Compensation of load unbalance, reactive power and harmonic distortion by cooperative operation of distributed compensators

Distribution grids are increasingly populated by a variety of renewable energy sources, which create new opportunities in terms of efficient use of energy and can also help to improve power quality. In fact, they are connected to the grid by means of power switching interfaces (PSI) which are capable to control power flow and waveform of absorbed currents as well. They can therefore contribute to power balance and compensation of asymmetry and distortion together with other compensation units, e.g., passive filters, SVC (static VAR compensators) and APF (active power filters). Of course, effective use of such distributed compensation capability requires cooperative operation of compensators and proper sharing of compensation duties. This paper shows that distributed compensation of load unbalance, reactive power and harmonic distortion can be achieved by a cooperative control approach. Energy efficiency and power quality can be managed as a whole at a system level, by taking full advantage of the distributed compensation capability.