Three SVCs provide voltage control and power oscillation damping in the Malaysian 275 kV transmission network

Since 1991, Tenaga Nasional Berhad of Malaysia (TNB) oper-ates three Static Var Compensators (SVC) supplied by ABB in its 275 kV power transmission network. The compensators, comprising two units at the Kuala Lumpur North substation and one unit at the Yong Peng North substation further to the south, have each a dynamic rating of 100 Mvar inductive to 100 Mvar capacitive at 275 kV.

The purpose of the SVCs is to provide voltage control during daily load cycles as well as to act as dynamic reactive power reserves in the event of major network disturbances, such as loss of generation and/or loss of transmission. Provisions for damping of active power oscillations are also included.

Furthermore, a number of mechanically switched shunt reac-tors (MSR) at Kuala Lumpur North and Yong Peng North are controlled from the SVCs.

Each compensator consists of two Thyristor-Controlled Reac-tors (TCR), each rated at 57.5 Mvar, two Thyristor-Switched Capacitors (TSC) rated each at 42.5 Mvar and two Harmonic Filters for harmonic suppression with a joint rating of 15 Mvar. The overall dynamic range as seen from the 275 kV side thus goes from 100 Mvar inductive to 100 Mvar capacitive.

The SVC control system is of a closed-loop voltage control type. To ensure optimum dynamic response for various net-work conditions, automatic gain supervision and optimizing is included in the regulator of each SVC.

In case of undervoltage, for example caused by short circuits in the surrounding network, action is initiated by the voltage regulator wherein the SVC is controlled to zero output and then automatically goes back to normal voltage control upon return of the voltage. This function will effectively reduce sys-tem disturbances on such occasions.

In order to achieve the greatest amount of flexibility of opera-tion, the two compensators at Kuala Lumpur North can work either independently or under joint control mode.

275 kV

100 MVA

TSC42.5 Mvar

TCR57.5 Mvar

TCR57.5 Mvar

TSC42.5 Mvar

5:th5 Mvar

7:th10 Mvar

Single-line diagram (one SVC)

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For more information please contact:

ABB ABFACTSSE-721 64 Västerås, SWEDENPhone: +46 (0)21 32 50 00Fax: +46 (0)21 32 48 10

www.abb.com/FACTS

SVC11 12

2

2

9 9

99 m

48 m

910 10 910 1011

2

23

3 3

6

6

6 6

6

6 4 4

4 47

22 2

2 2

3 36

6 6

4 47

68

5

68

5

SVC2 2

23

66

6

1 Power transformer2 Reactor3 Capacitor bank4 Disconnector5 Circuit breaker6 Current transformer7 Voltage transformer8 Surge arrester9 Cooling plant10 Thyristor valve11 Control room

Station layout (Kuala Lumpur North)

The SVC at Yong Peng North is furthermore provided with a slow-acting current regulator which can be activated by the operator. This function keeps the compensator output within set limits, thereby ensuring that there will be sufficient reactive power available in case of network contingency situations.

Technical data

Controlled voltage 275 kVSVC rating 100 Mvar inductive to(per compensator) 100 Mvar capacitiveControl system Three-phase voltage control by means of a voltage regulator. Regulator functions include strategy selection and gain supervision/ optimizingThyristor valves Water-cooled three-phase valves with magnetic triggering