Electricity meters for coordinated voltage control in medium voltage networks with wind power

Abstract

During the last years the amount of electricity generated by Distributed Energy Resources (DER), especially wind turbines, has been increasing a lot. These Distributed Generation (DG) units are often connected to rural distribution networks, where they have a large impact on the voltage and the network losses. The network voltage at the customers point of connection is an important quality criteria and has to follow different standards as e.g. EN 50160. Therefore the voltage change caused by the integration of production units in the distribution network is an important aspect when integrating more DG in distribution networks and often a limiting factor for the maximum DG capacity which is possible to integrate into an existing network without reinforcement. Using the available voltage band more efficient by applying coordinated voltage control is a possibility to increase the hosted DG capacity in an existing distribution network without reinforcement of the network. To get the actual network status the new generation of electricity meters, which have the feasibility to communicate real time voltage measurements from the customers side to a network controller, give some benefits to a more flexible and coordinated voltage control in the network. The voltage range in the network will be used adapted to the actual load and generation situation instead of using worst case assumptions as it is good practice until now. A main part of the voltage control in medium voltage distribution networks is done by the on-load tap changer (OLTC) which takes the voltage at the consumers point of connection into account. A generic 10 kV distribution network with three typical types of feeders, as pure load, pure generation and mixed load and generation feeder, has been outlined. Coordinated voltage control is implemented by a central voltage controller. Simulations on the voltage and the network losses have been done and will be presented in this paper. The maximum DG capacity in the test system increases most when introducing coordinated control of the OLTC but also the use of reactive power adds some benefit. Further increase of the DG capacity by more extensive use of curtailment is always possible but due to economical aspects not favoured.