Analysis and minimization of losses in electric power transmission and distribution systems

In this dissertation a comprehensive approach is taken to the loss analysis and minimization in electrical power systems at both transmission and distribution levels. Loss analysis and minimization constitute an important part of studies in planning and operation of power systems to improve the efficiency of operation.;This dissertation has two parts. The first part is devoted to the loss analysis in transmission systems, in the second part, loss analysis and minimization methods are studied at distribution level.;New methods have been developed to calculate the power and energy losses in bulk power transmission systems. The methods incorporate the effect of the actual on-line control and operation of the system to improve the accuracy of calculations. To calculate the capacity component of the losses specially tailored real and reactive power scheduling programs are used. In the energy loss calculations, changing operation conditions are grouped into operating modes and mode. Furthermore, sensitivity analysis for real power scheduling is performed to calculate the sensitivity parameters, participation factors of generators and the slope of power loss curve.;A new set of equations that are used to formulate the power flow in a radial distribution system and a new power flow analysis method which is based on these equations form the basis for loss analysis and minimization in distribution systems. The new power flow analysis method, called DistFlow, is numerically robust and computationally efficient.;For loss minimization in distribution systems, two problems are studied: optimal capacitor placement and network reconfiguration. Capacitor placement problem is formulated as a mixed integer programming problem. The location, type, and size of capacitors, voltage constraints, and load variations are considered in the problem. A new solution method is developed by decomposing it into a master and a slave problems. The master problem determines the location and the slave problem determines the type and size of the capacitors. The slave problem is further decomposed into sizing type subproblems. The capacitor sizing problem determines the optimal size of capacitors so that the real power losses is minimized for a given load profile. A solution algorithm, based on a Phase I-Phase II feasible directions approach, is proposed for the sizing problem.;A formulation and a solution algorithm are proposed for network reconfiguration in distribution systems for loss reduction or for load balancing. The solution involves a search over relevant radial configurations using branch exchanges. To aid the search for which branch to exchange, two approximate power flow methods with varying degree of accuracy have been developed. The methods are computationally attractive and in general give conservative estimates of loss reduction.;All the proposed solution methodologies have been implemented and tested. Test results are included in the dissertation.