Shunt Compensation Statcom: compensation devices P=0 It serves of link Current is in quadrature VsDC voltage for VSC DC capacitor
Statcom: GTO and ControllerHigh side voltageis used as a Less harmonics,controller input Require minimal or no harmonic filter GTOMulti stage converter
Equivalent CircuitVariable ac voltage Transformer leakage inductance
Principle Operation Vi = Vs No current or reactive Vi > Vs reactive will be sent Vi < Vs reactive will be absorbed
V-I Characteristic of a STATCOM• If the system voltage exceeds V1 or V2, STATCOM acts as a constant current source by controlling the converter voltage (Vi) appropriately.
The STATCOM Advantages• Quicker response time• Active power control is possible (with optional energy storage)• No potential for creating a resonance point (no required capacitor banks or reactors )• Has a smaller installation (no required capacitor banks or reactors , high capacity power semiconductor devices)• Allows for high availability (one/more STATCOM modules can be off without lossing the entire compensation system)
Application in Voltage Stability• One of the major causes of voltage instability is the reactive power limit of the system.• Series and shunt compensation can increase the maximum power network transfer capabilities, inject reactive power to maintain the voltage magnitude.• FACTS (ex:STATCOM) can adjust the voltage magnitude in some node of the system.