O.P. Malik

Wind Energy Conversion Using A Self-Excited Induction Generator

A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated over a wide speed range. Harmonic analysis of the proposed scheme shows that harmonic currents and their associated power loss is negligible.

Load-Flow Solutions for Ill-Conditioned Power Systems by a Newton-Like Method

In this paper mathematician K.M. Browns method is used to solve load-flow problems. The method is Particularly effective for solving of ill-conditioned non- linear algebraic equations. It is a variation of Newtons method incorporating Gaussian elimination in such a way that the most recent infonnation is always used at each step of the algorithm; similar to what is done in the Gauss-Seidel process. The iteration converges locally and the convergence is quadratic in nature. A general discussion of ill-conditioning of a system of algebraic equations is given, and it is also show by the fixed-point formulation that the proposed method falls in the general category of sucessive approximation methods. Digital computer solutions by the proposed method are given for cases for which the standard load-flow methods failed to converge, namely 11-, 13- and 43-bus ill-conditioned test systems. A comparison of this method with the standard load-flow methods is also presented for the well-conditioned AEP 30-, and 57-bus systems.

Sampled Data Automatic Generation Control Analysis with Reheat Steam Turbines and Governor Dead-Band Effects

In this paper a systematic method of choosing the frequency bias parameter and the integrator gain of the sampled data supplementary control is presented by using the discrete version of the Lyapunov technique. The reheat effect of the steam turbines is considered in the state space model. The effect of governor deadband nonlinearity is considered by using the describing function approach and including the linearized equations in the state space model. It is shown that the governor dead-band nonlinearity has a destabilizing effect on the transient response with deterministic and random load disturbances for purely integral ACE control. However, this destabilizing effect is reduced by proportional feedback of ACE.

Excitation Control of Synchronous Generators Using Adaptive Regulators Part I-Theory and Simulation Results

A recent trend in power system operation is towards computerised control and management. One class of digital adaptive regulators called self- tuning regulators is suitable for this purpose. In synchronous generator control a conflict arises between the small sampling interval necessary to track the dynamics and large computation time required by the process computer. A dual-rate sampling model is suggested to alleviate this problem. A class of self-tuning regulators called Dual-rate Sampling Self-Tuning regulators which use a dual-rate sampling model of the power system are described in this paper. Simulation results obtained are used to evaluate the merits, usefulness and viability of the proposed regulator.

Self-tuning regulator based on dual-rate sampling

A self-tuning regulator based on dual-rate sampling is described in this note. A pseudostate analysis technique, which can also be used to analyze plants where control interval and sample interval are different, is introduced. Comparison of the results with standard and dual-rate sampling self-tuning regulators shows that the variance can be reduced with the proposed technique.

Excitation Control of Synchronous Generators Using Adaptive Regulators-Part II Implementation and Test Results

A dual-rate sampling self-tuning regulator for the excitation control of synchronous generator has been implemented using M6800 microprocessor. General set up of hardware and software are described in this paper. Real time test results which compare the performance of the proposed AVR with an analog AVR are presented. This paper demonstrates that the microprocessor based adaptive AVR is a viable alternative to the analog AVRs.

A Computer Study of a Pid Automatic Voltage Regulator Part II: Digital Pid Voltage Regulator With Dynamically Varying Weighting Parameters

The influence of a digital PID voltage regulator on the transient performance of a synchronous machine is examined through a simulation study. The simulation model is described in Part I and the pertinent control algorithm is described in this paper. A dynamic variation of the weighting coefficients of the voltage regulator according to the variances of the manipulated output signals has been investigated. Simulation studies conducted on a micro-machine generating unit model under different types of system disturbance conditions show that the transient response of a generating unit having a digital PID regulator with dynamically changing weighting coefficients is superior to that of the same unit when equipped with a conventional continuous acting regulator.

Microprocessor-Based Universal Regulator Using Dual-Rate Sampling

Standard single-rate sampling self-tuning regulators may not be able to effectively control fast-acting systems if the minimum computation time required is larger than the largest sampling period permissible. A dual-rate sampling self-tuning regulator that overcomes this problem by allowing a data sampling rate to be chosen consistent with the system time constants and a control output interval based on the computation time is described in this paper. This algorithm is also very suitable for implementation using fixed word-length processors as the quantization problems are minimized. The algorithm has been implemented on a microprocessor. Implementation details with emphasis on data acquisition, interrupt controlled sampling, time sufficiency test and scaling, and experimental results are also given.