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Power hardware-in-the-loop (PHIL) simulation allows the connection of a physical power component (e.g., photovoltaic inverter) to a real-time simulated network. In this paper, PHIL simulation is used for laboratory education in a systematic way for the first time. Four important topics for the understanding of power system operation are selected and laboratory exercises are designed, respectively. The topics focus on the effects of increased integration of distributed generation (DG), namely, power sharing between synchronous generators and DG, voltage control with on load tap changer and DG, short circuits with inverter-based DG, and microgrid operation. The exercises start from the operation of the traditional power system and gradually incorporate DG-related topics that show both benefits and challenges. A hands-on approach is supported by the appropriate lab configuration consisting of two independent PHIL setups. The assessment of the laboratory exercises by the students is clearly positive underlining the value of PHIL simulation for power system education. [ABSTRACT FROM PUBLISHER]

There is increasing interest in the evaluation of the capability of power-electronic-interfaced distributed generators (DGs) connected to weak medium-voltage (MV) feeders, to provide ancillary services. Classic simulations using simplified DG models have their limitations and may prove insufficient due to the complexity of adequate modeling of power electronic interfaces. Moreover, conventional testing does not allow the investigation of the real generator with the distribution system interactions. Therefore, a scaled-down physical DG (i.e., inverter and dc source) with exactly the same functionalities can be used to evaluate the network integration of the actual DG, by means of power hardware-in-the-loop (PHIL) testing. In this paper, suitable scaling of the power rating and voltage level of the hardware is performed, and an interfacing approach is proposed that achieves stability of simulations without compromising accuracy. The PHIL tests successfully demonstrate potential problems in the coordination of the on-load tap changer controlling the MV feeder with the voltage controller of the DG, such as recurring tap changes, increased reactive power flows, and opposing actions. Moreover, recurring oscillations of the voltage controller of the hardware model are observed at certain system configurations. These inverter control instabilities, which are not visible in purely digital simulations, demonstrate the added value of employing PHIL testing for current and future power system analysis and testing. [ABSTRACT FROM PUBLISHER]

A stability study of distribution networks with a high penetration of distributed generators (DGs) actively supporting the network is presented in this paper. A possible way of mitigating the voltage rise caused by DGs is the local control of reactive power. Among the different possible options, the Q(U) control (reactive power as a function of the voltage) is one of the commonly suggested solutions. However, the Q(U) control can, under certain conditions, lead to instability. This paper summarizes the results of a stability study conducted on a single-inverter system and on a multiinverter system. It shows that the requirements for reaching a stable operation can easily be met for integrated systems but could be a significant constraint for systems relying on communication. [ABSTRACT FROM PUBLISHER]