The Functions of MCR Typed SVC
Stabilizing weak systems
Minimizing line loss
Increasing power transfer capability
Providing greater dynamic voltage control
Why choose SVC of MCR Type
1. High reliability: The SCR is installed in low voltage circuit, not in main circuit, so, the withstanding voltage is just 1% of main circuit voltage.
2. Low harmonic contents: THD is below of 5%, which comply with related national criterion, if the multiple connections are adopted, the THD can be reduced below of 1.2%.
3. Small dimension: The dimension of MCR is about 2/5 of TCR.
4. It can be able to connect in high voltage power grid, the cost and floor space are reduced dramatically.
5. Fast response time(100~300ms), it can fully meet the demand of dynamic reactive power compensation of power equipments.
6. No need of cooling devices, which reduce the fault rate, maintenance cost and floor space.
The advantage of MCR-typed SVC
The MCR-typed SVC was based on traditional saturation reactor technology; It was put forward by Russia scientists. They introduced the concept of magnetic valve creatively to just make the small section of iron core saturation, which solved the high harmonic problems caused by traditional saturation reactor, because all iron cores in traditional saturation reactor are excessive saturation, then result in nonlinear harmonic. At the same time, the SVC of MCR type reduced the dimension, weight and noise of entire system; It has many advantages, such as: Low harmonics, fast response time, high voltage withstanding level, stable operation, small floor space and long service life. Therefore, the SVC of MCR type is quickly spreading in Russia, Ukraine, America, India, China and other countries.
It plays a very important role in improving power quality, decreasing reactive power loss, stabilizing power grid voltage and enhancing the reliability of power grid operation. Because MCR-typed SVC adopted advanced micro-electronics technology, it can regulate reactive power demand and compensation on bus bar accurately:
1. The inductive reactive current in main circuit can be adjusted through changing low voltage DC to regulate main circuit impedance fast and smoothly, meanwhile, through cooperating with capacitor bank paralleled in bus bar, reactive power compensation demand can be realized on bus bar, and dynamic response and improved power factor can stabilize bus bar voltage.
2. Choosing reactor parameters properly connected in series with capacitor bank, the compensation on fundamental wave can be obtained, and the harmonic also can be filtered.
Because the SVC of MCR is free of frequent switching from mechanical parts, then it avoids surge and over-voltage impact caused by MSC, which enhances the reliability and the service life of the equipment, as well, protects the other instruments.
The SVC of MCR type fully absorbed advantages and functions of TCR-typed SVC by comparison; It solved the problems of smooth regulation which can not be realized by MSC and TSC, and also overcome some disadvantages of TCR-typed SVC. Because the reactor is connected to high voltage main circuit directly in series, it must stand extra high voltage and ultra high voltage. At present, the highest voltage of reactor in our country reach to 1000KV, and the maximum capacity reach to 320MVar.
The reactor also has over-load function; It will not generate big damage to system except heating, while, the thyristors in TCR-typed SVC is connected to high voltage circuit directly, the over-voltage will result in faults and break. So it is very stable for MCR-typed SVC to operate under the high voltage circuit with free of maintenance.