CN201608534U - Microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railway - Google Patents

Abstract

A microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railways, including voltage transformers and current transformers located in the grid circuit, the voltage analog signals collected by the voltage transformers and the current analog signals collected by the current transformers are passed through the sampling circuit and The A/D conversion circuit inputs reactive power automatic compensation microprocessor, the microprocessor is connected with the upper computer control system through the communication interface, and the output end of the microprocessor is connected with the capacitor bank through the voltage regulator unit. The utility model changes the compensation capacity of the parallel capacitor by automatically adjusting the terminal voltage of the parallel capacitor compensation device through the on-load auto-coupling voltage regulator. The equipment in the operation of the power grid will cause harm, and the power supply quality of the power grid will be improved.

Description

Microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railway

technical field

The utility model relates to a reactive power compensation device applied in the field of electric power systems, in particular to a microcomputer-controlled voltage-regulating automatic reactive power compensation device for electrified railways.

Background technique

In recent years, due to the speed increase of railway trains, the traffic density and load capacity have increased, the traction load has continued to increase, and the energy change of several thousand KW has occurred within ten seconds. At present, most traction substations are equipped with fixed parallel capacitor compensation devices, so the output reactive power is a constant, and it is impossible to dynamically compensate the traction load. It is easy to form overcompensation when there is no traction load, and undercompensation when there is traction load. The power factor of the traction substation is reduced. How to effectively compensate the reactive power of the traction substation to improve the power factor is a problem to be solved for the electrified railway. At present, although there are different types of dynamic compensation devices at home and abroad, they all have problems of varying degrees. For example, Chinese patent CN2533603Y discloses a dynamic reactive power compensation device for electric power filtering. Although the silicon compensation method can achieve reactive power compensation to a certain extent, it is not easy to solve the problems of switching zero-crossing accuracy and thyristor temperature rise when adjusting the reactive power compensation capacity, and it is easy to generate harmonics, which will aggravate the harmonic pollution of the power grid. In addition, there are other reactive power compensation methods currently on the market, but they all have shortcomings such as slow response speed, low safety factor, and small adjustment range.

Utility model content

The purpose of this utility model is to overcome the above-mentioned shortcomings existing in the prior art, and to provide a reactive power automatic compensation device with fast response speed, high safety factor, energy saving and good compensation effect for electrified railway microcomputer control and voltage regulation.

In order to achieve the above object, the utility model adopts the following technical solutions:

The microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railways of the utility model includes voltage transformers and current transformers located in the grid circuit, and the voltage analog signals collected by the voltage transformers and the current analog signals collected by the current transformers are sampled. The circuit and the A/D conversion circuit input reactive power automatic compensation microprocessor, the microprocessor is connected with the upper computer control system through the communication interface, and the output end of the microprocessor is connected with the capacitor bank through the voltage regulator unit.

The voltage transformer includes a main transformer voltage transformer and a capacitor voltage transformer, the main transformer voltage transformer collects the voltage signal of the bus, the capacitor voltage transformer collects the voltage signal at both ends of the capacitor bank, and the voltage signal is sent to the control system sampling circuit; The current transformer includes a main transformer current transformer and a capacitor current transformer. The main transformer current transformer collects the current signal of the busbar, and the capacitor current transformer collects the current signal of the capacitor bank, and the current signal is sent to the control system sampling circuit.

The drive unit of the voltage regulator is an on-load voltage regulator, which is composed of an on-load tap changer and an autotransformer, and the switching time of each gear of the on-load tap changer is not more than 1 second.

The utility model is provided with a vacuum circuit breaker between the grid busbar and the on-load voltage regulator, which is used for fault protection.

The voltage analog signal collected by the main transformer voltage transformer YH and the current analog signal collected by the main transformer current transformer LH are sent to the reactive power automatic compensation control cabinet ZWK, and sent to the reactive power automatic compensation control cabinet through acquisition, analog-to-digital conversion and other links The computer will process the collected voltage/current digital signal to calculate the current apparent power, reactive power, active power, power factor, phase angle, harmonic and other electrical parameters, and the set power factor threshold or reactive power threshold value for timely comparison, output control signals, drive the TW control mechanism of the on-load voltage regulator, so that the voltage regulator outputs voltages of different gears, thereby changing the terminal voltage of the capacitor bank C, so that it outputs different reactive power, Track reactive power automatic compensation to achieve timely compensation of line reactive power.

According to the acquisition and calculation of the terminal voltage and current signals of the capacitor bank, various protections such as overvoltage and overcurrent are taken for the capacitor bank, and the operation information, electrical parameters, and action events of the compensation device are stored in the memory and can form data file, you can view the saved data and generate a data table or curve.

Compared with the prior art, the utility model has the following beneficial effects:

(1) Low power consumption: the reactive power output is adjusted by an on-load voltage regulator, and the power consumption of the on-load voltage regulator is less than that of the series thyristor group and the shunt reactor.

(2) High safety: the on-load voltage regulator is used to avoid the use of series thyristor groups, which improves the safety of the compensation device. When multi-level thyristors are used in series, the conduction actions of the series thyristors must be consistent, and if there is a slight asynchrony, breakdown of the thyristors will occur.

(3) High reliability: The TTWB type reactive power compensation device is less affected by temperature and has a lower self-temperature rise, while the thyristor group is limited by heat dissipation conditions and has a large temperature rise, so it cannot operate under high temperature conditions.

(4) No harmonics: the use of on-load voltage regulators will not cause distortion to the current waveform and will not generate harmonics, but when using a thyristor group, harmonics will be generated due to changing the conduction angle of the thyristor , aggravate the grid harmonic pollution.

(5) Intelligent patrol inspection for fault detection of major components. The intelligent controller adopts the backup form. When the main controller fails, the backup controller will take over immediately to ensure the reliable operation of the compensation device.

(6) The compensation capacitor adopts a special parallel capacitor for railways, which is convenient for maintenance.

(7) The compensation device is installed on the two-phase traction load, and the compensation device is automatically adjusted according to the traction load of each phase, which can compensate the reactive load of each phase.

(8) The capacitor bank is equipped with a dedicated air-core series reactor for railways, with a reactance rate of 12.5%, which suppresses harmonics above the third order and weakens the damage to the capacitor bank.

(9) The intelligent controller is used to track the reactive power demand of the line in real time and automatically adjust the reactive power output; the controller also has the functions of reactive power curve change display, historical record, and remote monitoring.

(10) It has perfect protection measures. One is the hardware protection of the equipment, including fuse protection, lightning protection overvoltage protection, and differential pressure protection; the other is microcomputer protection, which includes overvoltage, undervoltage, overcurrent, undercurrent, harmonic protection, PT disconnection alarm, on-load voltage regulator abnormal alarm, control feeder disconnection alarm, on-load voltage regulator refusal/maloperation alarm.

(11) The frame structure is adopted, which is simple in structure and easy to dissipate heat.

Description of drawings

Fig. 1 is a working principle block diagram of the present utility model;

Fig. 2 is a schematic diagram of the principle of the utility model;

Fig. 3 is the functional block diagram of reactive power automatic compensation control cabinet in the utility model;

Fig. 4 is a schematic block diagram of the reactive power automatic compensation control cabinet control system in the utility model;

Fig. 5 is a functional block diagram of the drive unit of the reactive power automatic compensation control cabinet in the utility model.

Detailed ways

As shown in Figure 1, the microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railways of the present invention includes voltage transformers and current transformers located in the power grid circuit, and voltage analog signals collected by voltage transformers and current transformers. The current analog signal is input to the reactive power automatic compensation microprocessor through the sampling circuit and the A/D conversion circuit. The microprocessor is connected to the upper computer control system through the communication interface, and the output terminal of the microprocessor is connected to the capacitor bank through the voltage regulator unit.

The voltage transformer includes a main transformer voltage transformer and a capacitor voltage transformer, the main transformer voltage transformer collects the voltage signal of the bus, the capacitor voltage transformer collects the voltage signal at both ends of the capacitor bank, and the voltage signal is sent to the control system sampling circuit; The current transformer includes a main transformer current transformer and a capacitor current transformer. The main transformer current transformer collects the current signal of the busbar, and the capacitor current transformer collects the current signal of the capacitor bank, and the current signal is sent to the control system sampling circuit.

The drive unit of the voltage regulator is an on-load voltage regulator, which is composed of an on-load tap changer and an autotransformer.

The utility model is provided with a vacuum circuit breaker between the grid busbar and the on-load voltage regulator, which is used for fault protection.

A surge arrester is installed between the high voltage load switch and the on-load voltage regulator to ensure that the compensation device is protected from lightning strikes.

The voltage analog signal collected by the main transformer voltage transformer YH of the utility model and the current analog signal collected by the main transformer current transformer are sent to the reactive power automatic compensation control cabinet, and sent to the reactive power automatic compensation control cabinet through collection, analog-to-digital conversion and other links The microprocessor inside the microprocessor will calculate the current apparent power, reactive power, active power, power factor, phase angle, harmonic and other electrical parameters after data processing of the collected voltage/current digital signal, and The set power factor threshold or reactive power threshold is compared in time, and the output adjustment control signal is driven to drive the control mechanism of the on-load voltage regulator, so that the voltage regulator outputs voltages of different gears, thereby changing the terminal voltage of the capacitor bank and making it output differently. Reactive power, tracking reactive power automatic compensation, to achieve timely compensation of line reactive power.

According to the acquisition and calculation of the terminal voltage and current signals of the capacitor bank, various protections such as overvoltage and overcurrent are taken for the capacitor bank, and the operation information, electrical parameters, and action events of the compensation device are stored in the memory and can form data file, you can view the saved data and generate a data table or curve.

As shown in Figure 2, the microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railways of the present utility model mainly includes a control cabinet ZWK and an on-load voltage regulator TW. The transformer voltage transformer YH and the main transformer voltage transformer LH are provided with a vacuum circuit breaker ZN between the grid bus and the on-load voltage regulator TW for fault protection. A lightning arrester BL is installed between the vacuum circuit breaker and the on-load voltage regulator TW to ensure that the compensation device is protected from lightning strikes. There is a high-voltage isolating switch between the arrester and the on-load voltage regulator. The output terminal of the on-load voltage regulator TW is sequentially connected with a single-phase shunt capacitor C, an air-core series reactor L, a single jet-by-fuse fuse FU and a discharge coil FD; There is a high-voltage isolation switch SW between them, and a capacitive current transformer LH11 and a capacitive voltage transformer YH11 are connected between the control cabinet ZWK and the single-phase parallel capacitor C.

The parameters of each component are as follows:

The microcomputer-controlled voltage-regulating reactive power automatic compensation device for electrified railways of the utility model is specially designed for reactive power compensation of traction substations of electrified railways, and the design indexes of each component are in line with the technical requirements of electrified railways. The main parameters of the components of the compensation device are described below .

(1) Vacuum circuit breaker ZN

The rated operating voltage of the vacuum circuit breaker is 27.5kV, the maximum voltage is 31.5kV, and the rated breaking current of the capacitor bank is 400A. The relevant tests meet the requirements of the 27.5kV voltage level.

(2) Lightning arrester (high voltage) and discharge counter BL

The rated voltage of the surge arrester is 27.5kV, the working voltage is 42kV, and the relevant tests meet the requirements of the 27.5kV voltage level. The discharge counter is connected in series under the arrester to count the discharge of the arrester.

(3) On-load voltage regulator TW

The on-load voltage regulator is a key component of the compensation device, which adopts the self-coupling mode and has small loss. The on-load voltage regulator uses an on-load tap changer to change the output connector of the voltage regulator, thereby changing the output voltage of the voltage regulator. The rated voltage of the primary end of the on-load voltage regulator is 27.5kV, and the rated capacity and voltage regulation range are based on the traction substation The specific circumstances are determined. The on-load voltage regulator can operate for a long time at 1.36 times the rated voltage. Relevant tests meet the requirements of 27.5kV voltage level.

On-load tap-changer with fast switching speed and long service life. When the tap-changer operates, it adopts an excessive load mode, so that the load voltage is uninterrupted, and the arc light generated is very small, and there is basically no impact.

(4) Current transformer LH

The current transformer collects the output current of the traction transformer, and the transformation ratio is determined according to the traction load of the traction transformer. Dry-type transformers are used indoors, and oil-immersed transformers are used outdoors. The accuracy requirements are above 0.5. Relevant tests shall be carried out in accordance with the 27.5kV voltage level.

(5) Voltage transformer YH

The voltage transformer collects the output voltage of the traction transformer, and the transformation ratio is 27.5kV/100V. Dry-type transformers are used indoors, and oil-immersed transformers are used outdoors. The accuracy is above 0.5. Relevant tests shall be carried out in accordance with the 27.5kV voltage level.

(6) High voltage isolation switch SW

The isolating switch is single-phase, with a voltage level of 27.5kV and a rated current of 1250A. Its power frequency withstand voltage test and lightning impulse all meet the requirements of 27.5kV voltage level.

(7) Capacitor current transformer LH11

The current transformer collects the current of the capacitor bank, and the transformation ratio is determined according to the capacity of the capacitor bank. It is dry-type, single-phase, indoor, with an accuracy of 0.2, an output capacity of 50VA, and a rated voltage of the primary terminal of 35kV. Relevant tests meet the 35kV voltage level requirements.

(8) Capacitive voltage transformer YH11

The transformation ratio of the voltage transformer is 27.5kV/0.1kV, dry type, single phase, indoor, the precision is 0.2, the output capacity is 60VA, and it is used as a voltage protection sampling. Relevant tests meet the requirements of 27.5kV voltage level.

(9) Air-core series reactor L

The reactor is an air-core series reactor, which has good linearity and no magnetic saturation phenomenon. The rated reactance rate is 12.5-13%, and it can suppress the third harmonic to harm the capacitor. The rated voltage of the series reactor is 27.5kV, single-phase, improving inter-turn insulation, and can work for a long time at 1.36 times the rated voltage. Relevant pressure tests meet the 27.5kV voltage level requirements.

The reactor has a dry structure, no iron core, no magnetic saturation phenomenon, and good linearity. The reactor winding is a multi-layer parallel cylindrical structure, and the interior is divided into several packages (coil groups), each package has several layers of coils, and there are ventilation channels between each package to facilitate air convection and heat dissipation. The current-carrying conductor consists of small cross-section wires insulated from each other to reduce eddy current losses. The inside and outside of the coil are wrapped with glass fiber impregnated with epoxy resin, which is solidified at high temperature to form a solid whole, with high mechanical strength and low noise. The heat resistance of the reactor insulation is class F. It can work for a long time under outdoor environmental conditions.

(10) Single-phase shunt capacitor C

The shunt capacitor adopts BAM type, which is divided into 4 series. The rated voltage of a single unit is 8.4kV. The liquid medium is benzyltoluene, and the solid medium is full-film medium. There are discharge resistors and fuses inside, which can be used for a long time at 1.36 times the rated voltage. Work, allowing 1.36 times the rated current to pass through for a long time, the deviation between the measured capacitance value and the rated value is not more than 0-5%, and the tgδ value of the capacitor is less than 0.0003. The inter-electrode dielectric requires high electric strength, and the inter-electrode withstand voltage is 2.69U _IN (AC) or 5.38U _IN (DC)10S. The internal oil temperature does not exceed 65°C during operation.

(11) Fuse FU

Each capacitor is equipped with BRN-10 type fast jet-by-fuse, which is installed at 45° to the horizontal plane, and the rated current is selected to be 1.5-1.8 times the rated current of the capacitor.

(12) Discharge coil FD

The discharge coil suitable for series capacitor bank is adopted, with three primary terminals, the terminal voltage is 16.8*2kV, the rated capacity is greater than the capacity of the matching capacitor bank, the double secondary output voltage is 100V*2, the output capacity is 100VA*2, and the difference is adopted pressure protection. Oil-immersed outdoor structure, relevant tests meet the 27.5kV voltage level.

(13) Reactive power automatic compensation control cabinet

The reactive power automatic compensation control cabinet is the control core of the reactive power compensation device. It is an intelligent control cabinet integrating data collection, control output, various protections and communication. Its function is to collect grid voltage and current signals, and calculate parameters such as apparent power, active power, reactive power, power factor, harmonics, etc., and compare them with the set reactive power, power factor and other thresholds to automatically control on-load voltage regulation The gear output of the device changes the terminal voltage of the compensation capacitor bank, so as to achieve the purpose of compensating reactive power, improving power factor, and ensuring the quality of power supply.

The reactive power automatic compensation control cabinet is the main component of the reactive power automatic compensation device for voltage regulation. It takes the intelligent reactive power compensation controller as the core and integrates various protection and communication. The voltage signal of the bus bar and the voltage signal at both ends of the capacitor bank are collected by the voltage transformer, and the current signal of the bus bar and the current signal of the capacitor bank are collected by the current transformer and sent to the control system sampling circuit, and various signals are transmitted through the A/D converter. The analog quantity is converted into digital quantity and sent to the microprocessor for collection, and then converted into each original quantity. The control system calculates the active power, reactive power, power factor and harmonics on the line according to the detected bus voltage and bus current. and other parameters, and then control the reactive power output of the capacitor bank according to the reactive power jump threshold set by various control modes, quickly realize the local balance of reactive power compensation, improve power factor, save energy and reduce consumption, and improve system power transmission ability.

The internal structure of reactive power automatic compensation control cabinet is mainly composed of control system, drive unit, background computer and power supply. Its principle block diagram like chart 3 shows. After the sampling signal enters the control system, the control system outputs the jump signal to the drive unit through signal processing, data calculation, and logic judgment, and the drive unit amplifies it to directly drive the voltage regulator to operate, and at the same time, the drive system collects the voltage regulator The tap signal of the current gear position of the voltage regulator is fed back to the control system. After the control system is processed and calculated, it outputs and displays the current gear position of the voltage regulator on the background management computer. When the control system detects capacitor overvoltage, overcurrent, differential pressure and high transformer oil temperature, it will directly drive the vacuum circuit breaker to trip to protect the entire system. The power supply module adopts DC power supply, and after DC-AC conversion, it is filtered to ensure the quality and reliability of the power supply, so that the control system can always run safely and reliably.

The control principle block diagram of the control cabinet is shown in Figure 4. The signal enters the microprocessor of the control system, and the microprocessor performs signal processing, data calculation, and logic judgment on it, and outputs the control signal to the control system, and the control system has a jump signal Indicator lights are convenient for daily maintenance and troubleshooting. The data calculated by the microprocessor is transmitted to the background computer through the RS232 interface to display various data parameters of the operation of the power grid and its control system; the keyboard and mouse are used to set the reactive power compensation of each gear of the voltage regulator under various control modes Range threshold and slow reactive mode jump time delay, etc.

The functional block diagram of the drive unit of the reactive power automatic compensation control cabinet is shown in Figure 5. The tap position signal of the electric mechanism and the manual signal are isolated by photoelectric coupling, and sent to the CPU microprocessor for calculation and processing, and are dynamically scanned on the front panel. Display the current tap position number, and output passive BCD code and corresponding tap position signal from the rear panel; the CPU can also transmit the tap position signal to the background computer through the RS485 communication interface, and at the same time send the 1-N signal sent by the computer system , N-1, the stop command returns to the CPU operation processing to control the electric mechanism to run step by step.

The microprocessor automatically judges the limit position and intermediate position overrunning of the tap position signal sent by the motor.

In addition to using RS485 to transmit 1-N, N-1, and stop commands, the controller can also send 1-N, N-1, and stop commands through the "remote control command input" port and the button on the front panel of the controller. When the microprocessor receives After receiving the above instructions, the electric mechanism can be controlled to run, and the drive unit has an instruction interlock function.

The externally connected over-current blocking contact signal is sent to the microprocessor after secondary photoelectric isolation. When the microprocessor receives the signal, it judges and immediately closes all input/output interfaces, and the voltage regulator stops working.

The controller of the utility model is based on a high-speed programmable microprocessor and uses multi-functional application software. The customer can choose the compensation mode by himself, and can choose any one of fast reactive power, slow reactive power and power factor as the compensation mode.

The main controller of the utility model provides three compensation modes: fast reactive mode; slow reactive mode; power factor mode.

The protection and alarm functions of the utility model mainly include:

(1) Capacitor fuse protection: Each capacitor is equipped with a fast fuse. When the capacitor current exceeds the overcurrent threshold, the fuse will blow quickly to protect the safe operation of the entire system.

(2) Lightning protection: There is a lightning arrester at the front end of the whole compensation device to ensure that the compensation device is protected from lightning strikes.

(3) Capacitor differential pressure protection: If the voltage difference of the capacitor bank exceeds a certain threshold, the differential pressure relay contacts are closed, the vacuum circuit breaker is disconnected, and the entire device is disconnected from the busbar.

(4) Gas protection of the voltage regulator: When the gas inside the voltage regulator exceeds a certain threshold, the gas relay contacts are closed, the vacuum circuit breaker is disconnected, and the entire device is disconnected from the bus.

(5) Too high oil temperature protection of the voltage regulator: When the internal oil temperature of the voltage regulator is too high and exceeds a certain threshold, the controller outputs a protection signal, disconnects the vacuum circuit breaker, and disconnects the entire device from the busbar.

(6) Capacitor overvoltage, overcurrent, and excessive harmonic protection: When the controller detects that any of the above signals exceeds the set value, the controller outputs a protection signal, disconnects the vacuum circuit breaker, and disconnects the entire device from the connection to the busbar.

(7) Capacitor undercurrent alarm: When the control system detects that the capacitor current is too low and exceeds the set threshold, the control system sends an alarm signal to notify the user to take corresponding measures.

(8) Feeder error alarm: When the control system fails to detect the feedback signal of the voltage regulator, the control system sends out an alarm signal to notify the user to take corresponding measures.

(9) Voltage regulator refusal/misoperation protection: When the control system fails to detect the voltage signal at both ends of the capacitor, the voltage regulator will not operate to ensure the safety and reliability of the entire device.

Claims (4)

1. electric railway system controlled by computer voltage regulating imaginary power automatic compensation device, comprise the voltage transformer summation current transformer that is arranged in the electrical network circuit, the current analog signal that the voltage analog signal summation current transformer that voltage transformer is gathered is gathered is by sample circuit and A/D change-over circuit input imaginary power automatic compensation microprocessor, microprocessor links to each other with upper computer control system by communication interface, it is characterized in that: output end of microprocessor links to each other with the capacitor group by the voltage regulator unit.

2. electric railway system controlled by computer voltage regulating imaginary power automatic compensation device according to claim 1, it is characterized in that: described voltage transformer comprises main transformer voltage transformer and capacitor voltage transformer, the main transformer voltage transformer is gathered the voltage signal of bus, capacitor voltage transformer is gathered the voltage signal at capacitor group two ends, and voltage signal is delivered to the control system sample circuit; Current transformer comprises main transformer current transformer and capacitance current instrument transformer, and the main transformer current transformer is gathered the current signal of bus, and the capacitance current instrument transformer is gathered the current signal of capacitor group, and current signal is delivered to the control system sample circuit.

3. electric railway system controlled by computer voltage regulating imaginary power automatic compensation device according to claim 1 and 2, it is characterized in that: described voltage regulator unit is a Loading voltage regulator, be made up of on load tap changer and autotransformer, be not more than 1 second the switching time of the every gear of on load tap changer.

4. electric railway system controlled by computer voltage regulating imaginary power automatic compensation device according to claim 3 is characterized in that: be provided with vacuum circuit-breaker between electrical network bus and Loading voltage regulator, be used to carry out error protection.

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