Improvements of voltage stability of a solar PV dominated power system using SVC'S- Sri Lanka case study

Abstract

According to the Ceylon Electricity Board (CEB), Sri Lanka Long Term Generation Expansion Plan 2020-2039, in the forthcoming years the contribution to meet national energy demand by major hydro sources will become stagnant. However, the development of other renewable energy resources will enhance the renewable energy share to be maintained above 35-40% during next 20-year period. The increase in solar penetration to the grid can lead to voltage instability problems due to solar ramp rates. Currently solar inverters do not operate in the voltage controlling mode, and they are not capable of producing or absorbing reactive power. Thus, Flexible AC Transmission System (FACTS) devices, such as Static Var Compensators (SVC) are useful to support the reactive power need to sustain voltage stability in the system even under the loss of large generators supplying reactive power in the system. The behaviour of SVC with the maximum penetration of renewable energy, focusing on solar and wind power generation was studied to size and locate the SVC in the transmission system. The Sri Lankan transmission system of year 2030 base case model simulated in Power System Simulator for Engineers (PSS/E) was used for the study. The study showed the best location for placement of SVC was Biyagama Grid Substation considering SVC placement at Biyagama, Kotugoda and Pannipitiya Grid Substations (GSS). Furthermore, this study highlights that it is beneficial to consider a further increase of the currently proposed SVC capacity in order to improve the voltage collapse point under increased penetration of renewable sources in the Sri Lankan Power system in year 2030.