conditions for grid-connected / off-grid switching are met based on the reliability coefficients of voltage, phase angle, and frequency.

[0010] In this invention, the specific process of the data algorithm first involves calculating the voltage difference U between the flexible distribution area and the circuit breaker in the distribution area. dv Phase angle difference θ dv and frequency difference f dv Then, based on the above difference, the corresponding reliability coefficient is calculated, and finally, the judgment coefficient S is introduced to determine whether the grid connection regulation conditions are met.

[0011] Preferably, step S31 specifically includes: voltage difference U dv Represented as: U dv =U grid -U fc Phase angle difference θ dv Represented as: θ dv =θ grid -θ fc Frequency difference f dvRepresented as: f dv =f grid -f fc .

[0012] In this invention, the voltage difference U dv Phase angle difference θ dv and frequency difference f dv Both are the difference between flexible distribution zones and distribution zone circuit breakers.

[0013] Preferably, the reliability coefficients of the voltage, phase angle, and frequency are as follows: Among them, K u K θ and K f The reliability coefficients for voltage, phase angle, and frequency are respectively, U se θ se and f se It is based on the safety difference between the voltage, phase angle, and frequency allowed in the power system.

[0014] In this invention, if the safety tolerance is exceeded, it will cause a current surge in the system, and the excessive load will cause the flex table to crash.

[0015] Preferably, step S33 specifically includes: having a judgment coefficient S: When K u ×K θ ×K f When S > 1, S = 0, indicating that the conditions for grid connection regulation are not met; When K u ×K θ ×K f When S ≤ 1, S = 1, indicating that the grid connection regulation conditions are met, and the circuit breaker of the distribution area is allowed to close.

[0016] In this invention, a judgment coefficient S is used for judgment. S = 1 indicates that the grid connection regulation conditions are met, while S = 0 indicates that the grid connection regulation conditions are not met.

[0017] A simulation device for on-grid / off-grid switching of a flexible optical storage system (FOPS) is provided, applicable to the aforementioned on-grid / off-grid switching method, comprising: The analog signal acquisition unit acquires the voltage, phase angle, and frequency of multiple flexible distribution zones and the circuit breakers in those zones. The I / O unit controls the opening and closing of multiple circuit breakers in the distribution area and receives status information of the circuit breakers in the distribution area. The communication unit enables high-speed communication with flexible distribution areas and distribution area circuit breakers. The control processor can control the switching between on-grid and off-grid modes via data algorithms, and can also control the opening and closing of circuit breakers.

[0018] In this invention, the grid-connected / off-grid switching simulation device includes a control processor, an analog quantity acquisition unit, an I / O unit, and a communication unit. The communication unit establishes high-speed communication with the flexible distribution area and the circuit breaker of the distribution area to control the grid-connected / off-grid mode switching of the control area, and can also control the opening and closing of the circuit breaker of the control area.

[0019] Preferably, the device can also receive power system dispatch and perform active on-grid and off-grid switching.

[0020] In this invention, the passive grid connection switching corresponding to the active grid connection switching is determined and performed according to the process of step S3.

[0021] Preferably, the device is also used to control the changes in the power generation capacity and the direction of power storage capacity of the photovoltaic energy storage in the power system according to the state after the grid connection and off-grid switching.

[0022] In this invention, grid connection switching includes grid connection or grid disconnection, and the control is performed according to the state after the switch.

[0023] The beneficial effects of this invention are: The present invention provides a method and simulation device for switching between grid connection and off-grid operation of a flexible photovoltaic-storage transformer substation. This method enables monitoring before and after grid connection and off-grid operation in the flexible transformer substation system. Once the grid connection and off-grid operation conditions are met, the circuit breaker of the transformer substation is controlled to provide power support and transfer in case of power failure, thereby ensuring the stable and reliable operation of the power grid system. Simultaneously, it can receive power system dispatch control and actively perform grid connection and off-grid operation. Attached Figure Description

[0024] Figure 1 This is a connection diagram of a method for switching between on-grid and off-grid optical storage flexible radiator and a switching simulation device according to the present invention; Figure 2 This is a schematic diagram of analog quantity acquisition for a method for switching between on-grid and off-grid optical storage flexible cascades and a switching simulation device according to the present invention; Figure 3 This is a control schematic diagram of a method for switching between on-grid and off-grid optical storage flexible radiator and a switching simulation device according to the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only one preferred embodiment of this invention and are only used to explain this invention. They do not limit the scope of protection of this invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0026] Example 1: This embodiment describes a method for switching between on-grid and off-grid optical storage flexible radiators, referencing... Figure 1 , Figure 2 and Figure 3 The process includes the following steps.

[0027] Step S1: Connect the grid-connected / off-grid switching simulation device to several flexible distribution areas and several distribution area circuit breakers respectively; specifically, in this embodiment, refer to... Figure 1 The off-grid switching simulation device is connected to flexible distribution area 1 and flexible distribution area 2, and is connected to the circuit breaker of distribution area 1 and the circuit breaker of distribution area 2.

[0028] refer to Figure 2 In step S2, the voltage, phase angle, and frequency of the flexible distribution area and the circuit breaker in the distribution area are collected respectively; specifically, the data are collected in real time.

[0029] More specifically, in step S2, the voltage U of several flexible transformer areas is collected respectively. fc Phase angle θ fc Frequency f fc And the voltage U at the top of several circuit breakers in the distribution area grid Phase angle θ grid Frequency f grid In this embodiment, the voltage U of flexible transformer area 1 and flexible transformer area 2 is collected. fc Phase angle θ fc Frequency f fc And the voltage U of circuit breaker 1 and circuit breaker 2 in transformer substation. grid Phase angle θ grid Frequency f grid .

[0030] Step S3 involves calculating the collected data to determine whether the conditions for switching between the network and offline are met; this step also includes the following sub-steps.

[0031] Step S31: Calculate the voltage difference U between the flexible distribution area and the circuit breaker in the distribution area. dv Phase angle difference θ dv and frequency difference f dv Specifically, the voltage difference U dv Represented as: U dv =U grid -U fc Phase angle difference θ dv Represented as: θ dv =θ grid -θ fc Frequency difference f dv Represented as: f dv =f grid -f fc .

[0032] Step S32, based on the voltage difference U dv Phase angle difference θ dv and frequency difference f dv Calculate the reliability coefficients for voltage, phase angle, and frequency; specifically, the reliability coefficients for voltage, phase angle, and frequency are as follows: In the three equations above, K u K θ and K f The reliability coefficients for voltage, phase angle, and frequency are respectively, U se θ se and f se This is based on the allowable safety differences in voltage, phase angle, and frequency within the power system. In this embodiment, exceeding these safety differences will cause current surges in the system, potentially leading to excessive load and system shutdown.

[0033] Step S33: Determine whether the conditions for grid-connected / off-grid switching are met based on the reliability coefficients of voltage, phase angle, and frequency; specifically, this step involves a judgment coefficient S: When K u ×K θ ×K f When S > 1, S = 0, indicating that the conditions for grid connection regulation are not met; When K u ×K θ ×K f When S ≤ 1, S = 1, indicating that the grid connection regulation conditions are met, and the circuit breaker in the distribution area is allowed to close. In this embodiment, the judgment coefficient S is used for judgment. S = 1 indicates that the grid connection regulation conditions are met, and conversely, if S = 0, it means that the grid connection regulation conditions are not met.

[0034] In this embodiment, the connection between the grid-connected and off-grid switching simulation device and each flexible transformer area and each transformer area circuit breaker is first completed. The grid-connected and off-grid switching simulation device can collect the voltage, phase angle and frequency information of the flexible transformer area and the transformer area circuit breaker in real time, determine whether the grid-connected and off-grid switching conditions are met through data algorithms, and finally control the switching of the grid-connected and off-grid modes of the control area.

[0035] In this embodiment, the voltage U of the flexible transformer area fc Phase angle θ fc Frequency f fc And the voltage U at the top of the circuit breaker in the distribution area grid Phase angle θ grid Frequency f grid Real-time monitoring is conducted to ensure data synchronization.

[0036] In this embodiment, the specific process of the data algorithm first involves calculating the voltage difference U between the flexible distribution area and the circuit breaker in the distribution area. dv Phase angle difference θ dv and frequency difference f dv Then, based on the above difference, the corresponding reliability coefficient is calculated, and finally, the judgment coefficient S is introduced to determine whether the grid connection regulation conditions are met.

[0037] In this embodiment, the voltage difference U dv Phase angle difference θ dv and frequency difference f dv Both are the difference between flexible distribution zones and distribution zone circuit breakers.

[0038] In this embodiment, the judgment coefficient S is used for judgment. S = 1 indicates that the grid connection regulation conditions are met, and S = 0 indicates that the grid connection regulation conditions are not met.

[0039] Based on a method for switching between grid-connected and off-grid environments using a flexible photovoltaic (PV) power grid and energy storage (LPS) platform, this embodiment also proposes a simulation device for switching between grid-connected and off-grid environments using a flexible PV power grid and energy storage (LPS) platform. This device mainly includes an analog quantity acquisition unit for acquiring the voltage, phase angle, and frequency of multiple flexible PV power grid areas and the circuit breakers in the power grid areas; an I / O unit for controlling the opening and closing of multiple circuit breakers in the power grid areas and receiving status information from the circuit breakers in the power grid areas; a communication unit for high-speed communication with the flexible PV power grid areas and the circuit breakers in the power grid areas; and a control processor for controlling the switching between grid-connected and off-grid modes in the power grid areas through data algorithms, and also for controlling the opening and closing of circuit breakers.

[0040] refer to Figure 1 The photovoltaic-storage flexible distribution platform of this embodiment includes flexible distribution area 1 and flexible distribution area 2, photovoltaic power generation unit, energy storage unit, and circuit breakers of distribution area 1 and distribution area 2 interconnected with the flexible distribution areas. A grid-connected / off-grid switching simulation device is used to switch the grid-connected / off-grid function modes of flexible distribution area 1 and flexible distribution area 2 and to open the circuit breakers of distribution area 1 and distribution area 2, thereby completing the power outage support transfer for either flexible distribution area 1 or flexible distribution area 2.

[0041] In this embodiment, the grid-connected / off-grid switching simulation device includes a control processor, an analog quantity acquisition unit, an I / O unit, and a communication unit. The communication unit establishes high-speed communication with the flexible distribution area and the circuit breaker of the distribution area to control the grid-connected / off-grid mode switching of the control area, and can also control the opening and closing of the circuit breaker of the control area.

[0042] Example 2 Based on Example 1, and referring to Figure 3 The grid connection / off-grid switching simulation device of the present invention can also receive power system dispatch and perform active grid connection / off-grid switching. Simultaneously, it adjusts the grid connection / off-grid switching control strategy through power system dispatch control. The passive grid connection / off-grid switching corresponding to the active switching is determined and performed according to the process in step S3. The active and passive grid connection / off-grid switching work together to meet the needs of the power system.

[0043] Example 3 The grid-connected / off-grid switching simulation device can also be used to control the power generation and direction of photovoltaic energy storage in the power system based on the state after the grid-connected / off-grid switching. Grid-connected / off-grid switching includes grid connection or off-grid operation, and regulation is performed based on the state after the switching. Simultaneously, the grid-connected / off-grid switching simulation device can be connected to circuit breakers, flexible distribution areas, photovoltaic or energy storage systems via high-speed communication lines, and the control section is an I / O connection.

[0044] The specific embodiments described above are preferred embodiments of the present invention and are not intended to limit the specific scope of the present invention. The scope of the present invention includes, but is not limited to, these specific embodiments. All equivalent changes made in accordance with the shape and structure of the present invention are within the protection scope of the present invention.

Claims

1. A method for switching between on-grid and off-grid optical storage flexible radiator, characterized by comprising the following steps: S1 connects the grid-connected / off-grid switching simulation device to several flexible distribution areas and several distribution area circuit breakers respectively; S2 collects the voltage, phase angle, and frequency of the flexible distribution area and the upper end of the circuit breaker in the distribution area, respectively. S3 calculates the collected data to determine whether the conditions for switching between online and offline networks are met; S31, calculate the voltage difference U between the flexible distribution area and the circuit breaker in the distribution area respectively. dv Phase angle difference θ dv and frequency difference f dv ; S32, based on the voltage difference U dv Phase angle difference θ dv and frequency difference f dv Calculate the reliability coefficients for voltage, phase angle, and frequency. , and ; for , for , for , , and It is based on the safety differences in voltage, phase angle, and frequency allowed in the power system data; S33 determines whether the conditions for grid-connected / off-grid switching are met based on the reliability coefficients of voltage, phase angle, and frequency; the determination is made using the judgment coefficient S. when , and When the product of the three factors is greater than 1, S is 0, and the grid connection regulation conditions are not met. when , and When the product of the three factors is not greater than 1, S is 1, and the grid connection regulation conditions are met. S4, based on the judgment result, decides whether to execute and disconnect from the network.

2. The method for switching between on-grid and off-grid optical storage flexible radiator according to claim 1, characterized in that, Step S2 includes: The voltage U of several flexible transformer areas was collected in real time. fc Phase angle θ fc Frequency f fc And the voltage U at the top of several circuit breakers in the distribution area grid Phase angle θ grid Frequency f grid .

3. The method for switching between on-grid and off-grid optical storage flexible radiator according to claim 1, characterized in that, Step S31 specifically includes: voltage difference U dv Represented as: ， Phase angle difference θ dv Represented as: ， Frequency difference f dv Represented as: 。 4. The method for switching between on-grid and off-grid optical storage flexible radiator according to claim 1, characterized in that, When grid connection and regulation conditions are met, the circuit breaker in the distribution area is allowed to be closed.

5. A simulation device for parallel-to-offline switching of a flexible optical-storage system (FOS) and its associated grid connection, applicable to the parallel-to-offline switching method of an FOS as described in any one of claims 1-4, characterized in that, include The analog signal acquisition unit acquires the voltage, phase angle, and frequency of multiple flexible distribution zones and the circuit breakers in those zones. The I / O unit controls the opening and closing of multiple circuit breakers in the distribution area and receives status information of the circuit breakers in the distribution area. The communication unit enables high-speed communication with flexible distribution areas and distribution area circuit breakers. The control processor can control the switching between on-grid and off-grid modes via data algorithms, and can also control the opening and closing of circuit breakers.

6. The optical-storage flexible radiator and off-grid switching simulation device according to claim 5, characterized in that, The device can also receive power system dispatch and perform active on-grid and off-grid switching.

7. A photovoltaic storage flexible console and off-grid switching simulation device according to claim 5 or 6, characterized in that, The device is also used to control the changes in the power generation capacity and the direction of energy storage capacity of the photovoltaic energy storage in the power system according to the state after the grid connection and off-grid switching.

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