Analysis and design of regenerative load system for power system test

This paper presents a regenerative load system to replace the conventional passive load for the long-term testing of power equipment and motor-generator sets. This system has three merits: economic, safety and power quality improvement. The energy consumption can be less than 20% of the passive load and the utility source current can be shaped into a pure sinusoidal waveform with power factor near to unity. For realism, the utility source inductance is taken into consideration. Through root-locus analysis and PSpice simulation, the authors conclude that for a stable system, the following conditions must be met: (1) the addition of a damping circuit; and (2) the current gain of the inverter must be kept below one. In addition, they have developed a simple control method to regulate the energy-storage capacitor voltage, using the energy-balance concept and a memory circuit to calculate the required utility source current. The transient response is less than two cycles. Finally, PSpice simulation and experimental results are provided to verify the feasibility of this regenerative load system.