Black start system and method of integrated energy peak shaving gas power plant

Abstract

A black start system for an integrated energy peak-shaving gas-fired power plant includes a main power grid, a backup power grid, a photovoltaic power generation unit, an energy storage device, a diesel generator, a step-up transformer, and a 6kV load section for plant use. The main power grid is connected to the 6kV load section for plant use via a first switch. The backup power grid is connected to the 6kV load section for plant use via a second switch. The photovoltaic power generation unit includes photovoltaic panels and a photovoltaic inverter connected to the photovoltaic panels. The output of the photovoltaic inverter is divided into two paths: one path is connected to the photovoltaic power grid, and the other path is connected to the input of the energy storage device. The output of the energy storage device is connected in parallel with the output of the diesel generator via a discharge switch, and then connected to the low-voltage side of the step-up transformer. The high-voltage side of the step-up transformer is connected to the 6kV load section for plant use. The 6kV load section for plant use supplies power to the auxiliary systems of the gas turbine, achieving the fundamental purpose of successfully implementing the black start of the power plant by supplying power to the key auxiliary systems of the gas turbine.

Description

Technical Field

[0001] This invention relates to a black start system and method for integrated energy peak-shaving gas-fired power plants, belonging to the field of black start technology. Background Technology

[0002] Gas turbine power generation is characterized by its flexible start-up and shutdown and rapid load adjustment. In my country, most gas turbine units serve as peak-shaving and emergency backup power for the power grid. With the rapid development of new energy sources, some power plants have begun constructing photovoltaic power stations and energy storage devices, taking advantage of their advantageous geographical locations. In the event of a complete power outage, i.e., when the power plant loses its backup power, how to ensure the effective operation of gas turbine power plants as emergency peak-shaving power plants is a problem that needs to be addressed. Summary of the Invention

[0003] To address the aforementioned problems in existing technologies, this invention provides a black start system and method for integrated energy peak-shaving gas-fired power plants. This system can quickly construct an independent and stable isolated grid operation system, thereby achieving the fundamental goal of powering key auxiliary systems of the gas turbine and successfully implementing black start of the power plant.

[0004] The technical solution of the present invention is as follows: A black start system for an integrated energy peak-shaving gas-fired power plant includes a main power grid, a backup power grid, a photovoltaic power generation unit, an energy storage device, a diesel generator, a step-up transformer, and a 6kV load section for plant use. The main power grid is connected to the 6kV load section for plant use via a first switch. The backup power grid is connected to the 6kV load section for plant use via a second switch. The photovoltaic power generation unit includes photovoltaic panels and a photovoltaic inverter connected to the photovoltaic panels. The output of the photovoltaic inverter is divided into two paths: one path is connected to the photovoltaic power grid, and the other path is connected to the input of the energy storage device. The output of the energy storage device is connected in parallel with the output of the diesel generator via a discharge switch and then connected to the low-voltage side of the step-up transformer. The high-voltage side of the step-up transformer is connected to the 6kV load section for plant use. The 6kV load section for plant use supplies power to the auxiliary equipment system of the gas turbine. The auxiliary equipment system includes at least a feedwater pump, a condensate pump, a deaerator pump, and a circulating water pump driven by a frequency converter.

[0005] The system also includes a transient stability enhancement system, comprising a phasor measurement unit array and a central controller. The phasor measurement unit array is deployed at the diesel generator outlet, the energy storage converter outlet of the energy storage device, the high-voltage side of the step-up transformer, and the busbar of the 6kV load section of the plant, for synchronously measuring the real-time voltage, frequency, and phase angle of each node. The communication interface of the central controller is connected to the phasor measurement unit array, for dynamically calculating the equivalent center of inertia of the islanded network system formed by the parallel connection of the diesel generator and the energy storage device and the power angle stability margin of each power source point based on the real-time phasor data of the phasor measurement unit array. The command output terminal of the central controller is connected to the control terminal of the energy storage converter of the energy storage device, for issuing rapid power compensation commands to the energy storage converter.

[0006] The energy storage device includes a battery system, a battery management system, an energy storage converter, and a control unit. The battery system consists of a lithium-ion battery pack. The battery management system is electrically connected to the battery system and is used to monitor the total voltage, total current, state of charge, and temperature parameters of the battery system in real time, and to provide electrical protection. The DC side of the energy storage converter is connected to the battery system, and its AC side is connected to the parallel connection point between the output terminal of the diesel generator and the low-voltage side of the step-up transformer through the discharge switch. The control unit is communicatively connected to both the battery management system and the energy storage converter, and is scheduled by the central controller.

[0007] A black start method for an integrated energy peak-shaving gas-fired power plant includes the following steps: S1. When it is detected that both the main power grid and the backup power supply have lost power, resulting in a power outage of the 6kV load section of the plant, the discharge switch of the energy storage device is closed, and the diesel generator is started at the same time. The diesel generator and the energy storage device are connected in parallel to form an isolated grid operation system independent of the main power grid, which supplies power to the load of the 6kV load section of the plant. S2. After the diesel generator starts up to the grid connection condition, control the diesel generator output switch to close, so that the energy storage device and the diesel generator can operate in parallel. The electrical energy output by both devices is stepped up by the step-up transformer and then transmitted to the 6kV load section of the plant. S3. Utilize the electrical energy of the plant's 6kV load section to start the condensate pump in a frequency conversion mode. S4. After receiving the dispatch start command, the gas turbine is driven to rotate and accelerate until ignition by using the power energy of the 6kV load section of the plant through the start frequency converter. S5. After the gas turbine is successfully ignited and drives the main generator to the rated speed to generate electricity, the main generator outlet switch and the first switch are closed in sequence to restore power supply to the main power grid. S6. After the main boiler starts to heat up and pressurize, the power of the 6kV load section of the plant is used again to start the feed water pump and circulating water pump in sequence by frequency conversion. S7. After the operating parameters of the entire gas turbine, main generator and auxiliary system have stabilized, shut down the diesel generator and open its diesel generator outlet switch, and at the same time open the discharge switch of the energy storage device to complete the black start.

[0008] The central controller is configured to execute the following optimized control loop after step S2: S2.1 Continuously acquire the total load power of the plant's 6kV load section. The remaining power of the energy storage device and the real-time output of the photovoltaic power generation unit. ; S2.2 Control the diesel generator to operate at a constant power point between 70% and 85% of its rated power. ; S2.3, The energy storage device shall bear the real-time power difference. ,Right now To achieve dynamic power balance in the system; when When, the energy storage device discharges; when At that time, the energy storage device is charged; S2.4 When the remaining power of the energy storage device is detected When the output power remains below 30%, the central controller controls the output power point of the diesel generator. Increase to 90% of its rated power, until After recovering to more than 50%, then use Return to the original set value; when detected When the output power remains above 80%, the central controller controls the output power point of the diesel generator. Reduce to 60% of its rated power; S2.5 When the real-time output of the photovoltaic power generation unit is monitored... The load power remains higher than the total load power. And the remaining power of the energy storage device When the output power of the diesel generator is below 95%, the central controller will adjust the output power of the diesel generator. The power output is reduced to a minimum range of 40% to 50% of its rated power, with priority given to the photovoltaic power generation units to meet the load demand, while charging the energy storage devices.

[0009] The central controller is also configured to execute the following transient stability control process in parallel during the cyclic execution of steps S2.1 to S2.5: S2.6. By deploying phasor measurement unit arrays at the diesel generator outlet, the energy storage converter outlet of the energy storage device, and the 6kV load section bus of the plant, the frequency change rate of the isolated grid operation system is measured synchronously; when the absolute value of the frequency change rate exceeds the preset danger threshold, it is determined that the isolated grid operation system is facing the risk of transient instability. S2.7 The central controller immediately interrupts the current optimization control loop and prioritizes calculating the damping power component that needs to be injected by the energy storage device. and inertial power components It directly sends a rapid power compensation command to the energy storage converter; the energy storage device outputs power according to the command, simulating the damping and inertial characteristics of a synchronous generator to suppress oscillations and support the frequency of the islanded grid operation system; S2.8 The central controller continuously monitors the status of the isolated grid operation system until the frequency change rate returns to a safe and stable range, then instructs the energy storage device to stop outputting the damped power component. and inertial power components And resume the execution of the optimized control loop.

[0010] An automatic quasi-synchronous grid connection system is configured at the grid connection control node located between the main generator outlet and the 6kV auxiliary power load section. The automatic quasi-synchronous grid connection system includes a synchronization phasor measurement unit, a programmable logic controller (PLC), and a closing controller. The input terminals of the synchronization phasor measurement unit are electrically connected to the main generator outlet voltage transformer and the bus voltage transformer of the 6kV auxiliary power load section, respectively, for measuring the phase angle difference between the voltages on both sides. With frequency difference The input terminal of the programmable logic controller (PLC) is connected to the output terminal of the synchronous phasor measurement unit; the signal input terminal of the closing controller is connected to the output terminal of the PLC, and its power output terminal is connected to the operating mechanism of the main generator output switch; wherein, the PLC pre-stores the fixed mechanical closing action time of the main generator output switch. Programmable logic controllers are used for real-time reception. and And calculate the rate of change of phase angle difference. ,when Less than the set threshold and When it is a constant negative value, according to the formula Calculate the time of issuing the closing command. and in The closing command is sent to the closing controller at all times.

[0011] The present invention has the following beneficial effects: This invention achieves the fundamental goal of successfully implementing black start of a power plant by connecting the output of an energy storage device in parallel with the output of a diesel generator via a discharge switch and connecting them together to the 6kV load section of the plant through a step-up transformer. This is achieved by connecting the output of the energy storage device in parallel with the output of the diesel generator via a discharge switch and connecting them together via a step-up transformer. This enables the rapid construction of an independent and stable isolated grid operation system in the extreme case of power loss in both the main grid and the backup grid.

[0012] This invention, by configuring a transient stability enhancement system consisting of a phasor measurement unit array and a central controller, and connecting its command output terminal to the energy storage converter control terminal of the energy storage device, achieves real-time and accurate perception and rapid active intervention of the dynamic characteristics of the isolated grid system. It achieves the effect of using the energy storage device to simulate the damping and inertial characteristics of a synchronous generator, effectively suppressing system oscillations, preventing the risk of transient instability, and significantly improving the safety of small-capacity isolated grid systems.

[0013] This invention achieves decoupled control by dynamically setting the optimal economic operating power point of the diesel generator through a central controller and having the energy storage device handle the real-time power difference. This decouples the control of stabilizing the diesel generator in a high-efficiency operating condition with the rapid response of the energy storage to load fluctuations. This results in optimizing the overall system operating efficiency, reducing fuel consumption, extending the life of the diesel generator, and ensuring that the energy storage charge state is maintained at a healthy level.

[0014] This invention achieves unprecedentedly accurate prediction and control of grid connection timing by setting up an automatic quasi-synchronous grid connection system between the main generator outlet and the 6kV load section of the plant, and by utilizing its programmable logic controller to pre-store the switch closing time and calculate the closing command issuance time in real time. This results in a rapid, smooth, and shock-free quasi-synchronous grid connection after the main generator resumes power generation, minimizing the impact on the stability of the isolated grid system. Attached Figure Description

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

[0016] The reference numerals in the figure are as follows: 1. Main power grid; 2. Backup power grid; 3. Energy storage device; 4. Diesel generator; 5. Step-up transformer; 6. 6kV load section for plant use; 7. Discharge switch; 9. Photovoltaic panel; 11. Main generator; 12. Main generator outlet switch; 13. First switch; 21. Second switch; 41. Diesel generator outlet switch; 81. Feed water pump; 82. Condensate pump; 83. Deaerator pump; 84. Circulating water pump; 91. Photovoltaic inverter; 92. Photovoltaic grid. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] Please see Figure 1 The invention provides a technical solution: The black start system of the integrated energy peak-shaving gas-fired power plant in this embodiment includes a main power grid 1, a backup power grid 2, a photovoltaic power generation unit, an energy storage device 3, a diesel generator 4, a step-up transformer 5, and a 6kV load section 6 for plant use. The main power grid 1 is connected to the 6kV load section 6 for plant use via a first switch 13. The backup power grid 2 is connected to the 6kV load section 6 for plant use via a second switch 21. Both the first switch 13 and the second switch 21 are high-voltage circuit breakers with electrical interlocking functions to ensure that only one power source supplies power at a time and to prevent backfeeding. The photovoltaic power generation unit includes photovoltaic panels 9 and a photovoltaic inverter 91 connected to the photovoltaic panels 9. The output of the photovoltaic inverter 91 is divided into two paths, one of which is connected to the photovoltaic grid 92, and the other is connected to... When connected to the input terminal of the energy storage device 3, the photovoltaic energy can preferentially charge the energy storage device 3 under normal grid conditions, ensuring that the energy storage device is in a high-power standby state during black start. The output terminal of the energy storage device 3 is connected in parallel with the output terminal of the diesel generator 4 through the discharge switch 7, and then connected to the low-voltage side of the step-up transformer 5. The step-up transformer 5 not only completes voltage transformation here, but its impedance characteristics also help to balance the transient process when the diesel generator 4 and the energy storage device 3 are running in parallel. The high-voltage side of the step-up transformer 5 is connected to the 6kV load section 6 of the plant. The 6kV load section 6 of the plant supplies power to the auxiliary system of the gas turbine. The auxiliary system includes at least a feedwater pump 81, a condensate pump 82, a deaerator pump 83, and a circulating water pump 84 driven by a frequency converter.

[0019] Specifically, when the power grid is normal, the plant's auxiliary power is supplied by the main power grid 1 with priority, while the backup power grid 2 is in a hot standby state. At this time, the energy generated by the photovoltaic power generation unit can partially supply the plant's auxiliary load, and the remaining part is sent to the photovoltaic power grid 92 through the inverter or to charge the energy storage device 3.

[0020] The main power grid 1 and the backup power grid 2 are connected to the 6kV load section 6 of the plant through their respective first switch 13 and second switch 21, which ensures the hot standby relationship of the plant power supply under normal operating conditions. Electrical interlocking logic is usually set between the two power supplies to prevent parallel operation.

[0021] The core component of the photovoltaic power generation unit, the photovoltaic inverter 91, converts direct current into alternating current and then outputs two paths. One path is sent to the photovoltaic grid 92 to realize the local consumption or grid connection of green electricity, and the other path is connected to the input end of the energy storage device 3. This path allows photovoltaic energy to prioritize charging the energy storage device 3, thereby ensuring that the energy storage device 3 can maintain a high state of charge during daily operation and reserve the necessary energy to cope with sudden grid failures.

[0022] The core backup power source of the system consists of an energy storage device 3 and a diesel generator 4. Their outputs are connected in parallel on the low-voltage side via a discharge switch 7; this parallel connection point is crucial for the system's flexibility. The energy storage device 3 has an extremely fast response speed, providing power support for a short time; the diesel generator 4 provides stable and continuous power output. After being connected in parallel, the electrical energy is collected on the low-voltage side of the step-up transformer 5, stepped up to 6kV, and then sent to the 6kV load section 6 of the plant. The step-up transformer 5 not only performs voltage transformation here, but its inherent impedance characteristics also help balance the transient processes that may occur when different power sources are connected in parallel.

[0023] Ultimately, electrical energy is distributed from the plant's 6kV load section 6 to the critical auxiliary systems of the gas turbine. Notably, all important auxiliary equipment, including feedwater pump 81, condensate pump 82, deaerator pump 83, and circulating water pump 84, are explicitly designed to be driven by frequency converters. This design is a structural prerequisite for the system's safe and smooth startup of large power equipment. Because frequency converter starting enables soft starting of the motor, it significantly reduces the impact of starting current on the power supply system, avoiding the risk of power overload or voltage collapse that could occur when directly starting a large-capacity motor, thus laying a solid foundation for any subsequent orderly power restoration.

[0024] It is also equipped with a transient stability enhancement system; the transient stability enhancement system includes a phasor measurement unit array and a central controller; the phasor measurement unit array is deployed at the outlet of diesel generator 4, the outlet of energy storage converter of energy storage device 3, the high-voltage side of step-up transformer 5, and the busbar of 6kV load section 6 of the plant, and is used to synchronously measure the voltage, frequency, phase angle and real-time code of each node; the communication interface of the central controller is connected to the phasor measurement unit array, and is used to dynamically calculate the equivalent inertia center and the power angle stability margin of each power source point of the islanded network system composed of diesel generator 4 and energy storage device 3 connected in parallel based on the real-time phasor data of the phasor measurement unit array; the command output terminal of the central controller is connected to the control terminal of energy storage converter of energy storage device 3, and is used to send fast power compensation commands to energy storage converter.

[0025] When both the main power grid and the backup power grid lose power, the system automatically or manually switches to islanded operation mode. At this time, the diesel generator 4 provides voltage and frequency support as the main power source, and the energy storage device 3 compensates for the slow dynamic response of the diesel generator as a fast-response power source. The two work together through the step-up transformer 5 to construct a stable 6kV load section 6 for plant use, providing a power source for black start.

[0026] The hardware foundation of this transient stability enhancement system is a phasor measurement unit array; each phasor measurement unit is a high-precision measurement device, ensuring strict synchronization of measurement data at different nodes. Specifically, the phasor measurement unit at the outlet of diesel generator 4 is used to monitor the power angle and frequency of the main power source; the phasor measurement unit at the outlet of the energy storage converter of energy storage device 3 is used to monitor the operating status of the fast-response power source; the phasor measurement unit on the high-voltage side of step-up transformer 5 is used to monitor the quality of power delivered to the load point; and the phasor measurement unit on the busbar of the 6kV load section 6 is used to monitor the voltage stability of the system load center. These phasor measurement units are connected to a central controller via a high-speed communication network. The central controller typically consists of a high-performance industrial computer or a dedicated controller, which runs complex stability analysis algorithms.

[0027] Equivalent center of inertia calculation: Based on the inertial time constant and real-time rotational speed changes at each power source point, the formula is as follows:

[0028] in, Let be the inertial constant of each power source. This is for frequency deviation; Power angle stability margin calculation: Real-time tracking of the power angle difference between diesel generator 4 and the system's equivalent center of inertia; calculation of the distance margin between the current operating point and the stability limit, while considering the effects of damping coefficient and synchronous torque coefficient; The fundamental purpose of setting up the transient stability enhancement system is to solve the inherent vulnerability of the isolated grid system composed of diesel generator 4 and energy storage device 3, thereby ensuring the success of the black start process.

[0029] The transient stability enhancement system synchronously monitors the system through a phasor measurement unit array. Once it identifies instability risks such as power oscillations or rapid frequency changes caused by the switching of large auxiliary equipment or internal faults, the central controller can immediately instruct the energy storage device 3 with extremely fast response speed to simulate the damping and inertial characteristics of a synchronous generator and inject compensation power to resist disturbances.

[0030] The energy storage device 3 includes a battery system, a battery management system, an energy storage converter, and a control unit. The battery system consists of a lithium-ion battery pack. The battery management system is electrically connected to the battery system and is used to monitor the total voltage, total current, state of charge, and temperature parameters of the battery system in real time, and to provide electrical protection. The DC side of the energy storage converter is connected to the battery system, and its AC side is connected to the parallel connection point between the output terminal of the diesel generator 4 and the low-voltage side of the step-up transformer 5 through the discharge switch 7. The control unit is communicatively connected to the battery management system and the energy storage converter, and is scheduled by the central controller.

[0031] The black start method for a gas-fired power plant for integrated energy peak shaving in this embodiment includes the following steps: S1. When it is detected that both the main power grid 1 and the backup power supply 2 have lost power, resulting in the power outage of the 6kV load section 6 of the plant, the discharge switch 7 of the energy storage device 3 is closed, and the diesel generator 4 is started at the same time. The diesel generator 4 and the energy storage device 3 are connected in parallel to form an isolated grid operation system independent of the main power grid, which supplies power to the load of the 6kV load section 6 of the plant. S2. After the diesel generator 4 starts up to the grid connection condition, control the diesel generator output switch 41 to close, so that the energy storage device 3 and the diesel generator 4 can operate in parallel. The electrical energy output by both devices is stepped up by the step-up transformer 5 and then transmitted to the 6kV load section 6 of the plant. S3. Utilize the electrical energy of the 6kV load section 6 of the plant to start the condensate pump 82 in the frequency conversion mode first. S4. After receiving the dispatch start command, the gas turbine is driven to rotate and speed up until ignition by using the power of the 6kV load section 6 of the plant to start the frequency converter. S5. After the gas turbine is successfully ignited and drives the main generator 11 to the rated speed to generate electricity, the main generator outlet switch 12 and the first switch 13 are closed in sequence to restore power supply to the main power grid 1. S6. After the main boiler starts to heat up and pressurize, the power of the 6kV load section 6 of the plant is used again to start the feed water pump 81 and the circulating water pump 84 in sequence by frequency conversion. S7. After the operating parameters of the entire gas turbine, main generator 11 and auxiliary system have stabilized, shut down the diesel generator 4 and open its diesel generator outlet switch 41. At the same time, open the discharge switch 7 of the energy storage device to complete the black start.

[0032] The central controller is configured to execute the following optimized control loop after step S2: S2.1 Continuously acquire the total load power of the 6kV load section 6 of the plant. The remaining power of energy storage device 3 and the real-time output of photovoltaic power generation units. These data will undergo validity checks and smoothing filtering to eliminate outlier values ​​and ensure that control commands are issued based on reliable data. S2.2 Control the diesel generator 4 to operate at a constant power point between 70% and 85% of its rated power. ; S2.3, The real-time power difference is borne by the energy storage device 3. ,Right now To achieve dynamic power balance in the system; when When, the energy storage device (3) discharges; when At that time, the energy storage device (3) is charged; It should be added that the central controller will calculate... The value is compared with the real-time maximum charge / discharge capacity of energy storage device 3. If If the instantaneous regulation capacity of the energy storage device 3 is exceeded, the central controller will prioritize system stability and will adjust the power point of the diesel generator 4 accordingly. Alternatively, according to the preset load priority order, some non-critical loads can be cut off to prevent the energy storage device 3 from overloaded or the system from becoming unstable.

[0033] S2.4 When the remaining power of energy storage device 3 is detected When the power level remains below 30%, the central controller controls the output power of diesel generator 4. Increase to 90% of its rated power, until After recovering to more than 50%, then use Return to the original set value; when detected When the output power remains above 80%, the central controller controls the output power of diesel generator 4. Reduce to 60% of its rated power; hour, The purpose of increasing the power output to 90% of its rated capacity is to address the risk posed by insufficient regulation and backup energy in the system when the energy storage capacity is too low. By increasing the output of diesel generator 4, the charging power to the energy storage is increased while meeting the load requirements, allowing the energy level to quickly return to a safe level. hour, The purpose of reducing the output of the diesel generator to 60% of its rated power is to appropriately reduce the output of the diesel generator when the energy storage capacity is sufficient, so that it can operate in a more efficient range, reduce fuel consumption and wear, and at the same time avoid damage to the energy storage due to overcharging.

[0034] S2.5 When the real-time output of the photovoltaic power generation unit is monitored Continuously exceeding the total load power And the remaining power of energy storage device 3 When the output power of diesel generator 4 is below 95%, the central controller will reduce the output power of diesel generator 4. The power output is reduced to a minimum range of 40% to 50% of its rated power, and the photovoltaic power generation unit is given priority to meet the load demand while charging the energy storage device 3.

[0035] The purpose of optimizing the control cycle is to set the output power of the diesel generator 4 within the optimal economic operating range of 70%-85% of its rated power, thereby avoiding inefficient and high-wear low-load operating conditions, while maintaining a certain power margin to cope with emergencies, significantly improving operating efficiency and extending equipment life.

[0036] At the same time, by utilizing the power response characteristics of energy storage device 3, the power difference caused by load fluctuations and the randomness of photovoltaic output can be mitigated. This not only ensures real-time power balance, but more importantly, it frees the slow-responding diesel generator 4 from frequent power adjustment tasks, enabling it to operate stably and thus laying the foundation for frequency stability of the entire islanded grid system.

[0037] Finally, by introducing photovoltaic power... and settings The threshold management strategy establishes a priority for energy use, prioritizing the consumption of photovoltaic energy with zero marginal cost. By adjusting the power point of the diesel generator 4, the charging and discharging management of the energy storage device 3 is achieved, ensuring that this key resource of energy storage is always kept in a healthy and usable state, and reserving the necessary energy for the subsequent stages of black start.

[0038] The central controller is also configured to execute the following transient stability control process in parallel during the cyclic execution of steps S2.1 to S2.5: S2.6. The frequency change rate of the isolated grid operation system is simultaneously measured by the phasor measurement unit array installed at the outlet of diesel generator 4, the outlet of energy storage converter of energy storage device 3, and the 6kV load section 6 busbar of the plant. When the absolute value of the frequency change rate exceeds the preset danger threshold, it is determined that the isolated grid operation system is facing the risk of transient instability. The phasor measurement unit array synchronously measures the voltage phasors of key nodes and calculates the instantaneous frequency change rate of the entire system based on this. The central controller will operate in real time. The value is compared with multiple preset thresholds: Warning threshold (e.g.) >0.5 Hz / s): Triggers an early warning log, but does not interrupt the optimization loop.

[0039] Danger threshold (e.g.) >1.0 Hz / s): If the system is deemed to be at risk of transient instability, the emergency control logic of S2.7 is immediately triggered.

[0040] S2.7 The central controller immediately interrupts the current optimization control loop and prioritizes calculating the damping power component that needs to be injected by the energy storage device 3. and inertial power components It directly sends a fast power compensation command to the energy storage converter; the energy storage device 3 outputs power according to the command, simulating the damping and inertial characteristics of the synchronous generator to suppress oscillations and support the frequency of the islanded grid operation system;

[0041] in This is a virtual inertia constant. This component is used to simulate the inertia of a synchronizer to resist rapid changes in frequency.

[0042]

[0043] in The damping coefficient is... This represents the frequency deviation. This component is used to provide positive damping and suppress power oscillations.

[0044] Once the calculation is complete, the command is sent directly to the energy storage converter via a high-speed communication link.

[0045] S2.8 The central controller continuously monitors the status of the isolated grid operation system until the frequency change rate returns to a safe and stable range, then instructs the energy storage device 3 to stop outputting the damped power component. and inertial power components And resume the execution of the optimized control loop.

[0046] An automatic quasi-synchronous grid connection system is configured at the grid connection control node located between the outlet of the main generator 11 and the 6kV load section 6 of the plant. The automatic quasi-synchronous grid connection system includes a synchronization phasor measurement unit, a programmable logic controller, and a closing controller. The input terminals of the synchronization phasor measurement unit are electrically connected to the outlet voltage transformer of the main generator 11 and the bus voltage transformer of the 6kV load section 6 of the plant, respectively, to measure the phase angle difference between the voltages on both sides. With frequency difference The input terminal of the programmable logic controller (PLC) is connected to the output terminal of the synchronous phasor measurement unit; the signal input terminal of the closing controller is connected to the output terminal of the PLC, and its power output terminal is connected to the operating mechanism of the main generator output switch 12; wherein, the PLC pre-stores the fixed mechanical closing action time of the main generator output switch 12. Programmable logic controllers are used for real-time reception. and And calculate the rate of change of phase angle difference. ,when Less than the set threshold and When it is a constant negative value, according to the formula Calculate the time of issuing the closing command. and in The closing command is sent to the closing controller at all times.

[0047] The embodiments described above are merely illustrative of specific implementations of the present invention, and while the descriptions are detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A black start system for a comprehensive energy peak-shaving gas-fired power plant, characterized in that: The system includes a main power grid (1), a backup power grid (2), a photovoltaic power generation unit, an energy storage device (3), a diesel generator (4), a step-up transformer (5), and a 6kV load section (6) for plant use. The main power grid (1) is connected to the 6kV load section (6) for plant use via a first switch (13). The backup power grid (2) is connected to the 6kV load section (6) for plant use via a second switch (21). The photovoltaic power generation unit includes a photovoltaic panel (9) and a photovoltaic inverter (91) connected to the photovoltaic panel (9). The output of the photovoltaic inverter (91) is divided into two paths, one of which is connected to the photovoltaic power generation unit. One path is connected to the input terminal of the energy storage device (3); the output terminal of the energy storage device (3) is connected in parallel with the output terminal of the diesel generator (4) through the discharge switch (7), and then connected together to the low-voltage side of the step-up transformer (5); the high-voltage side of the step-up transformer (5) is connected to the 6kV load section (6) of the plant; the 6kV load section (6) of the plant supplies power to the auxiliary machine system of the gas turbine, and the auxiliary machine system includes at least a feed water pump (81), a condensate pump (82), a deaerator pump (83) and a circulating water pump (84) driven by a frequency converter.

2. The black start system for a comprehensive energy peak-shaving gas-fired power plant as described in claim 1, characterized in that: It is also equipped with a transient stability enhancement system; the transient stability enhancement system includes a phasor measurement unit array and a central controller; the phasor measurement unit array is deployed at the outlet of the diesel generator (4), the outlet of the energy storage converter of the energy storage device (3), the high-voltage side of the step-up transformer (5) and the bus of the 6kV load section (6) of the plant, and is used to synchronously measure the voltage, frequency and phase angle real-time code of each node; the communication interface of the central controller is connected to the phasor measurement unit array, and is used to dynamically calculate the equivalent inertia center and the power angle stability margin of each power supply point of the islanded network system composed of the diesel generator (4) and the energy storage device (3) in parallel based on the real-time phasor data of the phasor measurement unit array; the command output terminal of the central controller is connected to the control terminal of the energy storage converter of the energy storage device (3), and is used to send a fast power compensation command to the energy storage converter.

3. The black start system for a comprehensive energy peak-shaving gas-fired power plant as described in claim 2, characterized in that: The energy storage device (3) includes a battery system, a battery management system, an energy storage converter, and a control unit. The battery system is composed of a lithium-ion battery pack. The battery management system is electrically connected to the battery system and is used to monitor the total voltage, total current, state of charge, and temperature parameters of the battery system in real time, and to provide electrical protection. The DC side of the energy storage converter is connected to the battery system, and its AC side is connected to the parallel connection point of the output terminal of the diesel generator (4) and the low-voltage side of the step-up transformer (5) through the discharge switch (7). The control unit is communicatively connected to the battery management system and the energy storage converter, and is scheduled by the central controller.

4. The black start method for an integrated energy peak-shaving gas-fired power plant as described in claim 3, comprising the following steps: S1. When it is detected that both the main power grid (1) and the backup power supply (2) are de-energized, causing the 6kV load section (6) of the plant to be de-energized, the discharge switch (7) of the energy storage device (3) is closed, and the diesel generator (4) is started at the same time. The diesel generator (4) and the energy storage device (3) are connected in parallel to form an isolated grid operation system independent of the main power grid, which supplies power to the load of the 6kV load section (6) of the plant. S2. After the diesel generator (4) is started to the grid connection condition, the diesel generator output switch (41) is closed so that the energy storage device (3) and the diesel generator (4) are connected in parallel and the electrical energy output by both is stepped up by the step-up transformer (5) and then sent to the 6kV load section (6) of the plant. S3. Using the electrical energy of the plant's 6kV load section (6), the condensate pump (82) is started first in a frequency conversion mode. S4. After receiving the dispatch start command, the gas turbine is driven to rotate and speed up until ignition by using the power of the 6kV load section (6) of the plant to start the frequency converter. S5. After the gas turbine is successfully ignited and drives the main generator (11) to the rated speed to generate electricity, the main generator outlet switch (12) and the first switch (13) are closed in sequence to restore power supply to the main power grid (1). S6. After the main boiler starts to heat up and pressurize, the power of the 6kV load section (6) of the plant is used again to start the feed water pump (81) and the circulating water pump (84) in sequence by frequency conversion. S7. After the operating parameters of the entire gas turbine, main generator (11) and auxiliary system have stabilized, shut down the diesel generator (4) and open its diesel generator outlet switch (41), and at the same time open the discharge switch (7) of the energy storage device to complete the black start.

5. The black start method for a comprehensive energy peak-shaving gas-fired power plant as described in claim 4, characterized in that: The central controller is configured to execute the following optimized control loop after step S2: S2.1 Continuously acquire the total load power of the 6kV load section (6) of the plant. The remaining power of the energy storage device (3) and the real-time output of the photovoltaic power generation unit. ; S2.2 Control the diesel generator (4) to operate at a constant power point between 70% and 85% of its rated power. ; S2.3 The energy storage device (3) shall bear the real-time power difference. ,Right now To achieve dynamic power balance in the system; when When, the energy storage device (3) discharges; when At that time, the energy storage device (3) is charged; S2.4 When the remaining power of the energy storage device (3) is detected... When the output power remains below 30%, the central controller controls the output power of the diesel generator (4). Increase to 90% of its rated power, until After recovering to more than 50%, then use Return to the original set value; when detected When the output power remains above 80%, the central controller controls the output power point of the diesel generator (4). Reduce to 60% of its rated power; S2.5 When the real-time output of the photovoltaic power generation unit is monitored... The load power remains higher than the total load power. And the remaining power of the energy storage device (3) When the output power of the diesel generator (4) is below 95%, the central controller will control the output power of the diesel generator (4). The power is reduced to the lowest power range of 40% to 50% of its rated power, and the photovoltaic power generation unit is given priority to meet the load demand, while charging the energy storage device (3).

6. The black start method for a comprehensive energy peak-shaving gas-fired power plant as described in claim 5, characterized in that, The central controller is also configured to execute the following transient stability control process in parallel during the cyclic execution of steps S2.1 to S2.5: S2.

6. The frequency change rate of the isolated grid operation system is simultaneously measured by the phasor measurement unit array installed at the outlet of the diesel generator (4), the outlet of the energy storage converter of the energy storage device (3), and the bus of the 6kV load section (6) of the plant. When the absolute value of the frequency change rate exceeds the preset danger threshold, it is determined that the isolated grid operation system is facing the risk of transient instability. S2.7 The central controller immediately interrupts the current optimization control loop and prioritizes calculating the damping power component that needs to be injected by the energy storage device (3). and inertial power components And directly send a fast power compensation command to the energy storage converter; the energy storage device (3) outputs power according to the command, simulating the damping and inertial characteristics of the synchronous generator to suppress oscillation and support the frequency of the islanded grid operation system; S2.8 The central controller continuously monitors the status of the isolated grid operation system until the frequency change rate returns to a safe and stable range, then instructs the energy storage device (3) to stop outputting the damped power component. and inertial power components And resume the execution of the optimized control loop.

7. The black start method for a comprehensive energy peak-shaving gas-fired power plant as described in claim 6, characterized in that: An automatic quasi-synchronous grid connection system is configured at the grid connection control node set between the outlet of the main generator (11) and the 6kV load section (6) of the plant. The automatic quasi-synchronous grid connection system includes a synchronizing phasor measurement unit, a programmable logic controller, and a closing controller. The input terminal of the synchronizing phasor measurement unit is electrically connected to the outlet voltage transformer of the main generator (11) and the bus voltage transformer of the 6kV load section (6) of the plant, respectively, for measuring the phase angle difference of the voltage on both sides. With frequency difference The input terminal of the programmable logic controller is connected to the output terminal of the synchronous phasor measurement unit; the signal input terminal of the closing controller is connected to the output terminal of the programmable logic controller, and its power output terminal is connected to the operating mechanism of the main generator output switch (12); wherein, the programmable logic controller has a pre-stored fixed mechanical closing action time of the main generator output switch (12). Programmable logic controllers are used for real-time reception. and And calculate the rate of change of phase angle difference. ,when Less than the set threshold and When it is a constant negative value, according to the formula Calculate the time of issuing the closing command. and in The closing command is sent to the closing controller at all times.

Images