Chapters authored
Assessment of Reliability of Composite Power System Including Smart Grids
The large service interruptions of power supply in the transmission system have significant impact on modern society. The aim of the power system engineers is to prevent and mitigate such events with optimal decisions in design, planning, operation and maintenance. Due to the rapid growth in the power demand and competitive power market scenario, the transmission and distribution systems are frequently being operated under heavily loaded conditions. This tends to make failure of components more frequent in the power system necessitating large downtime to repair or replace the equipment. A majority of the service interruptions are happening due to lack of proper planning and operation of power system. Therefore, complete reliability assessment in generation, transmission and distribution systems is needed at the planning stage. The reliability assessment in smart grids is very much beneficial to the power operator and reduces the risk of grid failure due to failure of major components in power systems. This chapter is confined to composite power system reliability assessment. The composite power system combines both the generation and transmission systems’ adequacy. The generation system in the composite power system includes both conventional and renewable sources. The composite power system reliability assessment is quite difficult due to the large number of equipment, interconnected network topology and uncertainties in generation capacity. The reliability assessment concentrates mainly on the use of probabilistic states of components in generation and transmission systems to evaluate the overall reliability. This analysis will result in a cost-effective system configuration to provide continuous power supply to the consumers at reasonable cost. The reliability level of the system is measured by the defined indices. One of these indices is the probability of average power availability at load bus. This reliability assessment mainly focuses on development of methods to evaluate the probability of average power availability at load buses for a specified system configuration. This chapter discusses the two main techniques called node elimination method and modified minimal cut set method.
Part of the book: Smart Microgrids
Microgrid Protection Systems
Micro grids are miniature version of conventional large power grids functioning either autonomously or with inter connection to the main grid. Primary function of micro grid is to serve power at distribution level. Distributed energy resources (DERs) connected to the micro grid enables reliable and efficient operation of micro grid. Protection of micro grids assumed importance due to increased penetration of distributed energy resources. Most of the distribution systems in earlier days are radial in nature and protection systems are designed for that. These protection systems pose serious challenges when applied to present day distribution systems which are mesh connected and fed by the distributed energy resources. Limitation of the conventional protection scheme demands new insights and methodologies for micro grid protection. Due to intermediate current injection from DERs the conventional coordination of over current (O/C) relays is not possible. Further in meshed systems the fault current flow is bidirectional. Hence the protection of micro grid systems with DERs require different approach to ensure faults are cleared in less time and minimal number of consumers connected to the system are affected. A comprehensive analysis of the suitable techniques applicable for micro grid protection is presented in this chapter.
Part of the book: Micro-grids