Application of Inverter-Based Distributed Generators for Harmonic Damping Throughout a Distribution Network

The presence of inverter-interfaced distributed generators in a network provides an opportunity to mitigate the harmonic voltages caused throughout the network by non-linear loads. DG can be given a resistive characteristic at harmonic frequencies to provide a low impedance path to harmonic current and to damp resonant interaction of line inductance and shunt capacitance. Approaches to choosing a suitable resistance (gain) are examined and a scheme for gain adaptation that works within the current limitation of the inverter is proposed. The harmonic VA deployed by each inverter can be measured and controlled through the choice of resistance. It is possible to use a common resistance value for all harmonics or individually set resistance for each harmonic. A common resistance is significantly easier to implement, but an individual resistance for a few lower order harmonics is more effective