SVC Implementation

1. Basic Principles (TODO)

2. Inheritance of General FACTS Model

A SVC model can be inherited directly from the general FACTS model (Figure 1), as discussed as follow.

(TODO)

Figure 1. UML model of SVC in InterPSS

2.1. Properties

2.1.1. Topology of converter branch

SVC has only one converter, thus only one converter branch is included. SVC behaves as shunt compensation; the topology of the equivalent circuit is shown in Figure 2.

Figure 2. Equivalent circuit of SVC

The topology of the converter branch can be written as

while 1 corresponds to bus i and 0 corresponds to the ground (reference bus).

2.1.2. Z_sh

The impedance of the converter branch, need to be pre-defined when calculating load flow.

2.1.3. Terminals

Two terminals are required to define the SVC topology, one is the bus that the SVC connected to, which is the point to inject reactive power into the power network, the other is the ground (reference bus).

2.2. Functions

2.2.1. Control objectives defined by equation

An enumerate class called SVCControlObjective can be used to define the control objectives of the SVC device. Since a SVC has only one converter, only one physical quantity can be controlled at the same time. Those control objectives might be^[1]:

a) Bus voltage control

where is the bus voltage control reference.

b) Reactive power control

where is the specified reactive power injection control reference, and is defined by

where

c) Control of equivalent impedance

where is the specified reactance control reference of the SVC. is the equivalent reactance of the SVC, which is defined as

There are many other control objectives, such as control of current magnitude (capacitive/inductive compensation), control of the injected voltage magnitude,

remote voltage control, and so on. However, the three control objectives listed here are most common. More detailed SVC model can be developed in the future.

2.2.1. Constraints

a) Inequality constraints

b) Equation constraints

Reference

[1]. Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal, Flexible AC Transmission Systems: Modelling and Control, Springer, 2006

Data:

CapacitiveRating MVar, PU

InductiveRating MVar, PU

Slope Volt/MVar, PU

VoltageSetPoint Volt, KV, PU

ControlMode ReactivePower, Voltage, Off

V_t = V_ref + X_e I_svc

V_t - Bus voltage

V_ref- Reference voltage set point

X_e - Slope

I_svc - SVC current

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