English
The static var generator is to connect the self commutating bridge circuit to the power grid through the reactor or directly in parallel, adjust the phase and amplitude of the output voltage on the AC side of the bridge circuit, or directly control its AC side current, so that the circuit can absorb or emit reactive power that meets the requirements, so as to realize the purpose of dynamic reactive power compensation. This paper will introduce the working principle of static var generator.
The following is a list of contents
Working principle of static var generator
Application field of static var generator
Application scenario
SVG adopts the self commutation bridge circuit composed of turn off power electronic devices (such as IGBT), which is connected in parallel to the power grid through the reactor to appropriately adjust the amplitude and phase of the output voltage at the AC side of the bridge circuit, or directly control its AC side current. Quickly absorb or emit the required reactive power to achieve the purpose of rapid dynamic regulation of reactive power. As an active compensation device, it can not only track the impulse current of impulse load, but also track and compensate the harmonic current.
The voltage source inverter consists of DC capacitor and inverter bridge, in which the inverter bridge is composed of semiconductor device IGBT that can be turned off. In operation, the amplitude and phase of the voltage from DC inverter to AC can be controlled by adjusting the switch of IGBT device in the inverter bridge. Therefore, the whole device is equivalent to a phase modulation power supply. By detecting the reactive power required in the system, it can quickly send reactive power with equal size and opposite phase, realize the local balance of reactive power, and keep the system running with high factor.
In the power system, in order to reduce the success rate loss caused by the distribution network providing a large amount of reactive current to the load, reactive power compensation devices with corresponding voltage levels need to be configured at each power receiving point, so as to improve the transmission capacity of the power grid and save energy. At present, industrial and mining enterprises often use capacitor switching compensation, but the capacitor compensation configuration is relatively low, and the operation stability of switching compensation device is poor, which is specifically reflected in:
1. The compensation capacity of low-voltage fixed capacitor bank is not adjustable. The switching capacitor bank is switched by stages, and the problems of over compensation and under compensation often occur, which makes the transformer unable to operate under the best economic state, increases the line loss at the upper power side and reduces the economic benefit.
2. The capacitor cannot be switched on and off continuously and frequently, because the capacitor needs discharge time.
3. The corresponding speed of capacitor switching is slow, and the dynamic reactive power cannot be compensated, that is, the fast load cannot be compensated. Using AC contactor to switch capacitors, the corresponding speed is slow, and surge impact, operating overvoltage, arc and other phenomena will occur, and the switches and capacitors are seriously damaged.
4. Each group of capacitors has level difference and cannot be compensated continuously, and the power factor will not be compensated very high
5. It cannot be used in the case of harmonic, which will breakdown the capacitor, cause resonance and cause capacitor explosion. Active filter (APF) or reactor should be selected.
Metallurgical Industry: mainly the rolling mill on the production line.
Petroleum Industry: it is mainly the motor for winch, hoist for pumping unit and rotary table that are frequently and quickly started.
Rail transit: cable is widely used for long-distance transmission, and there is a serious three-phase imbalance due to demand characteristics.
Automobile manufacturing: electric welding machines or laser welding machines are widely used. After a short interval of welding, it is followed by no-load operation, and two voltage steps will be generated.
Application scenario
（1）Wind farm
（2）Electric arc furnace
（3）Ladle furnace
（4）Rolling mill
（5）Electric Power
（6）Coal mine
（7）Power transmission
（8）Photovoltaic Power Station
（9）Hoister and other heavy industry loads
Zhuhai Sinopak Electric Ltd. provides high-quality STATCOM. If you are interested in our products, please contact us:daniel.wu@sinopakelectric.com.
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