The measures to improve power quality of reactive power compensation devices involve a wide range of aspects, mainly including reactive power compensation, suppression of harmonics, reduction of voltage fluctuations and flicker, and solutions to three-phase imbalances.
1. Development history of reactive power compensation device
Devices used for reactive power compensation and harmonic control, such as: passive power filter, this device has both reactive power compensation and voltage regulation functions, and is generally specially designed according to the parameters of the harmonic source, the electrical characteristics of the installation point, and user requirements ; Static Var Compensator (SVC) device is an important device for comprehensively controlling voltage fluctuations and flicker, harmonics and voltage unbalance. Active power filter (APF), APF is a new type of power electronic device that dynamically suppresses harmonics and compensates reactive power. It can compensate harmonics and reactive currents that change in frequency and amplitude. The main application in low-voltage power distribution systems.
Among them, the development of reactive power compensation technology has gone through several different stages from synchronous condenser → switch switching fixed capacitor → static var compensator (SVC) → striking static var generator SVG (STATCOM).
According to different structural principles, SVC technology is divided into: self-saturated reactor type (SSR), thyristor phase-controlled reactor type (TCR), thyristor switched capacitor type (TSC), high impedance transformer type (TCT) and excitation control The reactor type (AR).
With the development and improvement of power electronics technology, especially high-power turn-off device technology, a more advanced static var compensation device static var power generator (SVG) is still being developed at home and abroad, although They are still in the stage of development and trial operation, and have not yet been commercialized, but SVG will be more and more widely used in power systems due to its superior performance characteristics.
2. Characteristics of reactive power compensation device
The characteristics of various reactive devices are as follows:
2.1 Synchronous condenser: slow response, high noise, high loss, outdated technology, and an obsolete technology;
2.2 Switching and switching fixed capacitors: slow response compensation method, poor continuous controllability;
2.3 Static Var Compensator (SVC): Relatively advanced and practical technology, it has been widely used in power transmission and distribution power systems;
2.4 Static var generator SVG (STATCOM): Although it has technical limitations and belongs to the stage of a few demonstration projects, SVG is a more advanced new static var compensation device and is a flexible and flexible AC transmission system (FACTS) An important part of technology and custom power (CP) technology, the development direction of modern reactive power compensation devices.
3. Considerations of reactive power compensation device
3.1 Harmonic content and distribution
The order and amplitude of current harmonics that may be generated by the power distribution system and the total distortion rate of voltage harmonics are determined according to the harmonic content. Compensation scheme.
3.2 Load type
The current load and nonlinear load of the power distribution system account for the proportion of the total load, and the compensation scheme is determined according to the proportion.
3.3 Reactive power demand
If the proportion of inductive load in the power distribution system is large, the reactive power demand will be large, and the compensation capacity should be increased.
3.4 Load changes
If there are many static loads in the power distribution system, static compensation is used, and if there are frequent changes in loads, dynamic tracking compensation is more appropriate.
3.5 Three-phase balance
In the power distribution system, if the three-phase load is balanced, three-phase co-compensation is used, and if the three-phase load is unbalanced, phase-separated compensation or mixed compensation is used.
4. High-voltage filter compensation device for reactive power compensation device
The high-voltage filter compensation device is mainly used for reactive power compensation and filtering of the 110KV busbar in the substation. The design of the device is based on the characteristics of the system and interesting wave sources, and the filter is optimized by using a special program to make the reactive power compensation and filtering effect the best. The device is safe and reliable, with reasonable configuration and less investment.
4.2 Application field
It can be widely used in power factor compensation and harmonic suppression with relatively stable load in electric power, metallurgy, chemical industry, coal mine, light industry, building materials and other industries.
4.3 Main technical indicators
4.3.1 Voltage level: 6~110KV;
4.3.2 The filtering effect meets the requirements of the national standard GB/T14549-93;
4.3.3 After compensation, the power factor is increased to above 0.92;
4.3.4 Rated capacity and external dimensions: all according to user requirements;
4.4 Technical Features
4.4.1 The filter capacitor adopts full-film or film-paper composite insulating medium, which has low loss and high reliability; the filter reactance value adopts a hollow-core cylindrical structure, and the reactance value is continuously adjustable by ±7%; the filter resistor adopts a non-inductive braided resistor device.
4.4.2 In order to achieve the best filtering effect, according to the short-circuit capacity, voltage level and harmonic content provided by the actual measurement, the best compensation scheme is proposed through the address calculation of the CHP harmonic analysis program.
4.4.3 The filter device can be equipped with BS series filter automatic switching controller.
126.96.36.199 It can be adjusted according to the reactive current and harmonic current of the load;
188.8.131.52 Fast tracking can be realized;
184.108.40.206 Display the power factor of the system in real time;
220.127.116.11 Bus voltage and protection action signal;
18.104.22.168 With communication function;
22.214.171.124 It has manual and automatic switching function;
4.4.4 The filter device is equipped with FB series filter microcomputer protection, which has a relatively comprehensive protection function, and can automatically identify the type of fault and coordinate with the controller.
126.96.36.199 Filter bank overcurrent protection;
188.8.131.52 Filter bank current quick-break protection;
184.108.40.206 Three-phase current unbalance protection;
220.127.116.11 Overvoltage protection;
18.104.22.168 Undervoltage protection.
5. The development trend of reactive power compensation device
In recent years, the domestic reactive power compensation market has developed extremely rapidly, and the quality and quantity of products have been greatly improved. A considerable number of advantageous enterprises have begun to aspire to the international market and have achieved good results. According to the statistics of the National Bureau of Statistics, in 2011, China's reactive power compensation device manufacturing industry achieved a total industrial output value of 33.561 billion yuan, a year-on-year increase of 11.99%; realized product sales revenue of 33.02 billion yuan, a year-on-year increase of 9.99%; realized a total profit of 1.907 billion yuan, a year-on-year increase 7.64%.
From the perspective of import and export, in 2010, the total import and export of the industry was 4.013 billion US dollars, an increase of 26.75% over the previous year. Among them, the import value was 2.153 billion US dollars, the export value was 1.86 billion US dollars, and the trade deficit was 293 million US dollars.
From the perspective of the international market, the international SVC market is basically occupied by 6-7 international companies such as ABB of Switzerland, SIEMENS of Germany, ALSTOM of France, TOSHIBA of Japan, and ANSALDO of Italy. Among them, ABB, Siemens, and ALSTOM specialize in large-capacity SVCs for power grids, and have a leading edge in super-high-power SVC technology for power systems, occupying more than 90% of the domestic power system market share. The main competitors of domestic companies are China Electric Power Research Institute Power Electronics Company and Xizheng Company. The two companies occupy more than 80% of the domestic market share.
From the perspective of the application market, the reactive power compensation device industry has developed rapidly at home and abroad, and has penetrated into all aspects of electric energy generation, transmission, distribution and application, and is widely used in industrial systems, power systems, transportation systems, communication systems, and computer systems. , new energy systems, and everyday life, it is the basic technology for all other industries that use electric energy. At the same time, under the strong support of the state for advanced manufacturing industries, the development of the reactive power compensation device industry has been promoted. Under the macro background of advocating energy conservation, emission reduction and safe production in the whole society, the market demand for products will continue to grow, and the market space will gradually expand. And development brings good opportunities and broad space.