CHAPTER I

THE PROBLEM AND ITS BACKGROUND

Introduction

Electricity sector around the world displays continuous growth as power demand

stands out despite any country’s economic changes. The industry is facing new significant

expectations and requirements to mitigate the effects of storms and other disruptive

events, secure the electric system and critical infrastructure that depends on electric

power against cyber and physical attacks, and maintain system stability.

In most parts of the Philippines, one cannot get through a few months without

experiencing storms, some of which are strong enough to damage or take down power

lines. One particularly massive case of power outage was during Typhoon Glenda which

took down power lines all over Luzon and Visayas back in 2014, affecting over 13.5 million

people. According to the National Grid Corporation of the Philippines (NGCP), blackouts

during typhoons can be caused by as small as a tree branch falling on power lines or as

massive as a collapsed tower. In some instances, outages can be as short as a few hours,

but in particularly dire circumstances, they can last much longer.

The cost for repairing physical damages on power lines can be tremendous. During

long outages after a catastrophe, there are also associated intangible impacts to a utility’s

customers such as despair, discomfort, anxiety and helplessness. In addition to the

intangible impacts, there are considerable direct economic impacts to customers resulting

from lost economic activity, food spoilage, looting, etc. These tangible and intangible

impacts challenge the electric utility industry’s attempts to justify the installation of

overhead electric distribution and transmission systems.

 Majority of the causes of power interruptions are found in the distribution parts of

the overhead power network mainly due to their physical location close to natural

vegetation e.g. trees, bushes, etc. Therefore, utilities must develop greater flexibility in

terms of supply and distribution of electricity in the best and most effective environmental-

friendly way possible.

Underground cables offer a justifiable solution for critical parts and in some cases,

the entire length of power lines. Underground cables have unique properties for

transmitting power. They are out of sight, often require only a narrow band of land to install,

emit no electric field and can be engineered to emit no magnetic fields, have better power

loss characteristics and can absorb emergency power loads. The higher cost of

underground cables was a significant deterrent to their use in the past. However, with

lower cost production methods, improved technologies and increased reliability, the cost

differential between underground cables and overhead power lines is narrowing. This

means that power project developers are more frequently turning to underground cables

as an economic and technically effective alternative when physical obstructions or public

opinion hinder the development of networks.

Replacing overhead lines with underground cables has been an increasing trend

in Europe over the last decade. New cable technology combined with improved production

processes and specifications of international testing has led to increased usage of

underground cables. In Germany, 73% of the medium voltage cables and 83% of low

voltage cables are underground. The high fraction of underground cables contributes to

the very high grid reliability with a SAIDI (System Average Interruption Duration Index)

value (minutes without electricity per year) of <20.

In the Philippines, on year 2014, the Department of Energy seriously looked at the

possibility of relocating vital power lines underground to protect them from damage during
typhoons. Currently, various projects on the conversion of overhead lines to underground

cables have been successfully carried out in several urban areas in the country including

Cebu, Davao and Taguig. These projects were designed to meet the local conditions of

the cable route, yet many technical issues have been raised before and during project

implementation. These issues will not only affect the delivery but the ongoing performance

of the network. This research shall discuss the implications of this process and shall

recommend scenarios for installing and maintaining underground cables to provide an

efficient, reliable and economical electricity supply.

The researchers shall investigate various technical aspects of converting overhead

distribution lines to underground cables in urban areas covered by Batangas I Electric

Cooperative (BATELEC I) Lemery substation which may include new ways of placing

underground cables and adopting latest cable technologies such as the new type of Cross-

linked Polyethylene (XLPE) cables and High Temperature Superconductive (HTS) cables.

Although there are already few researches and reports published on moving overhead

lines to underground cables, they have not been to the extent of investigating the

implementation of new technology and its effect on the efficiency, reliability and economic

points of view of the power supply. This study moves further with a pioneering project that

investigates the technical aspects of converting overhead distribution lines to underground

cables and their effects on BATELEC I, Lemery substation.

Objectives of the Study

This research proposal study aims to design an underground wiring system that

will suit the local conditions in urban areas covered by BATELEC I Lemery substation.

Specifically, the study attempts to attain the following objectives.

1. To evaluate the existing overhead distribution lines in terms of the following:

1.1. Area of Location

1.2. Construction Cost

1.3. Maintenance Cost

1.4. Reliability

1.5. Efficiency

2. To determine the local conditions in the coverage area

2.1. Urbanization Rate

2.2. Weather Conditions

2.3. Earth Movement

3. To design the underground wiring system based on the following provisions,

standards and guidelines

3.1. Philippine Electrical Code (PEC)

3.2. National Electrical Manufacturers Association (NEMA)

3.3. National Rural Electric Cooperative Association (NRECA)

4. To prepare the design plan

4.1. General Description of the Design

4.2. Construction Layout

 4.3. Circuit Diagram

4.4. Design Simulation

4.5. Design Computation and Analysis

4.6. Cost Estimate

5. To compare the designed underground cabling system with the existing overhead

distribution lines in terms of:

5.1. Safety

5.2. Cost Analysis

5.3. Reliability

5.4. Efficiency

5.5. Visual Impact

6. To summarize the impact of the conversion of overhead distribution lines to

underground wiring system

Conceptual Framework

The conceptual framework of this study is the outline of the possible courses of

action in analyzing the technical considerations and impact of converting overhead

distribution lines to underground wiring system. The ideal approach in each stage and the

flow of the study are presented in Figure 1.

Evaluation of Existing Overhead Determination of Local Conditions in the
Distribution Lines Coverage Area of BATELEC I Lemery
Substation
 Area of Location
 Construction Cost
 Maintenance Cost  Urbanization Rate
 Reliability  Weather Conditions
 Efficiency  Earth Movement

Design Provisions, Standards and Preparation of the Design Plan

Guidelines
 General Description of the Design
 Philippine Electrical Code (PEC)  Construction Layout
 National Electrical  Circuit Diagram
Manufacturers Association  Design Simulation
(NEMA)  Design Computation and Analysis
 National Rural Electric  Cost Estimate
Cooperative Association
(NRECA)

Comparison of Overhead Distribution Lines

and Underground Wiring System

 Safety
 Cost Analysis
 Reliability
 Efficiency
 Visual Impact

Summary of the Impact of Conversion of Overhead Distribution Lines to

Underground Wiring System

Fig. 1. Paradigm of the Study

 Figure 1 shows the synthesis of activities required to conduct the research

including the basis of the design and its analysis as well as the main objective of this study.

The preliminary phase of this study will cover the evaluation of the existing

overhead distribution lines installed by BATELEC I, Lemery Substation in terms of its area

of location, construction cost, maintenance cost, and its reliability and efficiency. Local

conditions such as weather, urbanization rate and earth movement are needed to be

considered for the appropriate construction of the wiring system.

The design shall be based on provisions, standards and guidelines stated in: (1)

Philippine Electrical Code (PEC) for safety, proper construction, and sizing of wires; (2)

National Electrical Manufacturers Association (NEMA) for cable tray systems and

installation, raceway products, high performance wires and cables including XLPE and

HTS, and utility products and systems and (3) National Rural Electric Cooperative

Association (NRECA) for the engineer guidelines on designing a high-quality underground

distribution (UD) system. These are necessary for the preparation of the design plan.

Using the gathered data, the design plan shall be prepared by constructing layouts

and circuit diagrams for the underground distribution system. The design shall be

simulated to test its reliability and efficiency. The resulting data will then be analyzed and

the cost for underground wiring construction and installation shall be estimated and

computed.

The data gathered from the preliminary phase of this study and the designed

underground distribution system shall be compared in terms of safety, costs, reliability,

efficiency and visual impact. This comparison will then be analyzed and summarized for

a clear statement of the impact of converting overhead distribution lines to underground

cables.
Scope and Delimitation of the Study

This study is descriptive in nature and its focus is the technical consideration and

impact of converting overhead distribution lines to underground cables in urban areas

covered by BATELEC I Lemery Substation. This study includes the design of underground

wiring system, the cost analysis of its construction, and the impact study of its

implementation.

The researchers shall gather essential data from the distribution utility. Such data

are the utility substation’s coverage area of distribution, the total area of land where their

utility poles and distribution lines are constructed, system loss, maintenance cost and the

rate of power interruption due to damaged overhead components. Other data such as the

area’s local conditions shall be gathered from various sources.

The underground wiring design shall be simulated using the software Electrical

Transient and Analysis Program (ETAP), a comprehensive analysis platform for the

design, simulation, operation, and automation of generation, distribution, and industrial

power systems. This study shall include the presentation of the schematic diagram of the

system design as well as the electrical materials needed for the construction. These

materials shall include the latest cable technologies such as the new type of Cross-linked

Polyethylene (XLPE) cables and High Temperature Superconductive (HTS) cables. A

techno-economic analysis from the cabling system construction to its implementation shall

also be conducted and presented.

This study is delimited to a single substation of BATELEC I which is located at

Lemery, Batangas. The underground wiring system shall be designed to meet the local

conditions of urban areas covered by the substation. The study is mainly focused on the
reliability, efficiency, and safety of converting overhead distribution lines to underground

distribution cables.

Significance of the Study

The research on the technical consideration and impact of converting overhead

distribution lines to underground distribution cables highlights its importance to the

following:

Residents of Lemery, Batangas. This study will be beneficial to the people of

Lemery, Batangas as they can enjoy the advantages in power supply and clean cityscape

upon implementing the underground wiring system. Employing this technology will

enhance the delivery of power in terms of safety, reliability and efficiency.

Batangas State University. The project will serve as another contribution to the

achievements in the field of engineering in the University. It may also yield valuable

information especially to students of Batangas State University which could be used in

future research and inventions.

Electrical Engineering Department. This study exemplifies a practical aspect of

learning in the science of electrical engineering. This may contribute to the students’

understanding of the principles and concepts of electrical power system design and

additional knowledge on another electrical cabling technology.

Future researchers. This may serve as a basis in conducting future researches

about underground wiring system and how it can enhance the power in this changing world.

They may apply the principles, standards and concepts used in the project and use the

study as a procedural guide to a related study.

Definition of Terms

The following terms are defined conceptually for a better comprehension of the

study.

Cable Tray. This is a rigid structure used to support insulated electric cables used for

power distribution and communication. It is especially useful in situations where changes

to a wiring system are anticipated, since new cables can be installed by laying them in

the tray, instead of pulling them through a pipe. It is practical to use cable trays in

underground wiring system construction since this is ideal for outdoor projects.

Cross-Linked Polyethylene (XLPE). In some applications, cables are exposed to

extremely high temperatures. In these cases, cross-linked polyethylene (PEX or XLPE)

is used as insulating material. XLPE can be used at temperatures of up to 150°C. The

use of this cable shall be included in the underground wiring system.

Distribution. This is the final stage which entails the delivery of electricity to the load. The

study is focused on distribution lines.

Earth Movement. This refers to the seismological observation in an area. Certain

standards are needed to be followed in which levels of earth movement must be

considered.

Efficiency. This is understood as the reduction in power and energy demands from the

electrical system without affecting the normal activities carried out in buildings, industrial

plants or any other transformation process. It is also the reduction of technical and

economic costs of operation. This is one of the electrical factors affected by the conversion

of overhead to underground distribution lines.

Emergency Power Load. This is an independent source of electrical power that

supports important electrical systems on loss of normal power supply. It is installed to

protect life and property from the consequences of loss of primary electric power supply.

One of the advantages of an underground wiring system is that it can absorb emergency

power load.

High Temperature Superconductive (HTS) cables. These are materials that behave

as superconductors at unusually high temperatures. They are also more environmentally

friendly, conserving energy and resources and delivering power while generating no

external magnetic fields. The use of this cable shall be included in the underground

wiring system.

Low voltage. The International Electrotechnical Commission (IEC) defines supply

system low voltage as voltage in the range 50 to 1000 V AC or 120 to 1500 V DC. In

electrical power systems low voltage most commonly refers to the mains voltages as used

by domestic and light industrial and commercial consumers. This is also an important

parameter in constructing a UDS project.

Overhead Distribution Line. This is a structure above ground used in electric power

distribution to transmit electrical energy across large distances in which most of the insulation

is provided by air. The conversion of this overhead structure to underground system is the

focus of this research design.

Raceway. This term is used to refer to an enclosed wiring method, including

both conduit and tubing. Some standards and provisions suggest the use of raceways in

installing electrical wires. The quality of raceways must be taken into consideration when

installing wires underground.

Reliability. This refers to the ability of an energy production system to provide consistent

and expected levels of energy under stated conditions for a specified period of time. This

is one of the electrical factors affected by the conversion of overhead to underground

distribution lines.

Simulation. This is a production of a computer model of the wiring system. The software

ETAP allows testing and simulation of distribution design showing its reliability and

efficiency.

System loss. This refers to the difference between electricity input and output as a result

of an energy transfer between two points. This affects the efficiency of a power system.

Underground wiring systems are shown to have better power loss characteristics.

Technical Consideration. “Technical” refers to the most technological aspect of the

media. Technical consideration is introduced by the electrical technology used to

make the medium work. The study takes into consideration the use of latest cabling

technology in the construction of the underground wiring system.

Techno-economic Analysis (TEA). TEA is methodology framework to analyze the

technical and economic performance of a process, product or service. Normally, it is a

combination of process modeling, engineering design and economic evaluation. This is

necessary for an organized analysis of data.

Transmission. This process is the bulk movement of electrical energy from a generating

site, such as a power plant, to an electrical substation. This is a pre-requisite to distribution.

Urban areas. These are areas with a density of human structures such as houses,

commercial buildings, roads, bridges, and railways. They can refer to towns, cities, and

suburbs. Underground wiring systems are more practical to install in these areas.