Voltage control in MV distribution networks with a large share of distributed renewable generation

Traditionally, voltage control in MV distribution networks has been focused on dealing with voltage drop along radially operated feeders. The actual implemented controllers use local voltage measurements and have been designed and calibrated for a passive and radial use of the MV system. The presence of distributed renewable generation (DRG) makes these assumptions no longer valid. The power generated by DRG units will increase the voltage at adjacent nodes and even cause it to be higher than the voltage at the primary substation. Consequently, the presence of DRG will affect voltage control in distribution systems and it needs to be reconsidered whether methods like local voltage control and reactive power injection can still enable the network operator to cope with the newly introduced voltage rise issues. The aim of this study is to create a new voltage control strategy, which will not only successfully limit voltage variations, but also allow for an increased penetration of DRG. The proposed coordinated voltage control strategy deploys control of HV/MV transformers On-Load Tap Changers in combination with active power control provided by Intelligent Nodes, that allows network reconfiguration. The Cigré MV distribution network benchmark is used as a basis for the test system, while appropriate models for the PV Power Plants, the Wind Power Plants and the Intelligent Nodes were developed. In order to draw realistic simulation results, a summer / winter seasonal variation is featured. The proposed voltage control algorithm is incrementally developed, allowing for the identification of factors hindering the controller performance and the development of a control algorithm which is more targeted towards dealing with specific issues. The commercial power system simulation software DIgSILENT PowerFactory 15.0 is used for carrying out these simulations. The analysis of simulation results shows that the proposed voltage control strategy is capable of facilitating the transition towards active MV distribution networks, by offering considerably higher DRG penetration levels and strictly bound network voltages. The modelled controller is particularly applicable to MV distribution networks across North Europe. Among others, the limiting factors for an increased DRG penetration are identified, along with the effects that the reactive power control and the choice of voltage limits have. Finally, recommendations for future research are provided.Sustainable Energy TechnologyChemical EngineeringApplied Science