Hosam K. M. Youssef

A genetic based algorithm for frequency-relaying applications

Abstract In this paper, a new method for on-line tracking of power system frequency is presented. The method is based on genetic algorithms (GAs) optimization technique. GAs are optimization and learning techniques based on natural selection and natural population genetics. The problem is formulated as an estimation problem. GAs with different fitness functions, that evaluate the solution are presented. Simulated examples are used to test the proposed method. Different voltage waveforms with different frequency deviation from the nominal value as well as different magnitudes are generated to perform the study. The bus voltage waveform in each case is sampled at a pre-selected rate to form the digital data set. The effects of sampling rate, sample window size as well as the effects of GAs parameters and operators, such as population size, crossover and mutation probabilities are studied. Results are reported and discussed.

Genetic based algorithm for security constrained power system economic dispatch

Abstract Genetic algorithms are relatively new, however they represent a powerful technique based on biological concepts and are very suitable for solving optimization problems. One such optimization problem is power system security with consideration of economic dispatch. This paper presents a new approach based on constrained genetic algorithms to solve such optimization problems. The operation of power systems demands a high degree of security in order to keep the system operating satisfactorily when subjected to disturbances, while at the same time it is required to take economic aspects into account. A pattern recognition technique is used first to assess dynamic security. Linear classifiers that determine the stability of electric power systems are presented and added to other system stability and operational constraints. The problem is formulated as a constrained optimization problem in a way that ensures a secure and economic system of operation. A genetic algorithm is then used to solve the formulated optimization problem. The method is tested using two different test systems and the results obtained show that the it is very useful for solving such problems.

Optimal sizing of fixed capacitor banks placed on a distorted interconnected distribution networks by Genetic Algorithms

In this paper, the optimal sizing of fixed capacitor banks problem in a distorted interconnected distribution system is formulated and solved by a genetic algorithm (GA) solution technique to minimize the cost of power production and capacitor banks under the constraints include voltage limits , sizes of installed capacitors and total harmonic distortion (THD), the algorithm is applied on IEEE 30-bus test system and the results are given for different cases: light and heavy harmonic cases. Computer simulation shows that the harmonic components affect the optimal capacitor sizing.

Genetic-based algorithm for identification of synchronous machine parameters using short-circuit tests

In this paper a new method for the digital identification of synchronous machine parameters from short-circuit tests is presented. The method is based on the genetic algorithm optimization technique. Genetic algorithms (GAs) are adaptive search procedures based on the mechanism of natural selection and genetics. This kind of algorithm can search for a global solution using multiple paths. The proposed method uses a digital set of measurements for the short-circuit current for estimating direct axis reactance and time constant. A set of over-determined system of equations is constructed using the digital current samples. The identification problem is then solved using the proposed GAs-based method. Different fitness functions that evaluate the solutions are suggested. A practical case study is presented in this work to evaluate the proposed method. Results are reported and conclusions are drawn. Copyright

Optimum VAr sizing & allocation using particle swarm optimization

This paper proposes a new solution technique for finding the optimum location and sizing of the shunt compensation devices in transmission system. This problem is not important only for improving the voltage profile but also for increasing the stability margin and enhancing the voltage stability of the system. The problem can be formulated as an integer nonlinear optimization problem. The newly developed evolutionary technique particle swarm optimization (PSO) is used to solve this problem. Case studies with the Ward-Hale 6-bus, IEEE 14-bus and 30-bus systems are presented to illustrate the applicability of the algorithm

Physical interpretation of electric energy flow under sinusoidal and non-sinusoidal conditions

This paper introduces an analytical derivation to evaluate the flow of electric energy in power networks. This derivation is based on the paper “New Notions Suggested to power theory development - part 1: analytical derivation” published in IEEE/PES general meeting 2008. It is proven that the true energy that totally transfers to (or from) the system is the energy which belongs to the average true power only i.e. active power produced from voltage and current of the same harmonic order. All other kinds of energy are fluctuating sinusoidaly and the net transferred energy belongs to these sinusoidal power components is nil. It is a theoretical attempt to prove that the new definitions of power components suggested in paper mentioned above are connected with their associated energies and to find the physical essence of the power components under sinusoidal and non-sinusoidal conditions.

Evaluation of current transformer performance in the presence of remnant flux and harmonics

This paper studies and evaluates the effect of current transformer (CT) distortion parameters on its performance using various secondary current calculation methods according to IEC 44–1 & 44–6 like: magnitude (ratio) error, peak instantaneous error, phase error and composite error. These parameters include: multiple short circuit level (Isc/IR), secondary burden value & type, DC component (X/R ratio & fault inception angle), remanent factor (Kr) and both external & internal harmonics.

New notions suggested to power theory development part 2: A concept for sharing the responsibility of harmonics

A new approach is introduced to determine the harmonic contributions between the customer and utility at the point of common coupling. This approach is based on new definitions of power components suggested by the same authors in [1]. It can determine the quantity and direction of power for each harmonic order. This method can be implemented in any power quality measurement device. Also, it will be useful in arriving at equitable ways of settling customer complaints, sharing the cost of harmonic distortion through rate structure and penalties, etc.

Computerized bus-bar joint preliminary design

Contact resistance of bus-bar joints (contacts) plays the major role in joints performance which leads us to study and evaluate such contact resistance and the factors affecting it. In this work, a mathematical model, for the bus-bar joint, has been implemented in order to predict temperature distribution along and beside the contact, based on the evaluation of heat generation as a function of time. Based on the above, the life time of the bus-bar system was then calculated versus loading current joint length and clamping force. The results indicated that increasing joint length and clamping force, up to certain limits, would improve joint performance. The mathematical model results have been experimentally verified using a test bus-bar system. The obtained analytical results were in a good agreement with the experimental results.<<ETX>>