Power Converter Based Impedance Emulation of Passive Loads for Anti-Islanding Tests

Abstract

A passive RLC load is essential for conducting anti-islanding tests of inverter based grid connected distributed generator (DG) systems. A variable load is desirable if the tests need to be carried out over a range of operating conditions and on multiple DG based inverters of different ratings. Use of a physical load results in increased cost and space requirements, particularly when the rating of the DG under test increases. This paper presents power converter based impedance emulation technique to actively implement such a parallel RLC load. The dynamic and steady-state response of the load are synthesized using closed loop control of the passive load emulation converter (PLEC), such that the terminal behaviour of the converter matches the passive RLC load characteristics closely. The proposed technique is verified using simulations and experiments that consist of proposed PLEC working in tandem with a current controlled 3φ DG based inverter on a 5 kVA hardware prototype in laboratory.