ABSTRACT
This project involves research on loss reduction in a distribution system. The Enugu distribution system is the case study. The type of losses, the causes of losses and methods of loss reduction in distribution system were presented. A method based on a heuristic technique for reactive loss reduction in distribution system is chosen for this work because it provides realistic sizes and locations for shunt capacitors on primary feeder at a low computational burden. The Gauss-siedel method was used for load analysis while simulation work was done using MATLAB software. The variation of the load during the year is considered. The capital and installation cost of the capacitors are also taken into account. The economical power factor is also determined so as to achieve maximum savings. This method is applied to a 34 bus,
11KV, 6MVA distribution system with original power factor of 0.85. The results from the analysis show that the losses are reduced from 59.2692 to 49.4KW using capacitor maximum rating of 1200 (750+450) KVAR at an optimum power factor of 0.96. This translates to a saving of N39,500.00 per year after amortizing the capital and installation costs of applying the compensating capacitors.
CHAPTER ONE INTRODUCTION
1.1 BACKGROUND OF STUDY
Electrical distribution systems include the distribution of electrical energy for light and power from the point of generation to the point of utilization [1].
Distribution of energy is accomplished in this project by the use of a.c system. Distribution system consists of two parts: the primary distribution which extends either from the generating station or substatio00n to distribution transformers, and the secondary distribution, which extends from the distribution transformers to the point of utilization. An electrical distribution system can normally be of overhead or underground construction. The overhead construction is generally used in Enugu because it offers the following advantages.
I It is less expensive
II It is easier to identify and repair fault
Overhead distribution system is accomplished by means of two types of conductors: the bare conductors and insulated conductors. The bare conductors are those used for long distribution lines while the insulated conductors are those used for short distribution lines. The insulated conductors are also called service cables. They are used between poles and houses so as to prevent electric shock incase the conductor gets in contact with any of the metals in the building.
Enugu Electrical system receives its energy from Onitsha at
330kV. The 330kV is stepped down to 132kV in Onitsha and transmitted from Onitsha to New-Haven transmission station. At New-Haven transmission station the 132kV was stepped down to 33kV and transmitted to the following injection substations in Enugu: Kingsway, Independent Layout, Thinkers Corner, 9th Mile, Ituku Ozara and Emene
Industrial Layout. At the injection substations, the 33kV is further stepped down to 11kV and distributed to various areas in Enugu. In this project, the loss reduction in 11kV Thinkers Corner distribution line will be considered [1].
The power network, which generally concerns the common man, is the distribution network of 11kV lines or feeders downstream of the 33kV substation. Each 11kV feeder which emanates from the 33kV substation branches further into several subsidiary 11kV feeders to carry power close to the load points (localities, industrial areas, villages, etc.). At these load points, a transformer further reduces the voltage from 11kV to
415V to provide the last-kilometer connection through 415V feeders (also called as Low Tension (LT) feeders) to individual customers in Enugu, either at 240V (as single-phase supply) or at 415V (as three- phase supply). The span lengths mainly used for electricity projects nationwide are 45/50 meters for Township Distribution Network (TDN) and between 65 and 90 meters for inter-township connection (ITC) lines. In Enugu State, the average span length for both 11kV and 415V distribution lines is 50 meters between two poles.
After electric power is generated, it is sent through the transmission lines to the many distribution circuits that the utility operates. The purpose of the distribution system is to take that power from the transmission system and deliver it to the consumers to serve their needs. However, a significant portion of the power that a utility generates is lost in the distribution process. These losses occur in numerous small components in the distribution system, such as transformers and distribution lines. Due to the lower power level of these components, the losses inherent in each component are lower than those in comparable components of the transmission system. While each of these components may have relatively small losses, the large
number of components involved makes it important to examine the losses in the distribution system [2].
There are two major sources of losses in power distribution
systems. These are the transformers and distribution lines. Additionally, there are two types of losses that occur in these two components. These losses are often referred to as core losses and copper, or I2R, losses. In the case of transformers, the core losses account for the majority of losses at low power levels. As load increases, the copper losses become more significant, until they are approximately equal to the core losses at peak load [2].
The economic implications of these losses are far reaching. In addition to the excess fuel cost needed to cover the energy, added generating capacity may be needed. Also, the power lost in the distribution system must still be transmitted through the transmission system which further adds to the loss in that system. It is very important for electric power suppliers to consider these losses and reduce them wherever practical.
1.2 MOTIVATION AND SIGNIFICANCE OF THE STUDY
Initially, as power factor falls below unity the current in the system increases with the following effects:
(i) Because of the increased currents, the I2R power loss
increases in cables and windlings leading to overheating and consequent reduction in equipment life.
(ii) Cost incurred by power company increases.
(iii) Efficiency as a whole suffers because more of the input is absorbed in meeting losses.
Since distribution losses cost the utilities a very big amount of profit, reduce life of equipment, attempts to reduce electricity cost, together with improving the efficiency of distribution systems,
have led us to deal with the problem of power loss minimization. The system is considered as efficient when the loss level is low. The significance of the expected outcome of the study include the following:
(i) It ensures that the rated voltage is applied to motors, lamps, etc, to obtain optimum performance.
(ii) It decreased loses in circuits and cables
(iii) It ensures maximum power output of transformers is utilized and not used in making-up losses.
(iv) It enables existing transformers to carry additional load
without overheating or the necessity of capital cost of new transformers.
(v) It achieves the financial benefits which will result from lower
maximum demand charges.
1.3 AIM AND OBJECTIVES
The major aim or purpose of the research effort is to reduce power losses in the 11Kv distribution system, achieve efficiency and financial benefits which will result from lower maximum demand charges by the electricity supply company.
The objectives of the research project are:
(i) To find the power losses in the distribution system and
(ii) To find means to reduce the losses and reduce them.
Once the objectives are properly carried out the aims will be achieved.
1.4 METHODOLOGY
Since the project topic embraces determination of High Power Loss Reduction in distribution lines, effort will be made to explain how materials were obtained for this research project.
The research design object being descriptive and explorative will involve theoretical and mathematical model analysis.
The methodology or systems of actualizing the project are as follows:
1.4.1 SOURCES OF DATA:
Sources of data for this research work under review are based on visits made to Power Holding Company of Nigeria (PHCN) to find how losses occur, how to reduce it and how to assess the most economical method of loss reduction computation.
Data collection was obtained at PHCN Distribution Zonal Head Quarters Okpara Avenue, New Haven Transmission station and Thinker’s Corner injection substation Enugu.
1.4.2 Techniques to be employed to achieve the objectives are as follows:
(i) Derivation of power loss reduction equations
(ii) Derivation of economic power factor. Economic power factor is the power factor at which the savings is maximum.
(iii) Heuristic technique for capacitor placement. This is the method of allocating capacitors at the sensitive nodes. Sensitive node is the node that has the largest power loss due to reactive component of load current.
(iv) Load flow technique in MATLAB should be employed as the software for the study.
1.4.3 The instruments employed in the study are as follows: Ammeter, Voltmeter, Wattmeter, Clip on Ammeter, Digital multimeter and Power factor meter.
More specifically, capacitor banks are required at locations where field measurements indicate a low voltage or
low power factor problem. This information can be obtained as follows:
(a) By making voltage measurements during full-load (Peak-
load) and light-load (off peak-load) conditions at various points on the distribution feeder; and
(b) By making kilowatt and kilovoltampere measurements on the distribution feeder at minimum and maximum daily loads and during a typical 24 hour period.
Once these measurements have been obtained, equation 2.41 can be used to determine voltage rise and kilovar parameters. The capacitor banks may be connected grounded star (wye), ungrounded star (wye), or delta.
1.4.4 The tools employed in the study are, set of spanners, set of screwdrivers and pliers.
1.5 PROJECT ORGANIZATIONS
Chapter one states the objective and serves as introduction to this project.
Chapter two presents the theory necessary to understand and meet the objective. It presents the reactive power control problems.
Chapter three, presents the system model and problem formulation adopted in this project and describes the solution methodology in detail.
Chapter four, presents the application of the solution methodology. It also discusses the results obtained when this methodology was applied to a test distribution system.
Finally, chapter five, provides conclusion and recommendations for future work.
This material content is developed to serve as a GUIDE for students to conduct academic research
HIGH POWER LOSS REDUCTION IN ENUGU ELECTRICAL DISTRIBUTION SYSTEMS USING HEURISTIC TECHNIQUE FOR CAPACITOR PLACEMENT.
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