Network development planning along with production

Dissertation for master's degree in power oriented electrical engineering

Abstract

In this thesis, a new method for optimal location of power plants has been discussed in order to simultaneously optimize production and network development. In the considered optimization problem, the goal is to choose the type and capacity of new power plants and the time and place of their construction so that all the objectives of the optimization problem are met. In this research, while modeling the aforementioned optimization problem, applying the cost index by considering the investment cost, production cost, unsupplied energy cost and maintenance cost has been attempted and it has been discussed in a new perspective in power grid planning. Based on this, the purpose of the research was to minimize the cost and better location of the power plants. Also, in the present research, genetic algorithm was used to solve the mentioned problem, and the software package prepared was tested on a Garver test power network with a design horizon of 10 years, and its results were compared with the ant colony algorithm method. Keywords: production development planning, transmission development planning, capital Placement, location of power plant, ant colony algorithm

1 Introduction

Planning the development of power plants is one of the most important parts of planning the development of power networks. Transmission networks are responsible for the transmission of produced electrical energy, the purpose of which is to find a suitable model for the development of power plants, which, by constructing them, while supplying the energy needed by consumers in a reliable manner, the lowest cost is also imposed on the network to supply loads, and the network also achieves the highest level of stability, and the losses of transmission lines by power plants are in their optimal conditions. Based on this, in the aforementioned planning, it should be determined when and where new power plants of the same capacity should be built in order to meet the above goals. This planning is usually done for a period of 10 to 20 years.[1] 

Researches carried out regarding planning the development of production and placement of power plants can be examined in three cases: firstly, the objective function of the mentioned optimization problem, secondly, the type of constraints, and finally, the method of solving the optimization problem has been used. Based on this, in many researches conducted, the goal has been to minimize costs and better location.

1-2 Introduction to simultaneous development planning

The total practical capacity of power plants installed in a power grid should be equal to the total power required by all consumers plus the total power losses, the total internal power consumption. substations and power plants and a percentage as rotating reserve in the studied time frame, if the total practical capacity of the installed power plants is less than the required amount, a combination of new power plants with minimum cost should be added to the total network. In development planning, the goal is to determine the type, capacity, construction location and time of entry of new power plant units to meet the balance of production and consumption in the network and with the lowest possible cost. To determine the location of power plants, it is necessary to consider how the load is distributed in the studied area, along with the environmental restrictions for the construction of power plants, the limits of transmission lines for the transmission of production power, and fuel supply limits. Due to the large dimensions of the production system development planning problem, it is usually divided into two separate problems. In the first problem, which is called the problem of planning the development of the production system in the network, the determination of the location of the power plants is omitted and only the type of power plants, their arrival time and capacity are determined. The second problem is usually that it is assumed that the first problem has been solved and as a result the type of power plants, their arrival time and capacity are known. Now, taking into account factors such as geographical distribution of load, environmental restrictions and fuel supply, transmission network structure, etc., the discussion of power plant location is followed.On the other hand, the distance of the power plants from the consumption centers may lead to an increase in the cost of development of the transmission lines, or the large distance of the power plants from the fuel centers may lead to an increase in the cost of production. Considering the above factors, it cannot be said that planning the development of production in the single-bus network is an optimal plan, but due to the difficulty of planning considering the location of the power plants at the same time, usually the issue of the location of the power plants is considered separately. The cost of developing power plants and operating them in a power system depends on the location of the power plants. Because in addition to creating a connection between the production and distribution of electrical energy, it provides a comprehensive and reliable platform for producers and consumers. Therefore, the design and planning of a suitable and flexible transmission system is of particular importance. The task of dynamic transmission network development planning (DTNEP), which is also interpreted as long-term planning in some sources, is to determine the location and time of construction of new transmission lines along with the relevant technical specifications (such as number, type, voltage level, etc.). To develop the transmission network in accordance with the growth of the load and the result of planning the development of the production network in the studied period until the delivery of electric energy to the load centers is done in the most economical way possible, taking into account a set of operational restrictions and reliability. While in STNEP, only the number and location of the construction of lines required for a specific horizon year is determined, and for the sake of simplification, the time parameter is removed from the unknowns of the problem.  In the meantime, the structure of the distribution lines is radial, while the above distribution and transmission lines are not of this type.  In terms of line development planning, transmission and super distribution network development methods are almost in the same category and the same methods are used for their development and they have almost the same model, while distribution lines are different from the two in terms of model and development planning. The transmission network is an accurate model of this problem.

In the case of development of transmission lines, the type and time of need for lines are taken into consideration.  In this case, it is assumed that the amount of loads of posts and production centers is known and the production is sufficient [22 and 1].  The researches conducted in this field have been different from each other in terms of problem solving method, considering the horizon year, competitiveness of the system and optimization tools.  The first step towards the precise planning of the transmission network development problem is to express a precise model of this problem.  In general, the network development model includes tools that select network development options from among the available options and by adding them to the existing network, it can provide an optimal plan for network development. To measure the reliability of a system, first the system is broken into components and the reliability of the system is expressed in terms of the reliability of its components. To calculate the reliability of each component based on the available statistical data, a model is selected for the rate of failure and its parameters are estimated based on the available data.

In recent years, the investigation of reliability has been considered in the design, planning and operation of power systems. Among the problems in this study, it can be mentioned that the information is scattered on different levels, so that it can answer problems such as: