A photovoltaic anti-islanding monitoring and protection method based on real-time topological relationship of the substation area

Abstract

The present invention discloses a photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation. Based on the real-time topological relationship of the substation, the substation intelligent fusion terminal adaptively accesses the intelligent photovoltaic grid-connected switch in the substation. When the substation is disconnected from the main power grid and the local island protection of the inverter fails, the substation fusion terminal monitors the real-time status of the substation transformer and the intelligent photovoltaic grid-connected switch, sends a control signal to the intelligent photovoltaic grid-connected switch, and disconnects the photovoltaic grid in time to prevent the substation from islanding. The fusion terminal uploads the islanding operation monitoring and the local control situation of the substation to the main station to notify the operating personnel. When the main power grid fails or the line fails, and the photovoltaic inverter does not automatically disconnect from the grid, the scheme of the present invention can automatically disconnect the photovoltaic grid-connected point switch to prevent the power quality problems caused by the islanding operation and the risk of electric shock to personnel, greatly improving the power supply quality of rural low-voltage substations and ensuring the safe and stable operation of the power grid.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic automation, and in particular relates to a photovoltaic anti-islanding monitoring and protection method based on real-time topological relationship of a transformer area. Background Art

[0002] The power supply company actively explores the construction of demonstration areas for the flexible consumption of rural distributed power sources and automatic power quality management. When a main grid fault or line fault occurs, the photovoltaic grid-connected inverter uses the changes in grid voltage and frequency when the grid is abnormal to passively detect the island.

[0003] However, when the output power of photovoltaic power generation in the substation is balanced with the local load power, the passive detection method will lose the ability to detect islands, resulting in a large non-detection area. The substation will then form an island operation. Since the power grid cannot control the voltage and frequency in the island, if the voltage and frequency exceed the allowable range, it will cause damage to the user's equipment. When the substation is operating in an island, the operation and maintenance personnel may not be aware of the existence of distributed photovoltaics, and the grid-connected photovoltaic inverter will continue to supply power, which will endanger the safety of the operation and maintenance personnel. Summary of the invention

[0004] To solve the above problems, the present invention discloses a photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation, which uses the substation fusion terminal to monitor the status of the transformer and the intelligent photovoltaic grid-connected switch to achieve anti-islanding protection for the distributed photovoltaic substation.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation is implemented by a photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation. The photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation includes: an intelligent photovoltaic grid-connected switch, a carrier module, and an intelligent fusion terminal in the substation; the intelligent photovoltaic grid-connected switch is installed at each photovoltaic grid-connected point in the substation, and is used to control the connection and disconnection of the photovoltaic inverter and the power grid, and has a topological characteristic current signal injection function; the intelligent fusion terminal device in the substation calculates the substation topological relationship, collects the status and electrical quantity of the substation transformer and the intelligent photovoltaic grid-connected switch, and controls the opening and closing of the intelligent photovoltaic grid-connected switch; the carrier module is used for carrier communication between the intelligent fusion terminal in the substation and the intelligent photovoltaic grid-connected switch; the method includes the following steps:

[0007] Step 1: The intelligent fusion terminal in the substation captures the characteristic waveform emitted by the intelligent photovoltaic grid-connected switch, and automatically identifies the intelligent photovoltaic grid-connected switch in the substation in real time; the intelligent fusion terminal in the substation generates a local topology structure according to the information updated by the data center;

[0008] Step 2: Based on the topological structure generated in step 1, the intelligent fusion terminal in the substation area automatically connects to the intelligent photovoltaic grid-connected switch in the substation area, collects the operation information of the grid-connected point, and collects the electrical quantity data of the intelligent photovoltaic grid-connected switch;

[0009] Step 3: The intelligent fusion terminal in the substation monitors the electrical quantity data of the transformer in real time, analyzes the fault situation in the substation, and determines in real time whether the substation is operating in an isolated manner;

[0010] Step 4: When an island operation occurs in the substation, the substation intelligent fusion terminal analyzes the photovoltaic inverters that are not off-grid based on the operation status of the photovoltaic grid-connected points in the substation;

[0011] Step 5: The intelligent fusion terminal in the substation area controls the intelligent photovoltaic grid-connected switch to open through carrier communication, disconnecting the photovoltaic power plant from the grid.

[0012] Furthermore, the method further comprises the following steps:

[0013] Step 6: The intelligent fusion terminal in the substation area sends the island operation information and local control status to the monitoring main station via remote communication.

[0014] Furthermore, in step 2, the electrical quantity data of the smart photovoltaic grid-connected switch collected by the smart fusion terminal in the substation area is sent to the remote monitoring platform.

[0015] Furthermore, the topology structure is used for device information input to ensure a one-to-one correspondence between physical devices and logical devices.

[0016] Furthermore, the substation fault condition includes any one of the following conditions: power outage, low frequency, overfrequency, low voltage, and overvoltage.

[0017] The beneficial effects of the present invention are:

[0018] 1. The intelligent fusion terminal in the substation area performs topological identification on the intelligent photovoltaic grid-connected switch and automatically connects to the intelligent photovoltaic grid-connected switch. The intelligent fusion terminal in the substation area collects the operating conditions of the transformer and the photovoltaic grid-connected point, analyzes the power outage, low frequency, overfrequency, low voltage and overvoltage faults on the transformer side of the substation area, and determines whether the substation area has island operation and photovoltaic inverters that are not off-grid, and promptly controls the intelligent photovoltaic grid-connected switch to disconnect the photovoltaic and power grid connection. The fusion terminal solves the problem of photovoltaic island operation through panoramic monitoring of distributed grid-connected points, supports large-scale consumption of distributed power sources, and realizes the implementation of energy Internet in the power distribution field. When the main power grid fails or the line fails, and the photovoltaic inverter does not automatically go off-grid, the solution of the present invention can automatically disconnect the photovoltaic grid-connected point switch to prevent power quality problems caused by island operation.

[0019] 2. When the substation is isolated due to power outage and maintenance, the photovoltaic grid-connected point switch will be automatically disconnected. The power supply unit can monitor the status of each grid-connected point in the substation in real time through the remote monitoring platform to ensure that the photovoltaic grid-connected point is clearly disconnected to prevent the risk of electric shock.

[0020] 3. The present invention solves the problem of isolated island operation caused by large-scale distributed photovoltaics and can be widely used in rural low-voltage photovoltaic areas, greatly improving the power supply quality of rural low-voltage areas and ensuring the safe and stable operation of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the architecture of the photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation area provided by the present invention.

[0022] Figure 2 A schematic flow chart of a photovoltaic anti-islanding monitoring and protection method based on real-time topological relationships of substations provided by the present invention. DETAILED DESCRIPTION

[0023] The technical solution provided by the present invention will be described in detail below in conjunction with specific embodiments. It should be understood that the following specific implementation methods are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0024] The solution of the present invention is implemented by a photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation area. The main architecture of the system is as follows: Figure 1 As shown in the figure, it is composed of intelligent photovoltaic grid-connected switches, carrier modules, substation intelligent fusion terminals and other equipment.

[0025] The intelligent photovoltaic grid-connected switch is installed at each photovoltaic grid-connected point in the substation area. It is used to monitor the voltage, current and other electrical quantities of the photovoltaic grid, form a real-time topological relationship of the substation area, control the connection and disconnection of the photovoltaic inverter and the power grid, and has the function of injecting topological characteristic current signals.

[0026] The carrier module (not shown in the figure) is used for carrier communication between the intelligent fusion terminal in the substation area and the intelligent photovoltaic grid-connected switch.

[0027] The intelligent fusion terminal equipment in the substation area calculates the substation area topology relationship, collects the status of the substation area transformer and the intelligent photovoltaic grid-connected switch, and controls the opening and closing of the intelligent photovoltaic grid-connected switch. Specifically, the functions of the intelligent fusion terminal equipment in the substation area include:

[0028] Real-time monitoring of transformer voltage, current and other electrical quantities, configuration of low-frequency protection, high-frequency protection, low-voltage protection, overvoltage protection and other logic, analysis of transformer power outages, grid abnormalities and other faults, automatic analysis of whether the substation is operating in an isolated manner.

[0029] Automatically identify the topological characteristic current signal of the intelligent photovoltaic grid-connected switch, automatically connect to the intelligent photovoltaic grid-connected switch, collect the voltage, current, power, switch status and other information of the intelligent photovoltaic grid-connected switch, and analyze the photovoltaic inverter that is not off the grid.

[0030] According to the isolated operation of the substation area and the photovoltaic inverters that are not off-grid, the carrier module sends a message to control the opening of the intelligent photovoltaic grid-connected switch to disconnect the photovoltaic inverters that are not off-grid from the grid.

[0031] Based on the above architecture, the present invention provides a photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation. Based on the real-time topological relationship of the substation, the substation intelligent fusion terminal adaptively accesses the intelligent photovoltaic grid-connected switch in the substation. When the substation is disconnected from the main power grid and the local island protection of the inverter fails, the substation fusion terminal monitors the real-time status of the substation transformer and the intelligent photovoltaic grid-connected switch, sends a control signal to the intelligent photovoltaic grid-connected switch, and disconnects the photovoltaic grid in time to prevent the substation from islanding. The fusion terminal uploads the islanding operation monitoring and local control status of the substation to the main station and notifies the operating personnel. Specifically, if Figure 2 As shown, the method of the present invention comprises the following steps:

[0032] 1. The intelligent fusion terminal of the substation area jointly with the intelligent photovoltaic grid-connected switch performs real-time substation area topology identification. The intelligent fusion terminal of the substation area captures the characteristic waveform emitted by the intelligent photovoltaic grid-connected switch and automatically identifies the intelligent photovoltaic grid-connected switch in the substation area; the intelligent fusion terminal of the substation area generates a local topology and generates a local topology structure based on the information updated by the data center. It is used for device information input during data collection, protocol analysis, and parameter processing to ensure that physical devices and logical devices correspond one to one.

[0033] 2. Based on the topology identification results, the intelligent fusion terminal in the substation area automatically connects to the intelligent photovoltaic grid-connected switch in the substation area, sends data reading messages according to the concurrent process, and collects data of the intelligent photovoltaic grid-connected switch, such as voltage, current, power, electricity, fault information, switch status, etc., and sends it to the remote monitoring platform.

[0034] 3. The intelligent fusion terminal in the substation monitors the voltage, current, power and other electrical quantity data of the transformer in real time, analyzes power outages, low frequency, overfrequency, low voltage and overvoltage faults in the substation, and determines whether the substation is operating in an isolated manner.

[0035] 4. The intelligent fusion terminal in the substation monitors the voltage, current, power and other data of the substation transformer in real time, determines when the substation is operating in an isolated island, and finds the photovoltaic inverter that is not off the grid based on the operation status of the photovoltaic grid-connected points in the substation.

[0036] 5. The intelligent fusion terminal in the substation sends a trip command to the intelligent photovoltaic grid-connected switch at its grid-connected point through carrier communication, disconnecting the photovoltaic and grid connections and disconnecting the photovoltaic inverter that should be off-grid.

[0037] 6. The intelligent fusion terminal in the substation area sends the island operation information and local control status to the monitoring main station through remote communication to realize remote monitoring and remote operation and maintenance.

[0038] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A photovoltaic anti-islanding monitoring and protection method based on real-time topological relationship of the substation, characterized in that: The photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation is adopted, and the photovoltaic anti-islanding monitoring and protection system based on the real-time topological relationship of the substation includes: an intelligent photovoltaic grid-connected switch, a carrier module, and an intelligent fusion terminal in the substation; the intelligent photovoltaic grid-connected switch is installed at each photovoltaic grid-connected point in the substation, and is used to control the connection and disconnection of the photovoltaic inverter and the power grid, and has a topological characteristic current signal injection function; the intelligent fusion terminal device in the substation calculates the substation topological relationship, collects the status and electrical quantity of the substation transformer and the intelligent photovoltaic grid-connected switch, and controls the opening and closing of the intelligent photovoltaic grid-connected switch; the carrier module is used for carrier communication between the intelligent fusion terminal in the substation and the intelligent photovoltaic grid-connected switch; the method includes the following steps: Step 1: The intelligent fusion terminal in the substation captures the characteristic waveform emitted by the intelligent photovoltaic grid-connected switch, and automatically identifies the intelligent photovoltaic grid-connected switch in the substation in real time; the intelligent fusion terminal in the substation generates a local topology structure according to the information updated by the data center; Step 2: Based on the topological structure generated in step 1, the intelligent fusion terminal in the substation area automatically connects to the intelligent photovoltaic grid-connected switch in the substation area, collects the operation information of the grid-connected point, and collects the electrical quantity data of the intelligent photovoltaic grid-connected switch; Step 3: The intelligent fusion terminal in the substation monitors the electrical quantity data of the transformer in real time, analyzes the fault situation in the substation, and determines in real time whether the substation is operating in an isolated manner; Step 4: When an island operation occurs in the substation, the substation intelligent fusion terminal analyzes the photovoltaic inverters that are not off-grid based on the operation status of the photovoltaic grid-connected points in the substation; Step 5: The intelligent fusion terminal in the substation area controls the intelligent photovoltaic grid-connected switch to open through carrier communication, disconnecting the photovoltaic power plant from the grid.

2. The photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation area according to claim 1 is characterized in that: The following steps are also included: Step 6: The intelligent fusion terminal in the substation area sends the island operation information and local control status to the monitoring main station via remote communication.

3. The photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation according to claim 1 is characterized in that: In the step 2, the electrical quantity data of the intelligent photovoltaic grid-connected switch collected by the intelligent fusion terminal in the substation area is sent to the remote monitoring platform.

4. The photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation according to claim 1 is characterized in that: The topology structure is used for device information input to ensure a one-to-one correspondence between physical devices and logical devices.

5. The photovoltaic anti-islanding monitoring and protection method based on the real-time topological relationship of the substation according to claim 1 is characterized in that: The substation fault condition includes any one of the following conditions: power outage, low frequency, overfrequency, low voltage, and overvoltage.

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