Off-grid operation method and system for wind turbine generator

Abstract

The invention provides a wind turbine generator off-grid operation method and system, and the method comprises the steps: enabling a battery pack and a generator set to be connected with a main control system through an energy storage converter when a wind turbine generator is off-grid; the main control module sends a first instruction to the DCS control system, and the DCS control system controls the variable resistance box to be connected with the main control system after receiving the first instruction; and the main control module sends a second instruction to the generator set, the generator set starts to generate power according to the second instruction and supplies power to the whole wind turbine generator, and the DCS control system dynamically adjusts the resistance of the variable resistance box according to the current in the line. The method solves the problems that in the prior art, when a power grid of a wind power plant breaks down or is in an off-network state, the wind power plant cannot be actively switched to a typhoon-resisting mode for active yawing load reduction, and serious accidents and economic losses are possibly caused.

Description

Technical Field

[0001] The present invention relates to the technical field of off-grid control of wind turbine generator sets, and in particular to an off-grid operation method and system for wind turbine generator sets. Background Art

[0002] With the development of offshore wind power in my country, offshore wind farm models have undergone a huge change from 2MW to 20MW and have been continuously expanded. The design of extreme wind loads and development costs of their models also face many challenges. The design of the whole machine and supporting structure also has great development difficulties. The design requirements for the unit under extreme conditions at sea are also getting higher and higher.

[0003] During a typhoon, the load on the entire wind turbine will increase, which may cause blade breakage and tower collapse. In order to reduce the damage to the wind turbine caused by the typhoon, it is necessary to control the wind turbine to actively yaw and reduce the load. However, when a typhoon comes, there is a potential risk of disconnection between the wind farm and the power grid. If the unit is disconnected from the grid and the power is lost, the wind turbine loses its working power supply and cannot switch to the anti-typhoon mode to actively yaw and reduce the load, which may cause major accidents and economic losses. Therefore, a backup energy system is required to power the main control system and yaw system of the wind turbine in an emergency. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for off-grid operation of a wind turbine, which solves the problem in the prior art that when the wind farm grid fails or is off-grid, the wind farm cannot actively switch to the typhoon resistance mode to actively yaw and reduce load, which may cause major accidents and economic losses.

[0005] According to an embodiment of the present invention, a method for off-grid operation of a wind turbine generator set is provided, and the method is applied to the above-mentioned off-grid operation system of a wind turbine generator set, comprising:

[0006] When the wind turbine is off-grid, the energy storage converter connects both the battery pack and the generator set to the main control system;

[0007] The main control module sends a first instruction to the DCS control system, and after receiving the first instruction, the DCS control system controls the variable resistor box to connect with the main control system;

[0008] The main control module sends a second instruction to the generator set, and the generator set starts to generate electricity according to the second instruction to supply power to the entire wind turbine set. The DCS control system dynamically adjusts the resistance of the variable resistor box according to the current in the line.

[0009] Preferably, the second instruction includes a weak current instruction and a strong current instruction;

[0010] The generator set starts to generate electricity according to the second instruction, and the process of supplying power to the entire wind turbine set includes:

[0011] The generator set operates at low power according to the weak power generation instruction to supply power to the main control system;

[0012] The energy storage converter disconnects the battery pack, and the main control system controls the wind turbine converter to start;

[0013] The generator set starts to generate electricity according to the strong power generation instruction, supplying power to the entire wind turbine set.

[0014] Preferably, when the generator set is running at low power, the main control system sends a third instruction to the DCS control system to increase the resistance value of the resistor box so that the difference between the output power of the generator set and the operating power of the adjustable load device is less than the starting power protection threshold of the wind turbine set.

[0015] Preferably, after the generator set starts generating electricity according to the strong power generation instruction, the DCS control system dynamically adjusts the resistance value of the variable resistor box according to the current in the line, so that the difference between the output power of the generator set and the operating power of the adjustable load device is less than the operating power protection threshold of the wind turbine set.

[0016] Preferably, the step of controlling the start-up of the wind turbine converter by the main control system comprises:

[0017] When the generator set is running at low power according to the weak power generation instruction, after the generator speed of the generator set reaches the first switching threshold, the main control module sends a start instruction to the wind turbine converter, and the wind turbine converter performs a status self-check after receiving the start instruction;

[0018] The generator set switches from a weak power generation command to a strong power generation command, and the generator speed of the generator set gradually increases. When the second switching threshold is reached, the busbar voltage of the machine-side module is built up;

[0019] After the generator is completely switched to the strong power generation command, the busbar voltage of the grid-side module is built up and the wind turbine converter switches to the off-grid operation mode.

[0020] Preferably, after the generator set is operated with a strong power generation instruction, the energy storage inverter switches the battery pack to a charging mode, and uses part of the electricity generated by the generator set to charge the battery pack.

[0021] On the other hand, according to an embodiment of the present invention, a wind turbine off-grid operation system is also provided, and the system is applied to the above-mentioned wind turbine off-grid operation method, which includes:

[0022] Backup power supply, wind turbine converter, main control system and adjustable load device connected to the wind turbine converter;

[0023] The backup power supply includes a battery pack, an energy storage converter and a generator set, the energy storage converter is connected to the battery pack and the generator set, and the energy storage converter is connected to the main control system;

[0024] The adjustable load device comprises a variable resistor box and a DCS control system which are connected in sequence, and the DCS control system is in communication connection with a main control system.

[0025] Preferably, the main control system includes a main control module and an auxiliary transformer cabinet, a tower base control cabinet and a cabin control cabinet connected to the main control module, the auxiliary transformer cabinet is connected to the tower base control cabinet, the cabin control cabinet and the energy storage inverter, and the main control module is communicatively connected to the energy storage inverter.

[0026] Preferably, the wind turbine converter comprises a machine-side module, a grid-side module and a chopper circuit which are connected to each other, and the grid-side module is connected to a main control system.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] When the wind turbine generator set fails in the power grid or is disconnected from the power grid, the wind turbine generator set connects the backup power supply to the main control system to supply power to the main control system. After the main control system is powered, it controls the wind turbine inverter to switch to off-grid operation mode, controls the generator set to start and supply power to the entire wind turbine generator set to ensure the normal operation of the wind turbine generator set. At the same time, the load is dynamically adjusted through the adjustable load device to reduce the current impact of the generator set during startup and the current shunting during stable operation, thereby protecting the life cycle of the device and ensuring the normal startup of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 4 is a system architecture diagram of an embodiment of the present invention.

[0030] Figure 2 The figure is a flow chart of the operation method of an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0032] like Figure 1 As shown, an embodiment of the present invention provides a wind turbine off-grid operation system, including:

[0033] Backup power supply, wind turbine converter, main control system and adjustable load device connected to the wind turbine converter;

[0034] The backup power supply includes a battery pack, an energy storage inverter and a generator set. The energy storage inverter is connected to the battery pack and the generator set. The energy storage inverter is connected to the main control system. The energy storage inverter (PCS) is used to realize energy conversion and two-way flow between the battery pack and the power grid, and communicate with the wind turbine main control system to realize data interaction and control. Under grid-off conditions, the battery pack or the generator set can power the main control system. Under grid-connected conditions, the battery pack can be charged by the power grid.

[0035] The adjustable load device comprises a variable resistor box and a DCS control system which are connected in sequence. The DCS control system is used to adjust the resistance of the variable resistor box according to the line current. The DCS control system is in communication connection with the main control system.

[0036] The main control system includes a main control module and an auxiliary transformer cabinet, a tower base control cabinet and a cabin control cabinet connected to the main control module. The auxiliary transformer cabinet is connected to the tower base control cabinet, the cabin control cabinet and the energy storage inverter. The auxiliary transformer cabinet is used for conversion and step-up and step-down when the battery pack and the generator set are powered. The main control module and the wind turbine inverter and the energy storage inverter are used for the wind turbine set.

[0037] The wind turbine converter comprises a machine-side module, a grid-side module and a chopper circuit which are connected to each other, and the grid-side module is connected to a main control system.

[0038] When the wind turbine generator set fails in the power grid or is disconnected from the power grid, the wind turbine generator set connects the backup power supply to the main control system to supply power to the main control system. After the main control system is powered, it controls the wind turbine inverter to switch to off-grid operation mode, controls the generator set to start and supply power to the entire wind turbine generator set to ensure the normal operation of the wind turbine generator set. At the same time, the load is dynamically adjusted through the adjustable load device to reduce the current impact of the generator set during startup and the current shunting during stable operation, thereby protecting the life cycle of the device and ensuring the normal startup of the unit.

[0039] On the other hand, Figure 2 As shown, the embodiment of the present invention further provides a method for off-grid operation of a wind turbine generator set, which includes:

[0040] When the wind turbine is off-grid, the energy storage converter connects both the battery pack and the generator set to the main control system;

[0041] When the public power grid is disconnected or fails, the entire wind turbine is disconnected from the grid, the main control system loses power, and the battery pack receives no power input. The energy storage inverter will immediately change the direction of power flow, connecting the battery pack and generator to the main control system, so that the power in the battery pack is output to the main control system. The main control system is powered and begins to control the wind turbine to switch to off-grid operation mode.

[0042] The main control module sends a first instruction to the DCS control system, and after receiving the first instruction, the DCS control system controls the variable resistor box to connect with the main control system;

[0043] Since the power output of the battery pack cannot make the entire wind turbine set operate normally, the generator needs to be started. During the starting process of the generator, current shocks will occur in the circuits within the wind turbine set. In order to protect the life cycle of the device and ensure the normal start-up of the unit, the adjustable load device should be started first so that the adjustable load device can play a current shunt role and reduce the current in the circuit.

[0044] Therefore, the main control system first sends a first instruction to the DCS control system. After sending the first instruction, the DCS control system controls the variable resistor box to connect with the main control system. At this time, the entire adjustable load device is in standby mode, the resistance value is 0, and no current is diverted.

[0045] The main control module sends a second instruction to the generator set, and the generator set starts to generate electricity according to the second instruction to supply power to the entire wind turbine set. The wind turbine converter switches to the off-grid operation mode, and the DCS control system dynamically adjusts the resistance of the variable resistor box according to the current in the line.

[0046] The second instruction sent by the main control module to the generator set includes a weak power generation instruction and a strong power generation instruction. The weak power generation instruction will cause the generator set to run at a low speed, and the electric energy generated by it cannot meet the normal operation of the entire wind turbine set. The strong power generation instruction will cause the generator set to run at a high speed and stably, and the electric energy generated by it can meet the normal operation of the entire wind turbine set.

[0047] After receiving the second instruction, the generator set first operates at low power according to the weak power generation instruction until the generator speed of the generator set reaches the first switching threshold to supply power to the main control system. Then the main control system sends a third instruction to the DCS control system to increase the resistance value of the resistor box so that the difference between the output power of the generator set and the operating power of the adjustable load device is less than the starting power protection threshold of the wind turbine set. Then the energy storage inverter disconnects the battery pack.

[0048] At the same time, after the current generated by the generator set flows through the main control system, the wind turbine inverter will also be energized. The main control module sends a start command to the wind turbine inverter. After receiving the start command, the wind turbine inverter performs a status self-check. If there is no abnormality in the self-check, it will close the switch and prepare for the off-grid mode transition.

[0049] Afterwards, the generator set switches from a weak power generation instruction to a strong power generation instruction, and the generator speed of the generator set gradually increases. When the second switching threshold is reached, the busbar of the machine-side module builds up voltage.

[0050] After the generator is completely switched to the strong power generation instruction, the busbar of the grid-side module builds up voltage and the wind turbine converter switches to the off-grid operation mode. At this time, the generator set starts to generate electricity stably to supply power to the entire wind turbine set.

[0051] In addition, after the generator set starts to generate electricity according to the strong power generation instruction, the DCS control system dynamically adjusts the resistance value of the variable resistor box according to the current in the line, which will make the difference between the output power of the generator set and the operating power of the adjustable load device smaller than the operating power protection threshold of the wind turbine set. At the same time, the energy storage inverter switches the battery pack to charging mode and uses part of the electricity generated by the generator set to charge the battery pack.

[0052] In this way, when the wind turbine generator set fails in the power grid or is disconnected from the power grid, the wind turbine generator set connects the backup power supply to the main control system to supply power to the main control system. After the main control system is powered, it controls the wind turbine inverter to switch to off-grid operation mode, controls the generator set to start and supply power to the entire wind turbine generator set to ensure the normal operation of the wind turbine generator set. At the same time, the load is dynamically adjusted through the adjustable load device to reduce the current impact of the generator set during startup and the current shunting during stable operation, thereby protecting the life cycle of the device and ensuring the normal startup of the unit.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for off-grid operation of a wind turbine generator set, characterized in that: include: When the wind turbine is off-grid, the energy storage converter connects both the battery pack and the generator set to the main control system; The main control module sends a first instruction to the DCS control system, and after receiving the first instruction, the DCS control system controls the variable resistor box to connect with the main control system; The main control module sends a second instruction to the generator set, and the generator set starts to generate electricity according to the second instruction to supply power to the entire wind turbine set. The DCS control system dynamically adjusts the resistance of the variable resistor box according to the current in the line.

2. A method for off-grid operation of a wind turbine generator set as claimed in claim 1, characterized in that: The second instruction includes a weak current instruction and a strong current instruction; The generator set starts to generate electricity according to the second instruction, and the process of supplying power to the entire wind turbine set includes: The generator set operates at low power according to the weak power generation instruction to supply power to the main control system; The energy storage converter disconnects the battery pack, and the main control system controls the wind turbine converter to start; The generator set starts to generate electricity according to the strong power generation instruction, supplying power to the entire wind turbine set.

3. A method for off-grid operation of a wind turbine generator set as claimed in claim 2, characterized in that: When the generator set is running at low power, the main control system sends a third instruction to the DCS control system to increase the resistance value of the resistor box so that the difference between the output power of the generator set and the operating power of the adjustable load device is less than the starting power protection threshold of the wind turbine set.

4. A method for off-grid operation of a wind turbine generator set as claimed in claim 2, characterized in that: After the generator set starts generating electricity according to the strong power generation instruction, the DCS control system dynamically adjusts the resistance value of the variable resistor box according to the current in the line, so that the difference between the output power of the generator set and the operating power of the adjustable load device is less than the operating power protection threshold of the wind turbine set.

5. A method for off-grid operation of a wind turbine generator set as claimed in claim 1, characterized in that: The steps for the main control system to control the start-up of the wind turbine converter include: When the generator set is running at low power according to the weak power generation instruction, after the generator speed of the generator set reaches the first switching threshold, the main control module sends a start instruction to the wind turbine converter, and the wind turbine converter performs a status self-check after receiving the start instruction; The generator set switches from a weak power generation command to a strong power generation command, and the generator speed of the generator set gradually increases. When the second switching threshold is reached, the busbar voltage of the machine-side module is built up; After the generator is completely switched to the strong power generation command, the busbar voltage of the grid-side module is built up and the wind turbine converter switches to the off-grid operation mode.

6. A method for off-grid operation of a wind turbine generator set as claimed in claim 1, characterized in that: After the generator set is running with a strong power generation command, the energy storage inverter switches the battery pack to charging mode and uses part of the electricity generated by the generator set to charge the battery pack.

7. A wind turbine off-grid operation system, characterized in that: The system is applied to a wind turbine off-grid operation method as claimed in claims 1 to 6, comprising: Backup power supply, wind turbine converter, main control system and adjustable load device connected to the wind turbine converter; The backup power supply includes a battery pack, an energy storage converter and a generator set, the energy storage converter is connected to the battery pack and the generator set, and the energy storage converter is connected to the main control system; The adjustable load device comprises a variable resistor box and a DCS control system which are connected in sequence, and the DCS control system is in communication connection with a main control system.

8. A wind turbine off-grid operation system as claimed in claim 7, characterized in that: The main control system includes a main control module and an auxiliary transformer cabinet, a tower base control cabinet and a cabin control cabinet connected to the main control module. The auxiliary transformer cabinet is connected to the tower base control cabinet, the cabin control cabinet and the energy storage inverter. The main control module is communicatively connected to the energy storage inverter.

9. A wind turbine off-grid operation system according to claim 7, characterized in that: The wind turbine converter comprises a machine-side module, a grid-side module and a chopper circuit which are connected to each other, and the grid-side module is connected to a main control system.

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