This paper focuses on the technical specifications and design of a power network for an oil depot. The power distribution network is probably the most important part in power engineering because it links the producer of the power to electrical loads. The principal advantages of designed power networks are efficient performance, continuous supply, safety equipment and uncomplicated maintenance. The design of the network specified in the paper provides minimum power losses and allows interchangeability of equipment and the addition of loads. The study implements practical experiences and theories in fault calculations, design and technical specifications related to power transformers, diesel generator, switchgear and power cable loads with the right selection of electrical equipment. To provide a stable network, the selection procedure related to the electrical equipment is required such as cables, transformers, diesel generators and circuit breakers is presented. The lifespan for designing will be approximately 30-years. This is achieved by adding spare feeders and estimating extra future loads. In addition, the design will be simulated by a software known as (ERACS). Although other factors (such as finance) are critical for choosing the equipment, they are not considered in this study, as the scope of the article concentrates primarily on the technical aspects.
Introduction
The distribution network consists of medium voltage (MV) and low voltage (LV) networks. The LV planning process of the in-power distribution involves determining the placement and moreover, rating the equipment used in the distribution network, such as (transformers, generators and feeders). While the planning process for the MV networks involves identifying the location and size of the substations and MV feeders. The primary purpose of the MV network planning is: reduce the power loss and increase the reliability indices. Petroleum depots are incredibly large industrial infrastructures and a significant source of the national budget in Iraq. The primary purpose of the oil depot is storing crude oil and a variety of oil products; specifically, it includes loading and unloading pumping stations, storage tanks and utility units.
The aim and objective of this paper is to design a power distribution system for an oil depot that is located in the south of Iraq (between Baghdad and Basra) at Longitude 45O and Latitude 32O (The aim of this paper is to design a power distribution system for an oil depot which will be suitable to the specification of electrical National Grid in Iraq.). The power network in this depot will be composed of three electrical stations which include the main station and two substations. The philosophy of choice related to more than one substations is to avoid a voltage drop due to the distance between the feeders and loads. The main substation consists of a 33/11kv power transformer and switchgear (MV and LV). One of the substations consists of 3.3/11kv and 3.3/0.4 kV power transformers and switchgear (MV and LV). The other one has a 3.3/0.4kv power transformer and switchgear (MV and LV). The main feeder supplies the main station via Iraq’s national electricity grid. The distance between the feeder source (National Grid) and the depot site is approximately six kilometres.
During the design process, the primary concerns should be improving network reliability and voltage level (the voltage range of the project equipment has to correspond to the technical specifications of the equipment in the data sheets and nameplate). Likewise, the supporting peak load level and load are significant factors to consider. To attain reliability and the loads level of the network, several limitations have to be satisfied. The limitations include the bus voltage and the actual feeder current. The bus voltage should be maintained at a conventional range, while the feeder current should not fall below the rated feeder current. During the design stage, line loss and voltage drop should also be considered. Although the voltage drop can be alleviated by determining the optimal voltage level, most power distribution network designers use the voltage level of the distribution system close to the area. An alternative means of controlling line loss and voltage levels are activating the Tap changers of transformer to reach the best rating voltage, installation of a capacitors bank and voltage regulators (whichever is better).
LITERATURE REVIEW
For a power distribution system to be effective, it is important to obtain information regarding the load profile and the types of power distribution applicable to the design [11]. Other basic factors that need to be considered include the standards of the electric power distribution system, structural functions of the distribution system, in addition to the flexibility and lifespan of the structure, service entrance location, power consumption and load diversity factors, the source of the power, and the quality and continuity of the required power [10]. There are many applied standards. The North American standard requires a secondary voltage level of 208/120 volts and 190/110 volts, while the European standard requires a secondary voltage level of 400(380)/230 (220) volts, which is compatible with the same voltage level in IRAQ.
Equipment that uses power from the utility system is designed to run at voltage levels specified by the manufacturer. It is therefore difficult to develop a power system that will match the requirement of each equipment, given that voltage drops are experienced during the generation, transmission and distribution of the power. However, the primary constraint in the distribution network design is voltage level consumption. Typically, the voltage drop in the distribution network varies proportionally to the magnitude of current demand and the distance between the source and the load [7]. The voltage drop results from the nature and type of load, the design of the electrical installations, the layout of the installation, system maintenance and lengthy service lines. Two methods can be used to determine the voltage drop along the feeder. The methods are the approximate method and the exact method. If the power distribution systems can continuously supply power to the consumption load point, then the system is said to be reliable.
Faults are considered to be some of the most critical aspects of a power system, seeing as 80% arise from the distribution networks [10]. This implies that it is essential to protect the devices such as breakers and fuses. Furthermore, integrating switches and DGs also influence the effectiveness of the power distribution network. This project will avoid voltage drop or any parameters which cause weaknesses in the electrical network.