In this topic, you study STATCOM – Definition, Working Principle, Diagram, VI characteristics, & Applications.
The static synchronous compensator (STATCOM) is a shunt connected device developed as an advanced static reactive power compensator, the schematic diagram of STATCOM is shown in Figure 1. The main components of STATCOM are DC link capacitor, voltage source converter, converter reactor, and a coupling transformer.
Fig. 1: STATCOM (Static synchronous compensator)
Working Principle of STATCOM
Working of the STATCOM is analogous to synchronous condenser which can supple variable reactive power and regulate the voltage of the bus to which it is connected. If the line voltage V is in phase with the converter output voltage E and has the same magnitude, no current flows into or out of the STATCOM, as shown in Figure 2. Thus, there is no exchange of reactive power with the line. If V < E, then the STATCOM behaves as a capacitor, generating reactive power. On the other hand, if V > E, then the STATCOM draws a lagging current, behaves as a reactor and absorbs reactive power. Thus the STATCOM can supple variable reactive power and regulate the voltage of the bus to which it is connected.
Fig. 2: STATCOM
V-I characteristics of STATCOM
The V-I characteristics of STATCOM is as shown in Figure 3. The working range or operating area of STATCOM is limited only by maximum voltage and current ratings of the converter.
Advantages of STATCOM
A STATCOM has many technical advantages over a SVC. They are:
- Smooth voltage control over a wide range of operating conditions.
- It has High dynamic and very fast response time.
- It always provides the maximum reactive current at any value of voltage.
- High efficiency.
Applications of STATCOM
It provides voltage support by generating or absorbing reactive power at the point of coupling. Thus, a STATCOM may be used for voltage control, reactive power compensation and damping oscillations.