Edge gateway and method for preventing reverse flow of new energy power station

Abstract

This invention provides a method and edge gateway for preventing backflow in renewable energy power plants. The method includes: collecting real-time power data from the point of common coupling (PCC), inverters, and PCS devices, as well as the remote signaling status of the bus tie switch; calculating load power based on the real-time power of the PCC and the inverters / PCS devices, identifying the power flow direction, calculating the power generation deviation based on preset power generation target parameters, dynamically adjusting the power generation plan, and distributing it to the inverters and PCS devices; real-time monitoring of the inverter and PCS device execution status, and achieving the required adjustment error after multiple iterations; if telemetry and remote signaling signals are not refreshed for an extended period, a communication anomaly is identified; in the event of a communication anomaly, the inverters and PCS devices are controlled to operate at a reduced capacity percentage or to stop operation. This invention reduces the investment cost of secondary equipment in renewable energy power plants and achieves active power regulation of distributed photovoltaic systems through group control of inverters and energy storage PCS.

Description

Technical Field

[0001] This invention relates to the field of power control technology for distributed new energy photovoltaic energy storage power stations, and in particular to an edge gateway and method for preventing backflow in new energy power stations. Background Technology

[0002] Currently, there are some technical solutions to address the reverse current problem caused by distributed photovoltaic (PV) grid connection. For example, inverters can be connected to smart meters to determine reverse power and reduce power generation. However, this method is only applicable to single inverter grid connection scenarios and requires the grid connection point and the common connection point with the grid to coincide. This method is not suitable for large-scale industrial and commercial distributed PV grid connection points that are widely distributed and connected to the grid using a dual-incoming-line approach. Furthermore, it lacks the ability to coordinate and control hybrid PV and energy storage power stations.

[0003] Another common approach is to use a conventional power monitoring system. This requires configuring photovoltaic power prediction, remote control devices, protection and monitoring devices, servers, AGVC control master station software, etc., to collect electrical data from the entire station and control the power generation of equipment such as inverters according to dispatch instructions. This method usually has a long adjustment time, generally within 60 seconds, making it difficult to respond quickly to load changes. It requires a high investment in system reliability and equipment costs, thus lengthening the investment payback period for photovoltaic projects.

[0004] Therefore, there is an urgent need for a low-cost, highly reliable device and method that can solve the reverse current problem, applicable to various voltage levels and grid connection methods, so as to facilitate large-scale application and promotion. Summary of the Invention

[0005] The main objective of this invention is to provide an edge gateway and method for preventing backflow in new energy power plants, aiming to reduce the investment cost of secondary equipment in new energy power plants. By grouping and controlling inverters and energy storage PCS, the active power of distributed photovoltaics can be regulated, adapting to the scenario of low-voltage multi-point grid connection of large-scale industrial and commercial photovoltaics.

[0006] To achieve the above objectives, this invention proposes a method for preventing backflow in renewable energy power plants, the method comprising the following steps:

[0007] Step S10: Collect the real-time power of the point of common coupling, as well as the real-time power of the inverter and PCS equipment, and the remote signaling status of the bus tie switch;

[0008] Step S20: Calculate the load power based on the real-time power of the common connection point, the real-time power of the inverter and the PCS equipment, identify the power flow direction, calculate the power generation deviation based on the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and the PCS equipment. Real-time data is collected on the execution status of the inverter and the PCS equipment. After multiple iterations, the adjustment error requirement is met.

[0009] Step S30: If the telemetry and teleindication signals are not refreshed for a long time, it is determined that a communication abnormality has occurred.

[0010] Step S40: When a communication anomaly occurs, control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating.

[0011] A further technical solution of the present invention is that, after step S10, it further includes:

[0012] Step S101: Determine whether the common connection point is a single common connection point or multiple common connection points. If it is a single common connection point, proceed directly to step S20; if it is multiple common connection points, proceed to step S102.

[0013] Step S102: Combine the real-time power of each common connection point into the virtual total power of the common connection point;

[0014] Step S103: Based on the remote signaling status of the bus tie switch, start the control of different AGVC substations, inverters, and PCS equipment.

[0015] A further technical solution of the present invention is that the control strategy in step S103 follows the principle of minimizing grouping; step S103 specifically includes:

[0016] Step S1031: If the new energy power station is connected to the power grid via a single busbar and has only one common connection point, then only one AGVC substation needs to participate in the calculation and allocation. All inverters or PCS devices are connected to this substation, and the process proceeds directly to step S20.

[0017] Step S1032: If the new energy power plant and the power grid have multiple points of common connection, the inverters or PCS equipment are grouped into substations according to the remote signaling status of the bus tie switch. The principle of minimizing substation grouping is as follows: when the high-voltage side bus tie switch status is a split position signal, the number of substations is divided according to the number of points of common connection. Each substation is only connected to inverters or PCS equipment that can cause reverse current at that point of common connection. This type of substation is marked as a substation. When the high-voltage side bus tie switch status is a closed position signal, all inverters or PCS equipment of the new energy power plant need to be connected to the same substation. This type of substation is marked as a main substation.

[0018] Step S1033: The AGVC algorithm module of the substation is started or stopped by the status of the high-voltage side bus tie switch. When the status of the high-voltage side bus tie switch is the open position signal, the substation operates independently and the main substation stops operating; when the status of the high-voltage side bus tie switch is the closed position signal, the substation stops operating and the main substation starts operating.

[0019] A further technical solution of the present invention is that step S101 specifically includes: determining the number of common connection points according to the connection method between the new energy power station and the power grid.

[0020] A further technical solution of the present invention is that step S102 includes:

[0021] The active power collected from each common coupling point is summed to synthesize the virtual total power of the common coupling point. The calculation formula is as follows:

[0022] ,

[0023] in, Virtual total power for the common connection point, Let N be the active power at the nth common coupling point, and N be the number of common coupling points participating in regulation.

[0024] A further technical solution of the present invention is that the preset power generation target parameters include: "maximum value of active power allowed to be fed into the grid", "safety margin of power fed into the grid", "adjustment dead zone" and "adjustment response delay time";

[0025] Among them, "the maximum active power allowed to be fed to the grid" refers to the maximum instantaneous reverse power that the grid can withstand due to reverse flow caused by rapid load shedding; "the safety margin of power fed to the grid" affects the utilization rate of photovoltaic power generation, and also affects the amount of electricity purchased from the grid by the new energy power plant during operation.

[0026] Step S20 includes:

[0027] Step S201: Determine the direction of active power at the point of common coupling. The direction of the power grid flowing to the new energy power station is taken as the positive direction. The ultimate goal of anti-backflow is to ensure that the direction of active power at this point is always positive and the value should always be greater than 0kW.

[0028] Step S202: Calculate the target value of active power to be fed into the power grid based on the preset power generation target parameters. The calculation formula is as follows:

[0029] ，

[0030] in, To feed the target value of active power to the power grid, To allow the maximum active power to be fed into the power grid, To ensure a safety margin for the power supplied to the power grid;

[0031] Step S203: Calculate the difference between the virtual total power at the point of common coupling and the target value of the active power of the feeder grid. ,like If the value is greater than the adjustment dead zone and the holding time is greater than the adjustment response delay time, then proceed to step S204.

[0032] Step S204: Using the collected active power of the inverter or PCS equipment, calculate the sum of the actual output active power of the inverter equipment or the discharge power of the PCS. The calculation formula is as follows:

[0033] ,

[0034] in, Let i be the sum of the actual power of the inverter at time i. Let N be the actual active power output of the nth inverter or PCS device at time i, and N be the number of inverters participating in the regulation.

[0035] Step S205: Allocate the target active power value for the inverters or PCS devices participating in the next moment of regulation, and issue a remote adjustment command to each inverter or PCS device. Based on the rated power of each inverter or PCS device, set the adjustment priority, prioritizing the adjustment of inverters and PCS devices with larger adjustable capacity, and providing the adjustment rate. For inverters or PCS devices with the same priority, the power allocation is proportionally distributed according to the rated power, as shown in the following formula:

[0036] ,

[0037] in, It is the output power allocated to the nth inverter. It is the rated power of the nth inverter. It is the sum of the rated power of all inverters. yes The remaining target power after the high-priority inverters have been fully configured;

[0038] Step S206: Synchronously track the execution status of the inverter or PCS equipment, and calculate the total actual power of the inverter or PCS equipment at time i+1. The calculation formula is as follows:

[0039] ,

[0040] in, This represents the total actual power of the inverter at time i+1. The actual active power output of the nth inverter or PCS device at time i+1, where N is the number of inverters participating in the regulation.

[0041] Step S207, calculate the adjustment error, the calculation formula is as follows:

[0042] | ,

[0043] In step S208, error verification is performed. If the adjustment accuracy requirements are met, the issuance of new active power target values ​​to the inverters is stopped, and the adjustment interval period is waited for to end before proceeding to step S10. If the accuracy requirements are not met, the process is restarted in step S202 to calculate the active power target values ​​for each inverter in a new round.

[0044] A further technical solution of the present invention is that, after step S40, it further includes:

[0045] Step S50: Modify the preset power generation target parameters and demonstrate the anti-reverse flow operation effect.

[0046] To achieve the above objectives, the present invention also proposes an edge gateway for preventing backflow in new energy power plants, comprising: an AC power acquisition module, a communication module, an AGVC algorithm module, a data anomaly detection module, a logic programming module, and a safety protection and control module;

[0047] The AC power acquisition module is used to acquire the real-time active power of the point of common coupling; the communication module is used to acquire the real-time power of the inverter and PCS equipment.

[0048] The AGVC algorithm module is used to calculate the load power based on the real-time power of the common connection point, the inverter, and the PCS equipment, identify the power flow direction, calculate the power generation deviation according to the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment through the communication module. It also collects the execution status of the inverter and PCS equipment in real time, and reaches the adjustment error requirement after multiple iterations.

[0049] The data anomaly detection module is used to monitor the refresh status of telemetry and teleindication signals. If the telemetry and teleindication signals are not refreshed, it is determined that a communication anomaly has occurred.

[0050] The safety protection control module is used to control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operation when a communication anomaly occurs.

[0051] A further technical solution of the present invention is that the communication module is also used to collect the remote signaling status of the bus tie switch when there are multiple common connection points. The edge gateway for preventing backflow of new energy power plants also includes a power calculation module. The power calculation module is used to synthesize the real-time power of each common connection point into a virtual total power of the common connection point when there are multiple common connection points, and then transmit it to the AGVC algorithm module.

[0052] A further technical solution of the present invention includes a human-computer interaction module, which is used to display the anti-reverse flow operation effect and configure and distribute the power generation target parameters used by the AGVC calculation module.

[0053] The beneficial effects of the edge gateway and method for preventing backflow in renewable energy power plants according to this invention are:

[0054] 1. The edge gateway AGVC algorithm module adopts the PID dynamic adjustment strategy, which has the advantages of small adjustment overshoot and small steady-state error compared with the traditional proportional regulation algorithm. The logic programming module can adapt to the scenario of multiple common connection points between new energy power plants and the power grid, thereby realizing the group adjustment and group control of inverters and PCS equipment by the edge gateway.

[0055] 2. Reduce investment in anti-backflow meters and load interval monitoring meters to avoid tripping of the grid-connected switch due to backflow issues caused by the operation of the microprocessor protection device for photovoltaic power. This can effectively improve the photovoltaic utilization efficiency of new energy power plants and the power supply stability of industrial parks.

[0056] 3. The edge gateway has a high degree of integration, replacing the traditional power monitoring system composed of photovoltaic power prediction, remote control devices, protection and control devices, servers, AGVC control master station software, etc., thereby reducing the investment cost of photovoltaic equipment.

[0057] 4. It has a wider range of applications, including industrial and commercial photovoltaic systems with low voltage of 0.4kV grid connection, photovoltaic systems with voltage levels of 10kV and above grid connection, and hybrid power stations containing photovoltaic and energy storage equipment. Attached Figure Description

[0058] Figure 1 This is a flowchart illustrating the first embodiment of the method for preventing backflow in new energy power plants according to the present invention;

[0059] Figure 2 This is a flowchart illustrating the second embodiment of the method for preventing backflow in new energy power plants according to the present invention;

[0060] Figure 3 This is a schematic diagram of the functional modules of the edge gateway for preventing backflow in new energy power plants according to the present invention;

[0061] Figure 4 This is a schematic diagram of the information flow generated by the cooperation between the functional modules of the edge gateway for preventing backflow in new energy power plants according to the present invention;

[0062] Figure 5 This is a schematic diagram of the measurement and control installation of the edge gateway for preventing backflow in new energy power plants in different types of new energy power plants according to the present invention;

[0063] Figure 6 This is a schematic diagram of the wiring method of the edge gateway for preventing backflow in new energy power plants according to the present invention.

[0064] 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. Detailed Implementation

[0065] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0066] This invention proposes a method to prevent backflow in renewable energy power plants, such as... Figure 1 As shown, the first embodiment of the method for preventing backflow in new energy power plants according to the present invention includes the following steps:

[0067] Step S10: Collect the real-time power of the common connection point, as well as the real-time power of the inverter and PCS equipment, and the remote signaling status of the bus tie switch.

[0068] In this embodiment, the method for preventing backflow from renewable energy power plants is applied to an edge gateway for preventing backflow from renewable energy power plants. The edge gateway includes an AC power acquisition module, a power calculation module, a communication module, an AGVC algorithm module, a human-machine interaction module, a data anomaly detection module, a logic programming module, and a safety protection and control module. Figure 3 As shown.

[0069] The AC power acquisition module is installed at the common connection point between the new energy power station and the power grid, and can collect the total active power and the active power of phase A / phase B / phase C at the installation location.

[0070] The AC power acquisition module is used to acquire the real-time power of the common connection point. If it is a single common connection point, it is directly transmitted to the AGVC algorithm module; if it is a multi-common connection point mode, it is transmitted to the power calculation module to synthesize the virtual total power of the common connection point, and then transmitted to the AGVC algorithm module.

[0071] The communication module can connect to inverters and PCS devices through a communication interface, and can collect the active power of each inverter and PCS device in real time. It can also set the active power output of inverters or PCS devices remotely.

[0072] The communication module collects the real-time power of the inverter and PCS equipment and transmits it to the AGVC algorithm module. If there are multiple common connection points, the remote signaling status of the bus tie switch needs to be collected. This is used by the logic programming module to control the AGVC algorithm modules of the main substation and substation to start or stop, adapt to the change in the absorption range after the switching operation, and adjust the group control of the inverter and PCS equipment.

[0073] Step S20: Calculate the load power based on the real-time power of the common connection point, the real-time power of the inverter and PCS equipment, identify the power flow direction, calculate the power generation deviation based on the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment. Real-time data is collected on the execution status of the inverter and PCS equipment, and the adjustment error requirement is met after multiple iterations.

[0074] In this embodiment, the AGVC algorithm module is used to calculate load power, identify power flow direction, calculate power generation deviation according to preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment through the communication module. It also collects the execution status of the inverter and PCS equipment in real time, and reaches the adjustment error requirement after multiple iterations.

[0075] Step S30: If the telemetry and teleindication signals are not refreshed for a long time, it is determined that a communication abnormality has occurred.

[0076] In this embodiment, if the data anomaly detection module detects that the telemetry and teleindication signals have not been refreshed for a long time, it will determine that a communication anomaly has occurred, activate the safety protection control module, and control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating.

[0077] It should be noted that the telemetry signal refers to the active power and voltage signal collected by the AC power acquisition module in step S10, while the telemetry signal refers to the communication status, active power, and active power setting value of each inverter and PCD device collected by the AC power acquisition module in step S10.

[0078] If the meter voltage is below 0.1kV (data is unreliable), the AC power acquisition module is considered to be in an abnormal operating state; if any of the following conditions is met, the inverter or PCS equipment is considered to be in an abnormal operating state: abnormal acquisition of remote signaling signals of inverter, PCS equipment, shutdown or standby status; if the communication status of the AC power acquisition module, inverter, or PCS equipment is interrupted, the communication module is considered to be in an abnormal acquisition state.

[0079] Step S40: When a communication anomaly occurs, control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating.

[0080] In this embodiment, when a communication anomaly occurs, the safety protection module controls the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating.

[0081] The safety protection module can reduce the active power of the photovoltaic or energy storage power station by a percentage of the total capacity. This percentage can be set, usually 10%, or the group control inverter and PCS equipment can stop operating. After the abnormal signal is restored, the AGVC algorithm module is activated to restore the active power of the inverter and PCS equipment.

[0082] based on Figure 1 The first embodiment shown presents a second embodiment of the method for preventing backflow in renewable energy power plants, as described in the first embodiment. Figure 2 As shown, in this embodiment, after step S10, the method further includes:

[0083] Step S101: Determine whether the common connection point is a single common connection point or multiple common connection points. If it is a single common connection point, proceed directly to step S20; if it is multiple common connection points, proceed to step S102.

[0084] In step S101, the number of common connection points is determined based on the connection method between the new energy power station and the power grid.

[0085] Step S102: Combine the real-time power of each common connection point into the virtual total power of the common connection point.

[0086] Step S102 includes:

[0087] The active power collected from each common coupling point is summed to synthesize the virtual total power of the common coupling point. The calculation formula is as follows:

[0088] ,

[0089] in, Virtual total power for the common connection point, Let N be the active power at the nth common coupling point, and N be the number of common coupling points participating in regulation.

[0090] Step S103: Based on the remote signaling status of the bus tie switch, start the control of different AGVC substations, inverters, and PCS equipment.

[0091] The control strategy in step S103 follows the principle of minimizing grouping. Step S103 specifically includes:

[0092] Step S1031: If the new energy power station is connected to the power grid via a single busbar and has only one common connection point, then only one AGVC substation needs to participate in the calculation and allocation. All inverters or PCS devices are connected to this substation, and the process proceeds directly to step S20.

[0093] Step S1032: If the new energy power plant and the power grid have multiple common connection points, and a single bus segmented connection method is used, the inverters or PCS equipment are grouped into substations according to the remote signaling status of the bus tie switch. The principle of minimizing substation grouping is as follows: when the high-voltage side bus tie switch status is a split position signal, the number of substations is divided according to the number of common connection points. Each substation is only connected to inverters or PCS equipment that can cause reverse current at that common connection point. This type of substation is marked as a substation. When the high-voltage side bus tie switch status is a closed position signal, all inverters or PCS equipment of the entire new energy power plant need to be connected to the same substation. This type of substation is marked as a main substation.

[0094] In step S1033, the edge gateway logic programming function module has logic controls. The AGVC algorithm module of the substation is started or stopped by the state of the high-voltage side bus tie switch. When the state of the high-voltage side bus tie switch is the open position signal, the AGVC algorithm module of the substation runs independently and the AGVC algorithm module of the main substation stops running. When the state of the high-voltage side bus tie switch is the closed position signal, the AGVC algorithm module of the substation stops running and the AGVC algorithm module of the main substation starts running.

[0095] In this embodiment, the preset power generation target parameters in step S20 include: "maximum active power allowed to feed into the grid", "safety margin of power fed into the grid", "adjustment dead zone" and "adjustment response delay time".

[0096] Among them, "the maximum active power allowed to be fed to the grid" refers to the maximum instantaneous reverse power that the grid can withstand due to the reverse flow caused by the rapid disconnection of loads; "the safety margin of the power fed to the grid" affects the utilization rate of photovoltaic power generation, and also affects the amount of electricity purchased from the grid by the new energy power plant during operation.

[0097] Step S20 includes:

[0098] In step S201, the edge gateway AGVC algorithm module determines the direction of active power at the point of common connection, taking the direction of the power grid flowing to the new energy power station as the positive direction. The ultimate goal of anti-backflow is to ensure that the direction of active power at this point is always positive and the value should always be greater than 0kW.

[0099] In step S202, the edge gateway AGVC algorithm module calculates the target value of active power to be fed into the power grid based on preset power generation target parameters. The calculation formula is as follows:

[0100] ，

[0101] in, To feed the target value of active power to the power grid, To allow the maximum active power to be fed into the power grid, This is to provide a safety margin for the power supplied to the power grid.

[0102] Step S203: Calculate the difference between the virtual total power at the point of common coupling and the target value of the active power of the feeder grid. ,like If the value is greater than the adjustment dead zone and the holding time is greater than the adjustment response delay time, then proceed to step S204.

[0103] Step S204: Using the collected active power of the inverter or PCS equipment, calculate the sum of the actual output active power of the inverter equipment or the discharge power of the PCS. The calculation formula is as follows:

[0104] ,

[0105] in, Let i be the sum of the actual power of the inverter at time i. Let N be the actual active power output of the nth inverter or PCS device at time i, and N be the number of inverters participating in the regulation.

[0106] In step S205, the edge gateway AGVC algorithm module allocates the target active power value of the inverters or PCS devices participating in the regulation at the next moment, and sends it to each inverter or PCS device through remote adjustment commands. Based on the rated power of each inverter or PCS device, the adjustment priority is set, prioritizing the adjustment of inverters and PCS devices with larger adjustable capacity, and providing the adjustment rate. For inverters or PCS devices with the same priority, the power allocation is proportionally distributed according to the rated power, as shown in the following formula:

[0107] ,

[0108] in, It is the output power allocated to the nth inverter. It is the rated power of the nth inverter. It is the sum of the rated power of all inverters. yes The remaining target power after the high-priority inverters have been fully configured.

[0109] Step S206: The communication module synchronously samples the execution status of the inverter or PCS equipment and calculates the total actual power of the inverter or PCS equipment at time i+1. The calculation formula is as follows:

[0110] ,

[0111] in, This represents the total actual power of the inverter at time i+1. Let N be the actual active power output of the nth inverter or PCS device at time i+1, where N is the number of inverters participating in the regulation.

[0112] Step S207: The AGVC algorithm module calculates the adjustment error using the following formula:

[0113] .

[0114] In step S208, the AGVC algorithm module performs error verification. If the adjustment accuracy requirement is met, it stops sending new active power target values ​​to the inverters and waits for the adjustment interval period to end before proceeding to step S10. If the accuracy requirement is not met, it re-enters step S202 to calculate a new round of active power target values ​​for each inverter.

[0115] In this embodiment, the method further includes the following after step S40:

[0116] Step S50: Modify the preset power generation target parameters and demonstrate the anti-reverse flow operation effect.

[0117] In this embodiment, the edge gateway also includes a human-machine interface module (HMI) for displaying the anti-reverse flow operation effect and configuring the power generation target parameters used by the AGVC calculation module. The HMI module has a built-in touchscreen output and can be remotely accessed via a web browser. It acquires real-time data through the edge gateway's internal interface and generates an operation screen using a graphical model generation method. The operation screen includes, but is not limited to, the following interfaces: the main wiring diagram of the new energy power plant, the power generation target parameter configuration interface, the anti-reverse flow operation effect such as the inverter and PCS power generation curves, and AGVC control command issuance records.

[0118] In this embodiment, after step S40, the method further includes: when the data anomaly detection module detects that the communication status has returned to normal, the AGVC algorithm module is put into operation, and the power generation of the inverter or PCS is gradually increased according to the power generation target value and the adjustment gradient.

[0119] The beneficial effects of the method for preventing backflow in renewable energy power plants according to the present invention are:

[0120] 1. The edge gateway AGVC algorithm module adopts the PID dynamic adjustment strategy, which has the advantages of small adjustment overshoot and small steady-state error compared with the traditional proportional regulation algorithm. The logic programming module can adapt to the scenario of multiple common connection points between new energy power plants and the power grid, thereby realizing the group adjustment and group control of inverters and PCS equipment by the edge gateway.

[0121] 2. Reduce investment in anti-backflow meters and load interval monitoring meters to avoid tripping of the grid-connected switch due to backflow issues caused by the operation of the microprocessor protection device for photovoltaic power. This can effectively improve the photovoltaic utilization efficiency of new energy power plants and the power supply stability of industrial parks.

[0122] 3. The edge gateway has a high degree of integration, replacing the traditional power monitoring system composed of photovoltaic power prediction, remote control devices, protection and control devices, servers, AGVC control master station software, etc., thereby reducing the investment cost of photovoltaic equipment.

[0123] 4. It has a wider range of applications, including industrial and commercial photovoltaic systems with low voltage of 0.4kV grid connection, photovoltaic systems with voltage levels of 10kV and above grid connection, and hybrid power stations containing photovoltaic and energy storage equipment.

[0124] To address the aforementioned technical problems, this invention also proposes an edge gateway to prevent backflow from renewable energy power plants, such as... Figure 3 As shown, the edge gateway for preventing backflow in new energy power plants according to the present invention includes: an AC power acquisition module, a communication module, an AGVC algorithm module, a data anomaly detection module, a logic programming module, and a safety protection and control module.

[0125] The AC power acquisition module is used to acquire the real-time active power of the point of common coupling; the communication module is used to acquire the real-time power of the inverter and PCS equipment.

[0126] The AGVC algorithm module is used to calculate the load power based on the real-time power of the common connection point, the inverter, and the PCS equipment, identify the power flow direction, calculate the power generation deviation according to the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment through the communication module. It also collects the execution status of the inverter and PCS equipment in real time, and reaches the adjustment error requirement after multiple iterations.

[0127] The data anomaly detection module is used to monitor the refresh status of telemetry and teleindication signals. If the telemetry and teleindication signals are not refreshed, it is determined that a communication anomaly has occurred.

[0128] The safety protection control module is used to control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operation when a communication anomaly occurs.

[0129] The communication module is also used to collect the remote signaling status of the bus tie switch when there are multiple common connection points. The edge gateway for preventing backflow of new energy power plants also includes a power calculation module. The power calculation module is used to synthesize the real-time power of each common connection point into a virtual total power of the common connection point when there are multiple common connection points, and then transmit it to the AGVC algorithm module.

[0130] The edge gateway for preventing backflow at new energy power plants also includes a human-machine interaction module, which is used to display the backflow prevention operation effect and configure and distribute the power generation target parameters used by the AGVC calculation module.

[0131] The information flow between the modules of the edge gateway of this invention is shown in the appendix. Figure 4As shown, the AC power acquisition module collects the real-time power of the point of common coupling (PCC). If there is a single PCC, it is directly transmitted to the AGVC algorithm module; if there are multiple PCCs, it is transmitted to the power calculation module to synthesize the virtual total power of the PCCs, and then transmitted to the AGVC algorithm module. The communication module collects the real-time power of the inverter and PCS equipment and transmits it to the AGVC algorithm module. If there are multiple PCCs, it needs to collect the remote signaling status of the bus tie switch, which is used by the logic programming module to control the start or stop of the AGVC algorithm modules of the main substation and substations, adapting to the change in the absorption range after switching operations and adjusting the group control of the inverter and PCS equipment. The AGVC algorithm module is used to calculate the load power, identify the power flow direction, calculate the power generation deviation according to the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment through the communication module. It also collects the execution status of the inverter and PCS equipment in real time, and after multiple iterations, it reaches the adjustment error requirement. If the data anomaly detection module detects that telemetry and tele-signaling signals have not been refreshed for an extended period, it determines that a communication anomaly has occurred and activates the safety protection control module. This module then controls the inverter and PCS equipment to operate at reduced capacity or shut down. The human-machine interface module displays the anti-reverse flow operation effect, such as inverter and PCS power generation curves, AGVC control command issuance records, etc., and can also configure and issue power generation target parameters used by the AGVC module.

[0132] This invention relates to an edge gateway for preventing backflow in renewable energy power plants. It is applicable to low-voltage (0.4kV) grid-connected industrial and commercial photovoltaic systems, photovoltaic systems with voltage levels of 10kV and above, and hybrid power plants containing both photovoltaic and energy storage devices, as shown in the attached diagram. Figure 5 This diagram illustrates the installation of an edge gateway for measurement and control in different types of new energy power plants.

[0133] Appendix Figure 6 The edge gateway wiring diagram for preventing backflow in renewable energy power plants is shown in this invention. The common connection point between the renewable energy power plant and the power grid is located on the low-voltage side of the transformer. These connection points are the anti-backflow points, totaling 4. Among them, the inverters in photovoltaic 1 are numbered (A1, A2...An), with a total of n units; the inverters in photovoltaic 2 are numbered (B1, B2...Bm), with a total of m units; the PCS devices in energy storage 1 are numbered (C1, C2...Ci), with a total of i units; and the PCS devices in energy storage 2 are numbered (D1, D2...Dj), with a total of j units.

[0134] The technical solution for preventing backflow from renewable energy power plants in this invention, using an edge gateway, primarily involves the edge gateway's AC acquisition module collecting the active power at the common connection point between the renewable energy power plant and the power grid. Specifically, it collects the active power P1, P2, P3, and P4 from the low-voltage side inlets of the four transformers on the 0.4kV bus.

[0135] When bus tie switch 1 is in the open position, the reverse current protection point 1 only covers the inverter of photovoltaic 1 and other loads on that bus section; the reverse current protection point 2 only covers the inverter of photovoltaic 2 and other loads on that bus section; when bus tie switch 1 is in the closed position, the reverse current protection point 1 and reverse current protection point 2 cover the inverters of photovoltaic 1 and photovoltaic 2 and all loads on both bus sections.

[0136] The same applies to bus tie switch 2 and bus tie switch 1.

[0137] The power calculation module needs to synthesize a virtual total power for use in the AGVC algorithm module calculation. The calculation formula is as follows:

[0138] ,

[0139] in, Virtual total power for the common connection point, Let N be the active power at the nth common coupling point, and N be the number of common coupling points participating in regulation.

[0140] The present invention requires calculation , .

[0141] Inverters numbered A1, A2...An are grouped into one group and bound to AGVC substation 1 (substation type); inverters numbered B1, B2...Bm are grouped into one group and bound to AGVC substation 2 (substation type); PCS devices numbered C1, C2...Ci are grouped into one group and bound to AGVC substation 3 (substation type); devices numbered D1, D2...Dj are grouped into one group and bound to AGVC substation 4 (substation type); inverters numbered A1, A2...An and inverters numbered B1, B2...Bm are combined into one group and bound to AGVC substation 5 (main substation type); PCS devices numbered C1, C2...Ci and PCS devices numbered D1, D2...Dj are combined into one group and bound to AGVC substation 6 (main substation type).

[0142] The logic programming function module has logic controls. In this invention, the position signal of bus tie switch 1 is collected. If the signal is in the open position, the AGVC algorithm modules of AGVC substation 1 and AGVC substation 2 are triggered to start running, and the AGVC algorithm module of AGVC substation 5 stops running. When the signal is in the closed position, the AGVC algorithm modules of AGVC substation 1 and AGVC substation 2 are triggered to stop running, and the AGVC algorithm module of AGVC substation 5 starts running.

[0143] The position signal of bus tie switch 2 is collected. If the signal is in the open position, the AGVC algorithm modules of AGVC substations 3 and 4 are triggered to start running, while the AGVC algorithm module of AGVC substation 6 stops running. When the signal is in the closed position, the AGVC algorithm modules of AGVC substations 3 and 4 are triggered to stop running, while the AGVC algorithm module of AGVC substation 6 starts running.

[0144] Through the above steps, the logic programming module can dynamically identify changes in the absorption range during the bus switching operation of a new energy power plant, and control the inverters and PCS equipment involved in the regulation within a minimum range, thereby adapting to the switching of power generation target values ​​under different operating conditions.

[0145] The AGVC algorithm module calculates load power, identifies power flow direction, calculates power generation deviation based on preset power generation target parameters, dynamically adjusts the power generation plan, and sends the data to the inverter and PCS equipment via the communication module. The algorithm allocation method is as follows: Figure 1 and Figure 2 As shown.

[0146] The data anomaly detection module monitors the communication status in real time. The safety protection control module is used to deal with special situations where the load changes drastically and the AGVC module cannot adjust in time. It controls the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating. When the data anomaly detection module detects that the communication status has returned to normal, the AGVC algorithm module is put into operation and gradually increases the power generation of the inverter or PCS according to the power generation target value and the adjustment gradient.

[0147] The edge gateway's human-machine interaction module has a built-in touchscreen output and can be remotely accessed via a web browser. The human-machine interaction module obtains real-time data through the edge gateway's internal interface and generates a running screen using a graphical model generation method.

[0148] The beneficial effects of this invention on the edge gateway for preventing backflow in renewable energy power plants are:

[0149] 1. The edge gateway AGVC algorithm module adopts the PID dynamic adjustment strategy, which has the advantages of small adjustment overshoot and small steady-state error compared with the traditional proportional regulation algorithm. The logic programming module can adapt to the scenario of multiple common connection points between new energy power plants and the power grid, thereby realizing the group adjustment and group control of inverters and PCS equipment by the edge gateway.

[0150] 2. Reduce investment in anti-backflow meters and load interval monitoring meters to avoid tripping of the grid-connected switch due to backflow issues caused by the operation of the microprocessor protection device for photovoltaic power. This can effectively improve the photovoltaic utilization efficiency of new energy power plants and the power supply stability of industrial parks.

[0151] 3. The edge gateway has a high degree of integration, replacing the traditional power monitoring system composed of photovoltaic power prediction, remote control devices, protection and control devices, servers, AGVC control master station software, etc., thereby reducing the investment cost of photovoltaic equipment.

[0152] 4. It has a wider range of applications, including industrial and commercial photovoltaic systems with low voltage of 0.4kV grid connection, photovoltaic systems with voltage levels of 10kV and above grid connection, and hybrid power stations containing photovoltaic and energy storage equipment.

[0153] The above description is only a preferred embodiment of the present invention and does not limit the scope of the invention. Any equivalent structural or procedural changes made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of protection of the present invention.

Claims

1. A method for preventing backflow in renewable energy power plants, characterized in that, The method includes the following steps: Step S10: Collect the real-time power of the point of common coupling, as well as the real-time power of the inverter and PCS equipment, and the remote signaling status of the bus tie switch; Step S20: Calculate the load power based on the real-time power of the common connection point, the real-time power of the inverter and the PCS equipment, identify the power flow direction, calculate the power generation deviation based on the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and the PCS equipment. Real-time data is collected on the execution status of the inverter and the PCS equipment. After multiple iterations, the adjustment error requirement is met. Step S30: If the telemetry and teleindication signals are not refreshed for a long time, it is determined that a communication abnormality has occurred. Step S40: When a communication anomaly occurs, control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operating. The preset power generation target parameters in step S20 include: "maximum active power allowed to be fed into the grid", "safety margin of power fed into the grid", "adjustment dead zone" and "adjustment response delay time"; Among them, "the maximum active power allowed to be fed to the grid" refers to the maximum instantaneous reverse power that the grid can withstand due to reverse flow caused by rapid load shedding; "the safety margin of power fed to the grid" affects the utilization rate of photovoltaic power generation, and also affects the amount of electricity purchased from the grid by the new energy power plant during operation. Step S20 includes: Step S201: Determine the direction of active power at the point of common coupling. The direction of the power grid flowing to the new energy power station is taken as the positive direction. The ultimate goal of anti-backflow is to ensure that the direction of active power at this point is always positive and the value should always be greater than 0kW. Step S202: Calculate the target value of active power to be fed into the power grid based on the preset power generation target parameters. The calculation formula is as follows: in, To feed the target value of active power to the power grid, To allow the maximum active power to be fed into the power grid, To ensure a safety margin for the power supplied to the power grid; Step S203: Calculate the difference between the virtual total power at the point of common coupling and the target value of the active power of the feeder grid. ,like If the value is greater than the adjustment dead zone and the holding time is greater than the adjustment response delay time, then proceed to step S204. Step S204: Using the collected active power of the inverter or PCS equipment, calculate the sum of the actual output active power of the inverter equipment or the discharge power of the PCS. The calculation formula is as follows: in, Let i be the sum of the actual power of the inverter at time i. Let N be the actual active power output of the nth inverter or PCS device at time i, and N be the number of inverters participating in the regulation. Step S205: Allocate the target active power value for the inverters or PCS devices participating in the next moment of regulation, and send it to each inverter or PCS device via remote adjustment command. Based on the rated power of each inverter or PCS device, set the adjustment priority, prioritizing the adjustment of inverters and PCS devices with larger adjustable capacity to increase the adjustment rate. For inverters or PCS devices with the same priority, the power allocation is proportionally distributed according to the rated power, as shown in the following formula: in, It is the output power allocated to the nth inverter. It is the rated power of the nth inverter. It is the sum of the rated power of all inverters. yes The remaining target power after the high-priority inverters have been fully configured; Step S206: Synchronously track the execution status of the inverter or PCS equipment, and calculate the total actual power of the inverter or PCS equipment at time i+1. The calculation formula is as follows: in, This represents the total actual power of the inverter at time i+1. The actual active power output of the nth inverter or PCS device at time i+1 is N, where N is the number of inverters participating in the regulation. Step S207, calculate the adjustment error, the calculation formula is as follows: | In step S208, error verification is performed. If the adjustment accuracy requirements are met, the issuance of new active power target values ​​to the inverters is stopped, and the adjustment interval period is waited for to end before proceeding to step S10. If the accuracy requirements are not met, the process is restarted in step S202 to calculate the active power target values ​​for each inverter in a new round.

2. The method for preventing backflow in new energy power plants according to claim 1, characterized in that, The process following step S10 also includes: Step S101: Determine whether the common connection point is a single common connection point or multiple common connection points. If it is a single common connection point, proceed directly to step S20; if it is multiple common connection points, proceed to step S102. Step S102: Combine the real-time power of each common connection point into the virtual total power of the common connection point; Step S103: Based on the remote signaling status of the bus tie switch, start the control of different AGVC substations, inverters, and PCS equipment.

3. The method for preventing backflow in new energy power plants according to claim 2, characterized in that, The control strategy in step S103 follows the principle of minimizing grouping; step S103 specifically includes: Step S1031: If the new energy power station is connected to the power grid via a single busbar and has only one common connection point, then only one AGVC substation needs to participate in the calculation and allocation. All inverters or PCS devices are connected to this substation, and the process proceeds directly to step S20. Step S1032: If the new energy power plant and the power grid have multiple points of common connection, the inverters or PCS equipment are grouped into substations according to the remote signaling status of the bus tie switch. The principle of minimizing substation grouping is as follows: when the high-voltage side bus tie switch status is a split position signal, the number of substations is divided according to the number of points of common connection. Each substation is only connected to inverters or PCS equipment that can cause reverse current at that point of common connection. This type of substation is marked as a substation. When the high-voltage side bus tie switch status is a closed position signal, all inverters or PCS equipment of the new energy power plant need to be connected to the same substation. This type of substation is marked as a main substation. Step S1033: The AGVC algorithm module of the substation is started or stopped by the status of the high-voltage side bus tie switch. When the status of the high-voltage side bus tie switch is the open position signal, the substation operates independently and the main substation stops operating; when the status of the high-voltage side bus tie switch is the closed position signal, the substation stops operating and the main substation starts operating.

4. The method for preventing backflow in new energy power plants according to claim 3, characterized in that, Step S101 specifically includes: determining the number of common connection points based on the connection method between the new energy power station and the power grid.

5. The method for preventing backflow in new energy power plants according to claim 4, characterized in that, Step S102 includes: The active power collected from each common coupling point is summed to synthesize the virtual total power of the common coupling point. The calculation formula is as follows: in, Virtual total power for the common connection point, Let N be the active power at the nth common coupling point, and N be the number of common coupling points participating in regulation.

6. The method for preventing backflow in new energy power plants according to claim 1, characterized in that, The process following step S40 also includes: Step S50: Modify the preset power generation target parameters and demonstrate the anti-reverse flow operation effect.

7. An edge gateway for preventing backflow from renewable energy power plants, characterized in that, include: AC power acquisition module, communication module, AGVC algorithm module, data anomaly detection module, logic programming module and safety protection and control module; The AC power acquisition module is used to acquire the real-time active power of the point of common coupling; the communication module is used to acquire the real-time power of the inverter and PCS equipment. The AGVC algorithm module is used to calculate the load power based on the real-time power of the common connection point, the inverter, and the PCS equipment, identify the power flow direction, calculate the power generation deviation according to the preset power generation target parameters, dynamically adjust the power generation plan, and send it to the inverter and PCS equipment through the communication module. It also collects the execution status of the inverter and PCS equipment in real time, and reaches the adjustment error requirement after multiple iterations. The data anomaly detection module is used to monitor the refresh status of telemetry and teleindication signals. If the telemetry and teleindication signals are not refreshed, it is determined that a communication anomaly has occurred. The safety protection control module is used to control the inverter and PCS equipment to operate at a reduced capacity percentage or stop operation when a communication anomaly occurs. The preset power generation target parameters include: "maximum active power allowed to be fed into the grid", "safety margin of power fed into the grid", "adjustment dead zone" and "adjustment response delay time"; Among them, "the maximum active power allowed to be fed to the grid" refers to the maximum instantaneous reverse power that the grid can withstand due to reverse flow caused by rapid load shedding; "the safety margin of power fed to the grid" affects the utilization rate of photovoltaic power generation, and also affects the amount of electricity purchased from the grid by the new energy power plant during operation. The AGVC algorithm module calculates the load power based on the real-time power of the common connection point, the inverter, and the PCS equipment, identifies the power flow direction, calculates the power generation deviation according to preset power generation target parameters, dynamically adjusts the power generation plan, and sends it to the inverter and PCS equipment through the communication module. It also collects real-time data on the execution status of the inverter and PCS equipment. The steps to achieve the adjustment error requirement after multiple iterations include: To determine the direction of active power at the point of common coupling, the direction of the power grid flowing towards the new energy power station is taken as the positive direction. The ultimate goal of preventing backflow is to ensure that the direction of active power at this point is always positive and that the value is always greater than 0kW. The active power target value for feeding into the power grid is calculated based on the preset power generation target parameters. The calculation formula is as follows: in, To feed the target value of active power to the power grid, To allow the maximum active power to be fed into the power grid, To ensure a safety margin for the power supplied to the power grid; Calculate the difference between the virtual total power at the point of common coupling and the target value of the active power of the feeder grid. ,like If the active power exceeds the regulation dead zone and the holding time exceeds the regulation response delay time, then the active power of the inverter or PCS device is used to calculate the sum of the actual output active power of the inverter device or the discharge power of the PCS. The calculation formula is as follows: in, Let i be the sum of the actual power of the inverter at time i. Let N be the actual active power output of the nth inverter or PCS device at time i, and N be the number of inverters participating in the regulation. The target active power value for the inverters or PCS devices participating in the next moment of regulation is allocated and sent to each inverter or PCS device via remote control command. Based on the rated power of each inverter or PCS device, a regulation priority is set, prioritizing the regulation of inverters and PCS devices with larger adjustable capacities and providing a regulation rate. For inverters or PCS devices with the same priority, power allocation is carried out proportionally according to the rated power, as shown in the following formula: in, It is the output power allocated to the nth inverter. It is the rated power of the nth inverter. It is the sum of the rated power of all inverters. yes The remaining target power after the high-priority inverters have been fully configured; To synchronize the execution status of the inverter or PCS equipment, calculate the total actual power of the inverter or PCS equipment at time i+1. The calculation formula is as follows: in, This represents the total actual power of the inverter at time i+1. The actual active power output of the nth inverter or PCS device at time i+1 is N, where N is the number of inverters participating in the regulation. The adjustment error is calculated using the following formula: | If the error is checked and the adjustment accuracy requirement is met, the new active power target value is stopped from being sent to the inverter. The adjustment interval period ends and then the process proceeds to step S10. If the accuracy requirement is not met, the process proceeds to step S202 to calculate the active power target value for each inverter in a new round.

8. The edge gateway for preventing backflow from renewable energy power plants according to claim 7, characterized in that, The communication module is also used to collect the remote signaling status of the bus tie switch when there are multiple common connection points. The edge gateway for preventing backflow of new energy power plants also includes a power calculation module. The power calculation module is used to synthesize the real-time power of each common connection point into a virtual total power of the common connection point when there are multiple common connection points, and then transmit it to the AGVC algorithm module.

9. The edge gateway for preventing backflow from renewable energy power plants according to claim 8, characterized in that, It also includes a human-computer interaction module, which is used to display the anti-reverse flow operation effect and configure and distribute the power generation target parameters used by the AGVC calculation module.

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