Distributed optical fiber longitudinal difference box transformer substation protection measurement and control system and control method thereof

Abstract

The invention discloses a distributed optical fiber longitudinal difference box transformer substation protection measurement and control system, which adopts an enhanced unit case, is designed according to strong vibration resistance and strong interference resistance, and mainly comprises a power supply output plug-in, an input plug-in, a communication plug-in, a CPU plug-in, an alternating current plug-in and a man-machine conversation plug-in, through the transformer protection measurement and control unit, the switch cabinet protection measurement and control unit and the central monitoring unit, functions of data acquisition and control, electric quantity protection, non-electric quantity protection, optical fiber differential protection, arc light protection, temperature monitoring and gas leakage monitoring are completed, and data communication functions of equipment such as a communication management machine and an optical fiber switch can be integrated. Communication information of intelligent equipment to which the power generation subsystem belongs is centralized and transmitted, and the self-healing ring optical fiber Ethernet is accessed to a booster station integrated automation system, so that remote management and automatic monitoring of the booster station on the wind power plant are realized, and a comprehensive and intelligent operation management mode of the wind power plant is satisfied.

Description

Technical Field

[0001] The present invention relates to the technical field of box-type transformer protection, and in particular to a distributed optical fiber longitudinal differential box-type transformer protection measurement and control system and a control method thereof. Background Art

[0002] At present, the application of power system control system is relatively extensive, from the control of generator sets, the control of various auxiliary machines to the comprehensive automation of substations, etc. In recent years, all new units have fully functional distributed control systems. Large units such as units above 300 megawatts generally use foreign systems, and some units use domestic products. With the increasing attention paid to safety and efficiency indicators, the requirements for power quality and reliability are also getting higher and higher. The entire power production is divided into several links: power generation, transmission, substation, and distribution. The power plant booster station is an important link connecting power generation and transmission. Therefore, it is necessary to use the measurement and control system to achieve all-round measurement and control protection for large wind turbine generator cabin transformers;

[0003] However, at present, it is impossible to provide all-round protection for the nacelle transformer of the wind power generation project. Therefore, in the process of measurement and control protection, the safety information of optical fiber differential protection, arc protection of low-voltage converter cabinet and high-voltage cabinet, optical fiber temperature measurement, and gas leakage cannot be fully and effectively monitored and collected, thus affecting the safe and stable operation of the nacelle transformer of large wind turbine generator. Summary of the invention

[0004] The present invention provides a distributed optical fiber longitudinal differential box transformer protection measurement and control system and a control method thereof, which can effectively solve the problem raised in the above background technology that it is impossible to provide all-round protection for the cabin transformer of the wind power generation project, so that in the process of measurement and control protection, the optical fiber differential protection, arc protection of the low-voltage converter cabinet and the high-voltage cabinet, optical fiber temperature measurement, and gas leakage safety information cannot be fully and effectively monitored and collected, thereby affecting the safe and stable operation of the cabin transformer of the large wind turbine generator.

[0005] To achieve the above object, the present invention provides the following technical solutions: a distributed optical fiber longitudinal differential box transformer protection measurement and control system, adopting a distributed deployment solution, specifically including a transformer protection measurement and control unit, a switch cabinet protection measurement and control unit and a central monitoring unit, adopting a reinforced unit chassis, designed to resist strong vibration and strong interference, and the main plug-ins include a power output plug-in, an input plug-in, a communication plug-in, a CPU plug-in, an AC plug-in and a human-computer dialogue plug-in;

[0006] The transformer protection and measurement and control unit, switchgear protection and measurement and control unit and central monitoring unit mainly complete the functions of data acquisition and control, electrical quantity protection and non-electrical quantity protection, optical fiber differential protection, arc protection, temperature monitoring and gas leakage monitoring;

[0007] The measurement and control system also includes a communication management machine, an optical fiber temperature measurement module and an arc protection module. The optical fiber temperature measurement module specifically includes an optical fiber temperature measurement demodulator module and a fluorescent optical fiber. The arc protection module specifically includes an arc protection unit module and an arc module sensor.

[0008] According to the above technical solution, the transformer protection measurement and control unit is deployed at the fan outlet, the switch cabinet protection measurement and control unit is deployed on the low-voltage side of the box transformer, and the central monitoring unit is deployed on the high-voltage side of the box transformer;

[0009] The transformer protection measurement and control unit is used for current and voltage collection on the low-voltage side of the wind farm booster transformer and switch control, and the switch cabinet protection measurement and control unit and the central monitoring unit are used for current and voltage collection on the high-voltage side of the wind farm booster transformer and switch control.

[0010] According to the above technical solution, the communication management machine refers to the built-in communication management and photoelectric conversion module of the box-type transformer intelligent monitoring device, which realizes the centralization and transmission of communication information of intelligent devices belonging to the wind power generation system, provides 8 RS485 master station interfaces, and can access intelligent devices such as instruments, partial discharge, arc protection, and optical fiber temperature measurement. Each RS485 interface can access 32 devices, and the transmission rate is configurable from 300bps to 115200bps. The transmission distance can reach 1000 meters, and it can support IEC60870-5-101, IEC60870-5-103 / 104, Modbus, CDT, 9702, and private protocols.

[0011] The box-type transformer intelligent monitoring device provides 2 fiber optic Ethernet interfaces, which can form a self-healing fiber optic ring network. The fiber optic interface is single-mode or multi-mode SC type, with a wavelength of 1310nm and a transmission distance of up to 50km.

[0012] According to the above technical solution, the optical fiber temperature measurement demodulator module can convert the temperature information of each temperature measurement point into a digital signal and transmit it to the background protection device in real time. It has a small size and reliable performance.

[0013] The fluorescent optical fiber converts the temperature information of the monitoring part of the temperature measuring probe into an optical signal and transmits it to the optical fiber temperature measuring transmitter. The probe size of the optical fiber sensor is extremely small and can be directly installed on the measured point. The temperature measurement is accurate and the response is fast.

[0014] The pigtail is made of soft and strong special optical fiber, which has the advantages of high transmission bandwidth, stable signal, anti-electromagnetic interference, anti-bending, high impact strength and fast connection;

[0015] The material of the pigtail sheath is polytetrafluoroethylene, which has the characteristics of high temperature resistance, aging resistance, corrosion resistance, high insulation, and non-adhesion. It can adapt to harsh operating environments such as high voltage, high temperature, and strong electromagnetic.

[0016] According to the above technical solution, the arc protection unit module detects the fault current and arc signal, and processes and judges the two received signals. When the tripping condition is met, a tripping command is issued to remove the fault. It has a flexible parameter configuration function, and can distinguish whether it is a busbar fault or an outgoing line fault according to the arc signal, and respectively trip the incoming line switch or the outgoing line switch;

[0017] The arc module sensor is a light sensing element that detects arc light. When an arc light fault occurs, the light intensity increases significantly. The arc sensor converts the light signal into an electrical signal and transmits it to the protection unit. The arc sensor wiring has no polarity. The arc sensor is installed in the relevant parts of the switch cabinet to monitor those fragile and important components. In front of the sensor, its sensitivity remains almost unchanged, while on the back of the sensor, the sensitivity will decrease.

[0018] According to the above technical solution, the power output plug-in integrates the power module of the device, eight-way programmable relay outputs and three-way signal contacts;

[0019] Each of the input plug-ins can provide 27 inputs, and the working voltage is AC220V;

[0020] The communication plug-in provides 2 fiber optic Ethernet interfaces, which can form a self-healing fiber optic ring network. The fiber optic interface can be ST or FC, with a wavelength of 1310nm and a transmission distance of up to 50km.

[0021] The CPU plug-in integrates data sampling processing, communication and protection functions. The plug-in adopts a multi-layer printed circuit board and surface mounting technology, and adopts a variety of anti-interference measures, which greatly improves the anti-interference performance;

[0022] The AC conversion part of the AC plug-in includes a current converter TA and a voltage converter TV, which are used to convert the secondary side current and voltage signals of the system TA and TV into weak current signals for conversion by the CPU plug-in and play a role in isolating strong and weak currents;

[0023] The human-computer dialogue plug-in is installed on the device panel and is the main component for the device to exchange information with the outside world. It uses a large-screen LCD display and a full Chinese menu display. The main functions include: keyboard operation, LCD display, and signal light indication.

[0024] A distributed optical fiber longitudinal differential box transformer protection measurement and control method, the control method comprises the following control steps:

[0025] S1, non-electrical quantity detection protection;

[0026] S2, device emergency failure alarm;

[0027] S3, electrical quantity protection;

[0028] S4. Measurement and control function.

[0029] According to the above technical solution, in S1, the device is provided with 8 non-electrical protections, which can be controlled by the soft pressure plate, i.e., the control word, and the outlet delay can be set. 4 actions are tripped, and 4 alarm trips are optional. When the non-electrical trip or alarm occurs, if the fault state persists, the trip signal or alarm signal is maintained until the standby non-electrical fault state is released, and the trip signal or alarm signal can be reset by pressing the reset key;

[0030] In S2, if the hardware of the main protection device fails, the LCD of the device can display the fault information and drive the device alarm relay, while locking the protection. After the fault is handled, the device is powered on again and the alarm information can be restored.

[0031] According to the above technical solution, in S3, the electrical quantity protection specifically includes calculation of the opposite CT ratio adjustment coefficient, calculation of differential protection current, differential quick-break protection, ratio differential protection, differential current over-protection, quick-break, time-limited quick-break, overcurrent protection, overload protection, PT line break protection, overvoltage protection, undervoltage protection, CT line break, single-phase grounding alarm, negative sequence current protection and measurement and control functions;

[0032] The calculation of the opposite-side CT ratio adjustment coefficient means that the device uses software to adjust the inconsistent CT ratios on both sides, that is, each side has a CT ratio adjustment coefficient, and no external auxiliary CT is required. Compared with using hardware loop adjustment, the reliability is higher;

[0033] The calculation of the CT ratio adjustment coefficient is based on the local side, that is, the CT ratio adjustment coefficient of the local side is set to 1. The calculation method of the CT ratio adjustment coefficient of the opposite side is as follows:

[0034]

[0035] Where: U Nx is the rated line voltage on the opposite side, K CTx is the transformation ratio of the contralateral CT, K Jx is the opposite winding connection coefficient. When the CTs on each side are connected to the differential protection device in Y shape, the opposite winding of the transformer is connected in Y shape. Jx =1, Δ connection

[0036] For on-load tap-changing transformers, U Nx The middle tap voltage should be used. If it is impossible to change the tap position in actual situation, the tap voltage actually used should be used;

[0037] The differential protection current calculation means that the device is suitable for three-winding and two-winding transformers with various wiring modes. The interface provides a transformer wiring mode configuration function. The software performs adaptive processing of the protection logic according to the transformer wiring mode. When it is a three-winding transformer, the main device collects the current on both sides of the low voltage, and the sub-device collects the current on the high voltage side;

[0038] In order to simplify the on-site wiring and improve the inrush current braking characteristics, the CTs on each side of the transformer are required to be connected in Y shape and connected in the same polarity, that is, the current on each side is in the positive direction of flowing into the transformer. The device performs phase correction on the current on the Y-shaped side of the transformer, and the effect is exactly the same as connecting the CT in Δ shape. For the reconstruction project of the old station, if the CT on the Y side of the transformer is originally Δ-connected, it is generally required to be transformed into Y-connection;

[0039] The ratio differential protection is to ensure the sensitivity of the differential protection during internal faults, and to prevent malfunction caused by transient unbalanced currents caused by external faults and inconsistent CT characteristics. The device adopts the ratio differential principle of second harmonic braking.

[0040] The negative sequence current protection is mainly aimed at various non-grounding asymmetric faults.

[0041] According to the above technical solution, in S4, the measurement and control functions include telemetry, telesignaling and remote control functions and temperature collection functions;

[0042] The telemetering, telesignaling and remote control functions include sub-device telemetering: measuring IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1 on the high-voltage side of the box-type transformer;

[0043] Main device telemetry: measure IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1, IA2, IB2, IC2, UA2, UB2, UC2, UAB2, UBC2, UCA2, P2, Q2, f2, COSφ2 on both sides of the low voltage box transformer;

[0044] Remote signal: various protection action signals and circuit breaker position remote signal, opening remote signal, remote control: remote control tripping / closing, pressure plate throwing and retreating, and setting value modification;

[0045] The temperature acquisition function can collect information from multiple thermal resistors or temperature transmitters, making it easier to monitor the temperatures at multiple locations within the box transformer.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention realizes a comprehensive protection scheme in the form of a large-scale wind turbine cabin transformer, adopts a distributed deployment scheme, and respectively deploys the transformer protection measurement and control unit, the switch cabinet protection measurement and control unit and the central monitoring unit at the fan outlet, the low-voltage side of the box transformer or the high-voltage side of the box transformer, to complete the functions of data acquisition and control, electrical quantity protection and non-electrical quantity protection, optical fiber differential protection, arc protection, temperature monitoring, and gas leakage monitoring. At the same time, it can also integrate the data communication functions of equipment such as communication management machines and optical fiber switches to realize the centralization and transmission of communication information of intelligent devices belonging to the power generation subsystem, and access the booster station integrated self-system through the self-healing ring optical fiber Ethernet, thereby realizing the remote management and automatic monitoring of the wind farm by the booster station, meeting the comprehensive intelligent operation and management mode of the wind farm;

[0048] At the same time, it realizes all-round fiber optic differential protection for the wind power project cabin transformer, arc protection for low-voltage converter cabinets and high-voltage cabinets, fiber optic temperature measurement, and comprehensive monitoring and protection of gas leakage. It has strong anti-interference ability, and the optical fiber is not affected by electromagnetic interference. It can work stably in a strong electromagnetic field environment, which is particularly suitable for high electromagnetic interference places such as substations and power plants. The system is based on advanced photoelectric effect and fiber optic signal transmission principles. By accurately measuring the time difference of light pulses transmitted in the optical fiber, it can quickly locate power system faults, reduce recovery time, and improve system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0050] Figure 1 It is a structural diagram of the measurement and control system of the present invention;

[0051] Figure 2 is an electrical schematic diagram of the present invention;

[0052] Figure 3 It is a schematic diagram of the networking of the present invention;

[0053] Figure 4 It is a schematic diagram of the outer dimensions of the chassis of the present invention;

[0054] Figure 5 It is the principle diagram of non-electrical quantity detection of the present invention;

[0055] Figure 6 This is the main action logic diagram of the differential quick-break protection of the present invention;

[0056] Figure 7 It is the action characteristic diagram of the present invention;

[0057] Figure 8 It is the action logic diagram of the differential protection element of the present invention;

[0058] Fig. 9 It is the action logic diagram of the differential current over-limit protection of the present invention;

[0059] Fig.10 It is the action logic diagram of the quick-break protection element of the present invention;

[0060] Fig.11 It is the action logic diagram of the time-limited quick-break protection element of the present invention;

[0061] Fig.12 It is the action logic diagram of the overcurrent protection element of the present invention;

[0062] Fig.13 It is the action logic diagram of the overload protection of the present invention;

[0063] Fig.14 It is a PT line break action logic diagram in the PT line break protection of the present invention;

[0064] Fig.15 It is a logic diagram of overvoltage protection of the present invention;

[0065] Fig.16 It is the logic diagram of undervoltage protection of the present invention;

[0066] Fig.17 It is a functional logic diagram of CT disconnection of the present invention;

[0067] Fig.18 It is the action logic diagram of the single-phase grounding alarm of the present invention;

[0068] Fig.19 It is an action logic diagram of the negative sequence current protection element of the present invention. DETAILED DESCRIPTION

[0069] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0070] Example: Figure 1-5 As shown, the present invention provides a technical solution, a distributed optical fiber longitudinal differential box transformer protection measurement and control system, which adopts a distributed deployment solution, specifically includes a transformer protection measurement and control unit, a switch cabinet protection measurement and control unit and a central monitoring unit, adopts a reinforced unit chassis, and is designed to resist strong vibration and strong interference. The main plug-ins include a power output plug-in, an input plug-in, a communication plug-in, a CPU plug-in, an AC plug-in and a human-computer dialogue plug-in;

[0071] The transformer protection and measurement and control unit, switchgear protection and measurement and control unit and central monitoring unit mainly complete the functions of data acquisition and control, electrical quantity protection and non-electrical quantity protection, optical fiber differential protection, arc protection, temperature monitoring and gas leakage monitoring;

[0072] The measurement and control system also includes a communication management machine, an optical fiber temperature measurement module and an arc protection module. The optical fiber temperature measurement module specifically includes an optical fiber temperature measurement demodulator module and a fluorescent optical fiber. The arc protection module specifically includes an arc protection unit module and an arc module sensor.

[0073] Based on the above technical solution, the transformer protection and measurement and control unit is deployed at the fan outlet, the switch cabinet protection and measurement and control unit is deployed on the low-voltage side of the box-type transformer, and the central monitoring unit is deployed on the high-voltage side of the box-type transformer;

[0074] The transformer protection measurement and control unit is used for current and voltage collection on the low-voltage side of the wind farm booster transformer and switch control. The switch cabinet protection measurement and control unit and the central monitoring unit are used for current and voltage collection on the high-voltage side of the wind farm booster transformer and switch control.

[0075] Based on the above technical solution, the communication management machine refers to the built-in communication management and photoelectric conversion module of the box-type transformer intelligent monitoring device, which realizes the centralization and transmission of communication information of intelligent devices belonging to the wind power generation system, provides 8 RS485 master station interfaces, and can access intelligent devices such as instruments, partial discharge, arc protection, and optical fiber temperature measurement. Each RS485 interface can connect 32 devices, and the transmission rate is configurable from 300bps to 115200bps. The transmission distance can reach 1000 meters, and it can support IEC60870-5-101, IEC60870-5-103 / 104, Modbus, CDT, 9702, and private protocols.

[0076] The box-type transformer intelligent monitoring device provides 2 optical fiber Ethernet interfaces, which can form a self-healing optical fiber ring network. The optical fiber interface is single-mode or multi-mode SC type, with a wavelength of 1310nm and a transmission distance of up to 50km. The communication protocol adopts IEC60870-5-103 / 104, which is oriented to the data of a single intelligent device, and realizes the unified conversion and transmission from Modbus to IEC60870-5-103 / 104, which can easily access the current mainstream power station monitoring system;

[0077] The built-in communication management machine of the box-type transformer intelligent monitoring device provides dual-machine redundancy and dual Ethernet multiple cascade working modes. It has flexible online and offline debugging methods, reliable program upgrade, parameter download and data query, and message monitoring functions. It has powerful self-diagnosis and self-recovery functions. When the program runs wrong due to external interference or other reasons, the system can recover by itself in a very short time.

[0078] Based on the above technical solution, the optical fiber temperature measurement demodulator module can convert the temperature information of each temperature measurement point into a digital signal and transmit it to the background protection device in real time. It has a compact size and reliable performance.

[0079] The fluorescent optical fiber converts the temperature information of the temperature probe monitoring part into an optical signal and transmits it to the optical fiber temperature transmitter. The probe size of the optical fiber sensor is extremely small and can be directly installed on the measured point. It has accurate temperature measurement and quick response.

[0080] The pigtail is made of soft and strong special optical fiber, which has the advantages of high transmission bandwidth, stable signal, anti-electromagnetic interference, anti-bending, high impact strength and fast connection;

[0081] The material of the pigtail sheath is polytetrafluoroethylene, which has the characteristics of high temperature resistance, aging resistance, corrosion resistance, high insulation, and non-adhesion. It can adapt to harsh operating environments such as high voltage, high temperature, and strong electromagnetic.

[0082] Based on the above technical solution, the arc protection unit module detects the fault current and arc signal, and processes and judges the two received signals. When the tripping conditions are met, a tripping command is issued to remove the fault. It has a flexible parameter configuration function and can distinguish whether it is a busbar fault or an outgoing line fault according to the arc signal, and trip the incoming line switch or the outgoing line switch respectively.

[0083] The arc module sensor is a light sensing element that detects arc light. When an arc fault occurs, the light intensity increases significantly. The arc sensor converts the light signal into an electrical signal and transmits it to the protection unit. The arc sensor wiring has no polarity. The arc sensor is installed in the relevant parts of the switch cabinet to monitor those fragile and important components. In front of the sensor, its sensitivity remains almost unchanged, while on the back of the sensor, the sensitivity will decrease.

[0084] Based on the above technical solution, the power output plug-in integrates the power module of the device, eight-way programmable relay outputs and three-way signal contacts;

[0085] Each input plug-in can provide 27 inputs, and the working voltage is AC220V;

[0086] The communication plug-in provides 2 fiber optic Ethernet interfaces, which can form a self-healing fiber optic ring network. The fiber optic interface can be ST or FC, with a wavelength of 1310nm and a transmission distance of up to 50km.

[0087] The CPU plug-in integrates data sampling processing, communication and protection functions. The plug-in adopts multi-layer printed circuit board and surface mounting technology, and adopts a variety of anti-interference measures, which greatly improves the anti-interference performance;

[0088] The AC conversion part of the AC plug-in includes a current converter TA and a voltage converter TV, which are used to convert the secondary side current and voltage signals of the system TA and TV into weak current signals for conversion by the CPU plug-in and play a role in isolating strong and weak currents;

[0089] The human-computer dialogue plug-in is installed on the device panel. It is the main component for the device to exchange information with the outside world. It uses a large-screen LCD display and a full Chinese menu display. The main functions include: keyboard operation, LCD display, and signal light indication.

[0090] A distributed optical fiber longitudinal differential box transformer protection measurement and control method, the control method comprises the following control steps:

[0091] S1, non-electrical quantity detection protection;

[0092] S2, device emergency failure alarm;

[0093] S3, electrical quantity protection;

[0094] S4. Measurement and control function.

[0095] Based on the above technical solution, in S1, the device is equipped with 8 non-electrical protections, which can be controlled by the soft pressure plate, that is, the control word, and the output delay can be set. 4 circuits are tripped and 4 circuits are optional for alarm tripping. When the non-electrical trip or alarm occurs, if the fault state persists, the trip signal or alarm signal will be maintained until the standby non-electrical fault state is removed. The trip signal or alarm signal can be reset only by pressing the reset key. The protection principle is as follows: Figure 5 As shown;

[0096] In S2, the hardware of the main protection device fails. The LCD of the device can display the fault information and drive the device alarm relay, while locking the protection. After the fault is handled, the device is powered on again and the alarm information can be restored.

[0097] Based on the above technical solution, in S3, the electrical quantity protection specifically includes the calculation of the opposite CT ratio adjustment coefficient, the calculation of the differential protection current, the differential quick-break protection, the ratio differential protection, the differential current over-protection, the quick-break, the time-limited quick-break, the overcurrent protection, the overload protection, the PT line break protection, the overvoltage protection, the undervoltage protection, the CT line break, the single-phase grounding alarm, the negative sequence current protection and the measurement and control function;

[0098] The calculation of the CT ratio adjustment coefficient on the opposite side means that the device uses software to adjust the inconsistent CT ratio on both sides, that is, each side has a CT ratio adjustment coefficient, and no external auxiliary CT is required. Compared with the adjustment using hardware loop, it has higher reliability. The CT ratio adjustment coefficient on each side is automatically calculated by the device, and the device LCD display interface provides the function of viewing the CT ratio adjustment coefficient, which is convenient for users to debug and use;

[0099] The user only needs to set the rated line voltage and CT rated primary current value on this side, the rated line voltage and CT rated primary current value on the opposite side, and the CT ratio adjustment coefficient on this side and the opposite side will be automatically calculated by the device;

[0100] The calculation of the CT ratio adjustment coefficient is based on the local side, that is, the CT ratio adjustment coefficient of the local side is set to 1. The calculation method of the CT ratio adjustment coefficient of the opposite side is as follows:

[0101]

[0102] Where: U Nx is the rated line voltage on the opposite side, K CTx is the transformation ratio of the contralateral CT, K Jx is the opposite winding connection coefficient. When the CTs on each side are connected to the differential protection device in Y shape, the opposite winding of the transformer is connected in Y shape. Jx =1, Δ connection

[0103] For on-load tap-changing transformers, U Nx The middle tap voltage should be used. If it is impossible to change the tap position in actual situation, the tap voltage actually used should be used;

[0104] Differential protection current calculation means that the device is suitable for three-winding and two-winding transformers with various wiring methods. The interface provides the transformer wiring configuration function. The software performs adaptive processing of the protection logic according to the transformer wiring method. When it is a three-winding transformer, the main device collects the current on both sides of the low voltage, and the sub-device collects the current on the high voltage side;

[0105] In order to simplify the on-site wiring and improve the inrush current braking characteristics, the CTs on each side of the transformer are required to be connected in Y shape and connected in the same polarity, that is, the current on each side is in the positive direction of flowing into the transformer. The device performs phase correction on the current on the Y-shaped side of the transformer, and the effect is exactly the same as connecting the CT in Δ shape. For the reconstruction project of the old station, if the CT on the Y side of the transformer is originally Δ-connected, it is generally required to be transformed into Y-connection;

[0106] Differential current and braking current calculation method

[0107]

[0108] The main action logic diagram of the differential quick-break protection is as follows: Figure 6 As shown in the figure, ICSDset is the differential breaking value, INCD is the differential current of any phase, and the differential breaking action trips the bridge switch, high voltage side and low voltage side;

[0109] The setting of ICSDset should satisfy two conditions:

[0110] 1) Avoid the maximum unbalanced current in various situations;

[0111] 2) Avoid transformer excitation inrush current;

[0112] The excitation inrush current is generally greater than the maximum unbalanced current, so ICSDset=1.2I yl,max , where I yl,max is the maximum excitation inrush current value, generally taken as in It is caused by the Y / Δ conversion in the process of differential current formation;

[0113] The ratio differential protection is to ensure the sensitivity of the differential protection during internal faults, and to prevent false operation caused by transient unbalanced currents due to external faults and inconsistent CT characteristics. The device adopts the ratio differential principle of second harmonic braking. The action characteristics are as follows: Figure 7 As shown;

[0114] The action logic diagram of the differential protection element is as follows: Figure 8 As shown in the figure, INCD is the differential current of any phase, and INCD2 is the second harmonic current of the differential current of any phase;

[0115] Recommended setting principle, ICDset recommended value range is:

[0116]

[0117] Where: S is the rated capacity of the transformer, U N1 is the rated line voltage on the first side, K CT1 is the CT ratio on the first side, where It is caused by the Y / Δ conversion in the process of differential current formation;

[0118] In addition, the device can automatically calculate the value of the transformer rated current. The differential ratio constant K1 is set according to the maximum error characteristic of the CT ratio when avoiding external faults, and can be taken as 0.5. The inrush harmonic braking coefficient constant K2 is based on operating experience. In order to reliably avoid the excitation inrush current, it is recommended to be set to 0.12;

[0119] The action logic diagram of differential current overload protection is as follows: Fig. 9 As shown in the figure, ICLset is the current setting value of differential current over-current protection, TCLset is the limit value of differential current over-current protection, and INCD is the differential current of any phase;

[0120] In quick-break, time-limited quick-break and overcurrent protection, the action logic diagram of quick-break protection element is as follows: Fig.10As shown in the figure, ISDset is the instantaneous protection current setting, U2set is the composite voltage negative sequence voltage setting, UDset is the composite voltage low voltage setting, TSDset is the instantaneous protection time limit value, IN is any phase protection current, ULN is any line voltage, U2 is the calculated negative sequence voltage, the negative sequence voltage can be calculated according to the three-phase phase voltage, and ULN is any line voltage;

[0121] The action logic diagram of the time-limited quick-break protection element is as follows: Fig.11 As shown in the figure, IXSSDset is the time-limited quick-break protection current setting, U2set is the composite voltage negative sequence voltage setting, UDset is the composite voltage low voltage setting, TXSSDset is the time-limited quick-break protection time setting, IN is any phase protection current, ULN is any line voltage, U2 is the calculated negative sequence voltage, the negative sequence voltage can be calculated according to the three-phase phase voltage, ULN is any line voltage;

[0122] The action logic diagram of the overcurrent protection element is as follows: Fig.12 As shown in the figure, IGLset is the overcurrent protection current setting, U2set is the composite voltage negative sequence voltage setting, UDset is the composite voltage low voltage setting, TGLset is the limit value during overcurrent protection, IN is any phase protection current, ULN is any line voltage, U2 is the calculated negative sequence voltage, the negative sequence voltage can be calculated according to the three-phase phase voltage, and ULN is any line voltage;

[0123] The action logic diagram of overload protection is as follows: Fig.13 As shown in the figure, IGFHse is the overload protection current setting value, TGFHset is the limit value when overload occurs, IN is the protection current of any phase, and an alarm signal is sent after the overload action;

[0124] The PT disconnection action logic diagram in PT disconnection protection is as follows Fig.14 As shown in the figure, U1 is the calculated positive sequence voltage, U2 is the calculated negative sequence voltage, and IN is the protection current of any phase;

[0125] The logic diagram of overvoltage protection is as follows: Fig.15 As shown in the figure, UGYset is the overvoltage protection voltage setting value, TGYset is the overvoltage protection limit value, and ULN is any line voltage;

[0126] The logic diagram of undervoltage protection is as follows: Fig.16 As shown in the figure, UQYset is the undervoltage protection voltage setting value, and ULN is any line voltage;

[0127] The functional logic diagram of CT disconnection is as follows Fig.17 As shown;

[0128] The action logic diagram of the single-phase grounding alarm is as follows: Fig.18 As shown;

[0129] In the figure, U0set is the zero-sequence voltage setting value of single-phase grounding protection, TU0set is the limit value when single-phase grounding occurs, and U0 is the zero-sequence voltage;

[0130] Negative sequence current protection is mainly used for various non-grounding asymmetric faults, such as when a phase of the transformer is broken or unbalanced:

[0131] Negative sequence current:

[0132]

[0133] The action logic diagram of the negative sequence current protection element is as follows: Fig.19 As shown in the figure, IFXset1 is the negative-sequence first stage protection current setting, IFXset2 is the negative-sequence second stage protection current setting, TFXset1 is the negative-sequence first stage protection time limit value, TFXset2 is the negative-sequence second stage protection time limit value, I2 is the calculated negative-sequence current, the negative-sequence first stage is an alarm, and the negative-sequence second stage is a trip.

[0134] Based on the above technical solution, in S4, the measurement and control functions include telemetry, telesignaling, remote control and temperature collection functions;

[0135] The telemetering, telesignaling and remote control functions include sub-device telemetering: measuring IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1 on the high-voltage side of the box-type transformer;

[0136] Main device telemetry: measure IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1, IA2, IB2, IC2, UA2, UB2, UC2, UAB2, UBC2, UCA2, P2, Q2, f2, COSφ2 on both sides of the low voltage box transformer;

[0137] Remote signal: various protection action signals and circuit breaker position remote signal, opening remote signal, remote control: remote control tripping / closing, pressure plate throwing and retreating, and setting value modification;

[0138] The temperature acquisition function can collect information from multiple thermal resistors or temperature transmitters, making it easier to monitor the temperatures at multiple locations inside the box transformer.

[0139] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A distributed optical fiber longitudinal differential box transformer protection and control system, characterized in that: A distributed deployment solution is adopted, including transformer protection and measurement and control unit, switch cabinet protection and measurement and control unit and central monitoring unit. A reinforced unit chassis is used, which is designed to resist strong vibration and strong interference. The main plug-ins include power output plug-in, input plug-in, communication plug-in, CPU plug-in, AC plug-in and human-computer dialogue plug-in. The transformer protection and measurement and control unit, switchgear protection and measurement and control unit and central monitoring unit mainly complete the functions of data acquisition and control, electrical quantity protection and non-electrical quantity protection, optical fiber differential protection, arc protection, temperature monitoring and gas leakage monitoring; The measurement and control system also includes a communication management machine, an optical fiber temperature measurement module and an arc protection module. The optical fiber temperature measurement module specifically includes an optical fiber temperature measurement demodulator module and a fluorescent optical fiber. The arc protection module specifically includes an arc protection unit module and an arc module sensor.

2. A distributed optical fiber longitudinal differential box transformer protection and control system according to claim 1, characterized in that: The transformer protection and measurement and control unit is deployed at the fan outlet, the switch cabinet protection and measurement and control unit is deployed at the low-voltage side of the box-type transformer, and the central monitoring unit is deployed at the high-voltage side of the box-type transformer; The transformer protection measurement and control unit is used for current and voltage collection on the low-voltage side of the wind farm booster transformer and switch control, and the switch cabinet protection measurement and control unit and the central monitoring unit are used for current and voltage collection on the high-voltage side of the wind farm booster transformer and switch control.

3. A distributed optical fiber longitudinal differential box transformer protection and control system according to claim 1, characterized in that: The communication management machine refers to the built-in communication management and photoelectric conversion module of the box-type transformer intelligent monitoring device, which realizes the centralization and transmission of communication information of intelligent devices belonging to the wind power generation system, provides 8 RS485 master station interfaces, and can access intelligent devices such as instruments, partial discharge, arc protection, and optical fiber temperature measurement. Each RS485 interface can access 32 devices, and the transmission rate is configurable from 300bps to 115200bps. The transmission distance can reach 1000 meters, and it can support IEC60870-5-101, IEC60870-5-103 / 104, Modbus, CDT, 9702, and private protocols. The box-type transformer intelligent monitoring device provides 2 fiber optic Ethernet interfaces, which can form a self-healing fiber optic ring network. The fiber optic interface is single-mode or multi-mode SC type, with a wavelength of 1310nm and a transmission distance of up to 50km.

4. A distributed optical fiber longitudinal differential box transformer protection and control system according to claim 1, characterized in that: The optical fiber temperature measurement demodulator module can convert the temperature information of each temperature measurement point into a digital signal and transmit it to the background protection device in real time. It has a small size and reliable performance. The fluorescent optical fiber converts the temperature information of the monitoring part of the temperature measuring probe into an optical signal and transmits it to the optical fiber temperature measuring transmitter. The probe size of the optical fiber sensor is extremely small and can be directly installed on the measured point. The temperature measurement is accurate and the response is fast. The pigtail is made of soft and strong special optical fiber, which has the advantages of high transmission bandwidth, stable signal, anti-electromagnetic interference, anti-bending, high impact strength and fast connection; The material of the pigtail sheath is polytetrafluoroethylene, which has the characteristics of high temperature resistance, aging resistance, corrosion resistance, high insulation, and non-adhesion. It can adapt to harsh operating environments such as high voltage, high temperature, and strong electromagnetic.

5. A distributed optical fiber longitudinal differential box transformer protection and control system according to claim 1, characterized in that: The arc protection unit module detects the fault current and arc signal, processes and judges the two received signals, and issues a trip command to remove the fault when the trip condition is met. It has a flexible parameter configuration function, can distinguish whether it is a busbar fault or an outgoing line fault according to the arc signal, and trip the incoming line switch or the outgoing line switch respectively; The arc module sensor is a light sensing element that detects arc light. When an arc light fault occurs, the light intensity increases significantly. The arc sensor converts the light signal into an electrical signal and transmits it to the protection unit. The arc sensor wiring has no polarity. The arc sensor is installed in the relevant parts of the switch cabinet to monitor those fragile and important components. In front of the sensor, its sensitivity remains almost unchanged, while on the back of the sensor, the sensitivity will decrease.

6. A distributed optical fiber longitudinal differential box-type transformer protection and control system according to claim 1, characterized in that: The power output plug-in integrates the power module of the device, eight-way programmable relay outputs and three-way signal contacts; Each of the input plug-ins can provide 27 inputs, and the working voltage is AC220V; The communication plug-in provides 2 fiber optic Ethernet interfaces, which can form a self-healing fiber optic ring network. The fiber optic interface can be ST or FC, with a wavelength of 1310nm and a transmission distance of up to 50km. The CPU plug-in integrates data sampling processing, communication and protection functions. The plug-in adopts a multi-layer printed circuit board and surface mounting technology, and adopts a variety of anti-interference measures, which greatly improves the anti-interference performance; The AC conversion part of the AC plug-in includes a current converter TA and a voltage converter TV, which are used to convert the secondary side current and voltage signals of the system TA and TV into weak current signals for conversion by the CPU plug-in and play a role in isolating strong and weak currents; The human-computer dialogue plug-in is installed on the device panel and is the main component for the device to exchange information with the outside world. It uses a large-screen LCD display and a full Chinese menu display. The main functions include: keyboard operation, LCD display, and signal light indication.

7. A distributed optical fiber longitudinal differential box transformer protection measurement and control method according to claim 1, characterized in that: The control method comprises the following control steps: S1, non-electrical quantity detection protection; S2, device emergency failure alarm; S3, electrical quantity protection; S4. Measurement and control function.

8. A distributed optical fiber longitudinal differential box transformer protection measurement and control method according to claim 7, characterized in that: In the S1, the device is provided with 8 non-electrical protections, which can be controlled by the soft pressure plate, i.e., the control word, and the output delay can be set. 4 circuits are operated on tripping, and 4 circuits are optional for alarm tripping. When the non-electrical tripping or alarming occurs, if the fault state persists, the tripping signal or alarm signal is maintained until the standby non-electrical fault state is released. The tripping signal or alarm signal can be reset only by pressing the reset key. In S2, if the hardware of the main protection device fails, the LCD of the device can display the fault information and drive the device alarm relay, while locking the protection. After the fault is handled, the device is powered on again and the alarm information can be restored.

9. A distributed optical fiber longitudinal differential box transformer protection measurement and control system and control method according to claim 7, characterized in that: In S3, the electrical quantity protection specifically includes calculation of the opposite CT ratio adjustment coefficient, calculation of differential protection current, differential quick-break protection, ratio differential protection, differential current over-protection, quick-break, time-limited quick-break, overcurrent protection, overload protection, PT line break protection, overvoltage protection, undervoltage protection, CT line break, single-phase grounding alarm, negative sequence current protection and measurement and control functions; The calculation of the opposite-side CT ratio adjustment coefficient means that the device uses software to adjust the inconsistent CT ratios on both sides, that is, each side has a CT ratio adjustment coefficient, and no external auxiliary CT is required. Compared with using hardware loop adjustment, the reliability is higher; The calculation of the CT ratio adjustment coefficient is based on the local side, that is, the CT ratio adjustment coefficient of the local side is set to 1. The calculation method of the CT ratio adjustment coefficient of the opposite side is as follows: Where: U Nx is the rated line voltage on the opposite side, K CTx is the transformation ratio of the contralateral CT, K Jx is the opposite winding connection coefficient. When the CTs on each side are connected to the differential protection device in Y shape, the opposite winding of the transformer is connected in Y shape. Jx =1,△ connection time For on-load tap-changing transformers, U Nx The middle tap voltage should be used. If it is impossible to change the tap position in actual situation, the tap voltage actually used should be used; The differential protection current calculation means that the device is suitable for three-winding and two-winding transformers with various wiring modes. The interface provides a transformer wiring mode configuration function. The software performs adaptive processing of the protection logic according to the transformer wiring mode. When it is a three-winding transformer, the main device collects the current on both sides of the low voltage, and the sub-device collects the current on the high voltage side; In order to simplify the on-site wiring and improve the inrush current braking characteristics, the CTs on each side of the transformer are required to be connected in Y shape and connected in the same polarity, that is, the current on each side is in the positive direction of flowing into the transformer. The device performs phase correction on the current on the Y-shaped side of the transformer, and the effect is exactly the same as connecting the CT in Δ shape. For the reconstruction project of the old station, if the CT on the Y side of the transformer is originally Δ-connected, it is generally required to be transformed into Y-connection; The ratio differential protection is to ensure the sensitivity of the differential protection during internal faults, and to prevent malfunction caused by transient unbalanced currents caused by external faults and inconsistent CT characteristics. The device adopts the ratio differential principle of second harmonic braking. The negative sequence current protection is mainly aimed at various non-grounding asymmetric faults.

10. A distributed optical fiber longitudinal differential box transformer protection measurement and control method according to claim 7, characterized in that: In said S4, the measurement and control functions include telemetry, telesignaling, remote control functions and temperature collection functions; The telemetering, telesignaling and remote control functions include sub-device telemetering: measuring IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1 on the high-voltage side of the box-type transformer; Main device telemetry: measure IA1, IB1, IC1, UA1, UB1, UC1, UAB1, UBC1, UCA1, P1, Q1, f1, COSφ1, IA2, IB2, IC2, UA2, UB2, UC2, UAB2, UBC2, UCA2, P2, Q2, f2, COSφ2 on both sides of the low voltage box transformer; Remote signal: various protection action signals and circuit breaker position remote signal, opening remote signal, remote control: remote control tripping / closing, pressure plate throwing and retreating, and setting value modification; The temperature acquisition function can collect information from multiple thermal resistors or temperature transmitters, making it easier to monitor the temperatures at multiple locations within the box transformer.

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