Simulation and analysis of Damghan circuit feeder for optimal positioning of the capacitor in order to improve the voltage profile and reduce ohmic losses

Dissertation for Master's degree

Abstract

Preventing losses caused by blackouts and undistributed energy is very important today. Therefore, one of the most important issues in the operation of the distribution network is the renewal of the load, which has a great impact on the constant service to the subscribers. When a part of the network is cut off due to an error or planning for repairs in the distribution network, all or part of this cut off section can be fed through healthy feeders or micro-grids, using network switches. The purpose of this thesis is to analyze the reorganization of the distribution network with technical goals (reduction of losses and improvement of the voltage profile) in the presence of the micro-grid connected to the distribution network. Micro-grids: the increase in the need to produce electric power, the restructuring of electricity, the bottlenecks and limitations of building new transmission lines for long distances and the economic and environmental problems of large power plants have increased the desire for distributed generation. On the other hand, in the last century, due to the required high reliability and due to the presence of scattered production sources in distribution lines, a new concept called microgrid has been proposed in distribution lines, which has attracted the attention of many researchers. In this regard, the presence of scattered production resources and the special characteristics of energy storage resources have caused the management of production in microgrids to face a new concept. For example, an LV of a microgrid can be defined as a network of a small urban area, a shopping center, or an industrial area with its loads and various small production systems connected to it, which may be able to supply both power and heat to local loads. Under normal system conditions, the microgrid is connected to the distribution network and the loads are fed through local sources or, if needed, through a distribution network. But in case of disturbance in the system, the production and the corresponding load of a microgrid can be separated from the distribution network so that the microgrid loads are protected from disturbance. Today, vast changes are taking place in the field of distribution of power systems. The density of the presence of small renewable sources such as solar cells, fuel cells and small internal combustion engines in distribution levels is increasing day by day. This increase in the presence of renewable energy sources in distribution systems has created a new structure called micro-grid, so that before, distribution systems were dependent systems because they existed next to transmission systems. With the emergence of distributed generation and micro-grid, both consumption and production modes appeared in the distribution systems.

Micro-grid systems have different sizes and can be connected to the main power grid or used as an island. Each micro-grid consists of several small electric power generation sources called distributed generation sources, whose task is to provide power to local loads. In sensitive places such as buildings Commercial-industrial and hospitals, which generally have low inertia and their total load consumption is below one megawatt, having a backup generation for blackouts is essential. So that if for any reason the distribution system is disturbed and the produced electricity does not reach the consumer and falls below global standards, the protection systems are activated and the microgrid is separated from the distribution system and takes over the task of providing power to sensitive and non-sensitive local loads. In other words, the main task of this type of microgrid is to maintain the optimal power quality for such sensitive places. Distributed generation resources in microgrid systems can Be it wind generators, micro turbines, solar cells, fuel cells or other sources along with energy storage devices such as batteries, aircraft wheels, and energy capacitors. Despite many advantages, microgrids have created new problems in distribution systems, such as reducing environmental problems, reducing costs due to the construction of new power plants, increasing system reliability, increasing efficiency due to reducing transmission power losses, and reducing congestion in distribution feeders. Among these problems, we can mention the change of the load distribution pattern, the increase of high frequency harmonics due to the use of power electronics and frequency and voltage fluctuations.Be it wind generators, micro turbines, solar cells, fuel cells, or other sources along with energy storage devices such as batteries, airplane wheels, and energy capacitors. Microgrids have created new problems in distribution systems despite many advantages such as reducing environmental problems, reducing costs due to the construction of new power plants, increasing system reliability, increasing efficiency due to reducing transmission power losses, and reducing congestion in distribution feeders. Among these problems, we can mention the change of load distribution pattern, the increase of high-frequency harmonics due to the use of power electronics and frequency and voltage fluctuations. In a microgrid, there are small production units with an inverter power electronics interface, which are called microsources. These sources are located in local areas and have advantages such as low cost for the consumer and producer, low voltage, high reliability, increased redundancy and system strength, and high flexibility.

So in this thesis, by using the intelligent method of Morchegan algorithm, we will try to reduce power losses and voltage distortion in the test network

1-1- Introduction

Electrical energy is one of the most effective and flexible types of energy. useful like light, heat and electricity. In the absence of this energy, there will be no large industrial equipment or very small electronic devices. The final goal of the design and operation of the electrical system is to deliver electrical energy at the most economical price and the best quality in safe conditions to the consumers. In the electrical industry, a lot of importance has been given to the establishment and continuity of consumer nutrition, because today, with the advancement of technology and the modernization of social life, the need for the continuity of the electrical current required by consumers throughout the day and night is vital and is felt more and more day by day. Due to the increasing growth of electricity demand and the further expansion of the use of electrical devices in today's societies, the need to increase the production of electrical energy is felt more than ever. According to the EAI report, the amount of electricity consumption will face a 45% growth in 2030. The growth of electric energy consumption in the country is 10% annually[1]

Usually, to provide this amount of increase in demand, we must increase both the production capacity and the transmission line capacity.  However, the lack of sufficient assurance of the return of investment has caused a decrease in the ratio of the level of production capacity and load demand. This has caused a decrease in the level of the network's generation reserve, which itself causes the power system to be more vulnerable to emergency situations. In addition, the wear and tear of the network also greatly increases its vulnerability to voltage collapse. The 24-hour blackout on August 24, 2003 in America is also a testimony to this story. This incident and other similar incidents increase the interest in the stability of the voltage profile and the impact of investment costs. [2] In our country, Iran, there are two types of blackouts, one occurred on May 30, 1980, and the other on April 12, 1982, which showed the vulnerability of power systems in the face of errors. Studies show that most interruptions and shutdowns of consumers (about 80%) are caused by instability. Therefore, stability in voltage stability has received more attention in recent decades. [3]

With the advancement of technology and studies on semiconductor parts, semiconductors have found a wide application in the electrical industry, and the stabilization of the ability of semiconductors and the construction of interfaces and power electronic converters, as well as the emergence of economic and environmental trends, another option to increase the transmission capacity has been placed on network engineers and power systems, which is the Facts tools. shows that Facts devices will play a very important role in power systems in the near future. [2 and 3]

The main task and goal of an advanced power system is to produce electricity in the most economical way possible and transmit it through transmission lines with the lowest cost and distribution with high efficiency in order to deliver to consumers at an acceptable level of voltage and frequency. A power system consists of three parts: generation, transmission and distribution. Today, with the advancement of technology and the modernization of life, the necessity of continuous service to subscribers and consumers of electric energy is felt more and more, but it is not possible to fulfill such a request despite the existence of different consumers (industry, commercial, domestic), considering the distance dimension which is often long and beyond the control of engineers.