In this dissertation topics of optimal meter placement and transaction-based loss allocation in deregulated power system operation are investigated. Firstly, Chapter II introduces the basic idea of candidate measurement identification, which is the selection of candidate measurement sets, each of which will make the system observable under a given contingency (loss of measurements and network topology changes). A new method is then developed for optimal meter placement, which is the choice of the optimal combination out of the selected candidate measurement sets in order to ensure the entire system observability under any one of the contingencies. A new method, which allows a natural separation of losses among individual transactions in a multiple-transaction setting is proposed in Chapter III. The proposed method does not use any approximations such as a D.C. power flow, avoiding method induced inaccuracies. The power network losses are expressed in terms of individual power transactions. A transaction-loss matrix, which illustrates the breakdown of losses introduced by each individual transaction and interactions between any two transactions, is created. The network losses can then be allocated to each transaction based on the transaction-loss matrix entries. The conventional power flow analysis is extended in Chapter IV to combine with the transaction loss allocation. A systematic solution procedure is formed in order to adjust generation while simultaneously allocating losses to the generators designated by individual transactions. Furthermore, Chapter V presents an Optimal Power Flow (OPF) algorithm to optimize the loss compensation if some transactions elect to purchase the loss service from the Independent System Operator (ISO) and accordingly the incurred losses are fairly allocated back to individual transactions. IEEE test systems have been used to verify the effectiveness of the proposed method.

The introduction of deregulation and subsequent open access policy in electricity sector has brought competition in energy market. Allocation of transmission loss has become a contentious issue among the electricity producers and consumers. A closed form solution for transmission loss allocation does not exist due to the fact that transmission loss is a highly non-linear function of system states and it is a non-separable quantity. In absence of a closed form solution different utilities use different methods for transmission loss allocation. Most of these techniques involve complex mathematical operations and time consuming computations. A new transmission loss allocation tool based on artificial neural network has been developed and presented in this thesis. The proposed artificial neural network computes loss allocation much faster than other methods. A relatively short execution time of the proposed method makes it a suitable candidate for being a part of a real time decision making process. Most independent system variables can be used as inputs to this neural network which in turn makes the loss allocation procedure responsive to practical situations. Moreover, transmission line status (available or failed) was included in neural network inputs to make the proposed network capable of allocating loss even during the failure of a transmission line. The proposed neural networks were utilized to allocate losses in two types of energy transactions: bilateral contracts and power pool operation. Two loss allocation methods were utilized to develop training and testing patterns; the Incremental Load Flow Approach was utilized for loss allocation in the context of bilateral transaction and the Z-bus allocation was utilized in the context of pool operation. The IEEE 24-bus reliability network was utilized to conduct studies and illustrate numerical examples for bilateral transactions and the IEEE 14-bus network was utilized for pool operation. Techniques were developed to expedite the training of the neural networks and to improve the accuracy of results.

The introduction of deregulation and subsequent open access policy in electricity sector has brought competition in energy market. Allocation of transmission loss has become a contentious issue among the electricity producers and consumers. A closed form solution for transmission loss allocation does not exist due to the fact that transmission loss is a highly non-linear function of system states and it is a non-separable quantity. In absence of a closed form solution different utilities use different methods for transmission loss allocation. Most of these techniques involve complex mathematical operations and time consuming computations. A new transmission loss allocation tool based on artificial neural network has been developed and presented in this thesis. The proposed artificial neural network computes loss allocation much faster than other methods. A relatively short execution time of the proposed method makes it a suitable candidate for being a part of a real time decision making process. Most independent system variables can be used as inputs to this neural network which in turn makes the loss allocation procedure responsive to practical situations. Moreover, transmission line status (available or failed) was included in neural network inputs to make the proposed network capable of allocating loss even during the failure of a transmission line. The proposed neural networks were utilized to allocate losses in two types of energy transactions: bilateral contracts and power pool operation. Two loss allocation methods were utilized to develop training and testing patterns; the Incremental Load Flow Approach was utilized for loss allocation in the context of bilateral transaction and the Z-bus allocation was utilized in the context of pool operation. The IEEE 24-bus reliability network was utilized to conduct studies and illustrate numerical examples for bilateral transactions and the IEEE 14-bus network was utilized for pool operation. Techniques were developed to expedite the training of the neural networks and to improve the accuracy of results.

Made available in DSpace on 2016-08-17T14:53:08Z (GMT). No. of bitstreams: 1 Bartolomeu ferreira.pdf: 2681101 bytes, checksum: 05d2fad3f69568c193c20ccd8addecd7 (MD5) Previous issue date: 2007-04-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The goal of loss allocation methodologies is to share the responsibility for transmission losses among generators and loads. Several loss allocation methods have been developed to solve this problem. However, there is not consensus regarding to the most appropriated approach methodology. There are some methods presenting suitable accuracy, however, still remains the equity question. It can say that there isn t an ideal method, although it is desirable that any method achieve efficient allocation criteria. In this work, it is proposed a methodology for active power transmission loss allocation, based on circuit laws, proportional sharing and superposition principles. The methodology uses a load flow solution to share the global loss of the system among market participants. The problem is divided into operation scenarios and taking into account transmission paths used by generators to supply the loads. Tests, analyses and comparison with some methods proposed in literature are performed, using a five bus test system, and IEEE 30 and IEEE 118 systems. / Os métodos de alocação de perdas têm como objetivo distribuir entre os geradores e cargas a responsabilidade por perdas no sistema de transmissão, de uma forma equilibrada. Embora existam vários métodos de alocação propostos na literatura para resolver este problema, ainda não existe um consenso sobre o melhor critério a ser seguido, sendo que atualmente cada país utiliza uma metodologia diferente com maior ou menor grau de aproximação. Há alguns métodos que poderiam ser considerados como exatos , entretanto a questão da equidade ainda continua em aberto. Pode-se afirmar que ainda não existe nenhum método ideal, embora seja desejável que qualquer metodologia objetive atingir a critérios eficientes de alocação. Neste trabalho é proposta uma metodologia para alocação de perdas ativas de transmissão, baseada nas leis de circuito, no princípio da divisão proporcional e no teorema da superposição. A metodologia utiliza os resultados de um fluxo de carga para alocar eficientemente a perda total do sistema entre os participantes do mercado, dividindo o problema em cenários de operação e considerando os caminhos de transmissão utilizados pelos geradores para suprir as demandas das cargas. São realizadas simulações e análises e comparações com alguns métodos já propostos na literatura, utilizando-se: um sistema teste de cinco barras, e os sistemas IEEE 30 e IEEE 118.

In recent years, the electric power industry around the world is changing continuously due to transformation from regulated market structure to deregulated market structure. The main aim of the transformation of electric supply industry under open access environment is to overcome the some of the limitations faced by the vertically integrated system. It is believed that this transformation will bring in new technologies, integration of other sources of energy such as wind, solar, fuel cells, bio-gas, etc., which are self sustainable and competitive, and better choice for the consumers and so on. As a result, several new issues and challenges have emerged. One of the main issues in power systems is to support reactive power for maintaining the system voltage profile with an acceptable margin of security and reliability required for system operation. In this context, the thesis addresses some of the problems related to planning and operation of reactive power in power systems. Studies are mainly focused on steady state operation of grid systems, grid connected wind farms and distribution systems as well. The reactive power support and loss allocation using Y-bus approach is proposed. It computes the reactive power contribution from various reactive sources to meet the reactive load demand and losses. Further, the allocation of reactive power loss to load or sink buses is also computed. Detailed case studies are carried out on 11-bus equivalent system of Indian southern region power grid under different loading conditions and also tested on 259-bus equivalent system of Indian western region power grid. A comparative analysis is also carried out with the proportional sharing principle and one of the circuit based approach in the literature to highlight the features of the proposed approach. A new reactive power loss index is proposed for identification of weak buses in the system. The new index is computed from the proposed Y-bus approach for the system under intact condition as well as some severe contingencies cases. Fuzzy logic approach is used to select the important and severe line contingencies from the contingency list. The validation of weak load buses identification from the proposed reactive power loss index with that from other well known existing methods in the literature such as Q-V sensitivity based modal analysis and continuation power flow method is carried out to demonstrate the effectiveness of the proposed index. Then, a short-term reactive power procurement/optimal reactive power dispatch analysis is also carried out to determine the optimum size of the reactive compensation devices to be placed at the weak buses for reactive compensation performance analysis in the system. The proposed approach is illustrated on a sample 5-bus system, and tested on sample 10-bus equivalent system and 72-bus equivalent system of Indian southern region power grid. A comprehensive power flow analysis of PQ type models for wind turbine generating units is presented. The different PQ type models of fixed/semi-variable speed wind turbine generating units are considered for the studies. In addition, the variable speed wind turbine generating units are considered in fixed power factor mode of operation. Based on these models, a comparative analysis is carried out to assess the impact of wind generation on distribution and transmission systems. 27-bus equivalent distribution test system, 93-bus equivalent test system and SR 297-bus equivalent grid connected wind system are considered for the studies. Lastly, reactive power coordination for voltage stability improvement in grid connected wind farms with different types of wind turbine generating units based on fuzzy logic approach is presented. In the proposed approach, the load bus voltage deviation is minimized by changing the reactive power controllers according to their sensitivity using fuzzy set theory. The fixed/semi-variable speed wind turbine generating units are also considered in the studies because of its impact on overall system voltage performance even though they do not support the system for voltage unlike variable speed wind generators. 297-bus equivalent and 417-bus equivalent grid connected wind systems are considered to present the simulation results. A comparative analysis is also carried out with the conventional linear programming based reactive power optimization technique to highlight the features of the proposed approach.