Reactive compensation. EHVseries capacitor equipment protection and control

Since the introduction of static VAR systems (SVS), interest in series compensation has been somewhat reduced. However, in aiming at an economical solution of maximum power transfer on a system, both methods have to be studied together objectively. Basically, to control the series impedance of a power system is, in fact, more effective than control of the shunt impedances. To meet transient stability demands, high-speed controls of the series capacitor have been developed, which have not always given expected service experience, perhaps because of an unnecessary degree of sophistication. The paper describes various schemes designed with the motto `The simpler the better¿¿. Also, the subsynchronous resonance (SSR), at present giving a somewhat negative attitude to series compensation, is discussed in the paper on the basis of computer studies and tests