Abdul Halim Abdul Rashid

Improved three-phase power-flow methods using sequence components

The paper presents the formulation and the solution of the three-phase power-flow problem using sequence components. An improved sequence component transformer model and a decoupled sequence line model were used. As a result, the three sequence admittance matrices are decoupled with three-phase power system features in sequence components. The sequence power-flow algorithm has been formulated such that the single-phase power-flow programs can be called as routines for solving the positive sequence network. The results for the proposed sequence power-flow methods are identical to those obtained from three-phase power-flow programs developed in phase components. The computational efficiency and convergence of the proposed sequence three-phase power-flow methods show that they are as fast and as robust as conventional the Newton-Raphson method.

An efficient method for optimal scheduling of fixed head hydro and thermal plants

An efficient and optimal method for scheduling thermal plants in coordination with fixed-head hydro units is presented. The method linearizes the coordination equation and solves for the water availability constraint separately from unit generation. Once the water constraint Lagrange multiplier is determined, the unit output can be computed easily. Case studies with various systems are presented and discussed. >

Global and local convergence of a filter line search method for nonlinear programming

A framework for proving global convergence for a class of line search filter-type methods for nonlinear programming is presented without assuming that the Jacobian has full rank everywhere. The underlying method is based on the filter concept where trial points are accepted, provided there is a sufficient decrease in the objective function or constraints violation function. The proposed methods solve a sequence of quadratic programming subproblems via line search techniques to induce global convergence. Under mild conditions, we will also show that the algorithm converges two step superlinearly when the iterates are near to the solution.

An algorithm for the optimal scheduling of variable head hydro and thermal plants

The authors present an efficient and optimal method of scheduling thermal plants in coordination with fixed and variable hydro units. From the system model of the cost function, energy balance and water availability constraints, a set of coordination equations were derived from Kuhn-Tucker conditions of optimality. The equations when linearized were found to be partially separable. By neglecting the second order differentials of power losses the equations were made separable and this enabled the coordination equations to be reduced to two sets of equations and thus the Lagrange multiplier for the water availability constraints can be solved separately from unit generations instead of simultaneously. once the Lagrange multiplier of the reservoir constraint was determined the values of other variables were calculated by back substitutions. The reduction of the coordination equations reduced the size of the matrix to be inverted. Furthermore the matrix has a special structure that allowed its inverse to be computed directly and easily. Case studies with various systems were carried out to test the efficiency of the proposed algorithm and the detailed result of one test case is discussed. >

Development of Power System Analysis Software Using Object Components

This paper presents experiences of developing a power system analysis software using a combination of object oriented programming (OOP) and component based development (CBD) methodologies. In this development, various power system analyses are developed into software components. These components are integrated with graphical user interface components to build up a power system analysis application. By using both OOP and CBD methodologies, updating or adding new algorithm can be done to any specific component without affecting other components inside the software. The component also can be replaced with any other better component whenever necessary. Hence, the software can be maintained and updated continuously with minimum resources. The performance of the components is described in comparison with the non-component applications in terms of reuse as well as execution time.

Use case approach for developing object oriented power system studies: object oriented three phase load flow

The paper presents the application of the use case approach for developing reusable power system components. Object oriented three phase load flow is introduced as an example. The three phase load flow development is based on the symmetrical components theory and the decoupled models of the untransposed transmission lines. The well known Newton Raphson and Fast Decoupled algorithms are chosen in the development. The three phase load flow is solved by incorporating the solution of the positive sequence load jlow and the negative sequence and zero sequence nodal voltage equations. The different use cases are studied before the code implementation. Based on these use cases, an analysis model is constructed The clear advantage of the use case approach is that it defines the reusable objects before the code implementation.

Use-case and Sequence Diagram Models for Developing Transient Stability Software

Transient stability (TS) software is a tool that is used to analyze the stability of power system after subjected a large disturbance. The transient stability software tool can be built by any approaches such as procedural programming, object-oriented programming (OOP), or component-oriented programming (COP). The component-oriented based on the object-oriented design (OOD) is proposed for developing the TS software in this paper. In the component development, use cases and sequence diagram models are required to identify the sub-system and process involved in the TS problem. The use-cases are made according to the components and objects required in the TS tool such as load flow solver, transient stability solver, linear solver, and object-oriented power system model (OO-PSM). A sequence diagram model represents the detailed process of a use case. Both use-case and sequence diagram models required for TS software tool are focused in this paper. The unified modeling language (UML) which is a standard object modeling for developing component- and object-oriented design is used to develop the use cases and sequence diagram models.