10KV to 750KV Series Static Var Compensator Based On MCR

タイトルまたは説明

Why choose SVC of MCR Type 

• 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.
• 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%.
• Small dimension: the dimension of MCR is about 2/5 of TCR.
• It can be able to connect in high voltage power grid, the cost and floor space are reduced dramatically.
• Fast response time(**0~**0ms), it can fully meet the demand of dynamic reactive power compensation of power equipments.
• 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:

• 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.
• 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 ***0KV, and the maximum capacity reach to **0MVar. 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.

Frequently Asked Questions

A. The SVC of MCR type adopted iron core reactor, while TCR-typed SVC adopted air-core reactor, if the loss of MCR-typed SVC is higher than the loss of SVC with TCR type?

At first appearance, it seems that the loss of MCR-typed SVC is higher than the loss of SVC with TCR type because of its iron core, but after respective loss analysis, we found:

1. Iron loss is lower compared with entire loss of SVC: the entire loss of SVC is composed of iron loss, line loss (copper line loss and aluminum line loss) and SCR heating loss, the iron loss is not over 5% of entire loss; the iron loss of ordinary transformer includes magnetic hysteresis loss and eddy current loss, the magnetic hysteresis loss takes up about *0%, while, the eddy current loss takes up *0%, because the working state of magnetically controlled saturation reactor drifts off the zero flux point, it avoids magnetic hysteresis loss, therefore, the iron loss of MCR is just *0% of ordinary transformer iron loss, in addition, iron loss is just *0% more of line loss, so, the iron loss of MCR is very low.
2. The main loss of SVC are line loss and SCR heating loss, the line loss of MCR and TCR is as below: First, TCR with air-core adopted aluminum lines, MCR with iron core adopted copper lines, the resistance of aluminum is bigger than the resistance of copper, so the heat of aluminum is also bigger. In addition, in terms of line length, we know from the impedance formula of reactor:   that the square of line length is in inverse proportion to magnetic permeability of medium under the same voltage and capacity. The magnetic permeability of iron core is ***0~***0times of air magnetic permeability, so the aluminum line of air-core reactor will be many times of copper line of iron core reactor under the same capacity (MCR also has a air gap, but it is very small and just about several centimeters, and most of magnetic circuits conduct in iron core ). The longer the aluminum line is, the more the line loss is, in case the line loss need to be decreased, the line cross section will be increased, which will result in more investment, the cost performance is very lower.
3. The SCR of TCR is connected in series to high voltage main circuit and wants high power capacity; it will generate heavy heating, so the complex and expensive cooling devices are inevitable, while, the SCR of MCR is working under the low voltage and small power, it is no need of cooling devices except that the capacity of MCR-typed SVC is over *0Mvar, air cooling devices are enough.

In conclusion, the loss of MCR-typed SVC is very low and just about 1/2 of TCR-typed SVC.

B. The SVC of MCR type adopted saturation reactor with iron core, does it generate big noise?

No matter transformer or reactor, they both generate noise, but the main reason of noise is not because of saturation (but of course, the higher the magnetic density, the bigger the noise, but it can be decreased or eliminated by technique improvement), it depends on manufacturing process. At present, the transformer technology in China is becoming more and more advanced; the noise of big transformer is decreased below *0db, it fully complies with State Environmental Protection Standards. We cooperate with the first-class transformer/reactor manufacturer to control the reactor noise below *0db.

Application industrial fields

A complete set of SVC system can be used to generate constantly varied inductive and capacitive reactive power with fast response time. So far, SVC system has been extensively used in electric power system and industrial field such as:

Rolling mill, Electric arc furnace and ladle furnace, Electric railway traction substation, Hoists and other heavy industrial loads, Long distance power transmission, Wind power plant and Secondary substation (*6KV to **0KV) Etc.