APPLYING THE “DYNAMIC CAPACITORS” FOR UNBALANCE COMPENSATION IN POWER GRID

To solve the problem of nonsinusoidality, unbalance and reactive power compensation in electric grid, active filters and devices for balancing are widely distributed. These devices are static compensators, active power filters, unified power flow controllers. Method of symmetrical components is widely used to calculate passive active filters and devices for balancing. It allows to obtain the desired active filters and devices for balancing conductivity values. It is shown that the unbalance compensation can be achieved using only the capacitive elements. But for active filters and devices for balancing containing only capacitive elements, simultaneous compensation of unbalance and reactive power is impossible. In this case, the concept of the objective function is introduced. It is a function which determines the possibility of "undercompensation": acceptable levels of unbalance and consumption (generation) of reactive power. The paper deals with a type of active active filters and devices for balancing, so-called "Dynamic capacitors" or inverter-less active filters, which consists of a capacitor bank connected to the grid through a direct AC/C converter. Load balancing using Dynamic capacitors is discussed. Dynamic capacitors allow for smooth control of reactive power, moreover, they can perform limited active harmonic filtering, similar to a shunt active power filter.