Static Shunt Compensator Case Study

CHAPTER-3 Static Shunt compensator

(STATCOM)

3.1 About STATCOM :

The first SVC with Voltage Source Converter called STATCOM (static compensator) was introduced in 1999. The STATCOM characteristics are nearly similar to the synchronous condenser, but being an electronic device it doesn’t have inertia and it is comparatively better to the synchronous condenser, such as better dynamics, a less installation cost and lower operating and maintenance costs.

A STATCOM is build with switching devices with turn-off capability like IGBTs or MOSFET’s.

The benefit of a STATCOM is that the reactive power provision is self-regulating from the actual voltage on the connection point. This can be seen in the diagram for the maximum currents

From the d.c. side capacitor, a three phase voltage is generated by the inverter. This is synchronized with the a.c supply. The link inductor links this voltage to the a.c supply side. This is the basic principle of operation of STATCOM.

Fig 3.2

STATCOM is nothing but static shunt compensator which is connected in parallel at the point of common coupling and consists of static power devices like IGBT, MOSFET. The advantage of these devices is the voltage can be easily varied by changing their firing angle. The converter used here is a full bridge converter having six power devices like MOSFET we are using here. As wind speed is always variable, the connection of wind turbine to the grid causes stability problems and which will reduce power quality. In case of any fault there may be voltage sag, swell, or sometimes blackout. STATCOM is connected at PCC as shown in fig

According to the type of ac output waveform, these methods are considered as voltage source inverters (VSIs), where the separately controlled AC output is a voltage waveform.Voltage source inverters are mostly used in variable speed drives, but can also be used to diminish voltage dips. These structures are the mostly used because they naturally behave as voltage sources as required by many industrial applications, such as variable speed drives, which are the most popular function of inverters. Similarly, these topologies can be found as current source inverters (CSIs), where the independently controlled AC output is a current waveform. These structures are still usually used in medium-voltage industrial