CN202103431U - MCR (Magnetically Controlled Reactor)-type static var compensator (SVC) - Google Patents

Abstract

An MCR type SVC static dynamic reactive power compensation device, which mainly supplies power to the compensation bus from the power supply system bus through the compensation outlet switch, and is provided with an FC branch and an MCR branch. The FC branch includes capacitors and fixed reactors , the MCR branch includes a magnetic valve type controllable reactor MCR, which is characterized in that it also includes an FC branch protection system, an MCR branch control protection system, a control power supply system, a first voltage transformer, and a second voltage transformer , a first current transformer, a second current transformer, a third current transformer and a fourth current transformer. The utility model improves the voltage stability and power factor of the power grid, reduces the loss of the power grid, realizes fast and smooth adjustment according to the load change, makes the reactive power of the system quickly reach balance, and improves the fast response capability of the compensation device. The utility model is not only simple in structure, small in volume, low in manufacturing and maintenance costs, but also stable in operation and easy in maintenance.

Description

MCR type SVC static dynamic reactive power compensation device

technical field

The utility model relates to a reactive power adjustment device for a power grid, in particular to an MCR type SVC static dynamic reactive power compensation device based on a magnetic valve type controllable reactor.

Background technique

In recent years, with the rapid economic development, the electrical capacity of high-power rolling mills, electric arc furnaces, electric welding machines and other electrical equipment in many modern industries has increased exponentially or even dozens of times. These large-scale equipment are impact loads. Their use not only consumes a lot of power, but also causes a large reactive power impact on the power grid, forming voltage flicker and generating harmonic pollution. The occurrence of these problems not only affects the normal operation of the equipment itself, but they can also spread in the power grid, thereby interfering with the normal use of other equipment or even damage it. What's more serious is that the generation of harmonics will cause consequences such as misoperation of power equipment protection, inaccurate measurement, failure of control system and interference of communication system, forming a major safety hazard of the power supply system.

With the rapid growth of my country's power supply and demand, the requirements for improving power quality and reducing power transmission and transformation losses are becoming increasingly urgent. Using capacitor reactor switching to achieve reactive power balance is the main means to improve power quality and reduce line loss, especially 110kV and 35kV substations, as the terminal substations in the power grid system, are responsible for directly providing voltage stability and reactive power balance to user loads The task of high-quality electric energy, reactive power compensation device is more important. At present, the reactive power automatic compensation of most 110kV and 35kV substations is not ideal. This kind of compensation equipment with step capacitors can track the dynamic compensation power of load changes, but most of them cannot achieve the best compensation effect because they cannot adapt to the fast load changes. , Some substation 10kV bus power factor is as low as below 0.96 during peak load.

There are two technical solutions: transforming the existing 10kV automatic reactive power compensation device and thyristor-controlled reactor (TCR) static dynamic reactive power compensation device. The first scheme to realize reactive power automatic tracking compensation is to input capacitors according to the load size, and divide the capacitors with total compensation capacity into multiple groups according to the change of load size, so as to achieve reactive power balance as much as possible. The compensation accuracy is proportional to the number of capacitor groups. The more capacitor groups, the higher the compensation accuracy, but the greater the equipment investment cost, the larger the occupied space, and the higher the reliability requirements of the equipment. To improve the compensation accuracy of the compensation device and realize group tracking compensation, it is difficult to popularize and use this scheme due to the limitation of investment cost and occupied space. In the second scheme, the thyristor valve group is connected in series with the air-core reactor. When the thyristor valve group is not conducting, no current flows through the reactor, and the reactor does not consume reactive power. The larger the current, the more reactive power absorbed by the reactor; the larger the conduction angle of the thyristor, the smaller the current flowing through the reactor, and the smaller the reactive power absorbed by the reactor. By controlling the conduction angle of the thyristor, to achieve Dynamic reactive power regulation. Although TCR has the feature of continuously adjustable compensation, its disadvantages are also obvious, such as complex structure, high manufacturing cost, large loss, and relatively complicated operation and maintenance.

Utility model content

In view of the above shortcomings, the utility model provides an MCR type SVC static dynamic reactive power compensation device, which not only has stable performance, but also has low manufacturing and maintenance costs.

The technical solution adopted by the utility model to solve the technical problem is: MCR type SVC static dynamic reactive power compensation device, which is mainly powered by the busbar of the power supply system through the compensation outlet switch to the compensation busbar, and is provided with FC branch and MCR branch. The FC branch includes a capacitor and a fixed reactor, and the MCR branch includes a magnetic valve type controllable reactor MCR, which is characterized in that it also includes a FC branch protection system, an MCR branch control and protection system, a control power supply system, a first voltage transformer, a second voltage transformer, a first current transformer, a second current transformer, a third current transformer, and a fourth current transformer;

The FC branch and the MCR branch are connected to the compensation bus through respective isolation switches; the first current transformer is arranged between the power supply system bus and the compensation bus; the second current transformer is arranged in the FC branch and the compensation bus; the third current transformer is set between the MCR branch and the compensation bus; the fourth current transformer is set between the load and the power supply system bus; the first voltage transformer and the power supply The system bus is connected, and the second voltage transformer is connected to the compensation bus;

The FC branch protection system includes a data acquisition unit, a processor CPU and a protection output unit, and the data acquisition unit of the FC branch protection system is connected to the first current transformer, the second current transformer and the FC branch respectively;

The MCR branch control and protection system includes a control and protection module, a monitoring module and an excitation module, and the control and protection module includes a processor CPU and a communication unit connected to the processor CPU, a data input unit DI, a data output unit DO, A data sampling unit and a photoelectric interface circuit; the monitoring module includes an upper monitoring machine and a display unit and a printer connected to the upper monitoring machine respectively, and the upper monitoring machine is connected with the communication unit of the monitoring and protection module; the excitation module includes sequentially A photoelectric interface circuit, a pulse circuit, a drive amplifier circuit and a thyristor connected in series; the excitation module and the monitoring and protection module are connected through the photoelectric interface circuit; the data sampling units of the control protection module of the MCR branch control protection system are respectively It is connected with the third current transformer, the fourth current transformer and the first voltage transformer; the pulse circuit of the excitation module of the MCR branch control protection system is respectively connected with the second voltage transformer and the third current transformer.

Its working principle is: the FC branch provides fixed capacitive reactive power to the power supply system, and the MCR branch absorbs excess capacitive reactive power according to the load change of the power supply system, so that the system's inductive and capacitive reactive power tend to balance. The FC branch and the MCR branch can share a set of outlet cabinets, and the isolating switch installed in each branch is isolated from the system when it is overhauled or disabled. The first voltage transformer is a system bus voltage transformer, which is used to detect the system bus voltage value; the second voltage transformer is a compensation bus voltage transformer, which is used to detect the compensation bus voltage signal, which is used as a trigger pulse synchronization signal for the MCR branch . Each branch is equipped with a current transformer for overcurrent protection detection. When a protection fault occurs in the FC branch, the FC branch protection system first sends an opening command to the compensation outlet switch through the protection output, and then uploads protection and alarm information to the monitoring part through the communication interface; when the MCR branch control protection system detects When the MCR branch or load circuit current exceeds its first-stage or second-stage overcurrent setting, the DO interface will send an opening command to the outlet switch of each branch, and upload the protection alarm signal to the monitoring part to issue an alarm message.

The beneficial effects of the utility model are: the MCR type SVC static dynamic reactive power compensation device improves the voltage stability and power factor of the power grid, reduces the loss of the power grid, and realizes fast and smooth adjustment according to the load change to make the system reactive Quickly achieve balance and improve the rapid response capability of the compensation device. The utility model is not only simple in structure, small in size, low in manufacturing and maintenance costs, but also stable in operation and easy in maintenance.

Description of drawings

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

Fig. 2 is a structural block diagram of the FC branch circuit protection system shown in Fig. 1;

Fig. 3 is a structural block diagram of the MCR branch circuit control and protection system shown in Fig. 1 .

Detailed ways

As shown in Figure 1, Figure 2 and Figure 3, the MCR type SVC static dynamic reactive power compensation device mainly supplies power to the compensation bus from the power supply system bus through the compensation outlet switch, and is equipped with FC branch and MCR branch. The FC branch includes a capacitor and a fixed reactor, and the MCR branch includes a magnetic valve type controllable reactor MCR, which is characterized in that it also includes a FC branch protection system, an MCR branch control and protection system, a control power supply system, A first voltage transformer, a second voltage transformer, a first current transformer, a second current transformer, a third current transformer and a fourth current transformer. The FC branch and the MCR branch are connected to the compensation bus through respective isolation switches; the first current transformer is arranged between the power supply system bus and the compensation bus; the second current transformer is arranged in the FC branch and the compensation bus; the third current transformer is set between the MCR branch and the compensation bus; the fourth current transformer is set between the load and the power supply system bus; the first voltage transformer and the power supply The system bus is connected, and the second voltage transformer is connected to the compensation bus.

As shown in Figure 2, the FC branch protection system includes a data acquisition unit, a processor CPU and a protection output unit, and the data acquisition unit of the FC branch protection system is connected with the first current transformer and the second current transformer respectively Connected to FC branch. FC branch circuit protection system is a microcomputer protection unit with 80C196 chip as the core. By collecting FC branch circuit and compensating outlet cabinet current and FC branch circuit zero-sequence voltage (can also collect capacitor protection signals such as unbalanced current and differential pressure), According to various protection algorithms, the protection functions such as FC branch overcurrent stage one, overcurrent stage two, overcurrent stage one, overcurrent stage two, unbalanced voltage (zero sequence voltage), unbalanced current, etc. are realized. When a protection fault occurs, the microcomputer protection unit first sends an opening command to the compensation outlet switch through the protection output, and then uploads protection and alarm information to the monitoring part through communication interfaces such as RS232, RS485 and CAN bus.

As shown in Figure 3, the MCR branch control and protection system includes a control and protection module, a monitoring module and an excitation module, and the control and protection module includes a processor CPU, a communication unit connected to the processor CPU, and a data input unit DI , a data output unit DO, a data sampling unit and a photoelectric interface circuit; the monitoring module includes an upper monitoring machine and a display unit and a printer connected to the upper monitoring machine respectively, and the upper monitoring machine is connected with the communication unit of the monitoring protection module; The excitation module includes a photoelectric interface circuit, a pulse circuit, a drive amplifier circuit and a thyristor connected in series in sequence; the excitation module and the monitoring and protection module are connected through a photoelectric interface circuit; the control and protection of the MCR branch control protection system The data sampling unit of the module is respectively connected with the third current transformer, the fourth current transformer and the first voltage transformer; the pulse circuit of the excitation module of the MCR branch control protection system is respectively connected with the second voltage transformer and the third voltage transformer. connected to the current transformer.

The control and protection module of the MCR branch control and protection system is a multi-CPU controller based on the 80C196 chip. The components share data with each other through the multi-port RAM; the control algorithm and protection logic are realized by the main control CPU, and the system parameters (voltage , current, active power, reactive power, power factor, etc.) acquisition and calculation are realized by the data acquisition unit; the communication unit specially responsible for communication is used to exchange data with the upper monitoring machine and other monitoring systems, providing RS232, RS485 and CAN bus, etc. Communication interface, easy to realize unattended and remote control. The system has high reliability, stability, and fast calculation speed, and can realize complex control algorithms. Its general working principle is as follows: First, the system bus voltage, load current and MCR branch current analog signals are collected by the data acquisition unit, and the real-time values such as system power factor, active power and reactive power are calculated through A/D conversion. Stored in the multi-port RAM; the processor CPU reads the required parameters from the RAM according to the program requirements; through the calculation of the control algorithm, the given value of the trigger angle of the thyristor is obtained; and then converted into an optical signal through the electro-optical conversion interface, through Fiber optics are sent to the excitation module inside the MCR field control box. Secondly, the excitation module converts the trigger pulse and the working condition of the thyristor into a photoelectric signal and sends it back to the control and protection module to realize the state monitoring of the excitation module. The automatic operation mode judgment and protection output of the control protector are undertaken by data input DI and data output DO. In terms of control algorithm, phase separation control, three-phase control, flicker control, power factor control, reactive power control, and constant voltage control can be realized according to different requirements.

The excitation module of the MCR branch control and protection system is composed of a photoelectric interface circuit, a trigger pulse circuit, a pulse amplifier circuit and a thyristor; after the photoelectric interface circuit receives the optical given signal, it generates an analog given signal through photoelectric conversion to form a control The trigger pulse of the conduction angle of the thyristor, and then the signal is shaped and amplified, and the conduction state of the thyristor is controlled by phase shifting, so as to realize the purpose of dynamically adjusting the inductive reactive current of the MCR branch.

The monitoring module of the MCR branch control and protection system is composed of an upper monitoring machine, a man-machine display interface and other corresponding terminal devices; the upper monitoring machine can choose an industrial computer, an industrial tablet computer and a touch screen. Through communication interfaces such as RS232, RS485 and CAN bus, it is connected with the communication unit of the control protector to upload or download various data. The host monitoring software runs on the Windows XP operating system, has a good man-machine interface, and is equipped with peripherals such as keyboard, mouse, and printer. Various functions such as system parameter setting, real-time monitoring of running status, running trend display, protection alarm information and processing, historical data query and running report printing have been realized. The power quality of the system (including voltage, current instantaneous value, voltage, current effective value, active power, reactive power, active energy, reactive energy, power factor, current 1---41 harmonic, voltage 1---41 harmonics, voltage flicker, voltage and current unbalance, voltage drop, voltage too high, voltage loss, etc.) for real-time and continuous monitoring.

The overcurrent protection of the MCR branch is divided into two measures: hard protection and soft protection; the hard protection is realized by the pulse circuit of the excitation module of the MCR branch control protection system, which is a mandatory overload protection. When the MCR branch current exceeds the set value , the pulse circuit directly blocks the pulse output and turns off the thyristor, and at the same time sends a protection alarm signal to the photoelectric interface circuit, notifying the control and protection part of the MCR branch for overcurrent protection. The soft protection is implemented by the control and protection module of the MCR branch control and protection system through software. When the control and protection part detects that the current of the MCR branch or the load circuit exceeds its first-stage or second-stage overcurrent setting value, it will send a message to each branch through the DO interface. The outlet switch sends out an opening command, and uploads the protection alarm signal to the monitoring part to send out an alarm message. Among them, the over-current first-stage protection is quick-break protection, and the over-current second-stage protection is time-limited protection. In addition, the system also provides some other protection and alarm functions.

In order to make the control circuit work normally, it is not only necessary to provide working power, but also to ensure that all equipment is protected even if the control power fails; therefore, the control power system must have a power-down protection function. The control power supply system is a UPS-based power distribution network, which guarantees the uninterrupted supply of power on the premise of providing working power for each functional circuit. It is used to provide processing time for the entire system to carry out corresponding fault protection after the control power supply protection action, to ensure that the system exits operation in the prescribed order, and protects the equipment from damage.

Claims (1)

1. MCR type SVC static dynamic reactive power compensation device, which is mainly powered by the power supply system busbar through the compensation outlet switch to the compensation busbar, and is equipped with FC branch and MCR branch. The FC branch includes capacitors and fixed reactors , the MCR branch includes a magnetic valve type controllable reactor MCR, which is characterized in that it also includes an FC branch protection system, an MCR branch control protection system, a control power supply system, a first voltage transformer, and a second voltage transformer , the first current transformer, the second current transformer, the third current transformer and the fourth current transformer; The FC branch and the MCR branch are connected to the compensation bus through respective isolation switches; the first current transformer is arranged between the power supply system bus and the compensation bus; the second current transformer is arranged in the FC branch and the compensation bus; the third current transformer is set between the MCR branch and the compensation bus; the fourth current transformer is set between the load and the power supply system bus; the first voltage transformer and the power supply The system bus is connected, and the second voltage transformer is connected to the compensation bus; The FC branch protection system includes a data acquisition unit, a processor CPU and a protection output unit, and the data acquisition unit of the FC branch protection system is connected to the first current transformer, the second current transformer and the FC branch respectively; The MCR branch control and protection system includes a control and protection module, a monitoring module and an excitation module, and the control and protection module includes a processor CPU and a communication unit connected to the processor CPU, a data input unit DI, a data output unit DO, A data sampling unit and a photoelectric interface circuit; the monitoring module includes an upper monitoring machine and a display unit and a printer connected to the upper monitoring machine respectively, and the upper monitoring machine is connected with the communication unit of the monitoring and protection module; the excitation module includes sequentially A photoelectric interface circuit, a pulse circuit, a drive amplifier circuit and a thyristor connected in series; the excitation module and the monitoring and protection module are connected through the photoelectric interface circuit; the data sampling units of the control protection module of the MCR branch control protection system are respectively It is connected with the third current transformer, the fourth current transformer and the first voltage transformer; the pulse circuit of the excitation module of the MCR branch control protection system is respectively connected with the second voltage transformer and the third current transformer.

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