Medium voltage Static Synchronous Compensator

Medium voltage Static Synchronous Compensator

A static synchronous compensator (STATCOM), also known as a static synchronous condenser (STATCON) or Static var generator (SVG), is a regulating device used on alternating current electricity transmission networks. SVG is the representative of newest technology in reactive power compensation field, which is connected in parallel to the grid, similar to a variable var current source. Its var current can change following the load rapidly and automatically.  

Main Functions

Sinopak magnetically controlled soft starter consists of the incoming line, switch, magnetically controlled reactor and controller. The equipment controls MCR reactance through changing magnetic permeability of iron core with DC excitation current, so it is called magnetically controlled soft starter. 

◆ Improve the stability of power transmission In long distance transmission system, SVG can not only compensate the power line losses caused by reactive power, increase line voltage and improve effective transmission capacity under normal operation, but also offer reactive power adjustment in time, damp system oscillation and improve system stability in case of fault. 

◆ Maintain the receiving-end voltage level Since high capacity load centers lack reactive power support, it is easy to cause grid voltage dip, even cause voltage collapse. However, SVG is capable of fast var adjustment. Therefore, the receiving-end voltage level is greatly stabilized. 

◆ Reactive power compensation leading to high power factor and low line losses Many types of loads need a mass of reactive power when operation, such as asynchronous motors, arc furnaces, rolling mills and high rating rectifiers. At the same time, the upstream transformer and line impedance also generate reactive power, which still leading to low power factor. For the power system, loads with lower power factor will increase the line losses, voltage drop and deteriorate voltage quality. Additionally, reactive power will reduce efficiency of power generation, transmission and distribution. For clients, low power factor will increase production costs. 

◆ Restrain voltage fluctuation and flicker. Voltage fluctuation and flicker are mainly caused by rapid loads variation. This rapid variation also causes the load current fluctuation dramatically. The current variation leads to system voltage losses changing very fast, which brings the receiving-end grid voltage flicker. The typical loads that cause voltage flicker are arc furnaces, rolling mills, electric locomotives, etc. SVG can offer fast reactive power regulation, which mitigate voltage fluctuation and flicker easily caused by loads variation. 

◆ Mitigate 3-phase imbalance. In distribution network, there are a lot of 3-phase unbalance loads, typically like electric locomotives and arc furnaces. At the same time, line and transformer impedance unbalances can also cause voltage unbalance problem. SVG can fast compensate negative sequence current caused by unbalance loads, which ensure balanced 3-phase grid current. Thus, it improves the power supply quality greatly.