The purpose of this study is to find a control method for three-phase four-wire shunt active power filters, which uses a load-equivalent conductance for obtaining a reference signal for compensating non-active current.
Changes of energy stored in an active filter’s reactance elements are monitored to find the active component of the load current. It is then used as a current reference to be realised as a supply source current. Computer simulation methods were used to verify the presented control method.
To calculate the reference signal for the active filter action, it is enough to measure the active filter’s DC-side capacitors’ voltages. It has been proved that P regulators are sufficient to realise compensating current and to stabilise active filter capacitors’ voltages. The supply source-neutral conductor current can be zeroed even for nonlinear and unbalanced load-generating DC-component in its neutral conductor. In addition, the active filter can buffer load-active power changes and act simultaneously as a local energy accumulator.
This paper provides an alternative approach to address the problem of the three-phase four-wire shunt active power filter control methods.
