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Customer Success Story


SVCs for mitigation of voltage collapses in large urban grids

The Saudi Electricity Company of the Western Region (SEC-WR) operates a power transmission system comprising 380 kV OH lines and underground cables. There are numerous 380/110 kV bulk supply stations, feeding local 110/13.8 kV substations through mostly underground cable circuits.

Operating conditions in the Saudi power grid are special due to the hot or very hot climate, with up to 80% of the total load consisting of air conditioners. From a grid point of view, air conditioning is a particularly demanding kind of load, with slow voltage recovery, motor stalling or even voltage collapse in conjunction with short circuits in the transmission or sub-transmission network. In the western region in particular, close to the Red Sea and with the major city of Jeddah as well as the holy cities of Makkah and Madinah as dominating load centres, grid stability is sorely strained particularly in summer and during the Hajj pilgrim period. To get to grips with this situation, three large SVCs have been installed in the region, with the explicit purpose of keeping the grid voltage stable as air conditioners all over the place are running at full speed. The SVCs, located at Madinah South, Faisaliyah and Jamia substations and rated each at 110 kV, -60/+600 Mvar (60 Mvar inductive to 600 Mvar capacitive), were taken into service in 2008 and 2009.

Main data
System SVC
Commissioning year 2006
Controlled voltage  110 kV
 SVC rating  60 Mvar inductive to 600 Mvar capacitive
 Control system  Voltage control by means of a closed loop system with control of the positive-phase sequence voltage 
 Thyristor valves  PCT type thyristors, water cooled, indirect light firing