CN103094906A - 750 kV magnetic-control type controllable highly resistance circuit based on compensation winding energy-getting excitation - Google Patents

Abstract

The invention provides a 750kV magnetically controlled high-resistance circuit based on the compensation winding for energy extraction and excitation. The circuit includes a reactor, a rectifier and a rectifier transformer; the rectifier transformer and the rectifier are connected in series to form an excitation system; the reactor includes three windings, and the high-voltage side winding Connected to the power grid, the compensation winding is connected to the AC side of the excitation system, and the DC side of the excitation system is connected to the compensation winding. The corresponding method is that the power grid supplies power to the rectifier through the reactor. When the power grid fluctuates, the excitation current of the control winding of the reactor is changed by controlling the trigger angle of the thyristor in the rectifier, and then the capacity of the reactor is changed, thereby suppressing the fluctuation of the power grid. The invention adopts the low-voltage equipment to control the high-voltage equipment, and the overall economical efficiency of the device is good; the output capacity can be smoothly and continuously adjusted, and it is suitable for the steady-state control of the bus voltage.

Description

750kV Magnetically Controlled Controllable High Impedance Circuit Based on Compensation Winding Energy Acquisition and Excitation

technical field

The invention belongs to the field of electric power systems, and in particular relates to a 750kV magnetic control type controllable high-resistance circuit based on compensation winding energy acquisition and excitation.

Background technique

Controllable high reactance is one of the effective means to improve the flexibility of power system regulation. Its main function is to solve the contradiction of limiting overvoltage and reactive power compensation of long-distance heavy-duty lines, improve voltage stability level and transient operation limit, and reduce line load. It is an important tool to realize the efficient and economical operation of ultra-high voltage and ultra-high voltage transmission channels by balancing the transmission loss, balancing reactive power, and effectively reducing the pressure of dispatching operation. The most concentrated application fields of controllable high resistance include: EHV/UHV long-distance heavy-duty lines, wind power centralized transmission channels, hydropower transmission channels, EH/UHV compact lines, etc.

The magnetically controlled high reactance can change the saturation of the iron core by changing the magnitude of the DC excitation current, so as to realize the continuous adjustment of the reactance value and capacity. The stability and reliability of the excitation system directly affect the operation of the magnetically controlled high-resistance system in the system. At present, most of the ultra-high voltage magnetron controllable high-resistance excitation systems adopt the structure of obtaining energy from an external power supply.

For the 750kV ultra-high voltage transmission system, it has the characteristics of large transmission power, long transmission distance, and large-scale and high-frequency fluctuations of wind power. In application, due to the randomness of wind power power, the line power fluctuates frequently and in a large range, resulting in relatively prominent problems of reactive power balance and voltage control. To meet the requirements of the degree, it is necessary to install a controllable high-resistance in the 750kV transmission channel to play its role in continuously and quickly adjusting reactive power within a certain range to ensure the normal operation of the power grid.

Contents of the invention

Aiming at the deficiencies of the existing technology, the present invention proposes a 750kV magnetically controlled high-resistance circuit based on compensation winding energy acquisition and excitation, which is applied in a 750kV ultra-high voltage power transmission system, which can realize smooth and continuous adjustment of output capacity, and is suitable for Steady-state control of the bus voltage.

The improvement of the 750kV magneto-controllable high-resistance circuit based on the excitation of the compensation winding provided by the present invention is that the circuit includes an excitation system and a reactor;

The excitation system includes a series rectifier connected in series with a rectifier transformer;

The reactor includes port I connected to the grid, port II connected to one end of the excitation system and port III connected to the other end of the excitation system.

Wherein, the reactor includes a high-voltage side winding, a compensation winding and a control winding;

The three-phase star connection of the high-voltage side winding;

The three phases of the compensation winding are delta-connected to provide excitation power for the control winding;

The control winding applies a DC excitation current to the control winding core in the form of auto-coupling rectification;

The input/output end of the high-voltage side winding corresponds to the port I connected to the power grid;

The input/output end of the compensation winding corresponds to port II connected to one end of the excitation system;

The input/output end of the control winding corresponds to the port III connected to the other end of the excitation system.

Wherein, the system includes at least two groups of excitation systems, which are set as master-slave excitation systems; the master-slave excitation systems operate in parallel, or when the master excitation system fails, the master excitation system is switched to the slave excitation system by triggering or blocking pulses system.

Wherein, the system includes a filter for eliminating harmonics; the filter is connected to the port II.

Wherein, the system includes a parallel capacitor bank for eliminating harmonics; one end of the parallel capacitor bank is connected to the port II, and the other end is grounded.

Wherein, the reactor is a 750kV magnetron controllable high reactance.

Wherein, the rectifier is a three-phase full-wave controllable rectifier;

The power grid supplies power to the rectifier through the reactor. When the grid voltage fluctuates, the excitation current of the control winding of the reactor is changed by controlling the trigger angle of the thyristor in the rectifier, thereby changing the capacity of the reactor, thereby suppressing the grid fluctuation.

Compared with the prior art, the beneficial effects of the present invention are:

The present invention optimizes the design of the energy-taking circuit of the excitation system on the basis of the structure of the magnetic-controlled reactor, increases the compensation winding of the reactor, and performs the AC current extraction of the excitation system from the compensation winding of the 750kV magnetic-controlled high-resistance body. Function, not dependent on external power supply, higher reliability, better technology development trend, more suitable for application in switching stations, and has a better application prospect.

The invention adopts the low-voltage equipment to control the high-voltage equipment, and the overall economical efficiency of the device is good; the smooth and continuous adjustment of the output capacity can be realized, and it is suitable for the steady-state control of the bus voltage.

In the present invention, when the smooth control of reactive power voltage and the suppression of power frequency overvoltage in the transient process require the magnetically controlled controllable high-resistance to play a role, the controllable high-resistance body is charged, and its compensation winding is also charged. By controlling the rectifier The firing angle can effectively overcome the voltage fluctuation problem of the compensation winding, and realize the smooth control of the output capacity and the suppression of power frequency overvoltage.

The multi-group excitation system of the present invention undertakes the task of supplying and controlling the excitation current of the winding, master-slave setting, online redundancy, switching by triggering or blocking pulses, which enhances the stability of the system.

In the present invention, a filter or a parallel capacitor is installed on the compensation winding to expand the range of reactive power compensation and improve the power quality of the system.

Description of drawings

Fig. 1 is a structural diagram of the system provided by the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

This embodiment provides a 750kV magneto-controllable high-resistance circuit based on the excitation of the compensation winding. Its structure is shown in Fig. 1. The rectifier transformer and rectifier form the excitation part. The magnetically controlled controllable high reactance includes high voltage side winding, control winding and compensation winding. The high-voltage side winding is connected in three-phase star shape; the control winding is in the form of auto-coupling rectification, and DC excitation current is applied to the control winding core; the three-phase compensation winding is connected in delta to provide excitation power for the control winding.

The high-voltage side winding is a magnetically controlled high-resistance winding that is directly connected to the system. The control winding is powered by a DC power supply, and the DC power supply voltage and the DC current in the winding are adjusted to change the magnetic saturation of the iron core, which can smoothly change the reactance capacity of the device.

The AC power of the rectifier in the excitation system is taken from the magnetically controlled high-resistance body compensation winding (also called the energy winding). To improve reliability, multiple sets of self-excitation rectifier units can be set for online redundancy. For example, one main and one backup can be used, or two sets can be operated in parallel. If there is a problem with the main power supply equipment, the backup power supply will be put into use immediately. There is no circuit breaker or contactor to switch between the two, and the switch is made by triggering or blocking the pulse. When the controllable high-resistance of the magnetically controlled bus is in normal operation, the two sets of rectification units jointly change the excitation current of the control winding.

In addition to the excitation system, the compensation winding can be connected with a filter or a parallel capacitor bank. On the one hand, it can provide reactive power to the system, increase the adjustment range of the magnetically controlled high reactance, and on the other hand reduce the working time of the magnetically controlled high reactance. The generated harmonic components can reduce the harmonic pollution of the controllable high-resistance system and improve the power quality of the system.

The magnetic control controllable high reactance is a FACTS (flexible AC transmission) device, which is connected in parallel to the power system. The saturation degree of the reactor core is changed by controlling the excitation system through the thyristor, so as to realize the online adjustment of the reactor. In this embodiment, the main It is used to solve the contradiction between limiting overvoltage and reactive power compensation in the 750kV transmission system.

The rectifier in this embodiment is a three-phase full-wave controllable rectifier; the power grid supplies power to the rectifier through the reactor, and when the voltage fluctuation occurs in the grid, the excitation current of the control winding of the reactor is changed by controlling the trigger angle of the thyristor in the rectifier, thereby changing the reactance The capacity of the inverter, thereby suppressing the fluctuation of the power grid.

For example, a magneto-controllable high-resistance is installed on the 750kV bus of the second channel Yuka station of Xinjiang and the Northwest main network. When the three-phase circuit breaker on either side of the 750kV line of the station trips, the trigger angle of the thyristor in the rectifier is controlled. Changing the excitation current of the control winding of the reactor, and then changing the capacity of the reactor, can effectively reduce the power frequency overvoltage level by rapidly increasing the output capacity through the linkage magnetic control type controllable high resistance; 750kV magnetic control based on the compensation winding energy excitation The smooth and continuous adjustment of the output capacity will suppress the 750kV bus voltage fluctuation of the Yuka station caused by the change of wind power output, and realize the coordinated and optimal control of the reactive power voltage of the whole station.

It also has obvious advantages in terms of system function realization and operational reliability, technology maturity and technology development trend, and demand for station power supply system capacity.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (7)

1. get the magnet controlled controlled high-threshold logic circuit of 750kV of energy excitation based on the compensation winding, it is characterized in that, described circuit comprises excitation system and reactor;

Described excitation system comprises that the rectifier of series connection connects with rectifier transformer;

Described reactor comprises the port I that accesses electrical network, the port II that is connected with described excitation system one end and the port III that is connected with the excitation system other end.

2. the system as claimed in claim 1, is characterized in that, described reactor comprises high-pressure side winding, compensation winding and controls winding;

The winding three-phase Y-connection of described high-pressure side;

Described compensation winding three-phase is that triangle connects, and provides field power supply for controlling winding;

Described control winding applies the DC excitation electric current by the form of self coupling rectification on control winding iron core;

The port I of the corresponding described access electrical network of the I/O end of described high-pressure side winding;

The port II that corresponding described excitation system one end of the I/O end of compensation winding connects;

Control the corresponding described port III that is connected with the excitation system other end of I/O end of winding.

3. the system as claimed in claim 1, is characterized in that, described system comprises the excitation system of at least two groups, is made as principal and subordinate's excitation system; Described principal and subordinate's excitation system paired running maybe when main excitation system breaks down, switches to main excitation system from excitation system by triggering or locking pulse.

4. the system as claimed in claim 1, is characterized in that, described system comprises the filter for harmonic carcellation; Described filter is connected with described port II.

5. the system as claimed in claim 1, is characterized in that, described system comprises the Shunt Capacitor Unit for harmonic carcellation; Described Shunt Capacitor Unit one end is connected with described port II, other end ground connection.

6. the system as claimed in claim 1, is characterized in that, described reactor is the magnet controlled controlled high resistance of 750kV.

7. the system as claimed in claim 1, is characterized in that, described rectifier is the three-phase full-wave controlled rectifier;

Electrical network to rectifier power supply, when voltage fluctuation appears in electrical network, changes the exciting current of the control winding of reactor by reactor by the trigger angle of controlling thyristor in rectifier, and then changes the capacity of reactor, thereby suppresses power network fluctuation.

Images