Volume 7, Issue 1

Recently, using a non-linear programming method authors have demonstrated that based on certain criteria if some non-significant selectivity constraints are relaxed, all remaining constraints happen to be feasible but the solution of coordination problem is not possible with the conventional objective function as optimization procedure leaves the solution space [20]. In coordination studies solution with the conventional objective function provides minimum relay operating times. The present paper describes an additional criterion so that the solution with the conventional objective function can be achieved. This paper also achieves the acceptable speed of the primary protection while attempting to coordinate the maximum relay pairs. Complete results are presented in this paper in this regard. This paper uses the non-linear Random Search Technique to solve the coordination problem, which has been successfully applied in many problem areas.

Dynamic behaviour analysis of electric power system has always played a vital role in operation and planning of power systems. This analysis relies on computer simulation which are usually based on simplifying assumptions which aim at rendering system modelling more amenable to numerical solution. However, it is well known that uncertainties and unmodelled dynamics could in some cases lead to unexpected results. In the paper a simplified dynamic model of transmission network is employed to evaluate the influence of network transients on dynamic behaviour of power systems. Although simplified, this model can easily capture usually neglected dynamics. Applications of this modelling is proposed with respect to two test systems, highlighting the effects of usually unmodelled dynamics.

Electrical energy planning of modern electric power system requires great attention for the air pollution problem. This is in accordance to the increasing tendency to optimise the production processes in the respect of their sustainability. Moreover, the advent of the deregulation in the electric energy market has involved substantial modifications of philosophy in planning and managing the electrical power system. These aspects together offer new challenge in defining proper system study methodologies and suitable planning strategies. One of the most complex problems in the planning strategies is the data management uncertainty related to load forecasting and environmental modelling. In this paper a robust optimal planning procedure is formalized, taking adequately into account the problem of stochastic variables presence, allowing to satisfy the air quality and load demand forecast constraints in spite of uncertainties. The proposed approach addresses generation planning, where the various aspects have been integrated to solve the problem in a feasible and realistic way. A numerical application to an electrical power system with respect to a regional area is reported in the final part of the paper, showing the applicability of the proposed methodology.

Japan imports almost all of the energy resources with 40% of them used for electricity generation. Electricity is generated mainly by five types of power plants (LNG-fired, LNG-CC, oil-fired, coal-fired, and nuclear), which have various environmental impacts, for example, fossil fuel depletion, global warming, acid rain, etc.The purpose of this paper is to make a life cycle assessment (LCA) of the electricity generating processes of power plants in Japan and to suggest some concrete measures to reduce the environmental impacts.Our study proceeds as follows. We focus on the fuel procuring process reflecting Japan's import of fuel resources and then the whole electricity generating process of the different types of power plants. Firstly, we quantify the environmental loads resulting from each type of plant by Life Cycle Inventory (LCI) analysis. Secondly, Life Cycle Impact Assessment (LCIA) method is applied to evaluate the total impacts of each type of plant. Thirdly, we make some concluding remarks on reduction of the environmental impacts. LCI analysis and LCIA evaluation are done with use of the 'LCA-NETS' scheme we have developed.Our LCIA evaluation shows that in the fuel procuring process nuclear plants rank top, coal-fired plants second, oil-fired plants third, and LNG-fired plants bottom in the ascending (better) order of the `NETS/MJ' values, and that in the whole electricity generating process LNG-CC plants rank top, LNG-fired and coal-fired plants second, oil-fired plants third and nuclear plants last in the ascending (better) order of the `NETS/kWh' values.Our findings about the fuel procuring process imply that if LNG-fired plants can find an effective usage of their byproduct of cold energy or import natural gas without liquefaction directly from nearby countries, they will rank up next to nuclear plants and that if any legal regulations of desulfurization are imposed on sea transportation the impacts of crude oil and coal will be reduced a great deal.It follows from the total evaluation of the whole electricity generating process that if coal-fired plants can reduce the total impacts by 20% by introducing a technology of coal gasification they will be superior to LNG-CC plants and that if nuclear plants can adopt a technology of recycling uranium to reduce the total impacts by 50% they will be as good as LNG-CC plants.

This paper presents the development of an artificial neural network (ANN) controller for a Static Var Compensator (SVC) system compensating unbalanced fluctuating loads. The proposed controller can balance and reduce the reactive power drawn from the source under unbalanced loads while keeping harmonic injection to the system due to SVC operation low. The first stage of controller development is a fuzzy logic based control algorithm. This algorithm determines a number of possible operating states of SVC for a given load condition and calculates corresponding harmonics injections. Then a fuzzy logic system is used to rank those operating states in terms of the magnitude of the reactive power drawn from the source and the harmonic injection level indicated by Total Demand Distortion (TDD). The best operating state is selected based on the ranking score assigned by the fuzzy logic ranking system. Finally, computational speed of the controller is improved by replacing the analytical and fuzzy computations by a set of neural networks trained with data generated with fuzzy logic based controller.

Power engineers are currently facing challenges to increase the power transfer capabilities of existing transmission system. Flexible AC Transmission system (FACTS) controllers can balance the power flow and thereby use the existing power system network most efficiently. Because of their fast response, FACTS controllers can also improve the stability of an electrical power system by helping critically disturbed generators to give away the excess energy gained through the acceleration during fault. Thyristor controlled series compensator (TCSC) is an important device in FACTS family, and is widely recognized as an effective and economical means to solve the power system stability problem. TCSC is used as series compensator in transmission system. In the present work a TCSC controller is designed and tested over a single machine infinite bus (SMIB) as well as a multi-machine power system. Detailed simulation studies are carried out with MATLAB/SIMULINK environment and the effect of the TCSC parameter variations over the system stability is studied.

A novel simulation-based spectral technique for power quality and electromagnetic compatibility (EMC) design of an independent electrical power system (EPS) has been proposed. Power filter optimization problem has been formulated to provide full solution of the electric power quality and conducted EMI problems in the EPS. The spectral technique has been implemented within a CAD tool. An example of power quality and EMC design has been provided for an independent EPS where an AC power source generates a power, which is comparable to the consumed power, and an additional power filter is calculated for an electronic product including a switch-mode power supply. Current and voltage spectra calculations have been verified with a block-oriented simulation program Simulink. Numerical experiments revealed a number of important features of the proposed spectral technique.