Reconfiguration of 11KV Feeder

 

1. Introduction

CE 2.1

I did this project as a graduate Electrical Engineering while pursuing my Bachelor of Engineering in the field of Electrical Engineering from Balochistan University of Engineering and Technology, Balochistan.
I wanted to conduct a project that would be challenging and would involve how to improve the existing power grid by helping the current or load at a given time. I wanted to create a system by improving the power factor or changing the conductor size or substituting the cables with conductors. I was able to improve my written and oral presentation skills as well as my interpersonal skills by the successful completion of this project.

2. Background

CE 2.2

For this project as an undergraduate student in electrical engineering, I wanted to start working on a project that would be challenging. I wanted to learn about the different and commonly used electrical/electronic components, the working mechanism and the implementation in a common every-day system. Feeder configuration is a very important step to enhance the quality and reliability of a distribution system. During my studies, I had learned that traditionally, in Pakistan, the feeder configuration is done by opening/closing or tie & sectionalizing the switches in order to alter network map and thus the flow of power from substation to customers.

I had studied during my bachelors that the reason Feeder configuration is done is to reduce system power loss and also for load balancing. As the loading conditions change, it is important to reconfigure it to reduce power losses in the network. And it is due to this reason that I selected the “Reconfiguration of 11KV Feeder” for my project.

CE 2.3

The objective of my project is to design a system to reconfigure the network for loss reduction for 11KV feeder. Or the reconfiguration of the distribution network under normal operation to reduce active losses and to balance loads in the system.

CE 2.4

CE 2.5

• I first had to conduct a detailed literature review to find the best applicable approach to this system for reconfiguration.
• I decided to use Branch exchange and Loop cutting methods along with a theoretical Heurestic approach to achieve my objectives.
• I used the computer software for “ELR” to analyse the feeder and to calculate the results.
• I initially, used an existing configuration based on actual data to calculate the current Energy Loss Reduction (ELR)
• I then tabulated all the results and obtained a schematic diagram to show my results.
• I completed the project within the time frame specified by the university.
• I presented my findings to my supervisor.

3. Personal Engineering Activity

CE 2.6

I approached a senior professor with an idea of conducting a project about the power grid. Along with my group members, I had a lot of brainstorming sessions and review meetings with my project supervisor to select a suitable topic. I suggested that I work on a project that was concerned with restructuring the power grid to minimize distribution losses and we suggested that we select a suitable location for this project to be carried out and thus the topic “Reconfiguration of 11KV feeder” came in to being and the supervisor agreed to this and asked us to begin working on this by first conducting a literature review on all the components we would require and the working of this project and to start working on this project.

CE 2.7

• I decided to select a Surab Town feeder of 11KV which starts from the 132KV Pakistan Railway Grid Station. I found that this grid has two transformers connected in parallel having a capacity of 10/13MVA each and 132/11KV. This particular feeder provided power of mixed loads to residential, commercial, agricultural and gas power plants. I carried out the Physical Survey of the existing 11KV Surab Town Feeder and plotted a Single line diagram of existing Surab town feeder.
• I calculated the energy losses and voltage drop of existing distribution system keeping in view the QESCO requirements. The length of feeder is 42.62km with annual energy loss 457898.1kWH and maximum percentage voltage drop is 6.5%, which is beyond the specified limit of QESCO i.e. 5.0% and is not acceptable as shown in the table below.

Month	Max Hour KWH Reading in Year-3 (KWH)		Units Sent in Year-3 (KWH)	Units Sold in Year-3 (KWH)	Losses
					KWH	%
January	0920108	0922574	1954326	1020746	933580	47.8
February	1809123	1811499	1504110	785804	719490	47.8
March	2577218	2580502	1233398	1324005	-90607	-7.3
April	2944920	2946703	1695002	1472175	223911	13.2
May	4197868	4199507	1758256	1693000	65256	3.7
June	4483081	4485732	1472868	1392621	84892	5.8
July	5663010	5665217	1452128	1146852	303276	21.0
August	6179532	6174379	1272432	1263513	8919	0.7
September	72162	76150	1636414	5107276	129138	7.9
October	1747258	172496	2070467	1654039	418057	20.2
November	4868322	4873227	2704009	1584898	1119111	41.4
December	6046270	602780	3086286	1626763	1459523	47.3

• I used the following simple algorithm for the algorithm:

Start with an existing configuration.

Read Input data…..Run ELR program…..Display results…..Compare KWH losses,

            If KWH loss <Existing KWH Loss then stop. If No then start with new configuration

CE 2.8

• My test system is a high loss, problematic distribution feeder of QESCO. In first, the existing Grid and feeder data are collected from Surab grid station. The data made run in ELR Software, which results high losses due to overloads. As the ampere load accedes then 300 amp on main Dog conductor , To overcome these overloads we recon figurate the feeder by using three different methods i.e. Branch Exchange Method, Loop Cutting Method and then we applied bifurcation method to isolate the existing feeder into two parts.
• I collected data from the Head office QESCO in Quetta, Pakistan and found that the monthly Peak Load is between 600-700 Amps and the off peak load between 5-90 Amps with the lowest being in November.

• I conducted a Load flow analysis was done using ELR Program with the following input Parameters at 5% annual Load growth rate

Load in Amp.=395 Amp @ 5% for 5 years

Bus Voltage=11KV

Feeder load factor=6.29%

Existing power factor=0.78%

Proposed power factor=0.79%

Capacitor installed=2Nos.

• I proposed the following one line diagram of QESCO feeder as prepared on the basis of field visits is shown below in figure. This figure clearly shows the difference between actual and proposed configuration of the feeder. In this figure 154 node are shifted. Also the route of power flow has been changed there by feeding all the consumers.

This configuration has reduced the line losses too as evident from the load flow analysis. The details are feeder given below.

              Power T/F #                                               ΙΙ

Feeder code                                           020201

Power T/F capacity                               10/13 MVA

Number of node                                     92

Number of transformers                         66

Number dog conductor                           18

Number rabbit conductor                       73

Total length of line                              18.42 KM

Total KVAS                                       5350 KVA

• I also proposed and conducted a Load flow analysis  using ELR Program with the following input Parameters at 5% annual Load growth rate.

Load in Amp= %for 5 years

Bus Voltage              = 11KV

Feeder load factor= 6.29%

Existing power factor = 0.78%

Proposed power factor = 0.95% (Improved Due to capacitor Placement)

CE 2.9

I conducted this project successfully and found that the ELR program could be used sappropriately and properly to find the optimal configuration of 11KV feeder, demonstrating the feasibility of such an approach for the solution of this problem.

However, refinements to the algorithm may be necessary in order to achieve satisfactory performance on large, real-world systems consisting of thousands of buses.

The following were my results:

• Losses (KWH) minimized from 457898 to 332944
• Voltage drop improved from 6.5% to 4.4%
• Power Factor improvement from 0.78% to 0.95%  (Result of proposed configuration)
• B/C Ratio is 24.25

CE 2.10

My contribution during this project was:

• Gathering Exact Grid data on realistic approaches.
• Gathering feeder data, one line diagram preparation physically through field visits.
• Exact measures and distances of node-to-node and exact electrical parameters information’s. Keeping in view different constraints, like Cost, Obstacles, Load. Losses, Environmental / social constraints, Betterment of WAPDA as well as general public.
• Re-notification of existing configuration and finding the optimal configuration by repetition the results obtained after execution of ELR Program.
• Removing haphazard road crossings and reducing the length of feeder.
• Load Balancing.
• Placement of Capacitor at best locations for obtaining best results.

4. Summary

CE 2.9

I successfully completed the project titled “Reconfiguration of a 11KV Feeder” along with my team members. I learned how to reconfigure a 11KV feeder and about the different approaches by execution of the ELR program I learned how to gather Grid data for realistic approaches to improve loading.

By the successful completion of this project, I was able to improve my written, oral and interpersonal skills. I was also able to improve my team work.

The main objective of this research is to develop methodology and guide lines for distribution engineers to show that by reducing the energy losses of distribution system, available capacity of the system may be conserved without putting up additional capacity. A generalized computer program is used to evaluate any given HT/LT system and propose capacitor banks at different points, different conductor sizes in different portions of system. This results in improving the stability as well as energy handling capacity of the system at minimum cost.