A new energy and off-grid control method and system for a power distribution district

Abstract

The application discloses a kind of new energy and off-grid control method of district distribution, main control equipment is deployed in distribution room, each new energy station is configured sub-control equipment under this distribution room, and the main control equipment and sub-control equipment are communicated connection;The district is divided into multiple area control libraries and off-grid main control equipment detects and collects distribution room incoming line current, voltage, collects the protection action information of each feeder relay protection device of distribution room, collects repair input switch quantity information, starts grid-connected switch quantity information, manual off-grid switch quantity information.Main control equipment determines fault state or repair state according to the above information, to trigger related new energy grid-connected or off-grid operation.

Description

Technical Field

[0001] The present invention relates to the field of distributed new energy in power systems, and in particular to a method and system for controlling the on-grid and off-grid connection of new energy in a distribution station area. Background Art

[0002] With the access of a large number of distributed new energy, the active nature of the distribution network is becoming increasingly obvious. The distribution substation is the direct aggregation end for the access of distributed new energy to the power grid. It is more timely and easy to maintain to complete the management of new energy in the distribution substation.

[0003] At present, distributed photovoltaic systems often encounter problems such as distribution network failures, equipment maintenance, and lack of passive island protection during actual operation. In addition, traditional low-voltage switches have simple functions and cannot meet the current refined management requirements of large-scale grid-connected distributed photovoltaics on the low-voltage side, posing many safety risks to photovoltaic power generation systems and the main power grid.

[0004] The present invention provides a method and system for controlling on-grid and off-grid operation of distributed new energy, thereby realizing safe off-grid operation and automatic on-grid operation of distributed energy in the power grid and improving the safety and reliability of distributed energy operation in the power grid. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to improve the safety and reliability of distributed energy operation in power grids.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for controlling the on-grid and off-grid operation of distributed renewable energy in a substation area includes deploying a master control device in a power distribution room, configuring sub-control devices at each renewable energy station within the power distribution room, and communicating with the master control device and sub-control devices. The substation area is divided into multiple regional control libraries, each of which is segmented by switches or circuit breakers, and each of which is a control group consisting of feeders.

[0008] On-grid and off-grid control methods include:

[0009] Step 1: The main control device detects the current and voltage in the distribution room, and the sub-control device collects the current and voltage of the distributed grid-connected port to provide auxiliary judgment for the main station; when the current value is greater than the set overcurrent value and reaches the action delay, the main control device records it as a fault memory. When the fault memory delay reaches the off-grid new energy time value, and the voltage loss reaches the delay value at the same time, the incoming line fault off-grid action is triggered, starting the feeder new energy off-grid action process, and jumping to step 2;

[0010] When the master control device detects the action of a specific feeder relay device and the switching value of the feeder relay device action meets the delayed action time, the feeder off-grid action is triggered, the feeder off-grid action process is started, and the process jumps to step 2;

[0011] When the main control device is under maintenance, the maintenance off-grid action is triggered, the maintenance off-grid action process is started, and the process jumps to step 2;

[0012] Step 2: After the master control device enters the off-grid action process, it determines the off-grid action type. If it is an incoming line fault off-grid or maintenance off-grid, the master control device controls the new energy on the corresponding bus to go off-grid. If it is a feeder off-grid action, the master control device controls the new energy station on the corresponding line to go off-grid.

[0013] Step 3: When the main control device detects that the maintenance is completed or the fault is eliminated, the sequential grid-connection process is carried out; based on the type of the last off-grid action, the method for judging whether the fault has disappeared is carried out; if the incoming line is off-grid, the main control device will detect the incoming line voltage and current. When the voltage returns to normal, the current is greater than the set value, and the direction is flowing toward the busbar, the fault is judged to be restored and the automatic grid-connection process is carried out; if the last time was a feeder off-grid, the feeder circuit breaker status is detected. When it changes from open to closed and the delay time is satisfied, the fault is judged to have disappeared and the automatic grid-connection process is started; when the maintenance status disappears, the automatic grid-connection process needs to be manually started.

[0014] Furthermore, the off-grid control strategy in step 2 is as follows:

[0015] After the master device determines the off-grid type, it selects the new energy station in the corresponding regional control library. The master device first sends a group adjustment command to reduce the output of distributed new energy to the minimum; the delay T0 time is used for the distributed new energy action to complete, and the master device sends a group control remote control command to the sub-control device to control the distributed energy off-grid.

[0016] Furthermore, the grid connection control strategy in step 3 is as follows:

[0017] The master control device automatically controls the stations to be connected to the grid in sequence according to the regional control library. The control strategy for each station is as follows:

[0018] The master control device sends a remote adjustment to the minimum output power of the distributed energy of the station; the master control device delays the time setting value T1 and issues a grid connection instruction to the sub-control device. The sub-control device controls the distributed energy and controls the power output of the station in accordance with the power balance principle and without reverse power to reduce the impact and influence of the grid connection on the line; the master control device completes all distributed energy control in turn. After completing the grid connection of all individual new energy stations, the master control device gradually increases the generated power of the distributed new energy station according to the progressive principle until the maximum output power is reached.

[0019] Furthermore, the division principle of the regional control library is specifically as follows: the distributed new energy on the same feeder is a control group, multiple control groups on the same I bus form another control group, and all control groups are aggregated into the main control library.

[0020] The present invention also provides a distributed renewable energy on-grid and off-grid control system for a substation, which is applied to the above method, including:

[0021] The main control module includes a main control device arranged in the power distribution room, which is used to detect and determine the type of fault and provide corresponding on-grid and off-grid control strategies according to the type;

[0022] The sub-control module includes sub-control devices arranged in each new energy station under the power distribution room. The sub-control devices are connected to the main control device in communication and receive control instructions from the main control device.

[0023] Regional control library, which divides the substation area into multiple regional control libraries. The regional control library is divided into sections based on switches or circuit breakers and feeders as a control group for sequential control and disconnection;

[0024] The on-grid and off-grid control strategies include:

[0025] Step 1: The main control device detects the current and voltage in the distribution room. When the current value is greater than the set overcurrent value and reaches the action delay, the main control device records the fault memory. When the fault memory delay reaches the off-grid renewable energy time value, and the voltage loss reaches the delay value, the incoming line fault off-grid action is triggered, starting the feeder renewable energy off-grid action process, and jumping to step 2;

[0026] When the master control device detects the action of a specific feeder relay device and the switching value of the feeder relay device action meets the delayed action time, the feeder off-grid action is triggered, the feeder off-grid action process is started, and the process jumps to step 2;

[0027] When the main control device is under maintenance, the maintenance off-grid action is triggered, the maintenance off-grid action process is started, and the process jumps to step 2;

[0028] Step 2: After the master control device enters the off-grid action process, it determines the off-grid action type. If it is an incoming line fault off-grid or maintenance off-grid, the master control device controls the new energy on the corresponding bus to go off-grid. If it is a feeder off-grid action, the master control device controls the new energy station on the corresponding line to go off-grid.

[0029] Step 3: When the main control device detects that the maintenance is completed or the fault is eliminated, the sequential grid-connection process is carried out; based on the type of the last off-grid action, the method for judging whether the fault has disappeared is carried out; if the incoming line is off-grid, the main control device will detect the incoming line voltage and current. When the voltage returns to normal, the current is greater than the set value, and the direction is flowing toward the busbar, the fault is judged to be restored and the automatic grid-connection process is carried out; if the last time was a feeder off-grid, the feeder circuit breaker status is detected. When it changes from open to closed and the delay time is satisfied, the fault is judged to have disappeared and the automatic grid-connection process is started; when the maintenance status disappears, the automatic grid-connection process needs to be manually started.

[0030] Furthermore, the off-grid control strategy in step 2 is as follows:

[0031] After the master device determines the off-grid type, it selects the new energy station in the corresponding regional control library. The master device first sends a group adjustment command to reduce the output of distributed new energy to the minimum; the delay T0 time is used for the distributed new energy action to complete, and the master device sends a group control remote control command to the sub-control device to control the distributed energy off-grid.

[0032] Furthermore, the grid connection control strategy in step 3 is as follows:

[0033] The master control device automatically controls the stations to be connected to the grid in sequence according to the regional control library. The control strategy for each station is as follows:

[0034] The master control device sends a remote adjustment to the minimum output power of the distributed energy of the station; the master control device delays the time setting value T1 and issues a grid connection instruction to the sub-control device. The sub-control device controls the distributed energy and controls the power output of the station in accordance with the power balance principle and without reverse power to reduce the impact and influence of the grid connection on the line; the master control device completes all distributed energy control in turn. After completing the grid connection of all individual new energy stations, the master control device gradually increases the generated power of the distributed new energy station according to the progressive principle until the maximum output power is reached.

[0035] Furthermore, the division principle of the regional control library is specifically as follows: the distributed new energy on the same feeder is a control group, multiple control groups on the same I bus form another control group, and all control groups are aggregated into the main control library.

[0036] The advantages of the present invention are:

[0037] The present invention uses on-grid and off-grid master control equipment deployed in the distribution room and distributed new energy slave equipment, establishes a channel through wireless / power carrier and distributed new energy on the feeder, and autonomously and orderly controls the distributed new energy to perform on-grid and off-grid operations based on the fault and maintenance information detected by the on-grid and off-grid master control equipment, reduces the impact of new energy on the distribution network, ensures line maintenance safety, simplifies operation and maintenance work, and improves the safety and reliability of distributed energy operation in the power grid.

[0038] The present invention utilizes distributed new energy and other resources to achieve the orderly connection and disconnection of distributed new energy, and completes the new energy management in the distribution station area in a more timely and easy-to-maintain manner.

[0039] This system collects and controls information from distributed renewable energy sources directly connected to the distribution room, as well as primary equipment such as transformers and switches. This enables orderly control of renewable energy sources during distribution network failures, equipment maintenance, and passive island protection. It also meets the demand for refined management of large-scale grid-connected distributed photovoltaic systems on the low-voltage side. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the control deployment and controller area of ​​Example 1 of the present invention. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment targets distributed renewable energy in the power grid, deploys control equipment, and builds a hardware environment for enabling distributed renewable energy to be automatically connected to and disconnected from the grid, including:

[0044] A master control device for on-grid and off-grid operation is deployed in the power distribution room, and each new energy station within this distribution room is equipped with a slave control device for on-grid and off-grid operation. The master control device collects information related to the power distribution room to implement the overall control strategy, and the slave control device receives control instructions from the master control device and executes actions.

[0045] Specifically, the master control device collects the information of the sub-control devices at regular intervals to form a regional control library. The regional control library is based on physical connections, with switches or circuit breakers as sections and feeders as a control group, such as Figure 1 If distributed renewable energy sources FG1 and FG2 are connected to feeder 102, they form a control group. If power source FG3 is connected to feeder 103, FG3 forms a control group. If FG1, FG2, and FG3 are connected to the same bus, they form a control group. All control groups are aggregated into a master control library.

[0046] Function of sub-control device:

[0047] 1: Collect the current and voltage of the distributed grid-connected ports to provide auxiliary judgment for the master station.

[0048] 2: The sub-control device controls the distributed new energy switch equipment to realize switch closing and opening.

[0049] 3: The sub-control device receives the instructions from the master station and directly controls the energy output of power electronic equipment such as the inverter.

[0050] The sub-control device's behavior in the process is as follows:

[0051] 1: In off-grid operation, the sub-controller first reduces the power generation according to the control instructions issued by the master station, then trips the switch or directly trips quickly to disconnect the device to go off-grid.

[0052] 2: During the grid-connected operation, the sub-controller first increases the power generation according to the control instructions issued by the master station, then trips and closes the switch to connect to the grid.

[0053] The above-mentioned neutron control operation requires establishing communication with devices such as inverters to achieve power control capabilities.

[0054] The main control equipment is used to detect the current and voltage in the distribution room and provide control strategies.

[0055] Example 2

[0056] This embodiment provides a control strategy based on the hardware environment of embodiment 1, including the following arrangements:

[0057] Step 1: The master control device monitors the current and voltage in the distribution room. If the current value exceeds the set overcurrent value and reaches the action delay, the master control device records the fault and creates a fault memory. When the fault memory delay reaches the off-grid renewable energy time setting, and the voltage loss reaches the delay setting, the incoming line fault off-grid action is triggered, initiating the feeder renewable energy off-grid action process. Go to step 4.

[0058] Step 2: When the master control device detects the actuation of a specific feeder relay device and the switching value of the actuation of the feeder relay device meets the delayed actuation time, the feeder off-grid action is triggered, and the feeder off-grid action process is started. Jump to step 4.

[0059] Step 3: When the main control device is input for maintenance, the maintenance off-grid action is triggered and the maintenance off-grid action process is started. Jump to step 4.

[0060] Step 4: When the master control device enters the off-grid action process, it determines the off-grid action type. If it is an incoming line fault off-grid or maintenance off-grid, the master control controls the new energy on the corresponding bus to go off-grid. If it is a feeder off-grid action, the master control controls the new energy station on the corresponding line to go off-grid.

[0061] The off-grid command follows the following control strategy

[0062] 4-1, after the main control determines the off-grid type, it selects the new energy station corresponding to the control area, such as Figure 1 If incoming line 101 fails, the FG1, FG2, and FG3 distributed renewable energy sources in the control area below the low-voltage bus I are selected. If feeder 102 fails, the FG1 and FG2 distributed renewable energy sources in the control area below feeder 102 are selected.

[0063] 4-2, the master controller first sends a group adjustment command to reduce the output of distributed new energy to the minimum.

[0064] 4-3, the delay T0 time (1s is recommended) is used to complete the distributed new energy action, and the master control sends the group control remote control command to the substation to control the distributed energy to go off the grid.

[0065] Step 5. When the main control device detects that the maintenance is complete or the fault is eliminated, the sequential grid connection process is carried out. The method for judging whether the fault has disappeared is determined based on the type of the last off-grid action. When it is an incoming line off-grid action, the main control will detect the incoming line voltage and current. When the voltage returns to normal, the current is greater than the set value, and the direction is flowing toward the busbar, the fault is judged to have recovered and the automatic grid connection process is carried out. If the last time was a feeder off-grid, the feeder circuit breaker status is detected. When it changes from open to closed and the delay time is met, the fault is judged to have disappeared and the automatic grid connection process is started. When the maintenance status disappears, the automatic grid connection process needs to be manually started.

[0066] The automatic grid connection process is as follows

[0067] The main control equipment automatically controls the grid connection of the distributed new energy stations in the control area in sequence. The control strategy for each station is as follows:

[0068] 5-1, the master control device sends the remote adjustment of the minimum output power of the distributed energy of the station

[0069] 5-2, the main control device sets the delay time to T1 (can be 2s) and issues a grid-connected instruction to the sub-control device. The sub-control device controls the distributed energy and controls the power output of the station according to the power balance principle and without reverse power conditions, so as to reduce the impact and influence of grid connection on the line.

[0070] 5-3, the master control device completes all distributed energy control of the controller in turn.

[0071] 5-4. After the master control device completes the grid connection of all individual stations, it will gradually increase the power generation capacity of the distributed stations according to the progressive principle until the maximum output power is reached.

[0072] Step 6: The automatic grid connection process ends here.

[0073] The present invention uses on-grid and off-grid master control equipment deployed in the distribution room and distributed new energy slave equipment, establishes a channel through wireless / power carrier and distributed new energy on the feeder, and autonomously and orderly controls the distributed new energy to perform on-grid and off-grid operations based on the fault and maintenance information detected by the on-grid and off-grid master control equipment, reduces the impact of new energy on the distribution network, ensures line maintenance safety, simplifies operation and maintenance work, and improves the safety and reliability of distributed energy operation in the power grid.

[0074] The main control device for on-grid and off-grid monitoring detects and collects the incoming current and voltage of the distribution room, as well as the protection action information of the relay devices on each feeder in the distribution room. It also collects information on switching values ​​for maintenance inputs, grid-connection activation, and manual off-grid operation. Based on this information, the main control device determines whether the device is in a fault or maintenance state, thereby triggering the relevant new energy grid connection or off-grid operation.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for controlling the connection and disconnection of distributed renewable energy in a substation, characterized in that: Deploy a master control device in the power distribution room, and configure sub-control devices in each new energy station under this power distribution room. The master control device and sub-control devices are communicatively connected; divide the substation area into multiple regional control libraries, each of which is divided into sections based on switches or circuit breakers, and each feeder is a control group; On-grid and off-grid control methods include: Step 1: The main control device detects the current and voltage in the distribution room, and the sub-control device collects the current and voltage of the distributed grid-connected port to provide auxiliary judgment for the main station; when the current value is greater than the set overcurrent value and reaches the action delay, the main control device records it as a fault memory. When the fault memory delay reaches the off-grid new energy time value, and the voltage loss reaches the delay value at the same time, the incoming line fault off-grid action is triggered, starting the feeder new energy off-grid action process, and jumping to step 2; When the master control device detects the action of a specific feeder relay device and the switching value of the feeder relay device action meets the delayed action time, the feeder off-grid action is triggered, the feeder off-grid action process is started, and the process jumps to step 2; When the main control device is under maintenance, the maintenance off-grid action is triggered, the maintenance off-grid action process is started, and the process jumps to step 2; Step 2: After the main control device enters the off-grid action process, it determines the off-grid action type. If it is an incoming line fault off-grid or maintenance off-grid, the sub-control device receives the instruction of the main control device and controls the new energy on the corresponding bus to go off-grid. If the feeder is off-grid, the new energy station on the corresponding line is controlled to go off-grid. Step 3: When the main control device detects that the maintenance is completed or the fault is eliminated, the sequential grid-connection process is carried out; based on the type of the last off-grid action, the method for judging whether the fault has disappeared is carried out; if the incoming line is off-grid, the main control device will detect the incoming line voltage and current. When the voltage returns to normal, the current is greater than the set value, and the direction is flowing toward the busbar, the fault is judged to be restored and the automatic grid-connection process is carried out; if the last time was a feeder off-grid, the feeder circuit breaker status is detected. When it changes from open to closed and the delay time is satisfied, the fault is judged to have disappeared and the automatic grid-connection process is started; when the maintenance status disappears, the automatic grid-connection process needs to be manually started.

2. A method for controlling the connection and disconnection of distributed renewable energy in a substation according to claim 1, characterized in that: The off-grid control strategy in step 2 is as follows: After the master device determines the off-grid type, it selects the new energy station in the corresponding regional control library. The master device first sends a group adjustment command to reduce the output of distributed new energy to the minimum; the delay T0 time is used for the distributed new energy action to complete, and the master device sends a group control remote control command to the sub-control device to control the distributed energy off-grid.

3. A method for controlling the connection and disconnection of distributed renewable energy in a substation according to claim 1, characterized in that: The grid connection control strategy in step 3 is as follows: The master control device automatically controls the stations to be connected to the grid in sequence according to the regional control library. The control strategy for each station is as follows: The master control device sends a remote adjustment to the minimum output power of the distributed energy of the station; the master control device delays the time setting value T1 and issues a grid connection instruction to the sub-control device. The sub-control device controls the distributed energy and controls the power output of the station in accordance with the power balance principle and without reverse power to reduce the impact and influence of the grid connection on the line; the master control device completes all distributed energy control in turn. After completing the grid connection of all individual new energy stations, the master control device gradually increases the generated power of the distributed new energy station according to the progressive principle until the maximum output power is reached.

4. A method for controlling the connection and disconnection of distributed renewable energy in a substation according to any one of claims 1 to 3, characterized in that: The division principle of the regional control library is specifically as follows: the distributed new energy on the same feeder forms a control group, multiple control groups on the same I bus form another control group, and all control groups are aggregated into the main control library.

5. A distributed renewable energy on-grid and off-grid control system for a substation, applied to the method according to any one of claims 1 to 4, characterized in that: include The main control module includes a main control device arranged in the power distribution room, which is used to detect and determine the type of fault and provide corresponding on-grid and off-grid control strategies according to the type; The sub-control module includes sub-control devices arranged in each new energy station under the power distribution room. The sub-control devices are connected to the main control device in communication and receive control instructions from the main control device. Regional control library, which divides the substation area into multiple regional control libraries. The regional control library is divided into sections based on switches or circuit breakers and feeders as a control group for sequential control and disconnection; The on-grid and off-grid control strategies include: Step 1: The main control device detects the current and voltage in the distribution room. When the current value is greater than the set overcurrent value and reaches the action delay, the main control device records the fault memory. When the fault memory delay reaches the off-grid renewable energy time value, and the voltage loss reaches the delay value, the incoming line fault off-grid action is triggered, starting the feeder renewable energy off-grid action process, and jumping to step 2; When the master control device detects the action of a specific feeder relay device and the switching value of the feeder relay device action meets the delayed action time, the feeder off-grid action is triggered, the feeder off-grid action process is started, and the process jumps to step 2; When the main control device is under maintenance, the maintenance off-grid action is triggered, the maintenance off-grid action process is started, and the process jumps to step 2; Step 2: After the master control device enters the off-grid action process, it determines the off-grid action type. If it is an incoming line fault off-grid or maintenance off-grid, the master control device controls the new energy on the corresponding bus to go off-grid. If it is a feeder off-grid action, the master control device controls the new energy station on the corresponding line to go off-grid. Step 3: When the main control device detects that the maintenance is completed or the fault is eliminated, the sequential grid-connection process is carried out; based on the type of the last off-grid action, the method for judging whether the fault has disappeared is carried out; if the incoming line is off-grid, the main control device will detect the incoming line voltage and current. When the voltage returns to normal, the current is greater than the set value, and the direction is flowing toward the busbar, the fault is judged to be restored and the automatic grid-connection process is carried out; if the last time was a feeder off-grid, the feeder circuit breaker status is detected. When it changes from open to closed and the delay time is satisfied, the fault is judged to have disappeared and the automatic grid-connection process is started; when the maintenance status disappears, the automatic grid-connection process needs to be manually started.

6. A distributed renewable energy on-grid and off-grid control system for a substation according to claim 5, characterized in that: The off-grid control strategy in step 2 is as follows: After the master device determines the off-grid type, it selects the new energy station in the corresponding regional control library. The master device first sends a group adjustment command to reduce the output of distributed new energy to the minimum; the delay T0 time is used for the distributed new energy action to complete, and the master device sends a group control remote control command to the sub-control device to control the distributed energy off-grid.

7. A distributed renewable energy on-grid and off-grid control system for a substation according to claim 5, characterized in that: The grid connection control strategy in step 3 is as follows: The master control device automatically controls the stations to be connected to the grid in sequence according to the regional control library. The control strategy for each station is as follows: The master control device sends a remote adjustment to the minimum output power of the distributed energy of the station; the master control device delays the time setting value T1 and issues a grid connection instruction to the sub-control device. The sub-control device controls the distributed energy and controls the power output of the station in accordance with the power balance principle and without reverse power to reduce the impact and influence of the grid connection on the line; the master control device completes all distributed energy control in turn. After completing the grid connection of all individual new energy stations, the master control device gradually increases the generated power of the distributed new energy station according to the progressive principle until the maximum output power is reached.

8. A distributed renewable energy on-grid and off-grid control system for a substation according to any one of claims 5 to 7, characterized in that: The division principle of the regional control library is specifically as follows: the distributed new energy on the same feeder forms a control group, multiple control groups on the same I bus form another control group, and all control groups are aggregated into the main control library.

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