A grid connection device and method for a power generation vehicle / generator set suitable for different voltage levels

Abstract

This invention relates to the field of power generation grid connection technology, specifically a grid connection device and method applicable to generator vehicles / generator sets at different voltage levels. It includes the following steps: S1, the grid voltage sampling module of the main grid connection device collects the grid voltage signal and transmits it to the main control module; S2, the main control module performs filtering and noise reduction, analog-to-digital conversion, and RMS value calculation on the collected grid voltage signal to obtain an accurate digital voltage value; S3, the grid voltage identification module receives the digital voltage value transmitted by the main control module and compares it with a preset standard voltage range to determine the voltage level; S4, the main control module automatically switches the device's internal parameters based on the determined voltage level, including sampling range, protection threshold, voltage and frequency regulation target values, grid connection control logic, and communication protocol parameters, completing the adaptive matching of the device with the current grid voltage level and entering grid connection preparation. Compared with existing technologies, it can automatically adapt to 10kV / 400V voltage levels, offers flexible sampling and disassembly / reassembly, and has high versatility.

Description

Technical Field

[0001] This invention relates to the field of power generation grid connection technology, specifically to a grid connection device and method applicable to generator vehicles / generator sets of different voltage levels. Background Technology

[0002] In scenarios of emergency power supply, temporary power supply and grid fault repair, grid connection between generator trucks / generator sets and the mains power is a common power supply guarantee method. However, existing grid connection technologies have many technical defects and application limitations: existing grid connection devices can only be adapted to a single voltage level grid and cannot simultaneously meet the grid connection requirements of 10kV high voltage and 400V low voltage grids. Different devices are required, resulting in poor versatility. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, this invention provides a grid connection device and method applicable to generator cars / generator sets of different voltage levels.

[0004] To achieve the above objectives, a grid connection method for generator trucks / generator sets applicable to different voltage levels is designed, including the following steps: S1, the grid voltage sampling module of the grid-connected main unit collects the grid voltage signal and transmits it to the main control module. S2, the main control module performs filtering and noise reduction, analog-to-digital conversion, and RMS value calculation on the acquired power grid voltage signal to obtain an accurate digital voltage quantity; S3, the power grid voltage identification module receives the digital voltage value transmitted by the main control module, compares it with the preset standard voltage range, and determines the voltage level; S4, the main control module automatically switches the internal parameters of the device according to the determined voltage level, completes the adaptive matching of the device with the current grid voltage level, and enters the grid connection preparation stage; S5, the voltage acquisition and comparison module of the grid-connected sub-device acquires the output voltage, frequency signal and phase parameters of the generator side in real time, and transmits the data to the grid-connected main device; S6, the grid-connected main unit receives data and compares the grid voltage and frequency parameters with the parameters of the generation side. It performs phase synchronization calculation through the frequency and voltage regulation interactive command control module, generates frequency and voltage regulation control commands, and then sends them to the frequency and voltage regulation execution module of the sub-unit through the communication module to drive the generation side to adjust the output parameters. S7, the grid-connected main unit performs synchronous detection of parameters on the generation side and the grid side. When the voltage deviation is ≤ ±5%, the frequency deviation is ≤ ±0.2Hz, the phase deviation is ≤ ±5° and the phase sequence is consistent, it is determined that the parameters are completely matched. S8, when the parameters are fully matched, the main control module of the grid-connected main unit issues an instruction to close the mains power supply switch and restore the mains power supply to the field load; at the same time, it issues a grid-connected trip instruction, and the grid-connected sub-unit on the generator side drives the grid-connected switch to trip, cutting off the connection between the generator side and the mains power. S9, the grid-connected main unit issues a shutdown command, and the power generation side gradually reduces the output power to 0kW to complete the shutdown.

[0005] The power generation side includes one or more of the following: a power generation vehicle and a generator set.

[0006] In step S1, the acquired signal includes the effective voltage value, frequency, phase, and waveform characteristics.

[0007] The specific method of step S3 is as follows: if the digital voltage value falls within the range of 360V to 440V, it is determined to be a 400V low-voltage power grid; if it falls within the range of 9.5kV to 11.5kV, it is determined to be a 10kV high-voltage power grid; if it does not fall within any range, it is determined to be abnormal and an abnormal signal is issued.

[0008] The internal parameters of the device in step S4 include sampling range, overvoltage protection threshold, undervoltage protection threshold, overfrequency protection threshold, underfrequency protection threshold, voltage regulation target value, frequency regulation target value, grid connection control logic, and communication protocol baud rate.

[0009] The grid-connected main device is clamped to the grid connection line by a detachable sampling clip. The generator truck / generator set on the power generation side arrives at the site and is electrically connected to the load end.

[0010] It also includes step S8, where the status monitoring module of the grid-connected main unit monitors the mains power supply status and the unit shutdown process in real time to ensure safe and orderly operation.

[0011] To achieve the above objectives, a device is designed for grid connection of generator vehicles / generator sets applicable to different voltage levels, comprising: A grid-connected main unit is installed on the grid side, and a grid-connected sub-unit is installed on at least one power generation side. The grid-connected main unit and the grid-connected sub-unit are communicatively connected. The grid-connected main device includes: The main control module is used to exchange data with other modules and send control commands to the grid connection execution module on the power generation side. The power grid voltage sampling module is used to collect power grid voltage signals and transmit them to the main control module. The power grid voltage identification module is used to identify the power grid voltage level and feed it back to the main control module.

[0012] The grid-connected sub-device includes a grid-connected execution module, which receives control commands sent from the grid side and executes the grid-connected operation.

[0013] The grid-connected main device on the grid side also includes: The voltage comparison module is used to compare parameters between the grid side and the generation side; The frequency modulation and voltage regulation interactive command control module is used to generate frequency modulation and voltage regulation control commands; The status monitoring module is used to monitor the operating status of the grid side and all grid-connected sub-devices in real time; The main communication module is used for communication connection with the grid-connected sub-devices; The grid-connection sub-device on the power generation side also includes: The frequency and voltage regulation execution module adjusts the output parameters on the power generation side according to the frequency and voltage regulation commands; The voltage acquisition module is used to acquire the output parameters of the generator side in real time and transmit them to the grid-connected main unit; The status feedback module is used to transmit the real-time operating status data of the power generation side to the grid-connected main unit; The communication submodule is used for communication connection with the grid-connected main unit.

[0014] Compared with the prior art, the present invention adopts a master-slave architecture of grid-connected main device at the grid end and grid-connected control sub-device pre-installed at the generator vehicle / generator set end. It can automatically adapt to 10kV / 400V voltage levels, and has flexible sampling, disassembly and assembly, and high versatility. Attached Figure Description

[0015] Figure 1 This is a diagram of the architecture of the present invention.

[0016] Figure 2 This is a schematic diagram of the grid-connected main device of the present invention.

[0017] Figure 3 This is a schematic diagram of the grid-connected sub-device of the present invention.

[0018] Figure 4 This is a schematic diagram of the connection on the power generation side of the present invention.

[0019] Figure 5 This is a schematic diagram of the connection on the power grid side of the present invention. Detailed Implementation

[0020] The present invention will now be further described with reference to the accompanying drawings.

[0021] like Figures 1 to 5 As shown, this embodiment provides a grid connection method for generator trucks / generator sets applicable to different voltage levels, including the following steps: S1, the grid voltage sampling module of the grid-connected main unit collects the grid voltage signal and transmits it to the main control module. S2, the main control module performs filtering and noise reduction, analog-to-digital conversion, and RMS value calculation on the acquired power grid voltage signal to obtain an accurate digital voltage quantity; S3, the power grid voltage identification module receives the digital voltage value transmitted by the main control module, compares it with the preset standard voltage range, and determines the voltage level; S4, the main control module automatically switches the internal parameters of the device according to the determined voltage level, completes the adaptive matching of the device with the current grid voltage level, and enters the grid connection preparation stage; S5, the voltage acquisition and comparison module of the grid-connected sub-device acquires the output voltage, frequency signal and phase parameters of the generator side in real time, and transmits the data to the grid-connected main device; S6, the grid-connected main unit receives data and compares the grid voltage and frequency parameters with the parameters of the generation side. It performs phase synchronization calculation through the frequency and voltage regulation interactive command control module, generates frequency and voltage regulation control commands, and then sends them to the frequency and voltage regulation execution module of the sub-unit through the communication module to drive the generation side to adjust the output parameters. S7, the grid-connected main unit performs synchronous detection of parameters on the generation side and the grid side. When the voltage deviation is ≤ ±5%, the frequency deviation is ≤ ±0.2Hz, the phase deviation is ≤ ±5° and the phase sequence is consistent, it is determined that the parameters are completely matched. S8, when the parameters are fully matched, the main control module of the grid-connected main unit issues an instruction to close the mains power supply switch and restore the mains power supply to the field load; at the same time, it issues a grid-connected trip instruction, and the grid-connected sub-unit on the generator side drives the grid-connected switch to trip, cutting off the connection between the generator side and the mains power. S9, the grid-connected main unit issues a shutdown command, and the power generation side gradually reduces the output power to 0kW to complete the shutdown.

[0022] S10, the status monitoring module of the grid-connected main unit, monitors the status of the mains power supply and the unit shutdown process in real time to ensure safe and orderly operation.

[0023] The power generation side includes one or more of the following: power generation vehicles and generator sets.

[0024] In step S1, the acquired signals include the effective voltage value, frequency, phase, and waveform characteristics.

[0025] The specific method for step S3 is as follows: if the digital voltage value falls within the range of 360V to 440V, it is determined to be a 400V low-voltage power grid; if it falls within the range of 9.5kV to 11.5kV, it is determined to be a 10kV high-voltage power grid; if it does not fall within any range, it is determined to be abnormal and an abnormal signal is issued.

[0026] The internal parameters of the device in step S4 include the sampling range, overvoltage protection threshold, undervoltage protection threshold, overfrequency protection threshold, underfrequency protection threshold, voltage regulation target value, frequency regulation target value, grid connection control logic, and communication protocol baud rate. In actual use, the parameters such as the sampling range, protection threshold, voltage and frequency regulation target value, grid connection control logic, and communication protocol baud rate corresponding to the 10kV and 400V voltage levels are all preset in advance in the main control module of the grid-connected main device according to PLC programming. The range values ​​of each parameter are set in combination with power industry standards and on-site grid connection operation requirements. In this embodiment, the preset ranges for each parameter are as follows: the sampling range for the 400V low-voltage grid is 0~600V AC, and the sampling range for the 10kV high-voltage grid is 0~15kV AC, adapting to grid voltage fluctuations and reserving a safe sampling range; the overvoltage protection threshold for the 400V low-voltage grid is 440V AC, and the overvoltage protection threshold for the 10kV high-voltage grid is 11.5kV AC. Reaching these thresholds immediately triggers overvoltage protection and cuts off the grid connection preparation process; the undervoltage protection threshold for the 400V low-voltage grid is 360V AC, and the undervoltage protection threshold for the 10kV high-voltage grid is 9.5kV AC. AC voltage protection is triggered immediately upon reaching the threshold, cutting off the grid connection preparation process. The over-frequency protection threshold for both 400V and 10kV high-voltage grids is 51Hz, with a standard power system frequency of 50Hz. The under-frequency protection threshold for both 400V and 10kV high-voltage grids is 49Hz, with a standard power system frequency of 50Hz. The voltage regulation target for both 400V and 10kV low-voltage grids is 360~440V AC rated voltage, and for the 10kV high-voltage grid, it is 9.5~11.5kV. AC rated voltage; the voltage on the generator side must match this target range when connected to the grid. The frequency regulation target value for the 400V low-voltage grid is 49~51Hz, and the frequency regulation target value for the 10kV high-voltage grid is also 49~51Hz. The voltage on the generator side must match this target range when connected to the grid. The grid connection control logic for the 400V low-voltage grid is low-voltage fast synchronization logic, with a phase synchronization calculation period ≤10ms. The grid connection control logic for the 10kV high-voltage grid is high-voltage stability control synchronization logic, with a phase synchronization calculation period ≤5ms. This improves the calculation accuracy on the high-voltage side and reduces grid connection impact. The communication protocol baud rate for the 400V low-voltage grid is 9600~19200bps, and the communication protocol baud rate for the 10kV high-voltage grid is 38400~115200bps. The high-voltage communication rate is higher, ensuring real-time parameter transmission.

[0027] In addition, the 400V low-voltage side adopts the "fast matching-instant grid connection" logic because the grid fluctuations are small and the load types are mostly low-voltage electrical equipment. After the phase synchronization calculation is completed, the grid connection command is issued directly. The 10kV high-voltage side adopts the "stability control matching-delay confirmation" logic because the grid capacity is large and the grid connection impact risk is high. After the phase synchronization calculation is completed, the grid connection command is issued after the parameters are continuously monitored for 300ms without fluctuation.

[0028] The grid-connected main unit is clamped to the grid connection line by a detachable sampling clip. The generator truck / generator set on the power generation side arrives at the site and is electrically connected to the load end.

[0029] The core method logic in steps S5-S8 is essentially the same for both 10kV and 400V voltage levels, following the process of "parameter acquisition → frequency and voltage regulation → synchronization detection → grid connection and closing → power adjustment". However, the hardware execution accuracy and parameter detection thresholds are differentiated according to the voltage level to ensure the safety and stability of grid connection at different voltage levels. Parameter acquisition accuracy: The voltage acquisition accuracy for the 400V side is ±0.5V, and the frequency is ±0.01Hz; the 10kV side has higher requirements for high-voltage measurement, with a voltage acquisition accuracy of ±5V and a frequency of ±0.005Hz. The phase acquisition accuracy is uniformly high-precision ±0.1° for both sides.

[0030] The apparatus for implementing the above method includes, A grid-connected main unit is installed on the grid side, and a grid-connected sub-unit is installed on at least one power generation side. The grid-connected main unit and the grid-connected sub-unit are communicatively connected. The grid-connected main unit includes: a main control module, used for data exchange with other modules and sending control commands to the grid-connected execution module on the generation side; a grid voltage sampling module, used for collecting grid voltage signals and transmitting them to the main control module; a grid voltage identification module, used for identifying the grid voltage level and feeding it back to the main control module; a voltage comparison module, used for comparing parameters on the grid side and the generation side; a frequency and voltage regulation interactive command control module, used for generating frequency and voltage regulation control commands; a status monitoring module, used for real-time monitoring of the operating status of the grid side and all grid-connected sub-units; and a communication main module, used for communication connection with the grid-connected sub-units. The grid-connected sub-unit includes a grid-connected execution module, which receives control commands from the grid side and executes grid-connected operations; a frequency and voltage regulation execution module, which adjusts the output parameters of the generation side according to the frequency and voltage regulation commands; a voltage acquisition module, which acquires the output parameters of the generation side in real time and transmits them to the grid-connected main unit; a status feedback module, which transmits the real-time operating status data of the generation side to the grid-connected main unit; and a communication sub-module, which communicates with the grid-connected main unit. Example

[0031] This example is a practical case of a single generator set being connected to a 400V low-voltage power grid, as detailed below: First, it should be noted that the grid side is the municipal 400V low-voltage grid (hereinafter referred to as the mains power), with a normal operating voltage of 390V, frequency of 50.0Hz, and phase of 0°, and a field load of 300kW. Complete grid connection includes primary and secondary grid connection. In this embodiment, primary grid connection uses a 500kW diesel generator set with an internal grid connection sub-device, which is electrically connected to the mains power grid and the 300kW low-voltage load at the site. No main grid connection device is required; the process is "generator set connected to mains power → mains power switch opened → generator set under load." Secondary grid connection occurs after mains power is restored. The main grid connection device is then activated to coordinate the synchronization of the generator set with the restored mains power, achieving "mains power restored → generator set shut down." The main grid connection device has pre-set all parameters for 400V and 10kV.

[0032] A single grid connection process involves only the grid connection sub-device of the generator set and includes the following steps: Y1, Grid-connected sub-device autonomous data acquisition: After the mains power is interrupted, the voltage acquisition and comparison module of the grid-connected sub-device collects the residual parameters of the mains power grid in real time: voltage 390V, frequency 50.0Hz, phase 0°, and the initial output parameters of the generator set: voltage 360V, frequency 49.2Hz, phase 10°. Y2, Autonomous processing of grid-connected sub-device: The built-in control module of the grid-connected sub-device performs filtering and noise reduction, analog-to-digital conversion and effective value calculation on the collected mains power parameters and generator parameters, and completes parameter comparison; Y3, Grid-connected sub-unit autonomous frequency and voltage regulation: The sub-unit's built-in control module performs phase synchronization calculations and generates voltage regulation commands, frequency regulation commands, and phase adjustment commands. In this embodiment, the voltage is increased to 390V, the frequency is increased to 50.0Hz, and the phase is adjusted to 0°, driving the self-regulating frequency and voltage execution module to adjust the output parameters to ensure that the unit matches the mains power parameters. Y4, Autonomous Synchronization Detection of Grid-Connected Sub-device: The sub-device continuously detects the parameters of the mains power and the generator set. When the voltage deviation is ≤ ±5%, the frequency deviation is ≤ ±0.2Hz, the phase deviation is ≤ ±5° and the phase sequence is consistent, it is determined that the parameters are fully matched and the preparation for grid connection of the generator set and the mains power is completed. Y5, Grid-connected Sub-device Autonomous Grid Connection + Mains Power Cut-off: The sub-device's grid connection execution module drives the generator set to close the grid connection switch with the mains power, completing the grid connection of the generator set with the mains power; the generator set increases its output power at a rate of 8kW / s, reaching the preset load of 300kW after 50s, and enters a stable power supply state, where the generator set supplies power to the field loads independently, undertaking all the loads of the power grid. Subsequently, the sub-device issues a command to open the mains power supply switch, cutting off the mains power supply. Y6, Grid-connected sub-unit autonomous power stabilization: The generator set supplies power to the on-site load independently, and the grid-connected sub-unit has a built-in status monitoring unit that monitors its own operating status and the power supply status of the load in real time.

[0033] The grid connection process was smooth and without any impact. After the generator set successfully connected to the mains power, it smoothly disconnected the mains power and supplied power to the load independently. The supply voltage was stable at 388~392V and the frequency was stable at 49.9~50.1Hz, which met the power demand of the low-voltage load on site. There were no abnormal warnings, which verified that the grid connection can be completed by the grid connection sub-device alone.

[0034] The generator set provides stable power supply under independent load. When the mains power returns to normal, the grid-connected main device is activated to perform a secondary grid connection operation, thereby restoring mains power supply and shutting down the generator set. The specific steps are as follows: S1, Secondary grid connection preparation: After the mains power is restored, the grid connection main device is activated. The main device is clamped to the 400V mains power connection line through the sampling clip to collect the real-time parameters of the mains power after restoration, including voltage 391V, frequency 50.0Hz, phase 0° and waveform characteristics, and simultaneously establishes a wireless communication connection with the grid connection sub-device of the generator set. S2: After filtering and denoising the acquired signal and performing analog-to-digital conversion, the main control module calculates the accurate digital voltage and frequency parameters. S3: The power grid voltage identification module determines that the power grid is 400V low voltage. S5, the main control module maintains the preset 400V parameter unchanged; S5: The grid-connected main unit synchronously receives the current operating parameters transmitted by the generator set grid-connected sub-unit: voltage 391V, frequency 50.0Hz, load 300kW; S6: The main unit voltage comparison module compares the parameters of the mains power side and the generator set. The frequency regulation and voltage regulation interactive command control module performs phase synchronization calculation, generates fine-tuning command, and ensures that the generator set and the mains power parameters are completely consistent without deviation. The command is then sent to the grid-connected sub-unit to drive the generator set to fine-tune the output parameters. S7: The main unit continuously performs synchronization detection. After confirming that the generator set and the mains power parameters are fully matched and there is no fluctuation for 300ms, the synchronization is considered complete. S8: The main control module issues a command to close the mains power supply switch and restore the mains power supply to the field load; at the same time, it issues a grid connection trip command, and the grid connection sub-device of the generator set drives the grid connection switch to trip, cutting off the connection between the generator set and the mains power. S9: The main unit issues a shutdown command, and the generator set gradually reduces its output power to 0kW to complete the shutdown. S10, the main unit status monitoring module monitors the mains power supply status and the unit shutdown process in real time to ensure safe and orderly operation.

[0035] The secondary grid connection process was smooth and without any disruptions. The mains power supply was restored smoothly, and the generator set shut down precisely and smoothly in sync with the mains power supply. After the shutdown, the on-site load was stably powered by the mains power supply with no voltage or frequency fluctuations and no abnormal warnings. This verified the rationality and feasibility of requiring the main unit to participate in the secondary grid connection. Example

[0036] This example is a practical case of connecting a 10kV high-voltage power grid generator vehicle to the grid, as detailed below: First, it should be noted that the grid side is an industrial 10kV high-voltage grid (hereinafter referred to as the mains power), with a normal operating voltage of 10.2kV, frequency of 50.0Hz, and phase of 0°, and an on-site load of 800kW. Complete grid connection includes primary and secondary grid connection. In this embodiment, primary grid connection uses a 1000kW mobile generator vehicle equipped with its own grid connection sub-device, electrically connected to the mains power grid and the on-site 800kW high-voltage load. No main grid connection device is required; the process is "generator vehicle connected to the mains power grid → mains power switch opened → generator vehicle under load." Secondary grid connection occurs after the mains power is restored. The main grid connection device is then activated to coordinate the synchronization between the mobile generator vehicle and the restored mains power, achieving "mains power restored → generator vehicle shut down." The main grid connection device has pre-set 400V and 10kV parameters. The primary grid connection steps involve only the generator set's grid connection sub-device, specifically including the following steps: Y1, Grid-connected sub-device autonomous data acquisition: After the mains power is interrupted, the voltage acquisition and comparison module of the grid-connected sub-device collects the residual parameters of the mains power grid in real time: voltage 10.2kV, frequency 50.0Hz, phase 0°, and the initial output parameters of the generator set: voltage 9.8kV, frequency 49.3Hz, phase 8°. Y2, Autonomous processing of grid-connected sub-device: The built-in control module of the grid-connected sub-device performs filtering and noise reduction, analog-to-digital conversion and effective value calculation on the collected mains power parameters and generator parameters, and completes parameter comparison; Y3, Grid-connected sub-unit autonomous frequency and voltage regulation: The sub-unit's built-in control module performs phase synchronization calculations and generates voltage regulation commands, frequency regulation commands, and phase adjustment commands. In this embodiment, the voltage is increased to 10.2kV, the frequency is increased to 50.0Hz, and the phase is adjusted to 0°. The phase synchronization calculation period is ≤5ms, which drives the self-regulating frequency and voltage execution module to adjust the output parameters to ensure that the unit matches the mains power parameters. Y4, Autonomous Synchronization Detection of Grid-Connected Sub-device: The sub-device continuously detects the parameters of the mains power and the generator set. If the parameters do not fluctuate for 300ms and the voltage deviation is ≤±5%, the frequency deviation is ≤±0.2Hz, the phase deviation is ≤±5° ​​and the phase sequence is consistent, the parameters are judged to be fully matched and the preparation for grid connection of the generator set and the mains power is completed. Y5, Grid-connected sub-device autonomous grid connection + mains power cut-off: The sub-device's grid connection execution module drives the generator truck to close the grid connection switch with the mains power, completing the grid connection of the generator truck with the mains power; the generator truck increases its output power at a rate of 40kW / s until it reaches the preset load of 800kW and enters a stable power supply state, and the generator truck supplies power to the high-voltage load on site independently. Then the sub-device issues a command to open the mains power supply switch and cut off the mains power supply. Y6, autonomous power stabilization of grid-connected sub-unit: The generator truck independently supplies power to the high-voltage load on site, undertaking the entire 800kW load of the power grid. The monitoring unit built into the sub-unit monitors its own operating status and the power supply status of the load in real time and records the operating data.

[0037] The grid connection process was smooth and without any impact. After the generator successfully connected to the grid, it smoothly disconnected from the grid and supplied power to the high-voltage load independently. The grid voltage was stable at 10.1~10.3kV and the frequency was stable at 49.9~50.1Hz, which met the power demand of the high-voltage load on site. There were no abnormal warnings, which verified that grid connection in high-voltage scenarios can be completed by only the grid connection sub-device.

[0038] The generator set provides stable power supply under independent load. When the mains power returns to normal, the grid-connected main device is activated to perform a secondary grid connection operation, thereby restoring mains power supply and shutting down the generator set. The specific steps are as follows: S1, Secondary grid connection preparation: After the mains power is restored, the grid connection main device is activated. The main device is clamped to the 10kV mains connection line through a sampling clip to collect the real-time parameters of the restored mains power, including 10.2kV, frequency 50.0Hz, phase 0° and waveform characteristics, and simultaneously establishes a wireless communication connection with the grid connection sub-device of the generator set. S2: After filtering and denoising the acquired signal and performing analog-to-digital conversion, the main control module calculates the accurate digital voltage and frequency parameters. S3: The power grid voltage identification module determines that it is a 10kV high-voltage power grid; S5, the main control module maintains the 10kV preset parameters unchanged; S5: The grid-connected main unit synchronously receives the current operating parameters transmitted by the generator set grid-connected sub-unit: voltage 10.2kV, frequency 50.0Hz, load 1800kW; S6: The main unit voltage comparison module compares the parameters of the mains power side and the generator set. The frequency regulation and voltage regulation interactive command control module performs phase synchronization calculation, generates fine-tuning command, and ensures that the generator set and the mains power parameters are completely consistent without deviation. The command is then sent to the grid-connected sub-unit to drive the generator set to fine-tune the output parameters. S7: The main unit continuously performs synchronization detection. After confirming that the generator set and the mains power parameters are fully matched and there is no fluctuation for 300ms, the synchronization is considered complete. S8: The main control module issues a command to close the mains power supply switch and restore the mains power supply to the field load; at the same time, it issues a grid connection trip command, and the grid connection sub-device of the generator set drives the grid connection switch to trip, cutting off the connection between the generator set and the mains power. S9: The main unit issues a shutdown command, and the generator set gradually reduces its output power to 0kW to complete the shutdown. S10, the main unit status monitoring module monitors the mains power supply status and the unit shutdown process in real time, realizing full-process safety monitoring and ensuring safe and orderly operation.

[0039] The secondary grid connection process was smooth and without any impact. The mains power supply was restored smoothly, and the generator set shut down precisely and smoothly in sync with the mains power. After the shutdown, the high-voltage load on site was stably powered by the mains power, with no voltage or frequency fluctuations and no abnormal warnings. This verified the rationality and feasibility of the main unit's participation in the secondary grid connection.

[0040] The phase synchronization calculation in the above embodiments uses the sinusoidal phase difference calculation method, and the calculation formula is as follows: in, The phase difference between the generation side and the grid side. For the grid-side phase, For the power generation side phase, This is the effective value of the grid-side voltage. This is the effective value of the generation-side voltage. It is the power frequency angular frequency. , This is the phase difference reference voltage.

[0041] During the first grid connection, the calculations are performed by the control module built into the grid connection sub-device to synchronize the generator set / generator with the mains power. During the second grid connection, the main control module of the grid connection main device performs calculations to synchronize the generator set / generator with the restored mains power, ensuring synchronization accuracy and operational safety. All preset parameters can be fine-tuned through the human-machine interface of the grid connection main device according to the actual situation of the power grid on site, adapting to the grid connection needs of different regions and types of 10kV / 400V power grids. During the first grid connection, the sub-device can adapt autonomously according to the on-site mains power parameters without the need for preset additional parameters, ensuring the independence and convenience of the first grid connection.

[0042] This invention employs a master-slave architecture consisting of a main grid-connected device at the grid end and a pre-installed grid-connected control sub-device at the generator vehicle / generator set end. It can automatically adapt to 10kV / 400V voltage levels, offering flexible sampling and assembly / disassembly, and high versatility. No dedicated grid-connected device is required; a single device can meet the voltage requirements of most temporary / emergency power supply scenarios, achieving 100% versatility.

Claims

1. A grid connection method for generator trucks / generator sets applicable to different voltage levels, characterized in that: Includes the following steps: S1, the grid voltage sampling module of the grid-connected main unit collects the grid voltage signal and transmits it to the main control module. S2, the main control module performs filtering and noise reduction, analog-to-digital conversion, and RMS value calculation on the acquired power grid voltage signal to obtain an accurate digital voltage quantity; S3, the power grid voltage identification module receives the digital voltage value transmitted by the main control module, compares it with the preset standard voltage range, and determines the voltage level; S4, the main control module automatically switches the internal parameters of the device according to the determined voltage level, completes the adaptive matching of the device with the current grid voltage level, and enters the grid connection preparation stage; S5, the voltage acquisition and comparison module of the grid-connected sub-device acquires the output voltage, frequency signal and phase parameters of the generator side in real time, and transmits the data to the grid-connected main device; S6, the grid-connected main unit receives data and compares the grid voltage and frequency parameters with the parameters of the generation side. It performs phase synchronization calculation through the frequency and voltage regulation interactive command control module, generates frequency and voltage regulation control commands, and then sends them to the frequency and voltage regulation execution module of the sub-unit through the communication module to drive the generation side to adjust the output parameters. S7, the grid-connected main unit performs synchronous detection of parameters on the generation side and the grid side. When the voltage deviation is ≤ ±5%, the frequency deviation is ≤ ±0.2Hz, the phase deviation is ≤ ±5° and the phase sequence is consistent, it is determined that the parameters are completely matched. S8, when the parameters are fully matched, the main control module of the grid-connected main unit issues an instruction to close the mains power supply switch and restore the mains power supply to the field load; at the same time, it issues a grid-connected trip instruction, and the grid-connected sub-unit on the generator side drives the grid-connected switch to trip, cutting off the connection between the generator side and the mains power. S9, the grid-connected main unit issues a shutdown command, and the power generation side gradually reduces the output power to 0kW to complete the shutdown.

2. The grid connection method for generator vehicles / generator sets applicable to different voltage levels according to claim 1, characterized in that: The power generation side includes one or more of the following: a power generation vehicle and a generator set.

3. The grid connection method for generator trucks / generator sets applicable to different voltage levels according to claim 1, characterized in that: In step S1, the acquired signal includes the effective voltage value, frequency, phase, and waveform characteristics.

4. The grid connection method for generator trucks / generator sets applicable to different voltage levels according to claim 1, characterized in that: The specific method of step S3 is as follows: if the digital voltage value falls within the range of 360V to 440V, it is determined to be a 400V low-voltage power grid; if it falls within the range of 9.5kV to 11.5kV, it is determined to be a 10kV high-voltage power grid; if it does not fall within any range, it is determined to be abnormal and an abnormal signal is issued.

5. The grid connection method for generator trucks / generator sets applicable to different voltage levels according to claim 1, characterized in that: The internal parameters of the device in step S4 include sampling range, overvoltage protection threshold, undervoltage protection threshold, overfrequency protection threshold, underfrequency protection threshold, voltage regulation target value, frequency regulation target value, grid connection control logic, and communication protocol baud rate.

6. The grid connection method for generator trucks / generator sets applicable to different voltage levels according to claim 1, characterized in that: The grid-connected main device is clamped to the grid connection line by a detachable sampling clip. The generator truck / generator set on the power generation side arrives at the site and is electrically connected to the load end.

7. The grid connection method for generator trucks / generator sets applicable to different voltage levels according to claim 1, characterized in that: It also includes step S8, where the status monitoring module of the grid-connected main unit monitors the mains power supply status and the unit shutdown process in real time to ensure safe and orderly operation.

8. An apparatus for grid connection of generator sets / generator units with different voltage levels according to any one of claims 1-7, comprising: A grid-connected main unit is installed on the grid side, and a grid-connected sub-unit is installed on at least one power generation side. The grid-connected main unit and the grid-connected sub-unit are communicatively connected. The grid-connected main device includes: The main control module is used to exchange data with other modules and send control commands to the grid connection execution module on the power generation side. The power grid voltage sampling module is used to collect power grid voltage signals and transmit them to the main control module. The power grid voltage identification module is used to identify the power grid voltage level and feed it back to the main control module; The grid-connected sub-device includes a grid-connected execution module, which receives control commands sent from the grid side and executes the grid-connected operation.

9. The apparatus for grid connection of generator cars / generator sets applicable to different voltage levels according to claim 8, characterized in that: The grid-connected main device on the grid side also includes: The voltage comparison module is used to compare parameters between the grid side and the generation side; The frequency modulation and voltage regulation interactive command control module is used to generate frequency modulation and voltage regulation control commands; The status monitoring module is used to monitor the operating status of the grid side and all grid-connected sub-devices in real time; The main communication module is used for communication connection with the grid-connected sub-devices; The grid-connection sub-device on the power generation side also includes: The frequency and voltage regulation execution module adjusts the output parameters on the power generation side according to the frequency and voltage regulation commands; The voltage acquisition module is used to acquire the output parameters of the generator side in real time and transmit them to the grid-connected main unit; The status feedback module is used to transmit the real-time operating status data of the power generation side to the grid-connected main unit; The communication submodule is used for communication connection with the grid-connected main unit.

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