H. H. Happ

Quadratically Convergent Optimal Power Flow

A newly developed sparse implementation of an optimization method using exact second derivatives is applied to the optimal power flow problem. Four utility systems are studied using a variety of objective functions, including fuel costs, active and reactive losses, and new shunt capacitors. Systems solved range from 350 buses to 2000 buses. Comparisons are made with an older algorithm which uses an Augmented Lagrangian to demonstrate the advantages of run time and robustness of the new method. The algorithm and accompanying software represent a technological breakthrough, since they are suitable for solving systems on the order of 2000 buses and demonstrate solution speeds of 5 minutes on large mainframe computers. The method is particularly well suited to infeasible, or even divergent starting points. An option to add shunt capacitors in the event of hopeless infeasibility guarantees an optimal solution for many difficult to solve systems. An automatic scaling feature is added to correct numerical ill-conditioning resulting from series compensation or poor R/X ratios.

Optimal power dispatchߞA comprehensive survey

This paper reviews the progress of optimal dispatch, also called economic dispatch, since its inception to the present in chronological sequence. The classic single area as well as multiarea cases are summarized, and the important theoretical work in optimal load flows suggested to date reviewed. Approaches to the optimal load flow taken by industry are also reported, as well as an itemization of problems that still remain to be solved.

Optimal Power Dispatch

This paper presents an economic dispatch procedure for allocating generation in a power system by the use of the Jacobian matrix. The major advantage of the procedure over other optimal dispatch procedures is its inherent simplicity and rapid convergence behavior which are characteristics particularly omportant for on-line implementation. Results obtained from an investigation of its convergence for the 118 bus IEEE system are given. Comparisons with the classical approach are conducted and logic for on-line implementation is presented.

Static and Dynamic Var Compensation in System Planning

This paper presents a comprehensive method for planning reactive compensation in power systems so as to maintain voltages in acceptable ranges during contingencies. The methodology allows the addition of further VAR compensation as may be economically justified. Reactive compensation considered consists of conventional shunt reactive compensation, synchronous condensers, as well as variable shunt reactive control devices called static VAR control devices. This work combines VAR optimization with static as well as with dynamic system performance evaluations. Necessary modelling of static VAR control devices for inclusion in dynamic performance programs is also given.

Large Scale Reactive Power Planning

A new methodology for planning future reactive compensation for large scale systems is presented. The planning technique is based on a restructuring of the network model and a special formulation of the revised simplex method. A preprocessor is incorporated for correcting systems which are not able to converge using conventional power flow or optimal power flow programs. A 600 bus example is provided which considers 285 transmission contingencies.

Power Flow Solution by Impedance Matrix Iterative Method

A new load flow program has been developed which employs the node-impedance matrix of a system. A special input routine was developed that allows the line data to be in any order desired. The program has the capacity to control generator voltages within a specified var (reactive volt-ampere) range, and also to incorporate off-nominal autotransformers. In every system studied using this program, the time for solution was less than that required by the usual nodal branch admittance iterative method.

Benefits of Voltage Scheduling in Power Systems

This paper concerns itself with the utilization and the coordination of reactive sources and other voltage control equipment in system operations. The reactive sources specifically considered are: generators, synchronous condensers, switched static capacitors and shunt reactors, and transformers with and without load tap changing capabilities. The paper presents a methodology for determining the benefits that can be achieved in the proper scheduling of these sources in a power system. The benefits as shown are: savings in fuel production costs, unloading of the system equipment, improved system security, and improved voltages over the system. From a large system study conducted, it appears that these benefits can be obtained with only minor modifications in present scheduling procedures.

Multi-Area Dispatch

This paper reports upon the development of new multi-area dispatch algorithms, their implementation and use in system operations.

Z Diakoptics - Torn Subdivisions Radially Attached

The Piecewise Method of solution, better known as Diakoptics, is a procedure for solving large-scale system problems by tearing or decomposing. The problems to be analyzed seem to grow at a very rapid pace. Neither the increased computer speeds nor the computer core storages seem to keep up with the size and complexity of the problems to be solved. Diakoptics appears to be a good tool with which to supplement the computer, or computers, to solve large-scale system problems.

Automatic Sectionalization of Power System Networks for Network Solutions

This paper describes a method for the automatic optimized sectionalization of power transmission networks as required for the application of piecewise solution techniques. The optimality criterion is the minimization of the total computer core memory requirement for storage of the network impedance or admittance matrices.