# Application Design Of Power Substation

The active power loss in the capacitor is composed of dielectric loss and conductor resistance loss, and the dielectric loss is more than 98% of the total active power loss of the capacitor, and its size is related to the temperature rise of the capacitor, which can be expressed in the following form: P is the active power loss of the capacitor, kW; Q is the reactive power of the capacitor, kvar; Tans is the dielectric loss angle tangent value; W for power grid angular frequency, rad/s; C is the capacitance of the capacitor, F; U for capacitor operating voltage, KV.Power Substation

By the formula: when the operating voltage exceeds the rated value will make the capacitor over load, and the capacitor operating voltage than the nominal value, then reduce the reactive power, such as the operating voltage of 90% rated voltage, reactive energy reduction of 19%, so that the capacity is not fully utilized, is also not economical. At the same time, the operating voltage increase, so that the capacitor heating and temperature rise, due to dielectric loss in the capacitor caused by the active power loss P=wcu2tans also with the voltage value of the square change, loss through the conversion of heat to be consumed, the operation voltage increased, calorific value also increased.Power Substation

On the other hand, the life of the capacitor is shortened with the increase of the voltage, and the insulation medium is accelerated and the life is shortened under high field strength. Therefore, the capacitor operating voltage in principle equals the rated voltage, and strictly controlled within a certain range, in order to ensure the safe operation of the capacitor.Power Substation

In recent years, with the wide application of non-linear power equipment such as large electric arc furnace, rectifier equipment and household appliances, the high harmonic currents generated by various harmonic sources are injected into the power grid, which causes the serious distortion of the voltage and current waveform of the power system. Power Substation

Capacitors are most sensitive to higher harmonics, because the high harmonic voltage superimposed on the fundamental voltage not only makes the capacitor's operating voltage effective value increase and its peak voltage increased, resulting in the capacitor due to excessive load and fever, and may occur partial discharge damage, high harmonic current superimposed on the capacitor fundamental current to make the capacitor current increase, Increase the temperature rise of the capacitor, resulting in overheating damage to the capacitor.Power Substation