Static Var Compensators (SVC) Studies

What is Static Var Compensators (SVC)?

• A static var compensator (SVC) is a shunt-connected static var generator or absorber whose output is adjusted to exchange capacitive or inductive current to maintain or control specific parameters of the electrical power system (typically bus voltage).

• A thyristor-controlled reactor (TCR) is a shunt-connected reactor in series with a thyristor valve. The effective reactance of the inductor is varied in a continuous manner by partial conduction of the thyristor valve.

• A thyristor-switched capacitor (TSC) is a shunt-connected capacitor in series with a thyristor valve which is used to switch the capacitor ON or OFF. A current limiting reactor or a damping network is connected in series with the capacitor and the thyristor valve.

• A thyristor-switched reactor (TSR) is a shunt-connected reactor in series with a thyristor valve that is used to switch the reactor ON or OFF.

What is the Importance of Static Var Compensators (SVC)?

• Steady-state voltage control: The controlled voltage may be at a different point from the point of connection of the SVC.

• Voltage stability

  • To increase the capacity of a circuit that is limited by the low voltage at the receiving end.

  • To restore busbar voltage to normal after a system disturbance (e.g., due to a fault or load rejection).

• System stability: To increase capacity that is limited by dynamic stability between machines or machine groups.

• Power oscillation damping: The adjustment of SVC reference voltage is also possible to increase the overall damping of power system oscillations following a disturbance usually in the range of 0.2 Hz to 2.0 Hz on the network close to the SVC.

• Reactive power control

  • Coordination of var contributions from other equipment.

  • Fast correction of variable loads, power factor, and unbalance.

• Harmonic and subharmonic filtering.

How Do We Perform Static Var Compensators (SVC) Studies?

• Step-1: Data collection such as single line diagram (SLD), SVC data, data requirement varies with the studies (load flow, short circuit, transient, harmonic, stability studies) as per IEEE Standard 1031-2011.

• Step-2: Modeling the SVC and study system using PSCAD/EMTDC software.

• Step-3: Preparation of simulation case studies with the study scenarios accepted by the clients.

• Step-4: Preparation of technical report and submission to clients.

What Standards can be Referred for Static Var Compensators (SVC) Studies?

• IEEE Std 1031TM-2011 - IEEE Guide for the Functional Specification of Transmission Static Var Compensators.

• IEC 61954 - Static VAR compensators (SVC) – Testing of thyristor valves.

Static Synchronous Compensator (STATCOM) Studies

What is Static Synchronous Compensator (STATCOM)?

• A STATCOM (static synchronous compensator) is a static synchronous generator operated as a shunt-connected compensator, whose capacitive or inductive output current can be controlled independently of the ac system voltage.

• STATCOM can be developed using forced commutated technology based on voltage-sourced converter topologies. The main objective of STATCOM is to provide reactive power compensation, voltage regulation and control, transient and dynamic stability.

What is the Importance of Static Synchronous Compensator (STATCOM)?

The main function of STATCOM is:

• To operate as a fixed reactive power mode

• To operate as a voltage control mode

  • Control of the positive sequence component of the fundamental frequency voltage in steady state and dynamic operation.

  • Control of phase voltages (based on positive and negative sequence voltages).

• Coordinated reactive power control of external devices: Optimize the use of dynamic vars versus steady state vars.

• Power oscillation damping: To increase the damping of power system oscillations occurring in the power system close to the STATCOM installation. These are usually in the range of 0.2 to 2.0 Hz.

• Gain control: To control regulator gain to prevent oscillations and excessive overshoot in the STATCOM response.

How Do We Perform Static Synchronous Compensator (STATCOM) Studies?

• Step-1: Data collection such as single line diagram (SLD), STATCOM data, data requirement varies with the studies (system dynamic, harmonic, stability, EMT and insulation coordination studies) as per IEEE Std 1052-2018.

• Step-2: Modeling the STATCOM and study system using PSCAD/EMTDC software.

• Step-3: Preparation of simulation case studies with the study scenarios accepted by the clients.

• Step-4: Preparation of technical report and submission to clients.

What Standards can be Referred for Static Synchronous Compensator (STATCOM) Studies?

• IEEE 1052-2018 - IEEE Guide for Specification of Transmission Static Synchronous Compensator (STATCOM) Systems.

• IEC 62927 - Voltage sourced converter (VSC) valves for static synchronous compensator (STATCOM) – Electrical testing.