Reactive compensation system for power plant

Abstract

The utility model relates to a reactive compensation system for a power plant, and relates to the technical field of power plant equipment. The power plant comprises a generator, a generator bus, a main transformer and a booster station bus which are connected in sequence, a station transformer connected with the other side of the generator bus and a station bus connected with the other side of the station transformer, and the booster station bus is connected into a power grid through a sending-out line. Comprising an electric energy meter, a controller and a reactive power compensation device, the electric energy meter is connected with the data input end of the controller and is used for being connected with the booster station bus; the control output end of the controller is connected with the reactive power compensation device; and the reactive power compensation device is used for being connected with the auxiliary power bus. Through the reactive power compensation system, the power factor of the output line can be compensated on the power plant side, and the reactive power compensation requirement of the power grid side is reduced.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power plant equipment, in particular to a reactive power compensation system for a power plant. BACKGROUND

[0002] As an important part of the power system, the optimization of the power factor of the power plant is of great significance to the safe and stable operation of the power grid.

[0003] In the operation of the power system, the power plant is connected with the power grid through a high-voltage transmission line (sending-out line). Due to the distribution of the capacitance, a large amount of capacitive reactive power will be generated when the high-voltage transmission line is in light load operation. When the generator set is shut down or in low load operation, the capacitive reactive power will cause the power factor to decrease significantly due to the small amount of auxiliary load. Since the metering point of the power factor and the compensation device are usually on the power grid side, the above-mentioned situation increases the demand for reactive power regulation on the power grid side.

[0004] Due to many objective conditions, there is currently a lack of effective compensation schemes for the low power factor problem. Especially when there is a spatial distance between the power factor metering point on the power grid side and the reactive power source on the power plant side, the reasonable configuration and control of the reactive power compensation device face great difficulties. CONTENT OF THE UTILITY MODEL

[0005] In order to solve the above-mentioned problems, the present disclosure provides a reactive power compensation system for a power plant, the power plant comprising a generator, a generator bus, a main transformer and a booster station bus connected in sequence, and the power plant further comprising a plant transformer connected with one side of the generator bus, a plant bus connected with one side of the plant transformer, and the booster station bus being connected to the power grid through a sending-out line, the reactive power compensation system comprising: an electric energy meter, a controller and a reactive power compensation device;

[0006] The first end of the electric energy meter is connected with the data input end of the controller, and the second end of the electric energy meter is used to be connected with the booster station bus.

[0007] The control output end of the controller is connected with the first end of the reactive power compensation device.

[0008] The second end of the reactive power compensation device is used to be connected with the plant bus.

[0009] Optionally, the reactive power compensation device is a static reactive power generator.

[0010] Optionally, the reactive power compensation device further comprises a voltage transformer and a current transformer, and the voltage transformer and the current transformer are used to connect the second end of the electric energy meter with the booster station bus.

[0011] Optionally, the reactive power compensation device further comprises a communication protocol converter, comprising an electric energy meter protocol interface and an Ethernet interface; wherein,

[0012] The first end of the electric energy meter is connected to the electric energy meter protocol interface of the communication protocol converter, and the Ethernet interface of the communication protocol converter is connected to the data input end of the controller.

[0013] Optionally, the electric energy meter protocol interface is a DL / T645-2007 protocol interface.

[0014] Optionally, the Ethernet interface is a Modbus TCP protocol interface.

[0015] Optionally, the reactive power compensation system further comprises an optoelectronic isolator, and the first end of the electric energy meter is connected to the electric energy meter protocol interface of the communication protocol converter through the optoelectronic isolator.

[0016] The power plant comprises a device state monitoring system connected with a generator, primary equipment and a diesel engine, and optionally, the reactive power compensation system further comprises a device state acquisition device, the first end of the device state acquisition device is connected to the data input end of the controller, and the second end of the device state acquisition device is used to be connected to the data output end of the device state monitoring system.

[0017] Optionally, the reactive power compensation system further comprises a data input device, which is connected to the data input end of the controller.

[0018] Optionally, the reactive power compensation system further comprises a display device, which is connected to the controller.

[0019] The above technical solution can obtain power data of a sending line in real time by arranging an electric energy meter at a booster station bus, the controller performs operation processing based on the obtained power data and outputs a control signal, and the reactive power compensation device performs reactive power compensation at a plant bus according to the control signal. The system can realize on-site compensation of a power factor of a sending line at a power plant side, and overcome problems caused by spatial separation of a power grid side factor metering point and a reactive power compensation device. Other features and advantages of the disclosure will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the disclosure and constitute a part of the specification, and are used together with the following specific embodiments to explain the disclosure, but do not constitute a limitation on the disclosure. In the drawings:

[0021] Figure 1 is a structural diagram of a reactive power compensation system for a power plant according to an exemplary embodiment;

[0022] Figure 2 is a structure diagram of a reactive power compensation system for a power plant according to another exemplary embodiment.

[0023] Legend of reference signs

[0024] Generator 101, generator bus 102, main transformer 103, booster bus 104, auxiliary transformer 105, auxiliary bus 106, outgoing line 107, circuit breaker 108, low-voltage switch 109, two-position switch 110, primary equipment 111, diesel engine 112, equipment state monitoring system 113, electric energy meter 201, controller 202, reactive power compensation device 203, voltage transformer 204, current transformer 205, communication protocol converter 206, opto-isolator 207, equipment state acquisition device 208, data input device 209, display device 210. DETAILED DESCRIPTION

[0025] The detailed description of the present disclosure is described in detail below with reference to the accompanying drawings. It should be understood that the detailed description described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0026] Figure 1 is a structure diagram of a reactive power compensation system for a power plant according to an exemplary embodiment. As shown in Figure 1 , the power plant includes generator 101, generator bus 102, main transformer 103 and booster bus 104 connected in sequence, and the power plant further includes auxiliary transformer 105 connected to one side of generator bus 102, auxiliary bus 106 connected to one side of auxiliary transformer 105, booster bus 104 connected to the power grid through outgoing line 107, and the reactive power compensation system includes electric energy meter 201, controller 202 and reactive power compensation device 203; the first end of electric energy meter 201 is connected to the data input end of controller 202, and the second end of electric energy meter 201 is used to be connected to booster bus 104; the control output end of controller 202 is connected to the first end of reactive power compensation device 203; the second end of reactive power compensation device 203 is used to be connected to auxiliary bus 106.

[0027] Here, electric energy meter 201 can be a general electric energy meter, or a high-precision intelligent electric energy meter, such as DTSD341-MB3 type three-phase four-wire multifunctional electric energy meter. Booster bus 104 is connected to outgoing line 107 and has the same voltage level. Therefore, booster bus 104 can be the metering point of the power factor of outgoing line 107. Electric energy meter 201 is installed at booster bus 104 and can measure active power and reactive power data of outgoing line 107. Electric energy meter 201 transmits the collected active power and reactive power data to controller 202 through a communication interface.

[0028] The controller 202 can be a dedicated reactive power compensation controller or a general programmable logic controller (PLC). After receiving the power data transmitted by the electric energy meter 201, the controller 202 combines the preset target power factor and the capacitive reactive power parameter of the transmission line 107 to obtain the required reactive power compensation amount through calculation and outputs the corresponding control instruction. Specifically, the controller 202 determines the control instruction by comparing the deviation of the actual power factor from the target value and using a compensation algorithm. The control instruction can be a pulse width modulation (PWM) modulation signal or a switching instruction, such as a switching control signal corresponding to the number of capacitors to be switched.

[0029] The reactive power compensation device 203 can be a TCR / TSC dynamic reactive power compensation device or a static var generator (SVG). After receiving the control instruction from the controller 202, the reactive power compensation device 203 automatically switches the corresponding capacitor bank through the internal thyristor or contactor switch group. The voltage level of the booster station bus 104 is high (e.g., 110 kV), and the voltage level of the generator bus 102 is also high (e.g., 10.5 kV). The voltage level of the auxiliary bus 106 is lower (e.g., 400 V), which is more suitable for the operation of the reactive power compensation device 203. When the reactive power compensation device 203 is working, it improves the power factor of the auxiliary bus 106 by injecting compensation current. This compensation is fed back to the generator bus 102 through the auxiliary transformer 105, then to the booster station bus 104 through the main transformer 103, and finally to the transmission line 107 through the booster station bus 104, thereby improving the power factor of the transmission line 107 at the power plant side.

[0030] The complete working process of the reactive power compensation system is as follows: the electric energy meter 201 collects data from the booster station bus 104 and transmits power data to the controller 202; the controller 202 calculates the reactive power compensation amount and outputs the control instruction; the reactive power compensation device 203 performs compensation action, thereby realizing the improvement of the power factor of the transmission line 107.

[0031] The above technical solution can obtain the power data of the transmission line 107 in real time by setting the electric energy meter 201 at the booster station bus 104; the controller 202 performs calculation and processing based on the obtained power data and outputs the control signal; and the reactive power compensation device 203 performs reactive power compensation at the auxiliary bus 106 according to the control signal. This system can realize the on-site improvement of the power factor of the transmission line 107 at the power plant side, overcome the problem of spatial separation of the power factor measurement point and the reactive power compensation device at the grid side in the traditional off-site compensation scheme, and make the power plant better meet the power factor demand of the grid.

[0032] In an embodiment, the reactive power compensation device 203 can be a static var generator.

[0033] Here, the static var generator (SVG) uses full-control power electronic devices and control strategy, with fast response, high compensation accuracy, low harmonic content, reliable operation and other advantages. The controller 202 converts the required reactive power compensation amount into a PWM modulation signal by real-time calculation, and sends it to the SVG. The insulated gate bipolar transistor (IGBT) module inside the SVG performs switching operation under the control of the PWM signal, and adjusts the phase and amplitude of the output current to achieve continuous, dynamic and smooth compensation of the reactive power, so as to improve the power factor.

[0034] Figure 2 is a structural diagram of a reactive power compensation system for a power plant according to another exemplary embodiment. In an embodiment, as shown in Figure 2 , the reactive power compensation system can further include a voltage transformer 204 and a current transformer 205 for connecting the second end of the electric energy meter 201 to the booster station bus 104.

[0035] Here, the voltage transformer 204 (PT) and the current transformer 205 (CT) are auxiliary measurement conversion devices of the electric energy meter 201. Since the booster station bus 104 has high operating voltage and current (the voltage is usually 110 kilovolts or higher), it cannot be directly measured, and needs to be converted to standard low voltage (such as 100 volts) and small current (such as 5 amperes or 1 amperes) signals by PT and CT in proportion.

[0036] The first end of the electric energy meter 201 includes a voltage sampling end and a current sampling end. The primary side of the PT is connected in parallel to the booster station bus 104, and the secondary side of the PT is connected to the voltage sampling end of the electric energy meter 201. The primary side of the CT is connected in series to the booster station bus 104, and the secondary side of the CT is connected to the current sampling end of the electric energy meter 201. The electric energy meter 201 can calculate the actual voltage and current values of the booster station bus 104 by simultaneously collecting these proportionally converted voltage and current signals, and according to the transformation ratio of the PT and CT. Further, active power (P = voltage U x current I x power factor cosφ, where φ is the voltage and current phase angle) and reactive power (Q = voltage U x current I x phase angle sine value sinφ) data can be obtained. This measurement method can improve the accuracy of measurement and ensure the safety of equipment and personnel.

[0037] In an embodiment, as shown in Figure 2 , the reactive power compensation system can further include a communication protocol converter 206, including an electric energy meter protocol interface and an Ethernet interface; wherein the first end of the electric energy meter 201 is connected to the electric energy meter protocol interface of the communication protocol converter 206, and the Ethernet interface of the communication protocol converter 206 is connected to the data input end of the controller 202.

[0038] Here, in the reactive power compensation system, the communication protocol converter 206 is used to realize data conversion between different communication protocols. The electric energy meter 201 usually adopts industrial field bus protocols such as Modbus-RTU or DL / T645, and can communicate through an RS-485 interface. The controller 202 supports the TCP / IP protocol family, and can receive and send communication data based on Ethernet. Therefore, the electric energy meter protocol interface of the communication protocol converter 206 can support various industrial field bus protocols such as Modbus-RTU, DL / T645, and the Ethernet interface supports industrial Ethernet protocols based on TCP / IP such as Modbus-TCP, HTTP, and FTP. The communication protocol converter 206 converts the industrial field bus protocol data sent by the electric energy meter 201 into industrial Ethernet protocol data that can be recognized by the controller 202 in real time.

[0039] In an embodiment, the electric energy meter protocol interface can be a DL / T645-2007 protocol interface.

[0040] Here, the DL / T645-2007 protocol is specifically for electric energy metering equipment, supports reading of various electric energy parameters, including active power, reactive power, power factor, and other data. The protocol has strong anti-interference ability and reliability, can be compatible with various smart electric energy meters, supports the data transmission needs of multifunctional electric energy meters, realizes extended functions such as time-sharing metering and demand measurement. The DL / T645-2007 protocol also has a data protection mechanism, which can reduce the data error rate in the communication process.

[0041] In an embodiment, the Ethernet interface can be a Modbus TCP protocol interface.

[0042] Here, the Modbus TCP protocol is one of the mainstream communication protocols in the field of industrial automation. It combines the traditional Modbus protocol with standard Ethernet technology, and can support various controllers. At the same time, the communication efficiency of the Modbus TCP protocol is high, and can meet the needs of real-time data acquisition and control of the reactive power compensation system.

[0043] In an embodiment, as shown in Figure 2 The reactive power compensation system can also include an optoelectronic isolator 207, and the communication protocol converter 206 is connected to the electric energy meter 201 through the optoelectronic isolator 207.

[0044] Here, the opto-isolator 207 serves as a signal isolation device, and realizes electrical isolation between the electric energy meter 201 and the communication protocol converter 206 through the principle of photoelectric conversion. The input end of the opto-isolator 207 can be connected to the communication interface of the electric energy meter 201 through the RS-485 bus, and the output end can be connected to the electric energy meter protocol interface of the communication protocol converter 206. When the signal is transmitted, the opto-isolator 207 converts the electrical signal into an optical signal, and then converts the optical signal back into an electrical signal. This conversion process can effectively block common-mode interference and surge voltage, prevent electrical interference from propagating through the communication line, and also eliminate the ground loop and reduce signal distortion. This isolation method can improve communication reliability while protecting the equipment from damage caused by high voltage or transient voltage.

[0045] As shown in Figure 2 , the power plant includes a device state monitoring system 113 connected with the generator 101, the primary equipment 111, and the diesel engine 112. In an embodiment, as shown in Figure 2 , the reactive power compensation system can include a device state acquisition device 208, a first end of the device state acquisition device 208 connected with the data input end of the controller 202, and a second end of the device state acquisition device 208 used for connecting with the data output end of the device state monitoring system 113.

[0046] Here, the primary equipment 111 refers to the main equipment directly related to electric energy production and transmission, including power distribution equipment such as the main transformer 103, the auxiliary transformer 105, the circuit breaker 108, and the low-voltage switch 109. The device state monitoring system 113 is responsible for real-time monitoring and recording the operating parameters and working conditions of the generator 101, the main transformer 103, the auxiliary transformer 105, the circuit breaker 108, the low-voltage switch 109, and the diesel engine 112. The device state acquisition device 208 serves as a data acquisition interface between the controller 202 and the device state monitoring system 113, and on the one hand, it is connected with the monitoring system through electrical isolation to acquire the operating state data of the generator 101, the primary equipment 111, and the diesel engine 112; on the other hand, it transmits the acquired state information to the controller 202, so that the controller 202 can control the switching of the reactive power compensation device 203 according to the operating conditions of different devices.

[0047] This control strategy is based on the following three operating conditions. When the generator 101 is stopped, the primary equipment 111 is normally operated, and the diesel engine 112 is stopped, the controller 202 controls the reactive power compensation device 203 to normally operate. When the generator 101 is normally operated, the controller 202 stops the operation of the reactive power compensation device 203 because the generator can self-adjust the power factor. When the diesel engine 112 is operated, the controller 202 stops the operation of the reactive power compensation device 203 to avoid exacerbating voltage fluctuations because the diesel engine has small inertia and unstable output power.

[0048] In one embodiment, such as Figure 2 As shown, the reactive power compensation system may also include a data input device 209, which is connected to the data input terminal of the controller 202.

[0049] Here, the data input device 209 is used to receive and transmit two parameters: the capacitive reactive power of the transmitting line 107 and the target power factor. The capacitive reactive power is the inherent reactive power of the transmitting line, a fixed value that can be obtained through no-load measurement of the line. The target power factor is the power factor requirement of the power grid for the power plant. The data input device 209 can be an industrial computer, a touch screen, a human-machine interface (HMI), or an industrial control panel with a numeric keypad, etc. The data input device 209 is connected to the data input terminal of the controller 202, and can transmit the two parameters input by the user to the controller 202 in real time. This allows the controller 202 to calculate the required reactive power compensation capacity based on the data, thereby controlling the switching operation of the reactive power compensation device 203.

[0050] The controller 202 first calculates the target reactive power based on the target power factor and the active power of the substation bus 104. Specifically, the target reactive power equals the active power multiplied by the tangent of the target power factor angle, where the target power factor angle is obtained by the inverse cosine of the target power factor. Then, the reactive power to be compensated is calculated by subtracting the actual reactive power of the substation bus 104 from the target reactive power and adding the capacitive reactive power of the transmitting line 107 to obtain the required reactive power compensation. Finally, the reactive power compensation is converted into an inductive current. In this way, the controller 202 can control the switching of the reactive power compensation device 203 based on the calculated inductive current value.

[0051] In one embodiment, such as Figure 2 As shown, the reactive power compensation system may also include a display device 210, which is connected to the controller 202.

[0052] Here, the display device 210 is connected to the controller 202, serving as a visual interface for the operation of the reactive power compensation system. The displayed information may include: active and reactive power of the substation bus 104, capacitive reactive power of the transmitting line 107, target power factor, current power factor, calculated reactive power to be compensated, actual compensation current value, and other operating data. It can also display the operating status of the generator 101, primary equipment 111, and diesel engine 112, as well as the switching status and alarm information of the reactive power compensation device 203. The display device 210 can be an industrial display screen, an LCD screen, or a touch screen, etc.

[0053] The preferred embodiments of the present disclosure are described in detail above with reference to the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Various simple modifications can be made to the technical solutions of the present disclosure within the technical concept of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0054] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0055] In addition, various different embodiments of the present disclosure can also be combined in any appropriate manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed in the present disclosure.

Claims

1. A reactive power compensation system for a power plant, said power plant comprising a generator (101), a generator bus (102), a main transformer (103) and a step-up station bus (104) connected in series, and said power plant further comprising a station transformer (105) connected to one side of said generator bus (102), a station bus (106) connected to one side of said station transformer (105), said step-up station bus (104) being connected to a power grid via a sending-out line (107), characterized in that, The reactive power compensation system comprises an electric energy meter (201), a controller (202), and a reactive power compensation device (203). A first end of the electric energy meter (201) is connected to a data input end of the controller (202), and a second end of the electric energy meter (201) is used to be connected to the booster station bus (104). A control output end of the controller (202) is connected to a first end of the reactive power compensation device (203). A second end of the reactive power compensation device (203) is used to be connected to the plant bus (106).

2. The reactive compensation system of claim 1, wherein, The reactive power compensation device (203) is a static reactive power generator.

3. The reactive compensation system of claim 1, wherein, Further comprising: A voltage transformer (204) and a current transformer (205) are used to connect the second end of the electric energy meter (201) to the booster station bus (104).

4. A reactive power compensation system according to any of claims 1-3, characterized in that Further comprising: A communication protocol converter (206) comprises an electric energy meter protocol interface and an Ethernet interface; wherein, The first end of the electric energy meter (201) is connected to the electric energy meter protocol interface of the communication protocol converter (206), and the Ethernet interface of the communication protocol converter (206) is connected to the data input end of the controller (202).

5. The reactive compensation system of claim 4, wherein, The electric energy meter protocol interface is a DL / T645-2007 protocol interface.

6. The reactive compensation system of claim 4, wherein, The Ethernet interface is a Modbus TCP protocol interface.

7. The reactive compensation system of claim 4, wherein, Further comprising: An optoelectronic isolator (207) is used to connect the first end of the electric energy meter (201) to the electric energy meter protocol interface of the communication protocol converter (206).

8. The reactive power compensation system according to any one of claims 1 to 3, said power plant comprising a plant condition monitoring system (113) connected to the generator (101), the primary equipment (111), and the diesel engine (112), characterized in that, The reactive power compensation system further comprises: A device state acquisition device (208) is connected to the data input end of the controller (202), and a second end of the device state acquisition device (208) is used to be connected to a data output end of the device state monitoring system (113).

9. A reactive power compensation system according to any one of claims 1-3, characterized in that Further comprising: A data input device (209) is connected to the data input end of the controller (202).

10. The reactive power compensation system of any one of claims 1-3, wherein, Further comprising: A display device is connected to the controller.

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