Investigation and Correction of Phase Shift Delays in Power Hardware in Loop Real-Time Digital Simulation Testing of Power Electronic Converters

Power Hardware in Loop (PHIL) digital simulation testing has been recently introduced as an alternative approach to traditional methods of high power / high voltage device level testing without the use of load banks and physical medium/high voltage test feeders. PHIL testing approach is very cost effective and highly applicable for performance evaluation of power electronic apparatus in distribution and transmission systems such as power converters in PV and wind generation plants, energy storage systems, and distributed/transmission level power conditioning units and FACTS devices.   

In PHIL testing, power hardware equipment selected for test, hereinafter called device-under-test (DUT), is virtually exchanging power with a power system at the point of interface represented in a real-time digital simulation environment. The main purpose of PHIL simulation is mimicking accurate operating characteristics of the associated power system (a distribution circuit or substation) during the performance evaluation tests, rather than representing the system with lump-sum equivalent impedances and voltage sources. Because of interacting with DUT through high power amplifiers, PHIL may encounter instability, poor performance, or low accuracy owing to phase shift or non-linearity of signal amplification schemes employed in typical power amplifiers.  

In this paper, the most impacting issue of phase shift in a PHIL simulation setup is investigated. Then, a simple and effective compensation method is proposed for PHIL to overcome instability, poor performance, and inaccuracy induced by phase shift. PHIL simulation and experimental results have been provided for both steady-state test cases and transient phenomena to demonstrate the effectiveness and functionality of the suggested PHIL.