Power is defined as product of voltage and current. Reactive power has to be delivered to most types of magnetic equipment, such as motors and transformers, because with no reactive power there is no transfer of active power either. The need for reactive power compensation is bigger and bigger due to it's abillity to improve performanses of AC systems. Some of the ways to compensate reactive power, which are described above, are: single compensation, group and central compensation, shut compensation and serial compensation. Devices of energy electronic in distributive networks are usually separated in three groups: semicondutor facilities, controlled reactive elements and active compenastion devices. It is important to say that although the main goal is improving the performanses of the electro system, control variable in all cases of modern var compensation is actually reactive power. All devices described above are used for wide purposes. Especially static var compensator and serial compensator with tyristor controll. Due to insecurity in reliability it seems that the use of compensating devices has a slow progress. Development in the field of active filters and converters is expected. With all kinds of technical virtues, modern compensation devices are enviroment friendly.