Island operation control circuit and control method

Abstract

The present application relates to a kind of island operation control circuit and control method, control circuit includes island operation trigger circuit and island operation action export;Multiple inputs of island operation trigger circuit are connected in the output end of power generation system and the input end connection of island operation action export;The output end of island operation action export is connected in the action execution unit in power generation system;Island operation trigger circuit generates island trigger signal and sends to island operation action export when detecting signal meets trigger condition;Island operation action export generates first action signal according to trigger signal and sends to action execution unit, and action execution unit executes corresponding action according to first action signal to make power generation system enter island operation mode.The control circuit of the present application is simple in configuration, trigger is reliable, without large-scale electrical reconstruction to the power generation system of generator-transformer line connection mode, so as to save power plant cost.

Description

Technical Field

[0001] This invention relates to the field of power generation system control technology, and in particular to islanded operation control circuits and control methods. Background Technology

[0002] To address the risk of widespread power outages caused by severe natural disasters and enhance the emergency response capabilities of critical load centers, coal-fired power units, serving as regional backup power sources, should possess islanding operation capabilities. This means that when an external power grid fails, the turbine and boiler can quickly reduce output to maintain normal operation, while the generator and grid system operate only with auxiliary plant load, ensuring the entire unit is in a "hot standby" state, thus enabling rapid restoration of power to the local grid. Therefore, in the event of a grid failure, a rapid assessment is needed to trigger the coal-fired power unit to enter islanding mode, allowing the unit to quickly disconnect from the grid and operate with its own auxiliary plant load.

[0003] Because the main electrical wiring methods and protection configurations of different power plants vary, there is no unified standard for quickly determining whether a unit has entered islanded operation. In existing technology, the output action contacts of the stability protection device and the operating position of the circuit breaker are typically used as criteria for judging power grid system faults.

[0004] However, older coal-fired power units typically use a generator-transformer unit connection, and therefore lack a generator output circuit breaker (GCB). Adding a GCB or a stable trip protection device to trigger islanding operation in these older power systems would require a large-scale electrical overhaul, significantly increasing power plant costs. Furthermore, current electrical triggering designs for islanding operation are relatively conservative and complex, lack sensitivity, have slow islanding initiation speeds, and are prone to the risk of units refusing to initiate islanding operation. Summary of the Invention

[0005] The embodiments of the present invention provide an islanding operation control circuit and control method to at least solve the problems of high cost and complex configuration in the related art of adding islanding operation function to power generation system.

[0006] In a first aspect, embodiments of the present invention provide an islanding operation control circuit, applied in a power generation system. The circuit includes an islanding operation trigger circuit and an islanding operation action output; wherein...

[0007] The islanding operation trigger circuit includes multiple input terminals connected to the power generation system for acquiring detection signals characterizing the current operating status of the power generation system; the output terminal of the islanding operation trigger circuit is connected to the input terminal of the islanding operation action output; the output terminal of the islanding operation action output is connected to the action execution unit in the power generation system.

[0008] When the detection signal meets the triggering condition, the islanding operation triggering circuit generates an islanding trigger signal and sends it to the islanding operation action output; the islanding operation action output generates a first action signal according to the trigger signal and sends it to the action execution unit; the action execution unit performs a corresponding action according to the first action signal to make the power generation system enter the islanding operation mode.

[0009] In some embodiments, the islanding operation trigger circuit includes a first AND gate, which includes a first input interface, a second input interface, a third input interface, a fourth input interface, a fifth input interface, and an output interface;

[0010] Specifically, the output interface of the first AND gate is connected to the input terminal of the islanding operation output; the first input interface is connected to the auxiliary node for the position of the main transformer high-voltage side circuit breaker in the power generation system, for acquiring the open / close position signal of the main transformer high-voltage side circuit breaker; the second input interface is connected to the line protection device in the power generation system, for acquiring the line fault signal; the third input interface is connected to the generator-transformer group protection device in the power generation system, for acquiring the fault signal of the generator-transformer group; the fourth input interface is connected to the auxiliary node for the position of the turbine main steam valve in the power generation system, for acquiring the open / close position signal of the turbine main steam valve; and the fifth input interface is connected to the generator-transformer group protection device in the power generation system, for acquiring the zero-power protection signal.

[0011] The detection signal satisfies the first triggering condition as follows: the detection signal includes the main transformer high-voltage side circuit breaker occupancy signal, line fault signal, generator-transformer unit no-fault signal, turbine main steam valve open signal, and zero-power protection signal.

[0012] In other embodiments, the islanding operation trigger circuit further includes a second AND gate; the second AND gate includes a sixth input interface, a seventh input interface, an eighth input interface, a ninth input interface, a tenth input interface, and an output interface;

[0013] Specifically, the output interface of the second AND gate is connected to the input terminal of the islanding operation output; the sixth input interface is connected to the generator-transformer unit protection device of the power generation system to obtain a fault signal of the generator-transformer unit; the seventh input interface is connected to the turbine main steam valve position auxiliary node in the power generation system to obtain the turbine main steam valve opening / closing position signal; the eighth input interface is connected to the generator-transformer unit protection device of the power generation system to obtain a zero-power protection signal; the ninth input interface is connected to the main transformer high-voltage side circuit breaker position auxiliary node in the power generation system to obtain the main transformer high-voltage side circuit breaker opening / closing position signal; and the tenth input interface is connected to the line protection device of the power generation system to obtain an over-frequency protection signal.

[0014] The detection signal satisfies the second triggering condition as follows: the detection signal includes the high-voltage side circuit breaker closed position signal, the over-frequency protection signal, the generator-transformer unit fault-free signal, the turbine main steam valve open position signal, and the zero-power protection signal.

[0015] Furthermore, the islanding operation trigger circuit also includes a first OR gate, the first input terminal of the first OR gate is connected to the output interface of the first AND gate; the second input terminal of the first OR gate is connected to the output interface of the second AND gate; and the output terminal of the first OR gate is connected to the input terminal of the islanding operation action output.

[0016] Furthermore, the islanding operation output includes a first switch and a first relay group, the first relay group including multiple relays; the first end of the first switch is connected to the output end of the islanding operation trigger circuit, the second end of the first switch is connected to the input end of each relay in the first relay group, and the output end of each relay is connected to the action execution unit.

[0017] Furthermore, the first relay group includes a first relay, a second relay, a third relay, a fourth relay, a fifth relay, and a sixth relay; the actuation unit includes a thermal control DCS, a relay protection device, an excitation regulation system, a demagnetization switch control system, a plant-use fast switching device, and a diesel generator starting system;

[0018] The output terminal of the first relay is connected to the thermal control DCS; the output terminal of the second relay is connected to the relay protection device of the power generation system, the relay protection device including an islanded operation setting area and a normal operation setting area; the output terminal of the third relay is connected to the excitation regulation system; the output terminal of the fourth relay is connected to the demagnetizing switch control system; the output terminal of the fifth relay is connected to the plant service fast switching device; and the output terminal of the sixth relay is connected to the diesel generator starting system.

[0019] In some embodiments, the control circuit further includes an islanding return output, which is used to receive an islanding return signal; and generate a second action signal based on the islanding return signal and send it to the action execution unit, which performs a corresponding action based on the second action signal to enable the power generation system to return to normal grid connection mode.

[0020] Furthermore, the islanded operation reset output includes a second switch and a second relay group, the second relay group including multiple relays; the second switch is connected to the central control system, the first end of the second switch is connected to the power supply, the second end of the second switch is connected to the input end of each relay in the second relay group, and the output end of each relay is connected to the action execution unit.

[0021] Furthermore, the second relay group includes a seventh relay and an eighth relay; the actuation unit includes a protection device and an excitation regulation system; wherein,

[0022] One end of the seventh relay is connected to the second switch, and the other end is connected to the relay protection device of the power generation system; one end of the eighth relay is connected to the second switch, and the other end is connected to the excitation regulation system.

[0023] Secondly, embodiments of the present invention provide an islanding operation control method, applied in a power generation system, comprising:

[0024] Real-time acquisition of detection signals characterizing the current operating status of the power generation system;

[0025] If the detection signal meets the triggering condition, and the determination result is yes, then an island triggering signal is generated.

[0026] The islanding trigger signal is converted into a first action signal and sent to the action execution unit, so that the action execution unit performs a corresponding action according to the first action signal to make the power generation system enter the islanding operation mode.

[0027] After a preset time, the output voltage and generator speed of the generator in the power generation system are acquired, and the power generation system is judged to have successfully entered islanded operation mode based on the output voltage and generator speed. If the judgment result is yes, the islanded operation mode is maintained; if the judgment result is no, the generator set is stopped and the emergency power diesel generator is started.

[0028] The system detects in real time whether an islanding reconnection signal is received. If the result is no, the islanding operation mode is maintained. If the result is yes, the islanding reconnection signal is converted into a second action signal and sent to the action execution unit, so that the action execution unit performs the corresponding action according to the second action signal to enable the power generation system to return to normal grid connection and operation mode.

[0029] The detection signal satisfies the triggering condition as follows: the detection signal includes the main transformer high-voltage side circuit breaker open position signal, line fault signal, generator-transformer unit fault-free signal, turbine main steam valve open position signal, and zero power signal; or, the detection signal includes the main transformer high-voltage side circuit breaker closed position signal, overfrequency protection signal, generator-transformer unit fault-free signal, turbine main steam valve open position signal, and zero power signal.

[0030] Compared to related technologies, the islanding control circuit and method provided in this invention monitor the power generation system by adding an islanding control circuit composed of commonly used electronic components. When the islanding trigger circuit detects that the triggering condition is met, it generates an islanding trigger signal and sends it to the islanding action output. The islanding action output generates a first action signal based on the trigger signal and sends it to the action execution unit. The action execution unit executes the corresponding action based on the first action signal to put the power generation system into islanding mode. The islanding control circuit of this invention has a simple configuration, reliable triggering, and does not require large-scale electrical modifications to the power generation system with generator-transformer connection, thereby saving power plant costs. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 This is a wiring diagram of a power generation system according to an embodiment of the present invention;

[0033] Figure 2 This is a logic diagram of an islanding operation triggering circuit according to an embodiment of the present invention.

[0034] Figure 3 This is a wiring diagram of the islanding operation output according to an embodiment of the present invention;

[0035] Figure 4 This is a wiring diagram of the islanded operation return output according to an embodiment of the present invention;

[0036] Figure 5 This is a wiring diagram of a relay protection device according to an embodiment of the present invention;

[0037] Figure 6 This is a logic diagram of an islanding operation triggering circuit according to another embodiment of the present invention.

[0038] Figure 7 This is a flowchart of an islanded operation control method according to an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention. Furthermore, it is understood that although the efforts made in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, some design, manufacturing, or production modifications based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the invention.

[0040] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention may be combined with other embodiments without conflict.

[0041] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," "an," "the," and similar words used in this invention do not indicate quantity limitation and may indicate singular or plural. The terms "comprising," "including," "having," and any variations thereof used in this invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units not listed, or may include other steps or units inherent to these processes, methods, products, or devices. The terms "connected," "linked," "coupled," and similar words used in this invention are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "A plurality" in this invention means two or more. "And / or" describes the relationship between related objects, indicating that three relationships may exist; for example, "A and / or B" can represent: A alone, A and B simultaneously, and B alone. The terms "first," "second," and "third" used in this invention are merely to distinguish similar objects and do not represent a specific ordering of the objects.

[0042] One embodiment of the present invention provides a control circuit for islanded operation of a coal-fired power unit, applied in a power generation system powered by a coal-fired generator. The system structure of the power generation system in this embodiment is as follows: Figure 1 As shown, the system includes a generator, excitation transformer, high-voltage main transformer, high-voltage station service transformer, high-voltage side circuit breaker of the main transformer, high-voltage common transformer, and the line opposite to the generator. In this embodiment of the invention, the generator and the high-voltage main transformer are connected as a unit, connected to the line opposite in the form of a generator-transformer line, such as the opposite substation system. No GCB (outlet circuit breaker) is installed at the generator outlet. During normal grid connection of the unit, [the system is as follows]. Figure 1 The high-voltage side main transformer is realized in the process.

[0043] The islanding control circuit of this invention includes an islanding operation trigger circuit and an islanding operation action output. (See reference...) Figure 2 The islanding operation trigger circuit 10 includes multiple input terminals connected to the power generation system to acquire detection signals characterizing the current operating status of the power generation system. The output terminal of the islanding operation trigger circuit 10 is connected to the input terminal of the islanding operation action output 20; the output terminal of the islanding operation action output 20 is connected to the action execution unit in the power generation system. In this embodiment, when the detection signal meets the triggering condition, the islanding operation trigger circuit 10 generates an islanding trigger signal and sends it to the islanding operation action output 20; the islanding operation action output 20 generates a first action signal based on the trigger signal and sends it to the action execution unit, which then performs a corresponding action based on the first action signal to cause the power generation system to enter islanding operation mode.

[0044] In this embodiment, the triggering conditions for islanding operation are: normal operation of the generator-transformer unit, line fault, tripping of the high-voltage side main transformer, and no tripping of the turbine main valve. In this case, the generator needs to operate with its own auxiliary power supply to enter islanding operation mode. The islanding operation triggering circuit 10 in this embodiment includes a first AND gate U1. The first AND gate U1 can acquire signals corresponding to the above triggering conditions and perform logical AND processing. If each signal meets the requirements, it outputs an islanding trigger signal. Specifically, the first AND gate U1 includes a first input interface I1, a second input interface I2, a third input interface I3, a fourth input interface I4, a fifth input interface I5, and an output interface.

[0045] Specifically, such as Figure 2As shown, the output interface of the first AND gate U1 is connected to the input terminal of the islanded operation action output 20. The first input interface I1 of the first AND gate U1 is connected to the auxiliary node of the main transformer high-voltage side circuit breaker position in the power generation system to obtain the operating status of the main transformer high-voltage side circuit breaker. The circuit breaker has 3 detection points. In this embodiment, any two detection points can be connected to the first input interface I1; or all 3 detection points of the circuit breaker can be connected to the first input interface I1, and the signals of any two detection points can be processed during the logical "AND" process. When the circuit breaker trips, the first input interface I1 receives a main transformer high-voltage side circuit breaker open signal; if the circuit breaker does not trip, the first input interface I1 receives a main transformer high-voltage side circuit breaker closed signal.

[0046] The second input interface I2 of the first AND gate U1 is connected to the line protection device of the power generation system to obtain the line's operating status. When a line fault occurs, such as a large-scale power outage caused by a natural disaster, the second input interface I2 will receive a line fault signal (line fault protection signal). If the power grid is operating normally, the potential of the second input interface I2 will not change. The third input interface I3 is connected to the generator-transformer unit protection device of the power generation system to obtain the generator-transformer unit's operating status. When the generator-transformer unit is operating normally, the third input interface I3 will receive a no-fault signal, indicating that the generator-transformer unit can operate normally and can be activated in islanded operation mode. When a fault occurs in the generator-transformer unit, the potential of the third input interface I3 will not change or a fault signal will be received, indicating that the generator-transformer unit cannot operate normally and islanded operation mode cannot be activated.

[0047] The fourth input interface I4 of the first AND gate U1 is connected to the auxiliary node for the main steam valve position of the turbine in the power generation system to obtain the operating status of the main steam valve. When the main steam valve is open, the fourth input interface I4 receives the main steam valve open position signal, indicating that islanding mode needs to be activated. If the main steam valve is closed, the potential of the fourth input interface I4 remains unchanged or receives the main steam valve closed position signal, indicating that islanding mode does not need to be activated. The fifth input interface I5 is connected to the generator-transformer unit protection device of the power generation system to obtain the zero-power protection signal (zero-power signal). When the system power is less than a certain power threshold range, the generator-transformer unit protection device issues a "zero-power protection signal". That is, when the load power of the power generation system is less than the set value, the fifth input interface I5 receives the zero-power signal, indicating that a fault has occurred on the opposite side of the generator-transformer unit, and it is not necessary to supply power to the grid and activate islanding mode.

[0048] Therefore, when the detection signals received by the islanding operation trigger circuit 10 include the main transformer high-voltage side circuit breaker occupancy signal, line fault signal, generator-transformer unit fault-free signal, turbine main steam valve open signal, and zero-power protection signal, the first AND gate U1 in this embodiment performs an AND operation on these five signals. When all five signals are true, the islanding operation action output 20 outputs an islanding trigger signal. The islanding operation action output 20 outputs an action signal to the corresponding position of the unit according to the trigger signal, so that the unit adjusts according to the action signal and enters the islanding operation mode.

[0049] refer to Figure 3 In this embodiment of the invention, the islanding operation output 20 includes a first switch K1 and a first relay group 21. The first relay group 21 includes multiple relays. The first switch K1 and the first relay group 21 are connected in series and powered by a 110V voltage. The first end of the first switch K1 is connected to the output end of the islanding operation trigger circuit 10, and the second end of the first switch K1 is connected to the input end of each relay in the first relay group 21. The output end of each relay is connected to the action execution unit and sends the first action signal to the corresponding action execution unit.

[0050] Specifically, the first relay group 21 includes a first relay KJ1, a second relay KJ2, a third relay KJ3, a fourth relay KJ4, a fifth relay KJ5, and a sixth relay KJ6. The first relay KJ1 is connected to the thermal control DCS; the second relay KJ2 is connected to the relay protection device of the coal-fired unit; the third relay KJ3 is connected to the generator excitation regulation system; the fourth relay KJ4 is connected to the demagnetization switch system; the fifth relay KJ5 is connected to the plant auxiliary fast switching device; and the sixth relay KJ6 is connected to the diesel generator start switch (diesel generator start switch).

[0051] Upon receiving the islanding trigger signal, the first relay KJ1 sends a first action signal to the thermal control DCS. Upon receiving the action signal, the thermal control DCS performs corresponding rapid load reduction control on the unit. The second relay KJ2 sends the first action signal to the relay protection device. The relay protection device of this invention has two setting zones; different setting zones can trigger different operating conditions. (Refer to...) Figure 5 This invention mainly includes two setting zones: an islanding operation setting zone and a normal operation setting zone. That is, the protection device of this invention has two sets of settings that can be switched back and forth as needed. When the protection device receives an action signal sent by the second relay KJ2, the setting zone will automatically switch to the islanding operation condition. Compared to the normal operation condition, the setting zone in the islanding operation condition appropriately amplifies the protection settings for overvoltage and overfrequency protection to avoid overvoltage and overfrequency protection actions during rapid load shedding by the generator, thereby preventing unnecessary alarms or even unit shutdown and inability to enter islanding operation.

[0052] The third relay, KJ3, sends an action signal to the excitation regulation system (AVR) to regulate the generator and achieve rapid demagnetization, enabling the generator to quickly switch to constant power operation mode and prevent overexcitation caused by excessive excitation current. The fourth relay, KJ4, sends an action signal to the demagnetization switch control system to lock the demagnetization switch, thus preventing the demagnetization switch from tripping and causing generator demagnetization. The fifth relay, KJ5, sends an action signal to the plant auxiliary power quick-change device to lock the plant auxiliary power switching, maintaining the generator in its self-supplied plant auxiliary load operation state. The sixth relay, KJ6, sends an action signal to the diesel generator starting system, putting the diesel generator in hot standby mode to cope with extreme situations, serving as an emergency power source for auxiliary equipment.

[0053] The generator set is adjusted by the action signal sent by the first relay group 21, causing it to enter islanded operation mode. After the generator set stabilizes in islanded operation mode, it sends feedback to the operator indicating that it has successfully entered islanded operation mode, and then waits for further instructions. In this invention, the generator set's islanded operation mode can be determined by detecting the generator's speed and output voltage. For example, after a period of time (e.g., 60 seconds), if the generator speed is detected to be around 3000 r / min (±12 rpm) and the output voltage is within the error range of the rated voltage, it proves that the generator set has successfully entered islanded operation mode. If, after a period of time, the speed or output voltage does not meet the above conditions, it proves that entering islanded operation mode has failed, and the generator set needs to be shut down and the diesel generator started.

[0054] In one embodiment of the present invention, reference is made to... Figure 4 The control circuit also includes an islanding reset output 30, used to control the power generation system to return to normal operation mode when the grid power supply is restored, i.e., to end the islanding state. Specifically, the circuit diagram of the islanding reset output 30 is as follows: Figure 4 As shown, the islanding operation reset output 30 receives the islanding reset signal; then, it generates a second action signal based on the islanding reset signal and sends it to the action execution unit. The action execution unit executes the corresponding action based on the second action signal to restore the power generation system to normal grid connection. If the grid is restored and a grid connection command is issued, the staff will reset the islanding operation status. For example, if the staff presses a button or closes the corresponding switch, the islanding operation reset output 30 will receive the islanding reset signal.

[0055] refer to Figure 4In this embodiment, the islanding reset output 30 includes a second switch K2 and a second relay group, which are connected in series and powered by 110V. The second relay group includes multiple relays. In this embodiment, the second switch K2 is connected to the central control system. After the power grid is operational, the operator sends an islanding reset signal to the second switch K2. Alternatively, the second switch K2 can be manually operated by the operator according to power grid requirements, such as after a line fault is resolved and a normal grid connection order is received. The first terminal of the second switch K2 is connected to the power supply, the second terminal of the second switch K2 is connected to the input terminal of each relay in the second relay group, and the output terminal of each relay is connected to the action execution unit.

[0056] The second relay group in this embodiment of the invention includes a seventh relay KJ7 and an eighth relay KJ8; wherein, one end of the seventh relay KJ7 is connected to the second switch K2, and the other end is connected to the relay protection device; one end of the eighth relay KJ8 is connected to the second switch K2, and the other end is connected to the generator excitation regulation system.

[0057] After grid connection, the generating unit operates stably according to the load specified by the power grid. Specifically, the seventh relay KJ7 sends the second action signal to the relay protection device, refer to... Figure 5 At this point, the normal operating setpoint zone will be triggered, and the protection device will switch the operating condition setpoint to the unit's normal operating condition. The eighth relay KJ8 sends the second action signal to the generator excitation regulation system (AVR). Upon receiving the second action signal, the AVR switches its operating mode to constant voltage operation mode, meaning the unit has stable voltage support. After the protection device switches to the normal operating setpoint zone and the AVR switches to constant voltage mode, the unit recovers from islanded operation to normal operation.

[0058] In one embodiment of the present invention, another triggering condition for islanded operation is provided, referring to... Figure 5 The islanding operation trigger circuit 10 in this embodiment also includes a second AND gate U2; the second AND gate U2 also includes five input terminals: a sixth input interface I6, a seventh input interface I7, an eighth input interface I8, a ninth input interface I9, and a tenth input interface I10. In this embodiment, the triggering conditions for islanding operation are: the generator-transformer unit is operating normally, no line fault occurs, the high-voltage side main transformer does not trip, and the turbine main valve does not trip. In this case, the generator needs to operate with its own plant auxiliary power to perform islanding operation mode.

[0059] To obtain the signal corresponding to the above triggering conditions, specifically as follows: Figure 6As shown, in this embodiment, the output interface of the second AND gate U2 is connected to the input terminal of the islanded operation action output 20; the ninth input interface I9 is ​​connected to the main transformer high-voltage side circuit breaker in the power generation system to obtain the operating status of the main transformer high-voltage side circuit breaker. The logic of the three auxiliary nodes of the circuit breaker is taken as 2 and then connected to the second AND gate as the input for logic judgment. If the circuit breaker trips, the ninth input interface I9 receives a main transformer high-voltage side circuit breaker open signal; if the circuit breaker does not trip, the ninth input interface I9 receives a main transformer high-voltage side circuit breaker closed signal.

[0060] The tenth input interface I10 is connected to the line protection device of the power generation system to obtain the over-frequency protection signal. When the system frequency is outside a certain frequency threshold range, the line protection device issues an "over-frequency protection signal," meaning that when the system frequency is too high, the tenth input interface I10 receives the over-frequency protection signal. The sixth input interface I6 is connected to the generator-transformer unit protection device of the power generation system to obtain the operating status of the generator-transformer unit. When the generator-transformer unit is operating normally, the sixth input interface I6 will receive a fault-free signal, indicating that the generator-transformer unit can work normally and can be activated in islanded operation mode. When a fault occurs in the generator-transformer unit, the potential of the sixth input interface I6 will not change or a fault signal will be received, indicating that the generator-transformer unit cannot work normally and islanded operation mode cannot be activated.

[0061] The seventh input interface I7 is connected to the auxiliary node for the main steam valve position of the turbine in the power generation system. It is used to acquire the operating status of the main steam valve. When the main steam valve is open, the seventh input interface I7 receives an open position signal, indicating that islanding mode needs to be activated. If the main steam valve is closed, the potential of the seventh input interface I7 remains unchanged or a closed position signal is received, indicating that islanding mode does not need to be activated. The eighth input interface I8 is connected to the generator-transformer unit protection device in the power generation system to acquire the zero-power protection signal (zero-power signal). When the system power is less than the power threshold, the generator-transformer unit protection device issues a "zero-power protection signal." That is, when the load power of the power generation system is less than the relay protection set value, the eighth input interface I8 receives a zero-power signal, indicating that a fault has occurred in the generator-transformer unit line, and power supply to the grid is not required, thus islanding mode should not be activated.

[0062] Therefore, when the detection signals received by the second AND gate U2 include the main transformer high-voltage side circuit breaker closed signal, overfrequency protection signal, generator-transformer unit fault-free signal, turbine main steam valve open signal, and zero-power protection signal, the second AND gate U2 in this embodiment performs a logical AND judgment on the above five signals. When all five signals are true, it outputs an islanding trigger signal to the islanding operation action output 20. The islanding operation action output 20 outputs an action signal to the corresponding position of the unit according to the trigger signal, so that the unit adjusts according to the action signal and enters the islanding operation mode.

[0063] The islanding operation trigger circuit 10 in this embodiment further includes a first OR gate U3. The first input terminal of the first OR gate U3 is connected to the output interface of the first AND gate U1; the second input terminal of the first OR gate U3 is connected to the output interface of the second AND gate U2; and the output terminal of the first OR gate U3 is connected to the input terminal of the islanding operation output 20. When the detection signal received by either the first AND gate U1 or the second AND gate U2 meets the corresponding triggering condition, the first OR gate U3 will output an islanding trigger signal. That is, in this embodiment, the power generation system will trigger and enter the islanding operation state under the following two conditions.

[0064] Scenario 1: The generator-transformer unit is operating normally, but a line fault occurs, tripping the high-voltage side circuit breaker of the main transformer (without tripping the turbine). At this time, the generator operates with its own auxiliary power, realizing islanded operation mode. In this case, the circuit breaker trip signal, line fault signal, generator-transformer unit fault-free signal, turbine main steam valve open signal, and zero power signal are logically ANDed to trigger islanded operation.

[0065] Scenario 2: The generator-transformer unit is operating normally, the line is not faulty, but the substation on the opposite side experiences a fault. In this case, the high-voltage side circuit breaker of the main transformer has not tripped, and the generator continues to operate with its own auxiliary power, achieving islanded operation mode. At this time, the circuit breaker closed signal, overfrequency protection signal, generator-transformer unit fault-free signal, turbine main steam valve open signal, and zero-power signal are logically ANDed to trigger islanded operation.

[0066] It should be noted that the specific process of entering the island operation mode in this embodiment can refer to the examples described in the above embodiments and optional implementation methods, so this embodiment will not repeat it here.

[0067] In one embodiment of the present invention, an islanding operation control method is provided, applied in a power generation system, as detailed in the following reference. Figure 7 The islanded operation control method in this embodiment includes the following steps.

[0068] Step S1: Real-time acquisition of detection signals characterizing the current operating status of the power generation system. In this embodiment, the detection signals include signals for determining the opening and closing of the main transformer high-voltage side circuit breaker, signals indicating whether a system line fault has occurred, signals indicating whether a generator-transformer unit fault has occurred, signals for determining the opening and closing of the turbine main steam valve, signals for detecting the load power of the power generation system, and signals for detecting whether the power generation system is operating at excessive frequencies. After obtaining the above detection signals, these signals are input into the configured unit islanding operation mode trigger logic, i.e., the islanding operation trigger circuit 10.

[0069] Step S2: Based on these detection signals, determine whether the generator set (or power generation system) needs to enter islanded operation mode, i.e., whether the detection signals meet the triggering conditions. If the determination result is yes, then an islanding trigger signal is generated. In this embodiment, the detection signals meet the triggering conditions as follows: the detection signals include the main transformer high-voltage side circuit breaker open position signal, line fault signal, generator-transformer unit no-fault signal, turbine main steam valve open position signal, and zero-power signal; or, the detection signals include the main transformer high-voltage side circuit breaker closed position signal, overfrequency protection signal, generator-transformer unit no-fault signal, turbine main steam valve open position signal, and zero-power signal.

[0070] In step S3, the islanding operation triggering unit sends a trigger signal to the islanding operation output. The islanding operation output converts the islanding trigger signal into a first action signal and sends it to the action execution unit, so that the action execution unit performs the corresponding action according to the first action signal to make the power generation system enter the islanding operation mode.

[0071] Specifically, upon receiving the islanding trigger signal, the first relay sends a first action signal to the thermal control DCS. Upon receiving the action signal, the thermal control DCS performs corresponding rapid load reduction control on the unit. The second relay sends the first action signal to the relay protection device. The setting range of the protection device of this invention includes two operating conditions: islanding operation and normal operation. That is, the protection device of this invention has two sets of settings that can be switched back and forth as needed. When the protection device receives the action signal sent by the second relay, the setting range will automatically switch to the islanding operation condition. Compared to the normal operation condition, the islanding operation condition appropriately amplifies the protection settings for overvoltage and overfrequency protection to avoid overvoltage and overfrequency protection actions during rapid load shedding by the generator, thereby preventing unnecessary alarms or even unit shutdown and inability to enter islanding operation.

[0072] The third relay sends an action signal to the excitation regulation system (AVR) to regulate the generator and achieve rapid demagnetization, enabling the generator to quickly switch to constant power operation mode and prevent overexcitation caused by excessive excitation current. The fourth relay sends an action signal to the demagnetization switch control system to lock the demagnetization switch, thereby preventing the demagnetization switch from tripping and causing generator demagnetization. The fifth relay sends an action signal to the plant auxiliary power quick switching device to lock the plant auxiliary power switching, maintaining the generator in its own plant auxiliary load operation state. The sixth relay sends an action signal to the diesel generator starting system, thereby putting the diesel generator in hot standby mode to cope with extreme situations and serve as an emergency power source for auxiliary equipment.

[0073] The unit is adjusted by the action signal sent by the first relay group, so that the unit enters the island operation mode. After the unit is running stably in the island operation mode, the unit sends relevant information such as "the unit has successfully entered the island operation state" to the central control system, and then waits for subsequent instructions.

[0074] Step S4: After a preset time, acquire the output voltage and generator speed of the generator in the power generation system, and determine whether the power generation system has successfully entered islanded operation mode based on the output voltage and generator speed. If the determination result is yes, maintain the islanded operation mode; if the determination result is no, stop the generator and start the diesel generator. For example, after a period of time (e.g., 60 seconds), if the generator speed is detected to be around 3000 r / min (plus or minus no more than 12 revolutions) and the output voltage is within the error range of the rated voltage, it proves that the unit has successfully entered the islanded operation state; if after a period of time, the speed or output voltage does not meet the above conditions, it proves that entering the islanded operation state has failed, and at this time it is necessary to stop the unit and start the diesel generator.

[0075] Step S5: Real-time detection of whether an islanding reset signal is received. If the result is no, the islanding operation mode is maintained. If the result is yes, the islanding reset signal is converted into a second action signal and sent to the action execution unit, so that the action execution unit performs the corresponding action according to the second action signal to enable the power generation system to return to normal grid connection and operation mode.

[0076] Specifically, the seventh relay sends the second action signal to the relay protection device. Upon receiving the action signal, the relay protection device switches its operating condition settings to the unit's normal operating condition. The eighth relay sends the second action signal to the generator excitation regulating system (AVR). Upon receiving the second action signal, the AVR switches its operating mode to constant voltage operation mode, meaning the unit has stable voltage support. After the relay protection device switches to the normal setting range and the AVR switches to constant voltage mode, the unit recovers from islanded operation to normal operation.

[0077] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0078] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated here.

[0079] Furthermore, in conjunction with the islanded operation control method in the above embodiments, this invention can be implemented using a storage medium. This storage medium stores a computer program; when executed by a processor, the computer program implements any one of the islanded operation control methods in the above embodiments.

[0080] One embodiment of the present invention also provides an electronic device, which can be a terminal. The electronic device includes a processor, a memory, a network interface, a display screen, and an input device connected via a system bus. The processor of the electronic device provides computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface of the electronic device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, it implements an islanded operation control method. The display screen of the electronic device can be a liquid crystal display screen or an e-ink display screen. The input device of the electronic device can be a touch layer covering the display screen, or buttons, a trackball, or a touchpad provided on the casing of the electronic device, or an external keyboard, touchpad, or mouse, etc.

[0081] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0082] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. 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 all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An islanded operation control circuit, applied in a power generation system without a generator output circuit breaker, characterized in that, The circuit includes an islanding operation trigger circuit and an islanding operation action output; wherein... The islanding operation trigger circuit includes multiple input terminals connected to the power generation system for acquiring detection signals characterizing the current operating status of the power generation system; the output terminal of the islanding operation trigger circuit is connected to the input terminal of the islanding operation action output; the output terminal of the islanding operation action output is connected to the action execution unit in the power generation system. When the detection signal meets the triggering condition, the islanding operation triggering circuit generates an islanding trigger signal and sends it to the islanding operation action output; the islanding operation action output generates a first action signal according to the trigger signal and sends it to the action execution unit; the action execution unit performs a corresponding action according to the first action signal to make the power generation system enter the islanding operation mode. The island operation trigger circuit includes a first AND gate, which includes a first input interface, a second input interface, a third input interface, a fourth input interface, a fifth input interface, and an output interface. Specifically, the output interface of the first AND gate is connected to the input terminal of the islanding operation output; the first input interface is connected to the auxiliary node for the position of the main transformer high-voltage side circuit breaker in the power generation system, for acquiring the open / close position signal of the main transformer high-voltage side circuit breaker; the second input interface is connected to the line protection device in the power generation system, for acquiring the line fault signal; the third input interface is connected to the generator-transformer group protection device in the power generation system, for acquiring the fault signal of the generator-transformer group; the fourth input interface is connected to the auxiliary node for the position of the turbine main steam valve in the power generation system, for acquiring the open / close position signal of the turbine main steam valve; and the fifth input interface is connected to the generator-transformer group protection device in the power generation system, for acquiring the zero-power protection signal. The detection signal satisfies the first triggering condition as follows: the detection signal includes the main transformer high-voltage side circuit breaker occupancy signal, line fault signal, generator-transformer unit no-fault signal, turbine main steam valve open signal, and zero-power protection signal.

2. The control circuit according to claim 1, characterized in that, The islanding operation trigger circuit also includes a second AND gate; the second AND gate includes a sixth input interface, a seventh input interface, an eighth input interface, a ninth input interface, a tenth input interface, and an output interface; Specifically, the output interface of the second AND gate is connected to the input terminal of the islanding operation output; the sixth input interface is connected to the generator-transformer unit protection device of the power generation system to obtain a fault signal of the generator-transformer unit; the seventh input interface is connected to the turbine main steam valve position auxiliary node in the power generation system to obtain the turbine main steam valve opening / closing position signal; the eighth input interface is connected to the generator-transformer unit protection device of the power generation system to obtain a zero-power protection signal; the ninth input interface is connected to the main transformer high-voltage side circuit breaker position auxiliary node in the power generation system to obtain the main transformer high-voltage side circuit breaker opening / closing position signal; and the tenth input interface is connected to the line protection device of the power generation system to obtain an over-frequency protection signal. The detection signal satisfies the second triggering condition as follows: the detection signal includes the high-voltage side circuit breaker closed position signal, the over-frequency protection signal, the generator-transformer unit fault-free signal, the turbine main steam valve open position signal, and the zero-power protection signal.

3. The control circuit according to claim 2, characterized in that, The islanding operation trigger circuit further includes a first OR gate, the first input terminal of which is connected to the output interface of the first AND gate; the second input terminal of which is connected to the output interface of the second AND gate; and the output terminal of which is connected to the input terminal of the islanding operation action output.

4. The control circuit according to claim 1, characterized in that, The isolated operation output includes a first switch and a first relay group, the first relay group including multiple relays; the first end of the first switch is connected to the output end of the isolated operation trigger circuit, the second end of the first switch is connected to the input end of each relay in the first relay group, and the output end of each relay is connected to the action execution unit.

5. The control circuit according to claim 4, characterized in that, The first relay group includes a first relay, a second relay, a third relay, a fourth relay, a fifth relay, and a sixth relay; the actuation unit includes a thermal control DCS, a relay protection device, an excitation regulation system, a demagnetization switch control system, a plant-use fast switching device, and a diesel generator starting system; The output terminal of the first relay is connected to the thermal control DCS; the output terminal of the second relay is connected to the relay protection device of the power generation system, the relay protection device including an islanded operation setting area and a normal operation setting area; the output terminal of the third relay is connected to the excitation regulation system; the output terminal of the fourth relay is connected to the demagnetizing switch control system; the output terminal of the fifth relay is connected to the plant service fast switching device; and the output terminal of the sixth relay is connected to the diesel generator starting system.

6. The control circuit according to claim 1, characterized in that, The control circuit also includes an islanding operation reset output, which is used to receive an islanding reset signal; and generate a second action signal based on the islanding reset signal and send it to the action execution unit. The action execution unit performs a corresponding action based on the second action signal to enable the power generation system to return to normal grid connection and operation mode.

7. The control circuit according to claim 6, characterized in that, The islanded operation reset exit includes a second switch and a second relay group, the second relay group including multiple relays; the second switch is connected to the central control system, the first end of the second switch is connected to the power supply, the second end of the second switch is connected to the input end of each relay in the second relay group, and the output end of each relay is connected to the action execution unit.

8. The control circuit according to claim 7, characterized in that, The second relay group includes a seventh relay and an eighth relay; the actuation unit includes a protection device and an excitation regulation system; wherein, One end of the seventh relay is connected to the second switch, and the other end is connected to the relay protection device of the power generation system; one end of the eighth relay is connected to the second switch, and the other end is connected to the excitation regulation system.

9. An islanding operation control method, applied in a power generation system without a generator output circuit breaker, characterized in that, The power generation system includes the islanding operation control circuit as described in any one of claims 1-8, comprising: Real-time acquisition of detection signals characterizing the current operating status of the power generation system; If the detection signal meets the triggering condition, and the determination result is yes, then an island triggering signal is generated. The islanding trigger signal is converted into a first action signal and sent to the action execution unit, so that the action execution unit performs a corresponding action according to the first action signal to make the power generation system enter the islanding operation mode. After a preset time, the output voltage and generator speed of the generator in the power generation system are acquired, and the power generation system is judged to have successfully entered islanded operation mode based on the output voltage and generator speed. If the judgment result is yes, the islanded operation mode is maintained; if the judgment result is no, the generator set is stopped and the emergency power diesel generator is started. The system detects in real time whether an islanding reconnection signal is received. If the result is no, the islanding operation mode is maintained. If the result is yes, the islanding reconnection signal is converted into a second action signal and sent to the action execution unit, so that the action execution unit performs the corresponding action according to the second action signal to enable the power generation system to return to normal grid connection and operation mode. The detection signal satisfies the triggering condition as follows: the detection signal includes the main transformer high-voltage side circuit breaker open position signal, line fault signal, generator-transformer unit fault-free signal, turbine main steam valve open position signal, and zero power signal; or, the detection signal includes the main transformer high-voltage side circuit breaker closed position signal, overfrequency protection signal, generator-transformer unit fault-free signal, turbine main steam valve open position signal, and zero power signal.

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