nonlinear load

Most modern industrial electrical grids are characterized by a significant content of nonlinear loads, creating many operation problems. Power harmonic filters are one of the most effective ways of reducing voltage distortion in electrical grids. The use of power filters solves two main concerns - to reduce the input current harmonic distortion of the power supply system and compensate for the reactive power of loads. As a rule, the sizing nominal parameters of filter circuits is carried out by the power supply system characteristics in stationary (steady) operating condition.

Current harmonics in industrial cable lines are accompanied by harmful phenomena that cause additional active power losses in cable cores. The phenomena are an increasing the insulation temperature and reduction cable lifetime. Failures are often noted in the cable electrical grids due to improper accounting for the impact of harmonics in the cable sizing. Therefore, the correct consideration of the active power loss in cables carrying distorted currents allows for the correct sizing its types and avoid potential problems in the power grid operation.

Reactive power compensation equipment in industrial electric power supply systems generally operates in environment of significant harmonic distortion currents, which are caused by presence of nonlinear loads. A common practice in such cases is the use of compensation schemes, which consist of a combination of filters and capacitor banks. The paper presents study of operation conditions such compensation scheme in the power grid supplying coal mine.