RMA assisted State Electric Company Limited (STELCO) to assess medium voltage protection coordination settings of the existing medium voltage network in Malé and Hulhumalé to improve network reliability, and to identify required changes in protection schemes to interconnect the existing network with under construction 132 kV network. Capacity building of STELCO on network modelling was carried out as part of the assignment.

Information such as network configuration, cable sizes and lengths, relay models, current transformer ratios, generator parameters, transformer loadings and generator operating patterns, future expansion plans were obtained from STELCO. The existing 132 kV and 11 kV networks in Malé and Hulhumalé were modelled in detail in DIgSILENT PowerFactory software to obtain fault levels at each ring main unit. Using simulated fault levels and other information, relay settings were calculated for the sectionalizing points proposed by STELCO. A capacity building program on power systems modelling was carried out for STELCO engineers covering introduction to network planning and planning software, steady-state analysis, contingency analysis, short-circuit criteria analysis, and frequency stability analysis.

Asian Development Bank
Electricity Utility Planning, Power Generation and Economics