Abstract:
The reliability assessment of composite generation and transmission systems now-a-days has
drawn prime interest in the area of power system plamung. designing and evaluation of
reliability. As the demand of the modem society is to have electrical energy as economically as
possible with a specified degree of reliability, therefore, there is a significant need to assess the
reliability of the composite systems. To evaluate the specified reliability of the composite
systems it is necessary to include all the operational factors. Power system reliability
assessment can be divided into two basic aspects: adequacy and security. Most of the
probabilistic techniques presently available for reliability evaluation are in the domain of
adequacy assessment. There are two basic techniques available in the literature for reliability
evaluation of composite systems: the analytical approach and simulation approach. Analytical
approach represents the system by analytical models and evaluate the indices from these models
using mathematical solutions. Monte Carlo simulation methods, however, estimate the indices
by a simulating the actual process and random behaviour of tile system. When complex
operating conditions are involved and! or the number of severe events is relatively large, Monte
Carlo methods are often preferable. Power system reliability evaluation by simulation can be
applied in two ways: non-sequential or randomly and sequential or chronological order.
The available technique for composite generation and transmission system nonnally consider
only simultaneous independent outages because usually the conunon.mode failure rate is small
i.e. typical values only of the order of 10% of independent failure rates. But such failures might
have severe consequence on the system performance. Many utilities are, tllereforc now using
common-mode representations for composite system adequacy analysis. AltllOugh the state
space transition diagram for conunon-mode outages are well established. But they can only be
utilized in random or non-sequential simulation not in sequential simulation. In case of
conunon.mode outage. several departure transition may occur from each state, then it is
difficult to predict the next transition. To overcome this difficulty a new approach has been
developed in this research. This new algorithm is accommodated in the sequential simulation
procedmes to evaluate power system with common-mode failures.
Several conunon-mode outage groups are considered and thdr effect on reliability indices are
shown in tlJis thesis. So the inadequacies associated with common-mode outages in a
composite power system are higWighted more accurately in this thesis. Therefore. the results of
such a study arc of great importance to the system planner and operator during the design and
operation phases of a power system for more exhaustive analysis. In this research IEEE-IUS is
evaluated using sequential Monte Carlo simulation technique for numerical evaluation.
