Working method of power generation system

Abstract

The invention relates to a working method of a power generation system, which comprises the following steps of: when a power generation operation mode is started, adjusting the rotating speed of a generator or the voltage of an excitation power supply through a driving converter to realize synchronous grid connection; when the operation condition of the power grid is normal, dispatching power generation, primary frequency modulation and steady-state voltage support are carried out, otherwise, a power generation operation abnormal mode is started for operation, and fault support is provided; when the phase modifier operation mode is started, the rotating speed of the generator or the voltage of the excitation power supply is adjusted through the driving converter, and synchronous grid connection is achieved; and when the operation condition of the power grid is normal, carrying out no-load hot standby operation, primary frequency modulation and steady-state voltage support, otherwise, starting an abnormal operation mode of the phase modifier, and providing fault support. According to the invention, the energy storage system is connected to the DC bus of the converter and is used for the DC voltage from the power grid after controllable rectification, and the device is mainly used for DC bus voltage balance control and phase modulation starting in the absence of wind.

Description

Technical Field

[0001] The invention belongs to the technical field of power market, and in particular relates to a working method of a power generation system. Background Art

[0002] A high proportion of new energy power grid is an inevitable development trend in the energy and power sector in the future. After a high proportion of new energy is connected to the power grid, a large number of new energy converters will replace synchronous generators, reducing system inertia, causing the power grid to present a high degree of power electronics characteristics, resulting in fundamental changes in the power supply characteristics of the power grid, and bringing huge challenges to the stable operation of the power system. Summary of the invention

[0003] In view of this, an object of the present invention is to overcome the deficiencies of the prior art and provide a working method of a power generation system to solve the problem of insufficient stability of the power system in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions: a working method of a power generation system, the power generation system comprising: a multi-energy input device, an alternator, a motor unit and a generator connected in sequence; the multi-energy input device outputs direct current, and outputs alternating current through the converter, the alternating current is used to drive the motor unit, the motor unit is coaxially connected to the generator to generate alternating current, and the generated alternating current is connected to the grid; wherein the multi-energy input device comprises an energy storage system, the energy storage system is connected to the DC side of the converter, and serves as a backup power source for insufficient energy of new energy; the new energy power generation is connected to the excitation winding after rectification as the excitation power source of the generator;

[0005] The controller controls the converter to realize the operation of the power generation system. The operation method includes:

[0006] The controller receives the start command and starts the power generation operation mode and the phase-shifting operation mode;

[0007] When the power generation operation mode is started, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the converter to achieve synchronous grid connection; when the grid is operating normally, the normal power generation operation mode is started to dispatch power generation, perform primary frequency regulation and steady-state voltage support, otherwise, the abnormal power generation operation mode is started to provide fault support; among which, the fault support includes transient overvoltage fault and voltage short circuit fault support;

[0008] When the phase-converter operation mode is started, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the inverter to achieve synchronous grid connection; when the grid operating conditions are normal, the phase-converter operates in normal mode, performs no-load hot standby operation, and provides primary frequency regulation and steady-state voltage support. Otherwise, the phase-converter operation abnormal mode is started to provide fault support.

[0009] Furthermore, before starting the power generation operation mode and the phase-shifting operation mode, the method further includes:

[0010] Determining the available energy of a multi-source complementary input device;

[0011] Determine power data and grid status; the power data includes grid voltage, frequency and phase;

[0012] Set the thresholds for each grid condition.

[0013] Furthermore, when the available energy of the multi-source complementary input device is greater than the no-load operation power consumption of the system, and the wind speed at the wind turbine unit site is greater than the cut-in wind speed, the power generation operation mode is started;

[0014] When the available energy of the multi-source complementary input device is greater than the system no-load operation power consumption, and the wind speed at the wind turbine unit position is less than the cut-in wind speed, the phase-shifting operation mode is started;

[0015] When the available energy of the multi-source complementary input device is less than the no-load power consumption of the system, and the wind speed at the wind turbine unit position is greater than the cut-in wind speed, the wind turbine unit is started, and the power generation output of the started wind turbine unit is stored in the energy storage module of the multi-source complementary input device through the DC bus until the available energy of the multi-source complementary input device is greater than the no-load power consumption of the system to start the power generation operation mode;

[0016] When the available energy of the multi-source complementary input device is less than the system no-load power consumption, the grid power rectifier in the DC bus cabinet is started, and the grid power is stored in the energy storage module through the DC bus until the available energy of the multi-source complementary input device is greater than the system no-load power consumption, and the phase-shifting operation mode is started.

[0017] Further, dispatching power generation is performed, including:

[0018] Compare the AGC command value and the maximum output capacity data of renewable energy power generation;

[0019] When the AGC command value is greater than or equal to the maximum output capacity data of the new energy power generation, the motor torque is calculated according to the maximum output capacity data of the new energy power generation, so that the generator set operates at maximum power;

[0020] When the AGC command value is less than the maximum output capacity data of the new energy power generation, the motor torque is calculated according to the AGC command value so that the generator set operates at limited power;

[0021] Among them, the motor torque result is used as the torque command of the converter.

[0022] Furthermore, in the power generation operation mode, a frequency regulation and steady-state voltage support are performed including:

[0023] Run frequency modulation once according to the power grid operating condition threshold to obtain the frequency threshold;

[0024] When the grid frequency is less than the frequency threshold, the required motor torque is calculated according to the frequency increase range for safe operation of the generator set, and the motor torque is used as the torque command of the converter based on the available energy of the multi-source complementary input device and the maximum output capacity data of the new energy power generation based on the primary frequency modulation time requirement. After exceeding the primary frequency modulation time requirement, the current grid frequency is used for scheduling power generation;

[0025] When the grid frequency is greater than or equal to the frequency threshold, the required motor torque is calculated according to the frequency reduction range for safe operation of the generator set, and the motor torque is used as the torque command of the converter. After exceeding the frequency modulation time requirement once, the current grid frequency is used for scheduling power generation;

[0026] According to the threshold of the power grid working condition, the voltage stabilization support is provided. The multi-source complementary input device provides the excitation power supply for the synchronous generator through the AC / DC rectifier excitation cabinet, and the corresponding reactive power is output by adjusting the excitation current of the synchronous generator to achieve the steady-state voltage support function; specifically,

[0027] Setting a first voltage threshold according to a power grid operating condition threshold;

[0028] When the grid voltage is less than the first voltage threshold, a first capacity difference between the system rated capacity and the current system output capacity is calculated according to the current system output capacity, and the first capacity difference is used as the excitation voltage increase amount, which is output to the excitation power supply to increase the inductive reactive output;

[0029] When the grid voltage is greater than the first voltage threshold, according to the limiting capacity of the generator set for safe phase leading operation and low excitation limit, the first capacity difference between the limiting capacity and the current system output capacity is calculated, and the first capacity difference is used as the excitation voltage reduction amount, which is output to the excitation power supply to increase the capacitive reactive output.

[0030] Furthermore, when the condenser is in operation mode, fault support is provided, including:

[0031] Provide grid transient overvoltage fault support according to grid operating thresholds; specifically:

[0032] Setting a second voltage threshold according to a power grid operating condition threshold;

[0033] When the grid voltage is greater than the second voltage threshold, according to the limiting capacity of the generator set for phase leading safety operation and the limiting of the low excitation limit, a second capacity difference between the limiting capacity and the current system output capacity is calculated, and the second capacity difference is used as the excitation voltage reduction amount, which is output to the excitation power supply to increase the capacitive reactive power output;

[0034] When the second capacity difference is less than the limiting capacity, the difference capacity between the second capacity difference and the limiting capacity is calculated, the motor torque is calculated based on the difference capacity, and the difference capacity is used as a torque command to output to the converter to reduce the active output. At the same time, the difference capacity can be used as an excitation voltage reduction amount to output to the excitation power supply to increase the capacitive reactive output.

[0035] Provide grid short-circuit fault support according to grid operating thresholds; specifically:

[0036] When the three-phase or any two-phase voltage of the power grid suddenly reaches zero, the controller controls the converter to stop running, and the generator runs as a motor unit. The maximum phase current is monitored in real time, and the maximum current supporting capacity of the generator set is integrated. The difference between the maximum phase current and the maximum current supporting capacity is used to calculate the shutdown time of the grid-connected circuit breaker. If the short-circuit time is greater than the shutdown time, the controller enables the grid-connected cabinet to be disconnected from the grid; if the short-circuit time is less than or equal to the shutdown time, the controller enables the converter to run, and the generator enters the power generation operation mode.

[0037] Furthermore, no-load hot standby operation is performed, including:

[0038] Detect the grid voltage and three-phase current, calculate the reactive output value based on the grid voltage and three-phase current, calculate the excitation voltage adjustment amplitude with the reactive output value as the difference, output it to the excitation power supply, adjust the excitation voltage, and maintain the reactive output at zero.

[0039] Furthermore, in the phase-shifting operation mode, a frequency modulation and steady-state voltage support are performed including:

[0040] When the grid frequency drops, the power generation system relies on rotational inertia to provide active support;

[0041] When the grid frequency rises, the power generation system relies on the rotational inertia to realize the flywheel energy storage function;

[0042] At this time, the generator is driven by the power grid and runs at no load, and is in a phase-shifting hot standby state.

[0043] Furthermore, when the condenser is in operation mode, fault support is provided, including:

[0044] Provide grid transient overvoltage fault support according to grid operating thresholds; specifically:

[0045] Setting a third voltage threshold according to a power grid operating condition threshold;

[0046] When the grid voltage is greater than the third voltage threshold, the shutdown time is calculated according to the overvoltage protection requirements of the motor unit and the grid-connected switch and the action time of the grid-connected switch; if the overvoltage time is greater than the shutdown time, an overvoltage fault is triggered and the grid-connected cabinet is enabled to be disconnected from the grid; if the overvoltage time is less than or equal to the shutdown time, no-load hot standby operation is performed.

[0047] Furthermore, the generator set adopts a direct-drive wind generator set or a doubly-fed wind generator set.

[0048] The present invention adopts the above technical solution, and the beneficial effects that can be achieved include:

[0049] This application can significantly improve the safe and stable operation level of ultra-high voltage AC and DC power grids.

[0050] The working method of the power generation system of the present invention effectively utilizes the rotational inertia of the generator to spontaneously adjust the frequency during a frequency modulation process. When the frequency of the power system increases, the speed of the power generation system decreases, and when the frequency of the power system decreases, the speed of the power generation system increases, breaking through the limitation of the maximum power of the traditional power generation system and being able to operate in overload.

[0051] The present invention, through a power generation grid-connected system and a corresponding control method, effectively overcomes the defects of traditional renewable energy power generation that requires a response through superior control instructions, requires multiple calculations to output instructions, and has a slow response speed. By directly collecting the grid-connected point voltage output instructions, the response speed is fast.

[0052] When a transient overvoltage fault or short circuit fault occurs in the power grid, the present invention outputs capacitive or inductive reactive power instantaneously through the self-response of transient reactance and ultra-transient reactance, and provides capacitive or inductive reactive power by adjusting the excitation current through the excitation power supply designed by the system. After a few minutes, the transient overvoltage problem of the power grid is solved by shared energy storage outside the station. Traditional photovoltaic power generation systems do not have transient reactance and ultra-transient reactance.

[0053] During the transient process, the generator set is required to have a strong short-term overload capacity. The present invention uses the strong excitation capacity to provide a large amount of dynamic reactive power support to help the system voltage recovery and power recovery, prevent voltage collapse, and improve the system voltage stability level. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 The structure of the power generation system of the present invention is shown in FIG. Figure 1 ;

[0056] Figure 2 The structure of the power generation system of the present invention is shown in FIG. Figure 2 ;

[0057] Figure 3The structure of the power generation system of the present invention is shown in FIG. Figure 3 ;

[0058] Figure 4 It is a schematic diagram of the steps of the working method of the power generation system of the present invention. DETAILED DESCRIPTION

[0059] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0060] The following describes a specific working method of a power generation system provided in an embodiment of the present application in conjunction with the accompanying drawings.

[0061] The working method of the power generation system provided in the embodiment of the present application is as follows: Figure 1 As shown, the power generation system includes: a multi-energy input device 1, an AC converter 2, a motor group 3 and a generator 4 connected in sequence; the multi-energy input device 1 outputs direct current, and outputs alternating current through the converter 2, the alternating current is used to drive the motor group 3, the motor group 3 is coaxially connected to the generator 4 to emit alternating current, and the emitted alternating current is connected to the grid; wherein, the multi-energy input device 1 includes an energy storage system (not shown in the figure), the energy storage system is connected to the DC side of the converter 2, and serves as a backup power supply for insufficient energy of new energy; after the new energy power generation is rectified, the excitation winding is connected as the excitation power supply of the generator; the present invention connects the energy storage system and the DC voltage after controllable rectification from the power grid to the DC bus of the converter, and the device is mainly used for DC bus voltage balance control and phase adjustment starting when there is no wind.

[0062] The generator set in the present application adopts a direct-drive wind generator set or a double-fed wind generator set.

[0063] At present, mainstream wind turbine generator sets include direct-drive wind turbine generator sets, semi-direct-drive wind turbine generator sets and doubly-fed wind turbine generator sets. The present invention is mainly aimed at these types of wind turbine generator sets.

[0064] like Figure 2As shown, the generator set in this application can be a direct-drive (semi-direct-drive) wind turbine generator set. The specific structure is that the wind turbine is connected to the converter. Compared with the traditional converter, the DC bus of the converter is connected to the energy storage system and the DC voltage after controllable rectification from the power grid. The device is mainly used for DC bus voltage balance control and phase adjustment start when there is no wind; the other end of the converter is connected to the motor; the motor is connected to the synchronous generator and the auxiliary control system, which is directly connected to the power grid. The main control cabinet is mainly used for the coordinated control of the converter and the synchronous generator control system.

[0065] like Figure 3 As shown, the generator set in this application can also be a doubly fed generator set. It can be understood that compared with the direct drive unit, the doubly fed generator set mainly has two output paths of the generator, the rotor and the stator. The rotor is directly connected to the power grid through the converter, and the stator is connected to the motor through the converter, and then the generator and its auxiliary control system are connected. The capacity of the converter and synchronous generator used in the direct drive system must be the same as the capacity of the unit, and the capacity of the converter and synchronous motor used on the stator side of the doubly fed system only needs to be 2 / 3 of the capacity of the unit.

[0066] like Figure 4 As shown, an embodiment of the present application provides a working method of a power generation system, the working method comprising:

[0067] S1, the controller receives the start command and starts the power generation operation mode and the phase-shifting operation mode;

[0068] S2, when starting the power generation operation mode, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the converter to achieve synchronous grid connection; when the grid is operating normally, the normal power generation operation mode is started to dispatch power generation, and primary frequency regulation and steady-state voltage support are performed; otherwise, the abnormal power generation operation mode is started to provide fault support; among which, the fault support includes transient overvoltage fault and voltage short circuit fault support;

[0069] S3, when the phase-converter operation mode is started, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the converter to achieve synchronous grid connection; when the grid operation condition is normal, the phase-converter operates in normal mode, performs no-load hot standby operation, and primary frequency regulation and steady-state voltage support, otherwise, the phase-converter operation abnormal mode is started to provide fault support.

[0070] In some optional embodiments, before starting the power generation operation mode and the phase-shifting operation mode, the method further includes:

[0071] Determining the available energy of a multi-source complementary input device;

[0072] Determine power data and grid status; the power data includes grid voltage, frequency and phase;

[0073] Set the thresholds for each grid condition.

[0074] The working method of the power generation system provided in the present application is provided with a pre-start state, that is, preparation before the system operation: ① The controller determines the current available energy through the energy storage system; ② The controller determines the grid voltage, frequency, phase and other electrical quantity data through the detection equipment, and determines that the grid state is normal; ③ According to the grid connection requirements, the controller presets the threshold values ​​of various working conditions of the grid.

[0075] At startup, the controller accepts local startup operation or remote startup command, and compares ① and system no-load operation loss ④: ①>④ and the wind speed at the wind turbine position is greater than the cut-in wind speed, the controller starts the system according to step 2 (power generation operation); ①>④ and the wind speeds at the wind turbine position are all less than the cut-in wind speed, the controller starts the system according to step 3 (phase-shifting operation); ①<④ and the wind speed at the wind turbine position is greater than the cut-in wind speed, the controller starts the wind turbine, and the power output of the started wind turbine is stored in the energy storage system through the DC bus until ①>④, and the controller starts the system according to step 2 (power generation operation); ①<④ and the wind speeds at the wind turbine position are all less than the cut-in wind speed, the controller starts the grid power rectifier in the DC bus cabinet, and the grid power is stored in the energy storage system through the DC bus until ①>④, and the controller starts the system according to step 3 (phase-shifting operation).

[0076] When the power generation operation mode is started, the DC bus is connected to the bidirectional AC / DC, energy storage DC / DC and grid power rectifier on the wind turbine side. According to data ②, the speed of the generator set is adjusted through the inverter and the excitation voltage of the generator is adjusted through the excitation power supply cabinet to achieve synchronous grid connection and system grid connection operation. According to data ③, the grid parameters are immediately detected and judged, and the operating conditions are selected: data ③ is in normal operating conditions, follow step 2.1 (power generation according to scheduling); data ③ is in primary frequency regulation and steady-state voltage support demand operating conditions, follow step 2.2 (grid support function); data ③ is in the condition of providing fault support capacity, follow step 2.3 (fault support function). During the operation of the system, the controller monitors the wind speed in real time, which is used as the calculation basis for the maximum output capacity of wind power generation data ⑤ when the controller needs the next control instruction.

[0077] Step 2.1 (Generate electricity according to the dispatch), as follows:

[0078] According to the AGC command and data ⑤, when the AGC command value ≥ data ⑤, the controller calculates the motor torque according to data ⑤, and the wind turbine operates in the maximum power mode; when the AGC command value < data ⑤, the controller calculates the motor torque according to the AGC command value, and the wind turbine operates in the limited power mode. The motor torque calculation result is used as the torque command of the inverter, and the inverter is in the torque control mode. At this time, the system transmits all or part of the wind power generation to the power grid.

[0079] Step 2.2 (grid support function), as follows:

[0080] Run a frequency modulation according to data ③. When the grid frequency is less than the frequency threshold set by data ③, the controller calculates the required motor torque according to the frequency increase range for safe operation of the generator set, and comprehensively utilizes data ① and data ⑤. According to the frequency modulation time requirement, the controller uses the motor torque calculation result as the torque command of the inverter, and the inverter is in torque control mode. After exceeding the frequency modulation time requirement, the controller runs step 2.1 (generating electricity according to scheduling) with the current state of the grid frequency. When the grid frequency is ≥ the frequency threshold set by data ③, the controller calculates the required motor torque according to the frequency reduction range for safe operation of the generator set, and the controller uses the motor torque calculation result as the torque command of the inverter, and the inverter is in torque control mode. After exceeding the frequency modulation time requirement, the controller runs step 2.1 (generating electricity according to scheduling) with the current state of the grid frequency.

[0081] Provide steady-state voltage support according to data ③. The grid power provides excitation power to the synchronous generator through the AC / DC rectifier excitation cabinet, and the corresponding reactive power is output by adjusting the excitation current of the synchronous generator to achieve steady-state voltage support. When the grid voltage is less than the voltage threshold set by data ③, the controller calculates the difference between the system rated capacity and the current system output capacity based on the current system output capacity, uses the capacity difference as the excitation voltage increase, and outputs it to the excitation power supply to increase the inductive reactive output; when the grid voltage is greater than the voltage threshold set by data ③, according to the limit of the generator set's phase-leading safe operation and low excitation limit, the controller calculates the difference between the limiting capacity and the current system output capacity based on the limiting capacity, uses the capacity difference as the excitation voltage reduction, and outputs it to the excitation power supply to increase the capacitive reactive output. In this process, the active output is executed according to the priority system, that is, the phase-leading safe maximum capacity capacity>AGC instruction>data ⑤ decision

[0082] Step 2.3 (fault support function), as follows:

[0083] According to data ③, support for transient overvoltage faults in the power grid is provided. When the power grid voltage is greater than the voltage threshold set by data ③, according to the limit of the generator set's phase-advancing safe operation and low excitation limit, the controller calculates the difference between the limit capacity and the current system output capacity based on the limit capacity, and uses the capacity difference as the excitation voltage drop amount, outputs it to the excitation power supply, and increases the capacitive reactive power output. When the capacity difference is less than the limit capacity, the controller calculates the difference between the capacity difference and the limit capacity, calculates the motor torque size based on the difference, and outputs it to the inverter as a torque command to reduce the active power output. At the same time, the difference capacity can be used as the excitation voltage drop amount, output to the excitation power supply, and increase the capacitive reactive power output. In this process, the controller should monitor various temperature indicators of the generator. When the temperature is greater than the set threshold, the general control calculates the drop in the excitation voltage based on the size of the temperature threshold interval, and outputs it to the excitation power supply to reduce the excitation voltage and reduce the capacitive reactive power output. In this process, the active output is executed according to the priority system, that is, the phase-advancing safe maximum capacity capacity>AGC instruction>data ⑤ decision.

[0084] Provide grid short-circuit fault support based on data ③. When the three-phase or any two-phase grid voltage suddenly reaches zero, the controller enables the inverter to stop running, and the generator runs as a motor. The maximum phase current is monitored in real time, and the maximum current support capacity of the generator set is integrated. The difference between the maximum phase current and the maximum current support capacity is used to calculate the off-time of the grid-connected circuit breaker. If the short-circuit time is greater than the off-time, the controller enables the grid-connected cabinet to disconnect from the grid; if the short-circuit time is less than or equal to the off-time, the controller enables the inverter to run, and the generator runs according to step 2 (generating electricity).

[0085] When the phase-shifting operation mode is started, the DC bus is connected to the photovoltaic combiner box, energy storage DC / DC and grid power rectifier. According to data ②, the speed of the generator set is adjusted through the inverter and the excitation voltage of the generator is adjusted through the excitation power cabinet to achieve synchronous grid connection and the system is grid-connected. After the grid connection is successful, the controller gives instructions and the inverter enters the standby state. According to data ③, the grid parameters are immediately detected and judged, and the operating conditions are selected: data ③ is in normal operating conditions, follow step 3.1 (no-load hot standby operation); data ③ is in primary frequency regulation and steady-state voltage support demand operating conditions, follow step 3.2 (grid inertia function); data ③ is in the operating condition of providing fault support capability, follow step 3.3 (fault support function).

[0086] Step 3.1 (no-load hot standby operation) is as follows:

[0087] The controller detects the grid voltage and three-phase current, calculates the reactive output value, takes the reactive output value as the difference, calculates the excitation voltage adjustment range, outputs it to the excitation power supply, adjusts the excitation voltage, and maintains the reactive output at zero. At this time, the generator is driven by the grid and runs electrically without load, and is in a phase-adjusting hot standby state.

[0088] Step 3.2 (grid inertia support function), as follows:

[0089] When the grid frequency drops, the system relies on the rotation inertia to provide active support; when the grid frequency rises, the system relies on the rotation inertia to realize the flywheel energy storage function. At this time, the generator is driven by the grid and runs electrically at no load, and is in a phase-shifting hot standby state. The controller controls according to step 3.1 (no-load hot standby operation)

[0090] Step 3.3 (fault support function), as follows:

[0091] Provide grid transient overvoltage fault support according to data ③. When the grid voltage is greater than the voltage threshold set in data ③, the controller calculates the shutdown time based on the overvoltage protection requirements of the motor and grid-connected switch and the grid-connected switch action time. If the overvoltage time is greater than the shutdown time, the controller triggers an overvoltage fault and enables the grid-connected cabinet to be disconnected from the grid; if the overvoltage time is less than or equal to the shutdown time, follow step 3.1 (no-load hot standby operation).

[0092] It can be understood that the method embodiments provided above correspond to the device embodiments, and the corresponding specific contents can be referenced to each other and will not be repeated here.

[0093] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) that contain computer-usable program code.

[0094] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction method, which is implemented in the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0096] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0097] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for operating a power generation system, characterized in that: The power generation system includes: a multi-energy input device, an AC converter, a motor unit and a generator connected in sequence; the multi-energy input device outputs direct current, and outputs alternating current through the converter, the alternating current is used to drive the motor unit, the motor unit is coaxially connected to the generator to generate alternating current, and the generated alternating current is connected to the grid; wherein the multi-energy input device includes an energy storage system, the energy storage system is connected to the DC side of the converter, and serves as a backup power source for insufficient energy of new energy; after the new energy power generation is rectified, it is connected to the excitation winding as the excitation power source of the generator; The controller controls the converter to realize the operation of the power generation system. The operation method includes: The controller receives the start command and starts the power generation operation mode and the phase-shifting operation mode; When the power generation operation mode is started, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the converter to achieve synchronous grid connection; when the grid is operating normally, the normal power generation operation mode is started to dispatch power generation, perform primary frequency regulation and steady-state voltage support, otherwise, the abnormal power generation operation mode is started to provide fault support; among which, the fault support includes transient overvoltage fault and voltage short circuit fault support; When the phase-converter operation mode is started, the speed of the generator or the voltage of the excitation power supply is adjusted by driving the inverter to achieve synchronous grid connection; when the grid operating conditions are normal, the phase-converter operates in normal mode, performs no-load hot standby operation, and provides primary frequency regulation and steady-state voltage support. Otherwise, the phase-converter operation abnormal mode is started to provide fault support.

2. The method according to claim 1, characterized in that Before starting the power generation operation mode and the phase-converter operation mode, it also includes: Determining the available energy of a multi-source complementary input device; Determine power data and grid status; the power data includes grid voltage, frequency and phase; Set the thresholds for each grid condition.

3. The method according to claim 2, characterized in that When the available energy of the multi-source complementary input device is greater than the system no-load operation power consumption, and the wind speed at the wind turbine unit is greater than the cut-in wind speed, the power generation operation mode is started; When the available energy of the multi-source complementary input device is greater than the system no-load operation power consumption, and the wind speed at the wind turbine unit position is less than the cut-in wind speed, the phase-shifting operation mode is started; When the available energy of the multi-source complementary input device is less than the no-load power consumption of the system, and the wind speed at the wind turbine unit position is greater than the cut-in wind speed, the wind turbine unit is started, and the power generation output of the started wind turbine unit is stored in the energy storage module of the multi-source complementary input device through the DC bus until the available energy of the multi-source complementary input device is greater than the no-load power consumption of the system to start the power generation operation mode; When the available energy of the multi-source complementary input device is less than the system no-load power consumption, the grid power rectifier in the DC bus cabinet is started, and the grid power is stored in the energy storage module through the DC bus until the available energy of the multi-source complementary input device is greater than the system no-load power consumption, and the phase-shifting operation mode is started.

4. The method according to claim 1, characterized in that: Dispatching power generation, including: Compare the AGC command value and the maximum output capacity data of renewable energy power generation; When the AGC command value is greater than or equal to the maximum output capacity data of the new energy power generation, the motor torque is calculated according to the maximum output capacity data of the new energy power generation, so that the generator set operates at maximum power; When the AGC command value is less than the maximum output capacity data of the new energy power generation, the motor torque is calculated according to the AGC command value so that the generator set operates at limited power; Among them, the motor torque result is used as the torque command of the converter.

5. The method according to claim 2, characterized in that: In the power generation mode, the primary frequency regulation and steady-state voltage support include: Run frequency modulation once according to the power grid operating condition threshold to obtain the frequency threshold; When the grid frequency is less than the frequency threshold, the required motor torque is calculated according to the frequency increase range for safe operation of the generator set, and the motor torque is used as the torque command of the converter based on the available energy of the multi-source complementary input device and the maximum output capacity data of the new energy power generation based on the primary frequency modulation time requirement. After exceeding the primary frequency modulation time requirement, the current grid frequency is used for scheduling power generation; When the grid frequency is greater than or equal to the frequency threshold, the required motor torque is calculated according to the frequency reduction range for safe operation of the generator set, and the motor torque is used as the torque command of the converter. After exceeding the frequency modulation time requirement once, the current grid frequency is used for scheduling power generation; According to the threshold of the power grid working condition, the voltage stabilization support is provided. The multi-source complementary input device provides the excitation power supply for the synchronous generator through the AC / DC rectifier excitation cabinet, and the corresponding reactive power is output by adjusting the excitation current of the synchronous generator to achieve the steady-state voltage support function; specifically, Setting a first voltage threshold according to a power grid operating condition threshold; When the grid voltage is less than the first voltage threshold, a first capacity difference between the system rated capacity and the current system output capacity is calculated according to the current system output capacity, and the first capacity difference is used as the excitation voltage increase amount, which is output to the excitation power supply to increase the inductive reactive output; When the grid voltage is greater than the first voltage threshold, according to the limiting capacity of the generator set for safe phase leading operation and low excitation limit, the first capacity difference between the limiting capacity and the current system output capacity is calculated, and the first capacity difference is used as the excitation voltage reduction amount, which is output to the excitation power supply to increase the capacitive reactive output.

6. The method according to claim 2, characterized in that In the phase-shifting operation mode, fault support is provided, including: Provide grid transient overvoltage fault support according to grid operating thresholds; specifically: Setting a second voltage threshold according to a power grid operating condition threshold; When the grid voltage is greater than the second voltage threshold, according to the limiting capacity of the generator set for phase leading safety operation and the limiting of the low excitation limit, a second capacity difference between the limiting capacity and the current system output capacity is calculated, and the second capacity difference is used as the excitation voltage reduction amount, which is output to the excitation power supply to increase the capacitive reactive power output; When the second capacity difference is less than the limiting capacity, the difference capacity between the second capacity difference and the limiting capacity is calculated, the motor torque is calculated based on the difference capacity, and the difference capacity is used as a torque command to output to the converter to reduce the active output. At the same time, the difference capacity can be used as an excitation voltage reduction amount to output to the excitation power supply to increase the capacitive reactive output. Provide grid short-circuit fault support according to grid operating thresholds; specifically: When the three-phase or any two-phase voltage of the power grid suddenly reaches zero, the controller controls the converter to stop running, and the generator runs as a motor unit. The maximum phase current is monitored in real time, and the maximum current supporting capacity of the generator set is integrated. The difference between the maximum phase current and the maximum current supporting capacity is used to calculate the shutdown time of the grid-connected circuit breaker. If the short-circuit time is greater than the shutdown time, the controller enables the grid-connected cabinet to be disconnected from the grid; if the short-circuit time is less than or equal to the shutdown time, the controller enables the converter to run, and the generator enters the power generation operation mode.

7. The method according to claim 1, characterized in that Perform no-load hot standby operation, including: Detect the grid voltage and three-phase current, calculate the reactive output value based on the grid voltage and three-phase current, calculate the excitation voltage adjustment amplitude with the reactive output value as the difference, output it to the excitation power supply, adjust the excitation voltage, and maintain the reactive output at zero.

8. The method according to claim 1, characterized in that When the phase regulator is in operation mode, the primary frequency modulation and steady-state voltage support include: When the grid frequency drops, the power generation system relies on rotational inertia to provide active support; When the grid frequency rises, the power generation system relies on the rotational inertia to realize the flywheel energy storage function; At this time, the generator is driven by the power grid and runs at no load, and is in a phase-shifting hot standby state.

9. The method according to claim 2, characterized in that: In the phase-shifting operation mode, fault support is provided, including: Provide grid transient overvoltage fault support according to grid operating thresholds; specifically: Setting a third voltage threshold according to a power grid operating condition threshold; When the grid voltage is greater than the third voltage threshold, the shutdown time is calculated according to the overvoltage protection requirements of the motor unit and the grid-connected switch and the action time of the grid-connected switch; if the overvoltage time is greater than the shutdown time, an overvoltage fault is triggered and the grid-connected cabinet is enabled to be disconnected from the grid; if the overvoltage time is less than or equal to the shutdown time, no-load hot standby operation is performed.

10. The method according to claim 1, characterized in that The generator set is a direct-drive wind generator set or a double-fed wind generator set.

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