INTRODUCTION

MiPower is highly interactive, user-friendly windows based Power System Analysis Software Package. It includes a set of modules for performing various studies like Load Flow, Short Circuit, Dynamic studies, etc. Numerous elements of power system can be modeled using MiPower. In the recent developments, Flexible AC Transmission systems (FACTS) such as Static VAR Compensator (SVC), Static Synchronous Compensator (STATCOM), Thyristor Controlled Series Capacitor (TCSC), Static Phase Shifter (SPS) and Unified Power Flow Controller (UPFC) are also added as new elements. Steady state models are developed for load flow analysis (LFA) studies. Dynamic model include transient simulation (TRS) studies.

FACTS devices are broadly classified into three different types. They are

Shunt compensators (SVC, STATCOM) Series compensators (TCSC, SPS) Series and shunt compensators (UPFC)

The models of FACTS devices are suitable for performing Grid Interconnected studies, transmission planning studies, stability studies etc. The impact of FACTS devices on system steady state performance and transient stability enhancement can be observed.

STATIC VAR COMPENSATOR (SVC)

All standard models WT1, WT2, WT3 and WT4 can be represented. The model is based on thyristor controlled reactor-fixed capacitor (TCR-FC) device model. Variable impedance model is used. The inductive and capacitive reactive power output limits are considered i.e. it can be operated in the capacitive region or inductive region as a TCR. The slope of the SVC determines the reactive power output of the SVC for a particular operating condition. The dynamic model of SVC is used to study the voltage regulation and power oscillation damping. Facility is provided for user to design controller for SVC.

STATCOM

Variable current source model is used. The inductive and capacitive reactive power output limits are considered. The slope of the STATCOM determines the reactive power output of the STATCOM for a particular operating condition.

Steady State & Dynamic FACTS Model

STATIC PHASE SHIFTER (SPS)

SPS regulates the active power flow in a line by injecting a phase shift between the sending and receiving end buses of the line. The model also considers the angle limits of the SPS. Steady state model provides the value of the phase shift that is required to maintain the regulated power flow in the line.

UNIFIED POWER FLOW CONTROLLER (UPFC)

UPFC regulates both active and reactive power flow in a line. The voltage at the UPFC bus is controllable. The model takes care of the limits of series voltage and shunt voltage injection.

Steady State & Dynamic FACTS Model

GRID INTERCONNECTION STUDIES Grid Interconnection studies include the following studies.

Power flow control & contingency management in networks. Frequency response behavior. Grid stability analysis studies include voltage, angle and frequency stability. Reactive power and voltage control. Power oscillation damping. Regulation and support strategies. Tie line flow control.

THYRISTOR CONTROLLER SERIES CAPACITOR (TCSC)

TCSC regulates the active power flow in a line by varying the reactance of the line. Variable impedance model is used for TCSC with variable inductor and fixed capacitor in parallel. The model also considers the limits of TCSC operation in inductive and capacitive modes. Facility is provided for user to enter practical data and compute the limits of TCSC operation. Steady state model provides the value of TCSC impedance required to maintain the regulated power flow in the line.

Series voltage

injection UPFC Regulated Active &

Reactive Power Flow

Shunt voltage

injection

TRANSMISSION PLANNING STUDIES Planning new transmission lines for power evacuation. Contingency analysis determining the loading profile of all the other lines. Study of shunt compensation requirement. Study of series compensation requirement.