Steady-State and Dynamic Performance of Oman Transmission System with Diesel-Engine Driven Distributed Generation

The paper presents simulation studies of installing a number of diesel-engine driven generating units at selected locations in the main transmission system of Oman. A total of 300MW generator units are proposed on a temporary basis to aid in meeting the peak demand in summer 2011. A digital model is developed to simulate the system including central power plants, transmission system, loads and the proposed Distributed Generation (DG). The model includes representation of governor and excitation systems. The simulation studies are performed by using the DIgSILENT PowerFacrory software package. The objective of the studies is to demonstrate effects of the DGs in improving system performance in terms of voltage profile, line and transformer loadings, and transmission losses. The sizes and locations of DGs have been selected based on practical considerations; including availability of spacing, short- circuit ratings of existing switchgears, circuit capacity, feasibility of connection, operation noise, site access roads for fuel delivery, environmental effects, etc. A number of performance indicators are defined to assess the contribution of the selected DGs. These include transformer loading index, line loading index, and voltage deviation index. In addition, active and reactive transmission losses are calculated and used for assessing the benefits of the DGs. The results include comparison of the contribution of individual distributed generation at each site and the case with all proposed DGs. In addition the system dynamic performance is assessed by simulating various DG outages at peak demand.