STATIC VAR COMPENSATION A PRACTICAL APPROACH

The use of static var compensators is suggested as a practical solution to the problem of economical operation of power system. The paper discusses the subject in detail for Pakistan water & power Development authority and ends into the conclusion that : - Fixed capacitors equal to 1/3rd of peak load requirements will be sufficient to keep the average power factor throughout the day very near to unity. Due to capacitance of transmission line the power factor at generating station may be unity and even may go on leading side. - The fixed capacitors will improve the voltage on 11 kv side of power transformers from 2 to 3% at peak laod hours. For stations with switched capacitors improvement in voltage will be from 4 to 5% - The fixed capacitors will reduce transmission & line losses approximately 1.8 upto 2.55'0' and with additional 225'0' switched capacity it can further be reduced up to 2 .2%. However. it will not be practically possible to install additional 22% switched capacitor at all stations as that will change power factor on the generator to leading side under certain conditions which is not desirable. - For normal power factor improvement and other related benefits fixed capacitors will be s ufficient. However, to cater for the future increase in load, and more benefits siwtched capacitors at substations supplying higher loads can be considered. As the level of minimum load in an area increases, some of the switched capacitors can be converted as fixed and switches can be shifted to other areas.