Voltage and Frequency Profile Analysis of Electricity Networks with Wind Energy Integration T.Matlokotsi S.Chowdhury Dept. of Electrical Engineering University of Cape Town Cape Town, South Africa mtltlh003@myuct.ac.za, Sunetra.Chowdhury@uct.ac.za Abstract— Wind energy conversion systems (WECSs) are currently the most matured and preferred as bulk renewable energy generation systems across the world. Hence extensive research is being done on investigating the impact of wind energy integration on voltage and frequency of electricity networks for proper planning of their grid-integration such that network performance is not deteriorated, rather enhanced in terms of power quality and stability. This paper presents explores through modeling and simulation in DIgSILENT Powerfactory, how wind power plant technology, capacity and point of integration affect the voltage profile and frequency profile of utility power grid. Ensuring enhanced power quality in electricity networks is important particularly in the current wind energy deployment in South Africa. Keywords—Voltage profile, frequency profile; wind energy conversion systems, doubly fed induction generator, permanent magnet synchronous generator; point of common coupling; I. INTRODUCTION To meet the rapid rise in energy demand and to combat global warming and emissions caused by conventional fossil-fuelled energy generation, the preference for renewable energy sources is growing across the globe. As a matured and clean technology, wind energy conversion systems are being deployed in both developed and developing countries as a means for alleviating the aforesaid energy challenges [1]. The challenge with wind power is the erratic nature of wind velocity that leads to variable turbine speed, consequently resulting in variations in the system voltage and frequency. This problem is eliminated in fixed speed wind turbines using a gearbox to adjust the speed [2]. Variable speed turbines use power electronics converters and control modules to achieve adjustable output voltage in terms of magnitude and frequency [3]. For higher levels power generation, variable speed turbines are preferred as they can be operated within a wider or narrower wind speed range to achieve the required energy production with reduced noise [3] Extensive research is being done on investigating the impact of wind energy integration on voltage and frequency of electricity networks for proper planning of their grid-integration such that network performance is not deteriorated, rather enhanced in terms of power quality and stability. Poor planning of wind integration may result in increased grid disturbances such as voltage dips, harmonics, swells, flickers, etc. [4][5][7][10]. This paper explores through modeling and simulation in DIgSILENT Powerfactory, how wind power plant technology, capacity and point of integration affect the voltage profile and frequency profile of utility power grid. Two types of wind energy conversion system (WECS), viz., Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG) have been considered for this research due to their popularity in the energy markets. Voltage and frequency profiles are investigated at different busbars of the test network for different scenarios of wind integration at different buses under normal operating conditions without considering any faults in the system. A comprehensive analysis of voltage and frequency profiles in WECS is crucial in design of flexible and innovative energy conversion systems which will take into account recent advances in technology while ensuring the security of energy supply [8][9].This paper therefore seeks to examine the possibility of integrating large scale wind resources to electricity networks such that the overall intermittency of wind-generated power is reduced. II. MODELLING OF THE TEST NETWORK AND WECS A. Test network model Fig. 1. Model of the test network The 8-bus, 50Hz test network is shown in Fig.1. The test network consists of an external grid with the strength of 100MVA, 66kV sub-transmission network supplying heavy industries and 11kV and 230V distribution networks supplying residential type loads. The test network is modelled comprising 8 buses, 3 transformers and overhead transmission lines as the interconnectors of the components. The synchronous generator 978-1-4799-7498-6/15/$31.00 ©2015 IEEE