N. Hosseinzadeh

An Advanced Optimal Approach for High Voltage AC Bushing Design

This paper proposes a new and advanced methodology for finding the optimum electrical design of high voltage ac capacitive graded bushings using an improved genetic algorithm approach as an effective meta-heuristic method. A case study has been conducted on a 145 kV oil impregnated paper (OIP) bushing and the IEC 60137 tests have been performed to evaluate its performance. Condenser-bushings contain concentric conductive foils which are isolated from each other. The partial capacitances between conducting cylinders can be modified by adjusting the number, diameter, place and length of these cylinders as well as the thickness of insulating material between foils. As a result, the voltage drop and also the electrical stress in the core and along the surface will change. This paper finds optimal value of bushing design parameters to achieve well-distributed electric stress with the lowest possible maximum value and also a constant voltage drop for different layers by using an improved genetic algorithm optimization method subject to practical and technological constrains. The proposed method of this research work has been applied to a 145 kV OIP bushing. The performance of optimal designed 145 kV OIP bushing under IEC 60137 tests is very promising.

Capacity Enhancement for Aging Distribution Systems using Single Wire Earth Return

Single wire earth return systems, (SWER), are the low cost technology for rural power distribution and have global application. In the Australian setting, voltage regulation is becoming the determining factor for older SWER systems. In long systems, directly connected shunt reactors are used to compensate the effects of line to ground capacitance. The replacement of fixed shunt reactors with controllable reactors provides an opportunity to approximately double the capacity of an aging infrastructure. Three case studies based on the North Jericho system are presented and a range of practical implementation issues are discussed.

Economic assessment of transmission expansion projects in competitive electricity markets - an analytical review

Restructuring of the electricity market has changed many aspects of the transmission system operation and planning. Reliability-Driven and Economic-Driven transmission expansion planning by regulated and private utilities are the substitutes of the traditional Cost-Driven transmission expansion planning. Reliability-based criteria for assessment of the transmission projects are almost well-developed while there exists a lack of a comprehensive framework for the economic evaluation of the transmission projects. Definition of a quantitative and monetary framework for economic evaluation of future transmission projects demands a detailed market analysis. In addition, specific characteristics and responsibilities of the transmission system in the open access structure must be understood comprehensively. To reaching the aforementioned goal, an analytical review on the existing economic assessment methodologies would be highly beneficial for the researchers in this area. Moreover, most of the review literatures on transmission investment in competitive electricity markets are general. These review literatures have tried to address all aspects of this challenging issue with devoting only few paragraphs to economic assessment of transmission projects. Given the aforementioned shortcomings, this article would bridge the gap by the following contributions: Firstly, reviewing available approaches for economic assessment of transmission projects based on research papers and industrial reports .Secondly, analysing the reviewed criteria critically by applying them to a modified Wood and Wollenberg 6-bus case study and Finally, summarizing the key components of a successful Economic Assessment Framework for transmission expansion or upgrade projects. Practical experiences of California Electricity Market, New England Electricity Market, Pennsylvania, New Jersey, and Maryland (PJM) and National Electricity Market, Australia have been accommodated in the article.

Design and study of a switch reactor for Central Queensland SWER system

Single wire earth return (SWER) systems are a widely applied, low cost electrification method used in many rural areas. In central queensland a single SWER system supplying approximately 100 kW may extend more than 300 km. Many SWER systems include shunt reactors to control the effects of the line charging capacitance. One effect, the Ferranti effect, causes the line voltage to rise with the distance. In three phase distribution systems this effect is not visible but in SWER systems, this effect makes it difficult to maintain the consumers supply within the acceptable regulation range. As the second effect, the loading of the SWER system supply transformer increases. Controllable shunt reactors are used as one solution to the aforementioned problems. Stanage Bay feeder in central queensland area has been chosen for the installation of the designed shunt reactor. Stange Bay feeder is supplied by an isolating transformer with the total capacity of 150 kVA and the voltage level of 22 kV. Using the Stanage Bay feeder, this paper details the process of design and simulation of a suitable switch reactor. This step has been carried out by firstly, the design of the switch reactor and secondly, the proper modelling of the designed reactor for the voltage regulation studies.

An Innovative Linkage of Curricula Design, Power Engineering Industries and Universities in Queensland Australia to Promote Engineering Education

The demand for engineers and their educators has been continuously growing in Australia. In recent years, the academia and industry leaders have proposed and implemented a number of strategies to meet the demand. One of these strategies in the State of Queensland has been the formation of power engineering alliance (PEA), which brings together industry and university partners with a common interest in education, research and professional development associated with power engineering. The objectives of the PEA are to boost the quality and number of engineering graduates with the skills and motivation for a career in power engineering, and to contribute to their ongoing professional development. Central Queensland University (CQU) has been one of the leading university partners to this alliance. CQU has been recognised as a provider of engineering teaching excellence to the Central Queensland region and beyond.

Derivation of a mathematical structure for market-based transmission augmentation in oligopoly electricity markets using multilevel programming

In this paper, we derive and evaluate a new mathematical structure for market-based augmentation of the transmission system. The closed-form mathematical structure can capture both the efficiency benefit and competition benefit of the transmission capacity. The Nash solution concept is employed to model the price-quantity game among GenCos. The multiple Nash equilibria of the game are located through a characterisation of the problem in terms of minima of the R function. The worst Nash equilibrium is used in the mechanism of transmission augmentation. The worst Nash equilibrium is defined as the one which maximises the social cost, total generation cost + total value of lost load. Thorough analysis of a simple three-node network is presented to clearly highlight the mechanism of the derived mathematical structure from different perspectives.

A Bi-level Formulation of Transmission Planning Problem in Liberalised Electricity Markets

Abstract This paper sets out an alternative formulation for transmission planning in liberalised electricity markets. The formulation follows the concept of the leader-follower game in applied mathematics. In this new formulation, the transmission network service provider acts as the leader of the game and the electricity market operator acts as the follower of the game. Using this new formulation, the transmission network service provider can measure the impact of additional transmission capacity on nodal (or regional) market prices. This allows the transmission network service provider to implicitly model the competitive effect of additional transmission capacity in its investment decisions. A metric termed L-Shape Area is developed to measure the deviation of market prices from the competitive ones. The alternative formulation is a bi-level optimisation problem. To solve this problem, the inner optimisation problem is replaced by its equivalent Karush-Kuhn-Tucker optimality conditions. The result is a non-linear programming problem that is solved using a gradient search method. IEEE 14-bus example system is used for numerical studies.

Transmission Augmentation with the Competition Benefit Modelling of Additional Transmission Capacity

Abstract Additional transmission capacity can improve the performance of the electricity market from two perspectives: firstly, efficiency benefit in terms of improving the social welfare of the electricity industry; and, secondly, competition benefit that leads to increasing competition among generating companies. This paper introduces an algorithm to model both the efficiency and competition benefits of additional transmission capacity in the process of transmission augmentation. The economic mathematical model is developed based on game theory in applied mathematics and the concept of social welfare in microeconomics. Transmission network service providers, generating companies and market management companies are placed in different stages of the developed model. The multiple Nash equilibria problem is tackled through the introduced concept of worst-Nash equilibrium. A numerical algorithm is designed to solve the developed model. The Garver’s and IEEE 14-bus example systems are carefully modified to suit the purpose of this study; the former is used for conceptual evaluation of the algorithm, and the latter for testing the developed numerical solution. The results show that the proposed approach can improve the efficiency of the electricity market and reduce the market power in the generation sector using the transmission augmentation policies.

Derivation of a new mathematical framework for transmission system augmentation using von Stackelberg game

The market-based augmentation of the high voltage transmission systems as a legacy of the previous regulated regimes has been a challenging issue for the central transmission entities. The economic assessment framework for transmission upgrades or expansion projects, considering the interaction of the central transmission entity (CTE) with the electricity market management (MMC) company both as independent players needs to be addressed appropriately at least in the National Electricity Market, Australia. To assist in bridging this gap, this paper introduces a novel metric, namely, the L-Shape Area, for the economic assessment of the transmission expansion options. The proposed methodology employs a von Stackelberg game for the interaction modelling of the central transmission entity and the market management company. The upper subproblem minimises the objective of the CTE as the leader player and the lower subproblem solves the security-constrained economic dispatch as the follower subproblem. The bi-level programming problem has been solved by applying the Kuhn-Tucker optimality conditions to the follower subproblem and the use of a gradient search method to solve the resultant single level non-linear programming problem. A modified IEEE 14-bus test system has been used to show the effectiveness of the proposed formulation.

Sensitivity based procedures for short term augmentation of transmission system in restructured electricity market

Transmission network was recognized as natural monopoly and almost everywhere subject to some kind of regulation in a restructured electricity market. The role of the transmission system is to provide an indiscriminate access for all market players along with an acceptable level of reliability and security. Regulating authorities have to decide about the augmentation investment. As an on going research on forming a robust algorithm for the expansion planning of transmission system in Queensland State, Australia, this paper presents two procedures for the quasi-optimal short-term augmentation of the transmission system. The proposed approaches can accommodate (1) Security of the power delivery to the load points of the transmission system in terms of single line outages (2) Minimization of the transmission system lost load (3) Providing full competitive electricity market for market participants (4) Construction and maintenance costs of transmission augmentation options and (5) Operation efficiency of the transmission grid in their planning frameworks. Each expansion option of the transmission system is evaluated by the aforementioned criteria through designation of a set of indices. The proposed procedures benefits from the concepts of the sensitivity analysis and dynamic programming as well as aggregation method, weighted sum function, in their multi- criteria decision making. The introduced procedures are very promising in case of short term expansion planning of the transmission system. Considering the sensitivity analysis concept employed, in case of long term planning the method is appreciable in smart detection of the suitable zones for expansion. The procedures would be very useful in case of large scale power systems. A 6 bus test system and modified IEEE 30 bus test system are used to validate the effectiveness of the proposed procedures.