Bernd Engel

Voltage control strategies of low voltage distribution grids using photovoltaic systems

In this investigation, some strategies are presented for the optimized provision of reactive power by photovoltaic (PV) systems to perform voltage regulation in a low voltage distribution grid. The optimization is based on an optimal power flow algorithm that determines the minimum amount of reactive power needed for voltage regulation, also resulting in the minimization of losses in the network. In addition to solving overvoltage problems caused by high penetration of PV systems, reactive power exchange with the superimposed medium voltage grid is also minimized. This is accomplished by performing reactive power balance with respect to a power factor set-point at the interface of medium (MV) and low voltage (LV) grids. In one strategy, the benefits of voltage support provided by battery-based energy storage system (BESS) in parallel to PV systems are also presented.

New strategies for coordinated control in power distribution grids — Effective integration of photovoltaic plants utilizing sensitivity analysis

This investigation aims at providing recommendations to distribution system operators on how to effectively integrate photovoltaic plants in the distribution network. The focus is laid on utilizing the sensitivity analysis to coordinate voltage control and optimize the total reactive power required. Furthermore novel strategies are introduced for an effective use of the reactive power capability of PV plants. The main goal is to pave the way for system operators to use PV plants for operation management purposes by means of integrating them in their SCADA system.