Determining the location, capacity and optimal start-up time of gas-burning generators in order to maintain the reliability of the network, taking into account the problem of electricity transit.

Electrical Engineering Master's Thesis - Restructuring

Abstract

As the last link in the electricity supply chain to subscribers, the managers of distribution systems face problems in their long-term decisions. Paying attention to electricity markets and rates affected by the performance of electricity market players challenges distribution companies, who are responsible and own distribution systems, in making major decisions. On the other hand, scattered productions are sources and options that are developed in order to provide power to subscribers and immunity from additional costs, along with the development of lines, posts, etc. They are considered by decision makers. On the other hand, these resources can be useful in reducing losses and improving reliability. In this thesis, the development of scattered production resources is exclusively considered, and among the various technologies, we choose the gas generator and carry out the development in such a way as to determine the optimal time, place and capacity of the resources needed in the planning period, according to reliability considerations. Studies are conducted in several models, in which retailers will not have a place in the market.  Investigating the development of scattered production resources belonging to distribution companies, investigating the development in the presence of private producers, and investigating the development in the case where there is a possibility of electricity transit in the system, are among the studies of this thesis. But before starting the studies according to the defined models, in the first chapter we will have a brief introduction to distribution networks. In the second chapter, an overview of the types of technology of distributed production resources and the importance of examining them is done. The third chapter presents how to model the problem and the fourth chapter describes the formulation of this problem. Finally, in the fifth chapter, simulation and numerical studies will be carried out to achieve the above goals.

Introduction

In today's societies with the rapid growth of the use of electrical energy, the vital role of this energy is more obvious than ever. Distribution systems play an essential role in providing quality and appropriate service to consumers. There are various objectives in the series of electrical energy distribution system design. However, in this process, first the growth of subscribers is predicted and then the need or lack of capacity development is determined. In a general view, the proposed options in capacity development include the construction or upgrading of posts and lines and scattered production sources, which have recently been considered.  

Since the use of distributed production resources can have many advantages, in this thesis it is used as the only option in development. Therefore, the course of the thesis will be according to figure (1). As it is known, in the first chapter, a brief overview of power networks will be done with an emphasis on electrical distribution systems. In the second chapter, a brief introduction to the types of distributed production sources and their impact on the electrical distribution networks along with the studies conducted in this field are specified. In the third chapter, how to model the problem will be described. In the fourth chapter, the formulation of the development of distributed production resources is described, and in the fifth chapter, the simulation and results in different situations will be described. Finally, in the sixth chapter, conclusions and suggestions will be presented.

Figure 1: Structure of the thesis

Chapter One

Familiarity with the structure of electrical networks with an emphasis on the distribution section

1 Familiarization with the structure of electrical networks with emphasis on the distribution sector

1-1 Introduction

Today, due to the strong dependence on electrical energy, the vital role of this energy in life is not hidden from anyone. Distribution systems, which are the last part of the electricity supply chain to the consumers of this energy, play an essential role in providing a suitable, reliable and quality service. In this section, due to the mentioned importance, we will present the structure of a power system relying on the electrical energy distribution section.

1-2       The structure of power systems

The importance of electrical energy in the life of today's societies is not hidden from anyone. Due to the simplicity of conversion to other types of energy, ease of transfer, easy control and environmental considerations, electric energy has been used more than other types of energy.The main goal of a power system is to provide the electrical energy needed by subscribers with the lowest price and the best possible quality. In the current situation, electrical energy is mainly produced in thermal power plants, either thermal or gas, as well as hydroelectric and nuclear power plants, which are usually located at great distances from consumption centers. The location of power plants is chosen according to environmental considerations, the availability of fuel and usually a lot of water, proximity to consumption centers and many other factors, generally in such a way that the cost of construction and operation is minimized according to all factors. In order to reduce losses, the energy produced is transported with very high voltages and by transmission lines near the consumption centers, and after reducing the voltage, it reaches the consumers through the distribution network. Therefore, the electricity industry has always been associated with the three main activities of production, transmission and distribution, and most of the institutions that are active in the field of energy cover one of the above-mentioned three activities in a specific geographical area [1]. be environmental. Therefore, it seems necessary to have a proper energy transmission system available to transfer the energy of these power plants to the consumption centers. To transmit large amounts of energy over long distances, a very high voltage system is needed, which is sometimes called the main transmission system. These systems work with voltages above 300 kV, usually 400 or 500 or 765 kV. Usually the following definitions are used for different voltage levels. Weak or low voltage (LV) refers to less than one kilovolt. Medium voltage (MV) covers voltages between 1 to 36 kV and is especially used in distribution networks, and high voltage (HV) is used for voltages above 36 kV. Of course, in each electrical energy system, the concepts of low, medium and high voltage are relative and do not necessarily match perfectly with what is used in another system. Very high voltage (EHV) is usually used to emphasize voltages above 300 kV. Transmission networks are usually interconnected, and for complex networks, even simultaneous faults and errors may not cause interruption of consumers. At the lower level of the transmission network, there are two or three levels of distribution voltage to meet the load and requirements of different subscribers. In general, medium and low voltage networks are designed and operated radially. Figure 1-1 shows the hierarchy of sending electric energy from production points to consumption [8]. Figure 1-1: How to send electric energy from production points to consumption [8]. In figure (1-2), the connection of different networks is shown schematically and the voltage levels used in these networks are from low voltage LV, to medium voltage MV, high voltage HV, and finally very high voltage EHV. Figure 1-2: The connection of power system parts from the point of view of voltage levels [1]. consumption, all kinds of distribution networks can be used to meet the needs of subscribers. The classification of networks is as follows [1]:

<>Simple radial networks: this network is fed only from one feeder of the post above distribution, and only one input line and one output line can be connected to each bus. Compound radial network: these networks are also fed from only one feeder of the post, but more than one output line is connected to some buses. Radial networks are simple and cheap. The cheapness of these networks is due to the small number of equipment on the one hand and the relatively low power of the short circuit and as a result the equipment is simple and cheap on the other hand. Ring networks with feeding on one side: this network, like the radial network, is fed only from one feeder of the super distribution post, but each substation is connected to this feeder from two sides. Usually, in ring networks, a key that is open under normal conditions is used, and the network is operated radially.