Challenges faced for Installation of Emergency Restoration System (ERS) in the Major Natural Disaster Hit High Voltage Transmission Lines in India
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Disaster Advances Vol. 12 (6) June (2019)
Challenges faced for Installation of Emergency
Restoration System (ERS) in the Major Natural Disaster
Hit High Voltage Transmission Lines in India
Tamil Selvan M.1* and Kodi Malar2
1. CSRD, SSS, Jawaharlal Nehru University, New Delhi – 110 067, INDIA
2. Department of Energy and Environment, TERI School of Advance Studies, Institutional Area, Vasant Kunj, New Delhi - 110 070, INDIA
*mtselvan@mail.jnu.ac.in
Abstract These events include human error, vehicle accidents,
High Voltage Transmission lines are subjected to vandalism, terrorism, design faults and poor maintenance
several natural disasters like earthquake, flood, practice. High voltage transmission lines are expected to
landslides, hurricanes etc. Power line failure due to certain level of damage risks, threatening to disrupt power
supply infrastructure and can affect public safety. Utilities
these scenarios makes a severe financial damage to
cannot avoid emergencies; therefore, it is important to know
consumers, utilities and the power producing agencies. their cause and respond quickly and efficiently to the
Also, transmission line failures occur due to harsh problem on timely manner.
weather and non-climatic reasons such as human
errors and mechanical failures. While it is impossible Emergency situations may include failure of structural
to prevent all such situations, electrical utility officials systems and foundations, failure of conductor splices and
and contractors have to be equipped to meet such damage to conductor strands leading to conductor failure etc.
emergencies. Transmission line tower damage may also occur due to
degradation of conductors due to wild-fires, flood, insulator
Emergency Restoration System (ERS) structures are breakage, failure of cross-arms and buckling of tower angle
members or connection failures.
temporary solution designed to bypass the existing
transmission towers of any voltage in any terrain. They During winter, icing on Transmission Line causes line break
will be used until the main line is re-conductored or accident. So, the restoration of these kind of accident that in
restored. Planning includes determining which the event of the ice cover the intensity of work, repair and
transmission lines are important and the possible ways maintenance, takes relatively longer time as compared to
in which they can fail and how best to restore them. other places6. When the ice cover is formed, the overall
This includes general information about existing weight of the transmission line increases, which leads to the
structures and foundations, data on past weather- failure of the line.
related failures, weather criteria and structural
loading and the extent of damages. In this study, we are In all these cases, the utility demand is to restore the power
analyzing various challenges faced due to the major system to normalcy rapidly. The primary requirement in
Emergency Restoration work is to revive the transmission
transmission lines failures in India during various past
network, get the line back into normal operation as quickly
natural disasters. Supply of continuous power will be as possible and to restore electricity supply to the affected
the most important aspect of a transmission line consumers at the earliest. Another important concern is to
network during emergency time. minimize the economic impact of the costs associated with
the devastation and rebuilding. So, it is important to
Keywords: Emergency Restoration System, Transmission calculate the total cost to rebuild or restore a failed
Line, Powergrid, Natural Disaster. transmission line, which is inversely proportional to the
restoration time; the total losses are directly proportional to
Introduction the outage time. Therefore, one can view any Emergency
High voltage transmission lines carry electrical energy from Restoration Plan as a combination of technical or
power generating stations to long distances and reach engineering processes with the financial planning.
substations. These transmission lines are passing through a
wide range of terrains, climates and physical environments Use of composite insulated cross-arms is expected to reduce
and are always at risk to experience catastrophic events, both the cross-arm load on the structure and the clearance
weather-related and man-made. Weather-related events required for insulator swings. These towers are best suited to
include high winds, ice buildup, ice storms, flash floods, maintain uninterrupted power supply in an event of tower
rock or mud slides, erosion of foundations etc. Sudden failure. These ERS towers bypass the original transmission
power failures caused by nature are very common, however, system to restore power at the earliest, while the original
non-weather-related events are just likely. tower is being rectified. These towers are useful for restoring
*Author for Correspondence power supply following various natural calamities like
floods, hurricane, cyclone etc. for conducting scheduled
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Disaster Advances Vol. 12 (6) June (2019)
maintenance work on the existing towers without major Training. To perform any quick emergency restoration work,
interruptions. critical materials must be readily available for installation.
The inventory must include standard wire sizes in sufficient
Figure 1 shows the typical look of the 400kV ERS Tower quantities8. If the line consisted of poles, then the inventory
installation at a testing ground in Bihar State, India including stock must have a reasonable number of poles of similar size
the erection of IEEE Standard 1070 emergency restoration and strength of the same line. Structures used for restoration
towers thereby keeping field personnel well trained towards work can be modular, temporary or permanent type.
latest developments. Also, it was planned to reduce the time
required to transport emergency materials to the job site by An important part of any restoration work is to mobilize the
utilizing heavy helicopters and other air transport equipment well-trained field personnels in the erection of the
as required. This ERS structure is supported by combination replacement structures and stringing operations. A rapid
of guys and can be installed without any civil foundation. mobilization of trained work force is vital to the process of
The ERS Tower erection is made with ease with the usage emergency restoration. The restoration process consisted of
of Gin Pole which negates the need of heavy machineries. a simple design with standard weather criteria for the re-
route, required wood poles and other materials shifted to the
affected site from inventory stock collected from every
region of the country and special construction methods
devised for quick restoration.
Normally, a double circuit line will be transferred to 3 sets
of ERS tower with two towers in each set thereby forming a
double circuit. Surveying and transportation of materials to
site is a major challenge. The real challenge will be at the
time of installing the anchors as we can see the standard
towers. If the soil is too soft, then it was not suitable for
installing any type of anchors. Modular supports were
specially designed for this by considering the guy angles and
ease for transportation to the site. In ERS towers, the long
modular steel supports offer the large width which is
necessary for both connecting the guy wires and also
increasing the stability of the ERS structure installed.
Material and Methods
One of the noteworthy features of ERS structures is that
these are easy and quick to install. These structures do not
require any foundation and can be set up on any soil type.
Figure 1: Typical look of an ERS Tower Installation The base of the tower comprises a four-meter box upon
which strong metallic angles can be assembled. These
When a high voltage transmission line goes down with one towers are light in weight and can be transported easily using
or several damaged towers, the responsible utility agency helicopters or manually.
incurs huge monetary losses and hundreds of non-
transmission hours. Given that the total losses and damages Due to the vast expanse of India and the variety of climatic
are directly proportional to the outage duration, time is a conditions, Powergrid is subjected to transmission lines that
crucial factor in reinstating or remediating the failed towers. occasionally fail due to natural disasters. These natural
In some cases, the process of formally rebuilding a new line disasters are result of mudslides, heavy ice, cyclones and
with original towers can take as long as 5 to 6 weeks. floods. Traditionally, restoration of these transmission lines
was accomplished using available spare of normal towers.
However, by using an effective Emergency Restoration The typical self-supporting lattice type towers used in India
Plan, the field transmission structures can be replaced in few were erected using derricks and in some cases, a complete
hours depending on the nature and depth of the damage. new foundation has to be constructed. These processes are
Proper planning benefits not only for maximized restoration very time consuming and often resulted in prolonged
efficiency but can also minimize inventory levels. To face outages.
this challenge, large amounts of inventory were required in
order to have spare lattice towers available for emergency Many of the sites of these damaged transmission structures
restoration work. were difficult to access physically. The loss of these towers
would sometimes result in backing down the generation and
An effective Emergency Restoration Plan contains three load shedding at industrial area in India. When major natural
essential elements like Planning, Emergency Materials and disasters occurred, it was calculated that lost Gross Domestic
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Disaster Advances Vol. 12 (6) June (2019)
Product for India could be eighteen times the value of the precautionary measure power supply was cut off in many
power that was lost. parts. Chennai, Kanchipuram and Tiruvallur were the worst
affected districts. In these districts, EHT transmission towers
Results and Discussion and transmission lines collapsed due to the high wind speed
Vardah Cyclone, Tamil Nadu, 2016: The cyclone Vardah and the substation equipments also got damaged.
struck land at Chennai Coast, Tamil Nadu on 12.12.2016
with a wind speed of 130 to 140 kmph, bringing with its The power lines, poles and distribution transformers of
heavy rain that lashed the coast in Tamil Nadu devastating distribution network was also affected due to high wind
the electrical infrastructures. To avoid accidents, speed as the uprooted trees fell on the electrical network
lines and structures.
Figure 2: Various Transmission Lines of Powergrid in India (Source: Powergrid Website)
Figure 3: Load Pattern before and after Cyclone Vardah (Source: TANGEDCO Report, 2017)
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Disaster Advances Vol. 12 (6) June (2019)
trees are removed, so it faced difficulties in restoring the
power.
The average demand of Chennai City is around 2500 MW.
On the day of Vardah Cyclone, due to pulling of 230 KV
feeders on 12.12.2016, the load went to Zero MW. After
restoration, the load gradually increased and is being
maintained at around 2100 MW. Sum of about Rs.350 Crore
was spent towards temporary restoration of damaged
infrastructure of electricity network.
Hudhud Cyclone Andhra Pradesh, 2014: In the past
couple of years, the deployment of ERS towers has gained
traction in India. As a result of Hudhud cyclone that struck
Andhra Pradesh on 12.10.2014, some areas in the State went
without power for few days. In order to prepare itself for
such emergencies in the future Andhra Pradesh
Transmission Corporation Limited has procured a total of 10
ERS towers for three zones namely Visakhapatnam, Kadapa
and Vijayawada7. Powergrid extended all out support to AP
Transco, Railways and Vizag Steel Plant to restore the power
system on emergency mode using ERS towers. Supply to the
emergency services like hospitals, water supply pump
Figure 4: Tower collapsed during Vardah Cyclone, houses were restored by 14.10.2014.
Tamil Nadu
Flood in J and K, 2014: In Sept 2014, devastating flood hit
It is calculated that total 59 nos. of EHT towers collapsed the majority of portion of J and K resulting in damage of
and around 800 distribution transformers, 49,100 poles, number of transmission line towers and sub-stations, which
4500 pillar boxes and 15,000 km conductors were damaged. were submerged in water7. Powergrid extended manpower
ERS Towers are mainly used in place of damaged tower to and material support to restore the transmission network and
enable power supply with very short time. But in certain distribution network with supply of ERS, distribution
areas, power has been suspended to avoid accidents, unless transformers, transformer oil and filter machine.
Figure 5: ERS Tower Installed during Hudhud cyclone restoration work
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Disaster Advances Vol. 12 (6) June (2019)
Figure 6: Installation of ERS Tower in J and K during restoration work
Super Cyclone Phailin, Odisha and Andhra Pradesh, complete1. After transporting the ERS to location of
2013: A severe storm hit on 10/13/2013 at coastal area of damaged tower of the 400kV Uri-Wagoora line, the actual
Odisha and Andhra Pradesh where most of the utilities were work started on the 19/01/2000 under very adverse situation-
vastly disrupted by the strong winds that went up to a speed very cold and snow climate as per figures 8 and 9.
of 220 kmph. When this very severe cyclonic storm crossed
the coast near Gopalpur and weakened before turning into a Super Cyclone Damage in Orissa State, 1999: In the early
depression. Ganjam district in Odisha was totally destroyed hours of the 29/10/1999, a massive and merciless cyclonic
by this storm. There were major disturbances in electricity storm hit the coastal belt of Orissa killing thousands and
transmission utilities due to this cyclone Phailin. So, for displacing millions. During the cyclone, it was observed that
precautions, load schedule was planned as in Andhra the wind blew at a velocity of 250-260 km per hour and the
Pradesh and the load was reduced to about 9,000 megawatt sea rose up to 5-8 meters high with accompanying
(MW) against normal demand of 10,000MW and in Odisha, continuous rain sweeping hundreds of thousands of houses
it was reduced to 600MW against the normal demand of out of existence in the most part of Orissa.
2800MW.
The worst affected districts ware Jagatsingpur, Kendrapada,
Based on IMD weather forecast information, extensive prior Puri, Khurda, Bhadrakh and Balasore, those were totally de-
preparations were undertaken to tackle the effects of cyclone linked from the rest of the country. Bhubaneswar, the capital
Phailin in the context of power requirements and supply. city of Orissa state, was in darkness and all possible links
Advance planning was made to manage the generation and with the outer world were cut off by this Super Cyclone.
load balance for unhindered and secure grid operation during Communication within the State was impossible due to
cyclone period. The required power load and generation complete ransacking of the electric and telecommunication
were managed in a balanced manner so as to achieve stable wires and cables. Many ERS Towers were installed in large
transmission frequency. There were three Emergency number at different location to restore the power.
Restoration Systems (ERS) of PGCIL which were put on
standby readiness in AP and Odisha for quick deployment in Cyclone Damage in Gujarat State, 1998: On 09/06/1998,
the event of damage. a severe cyclone hit the coastal area of Gujarat State on the
Arabian Sea. Wind speeds were measured at 130km/h and
Heavy Snowfall in J and K, 2000: The entire Kashmir estimated to be much higher in many locations. This cyclone
valley became almost dark because of the sabotage of two caused major loss of life and properties in the coastal areas
towers feeding power to the Kashmir Valley on 16/01/2000. of Gujarat state. Due to the high winds and severe flooding,
Successful deploying of ERS is on the 400kV double circuit several major transmission lines of Gujarat State Electricity
Uri-Wagoora transmission line which carries the power from Board were destroyed. Because of the much-needed
480 MW Uri Hydro Project in Jammu and Kashmir. The requirement of power in the cyclone affected area,
only highway from Jammu to Srinagar was closed due to Powergrid undertook the challenge of rapidly restoring
heavy snowfall for few days. Thus, the ERS was transported several of the vital transmission lines using ERS structures.
in an AN32 (Russian) Transport by the Air Force plane. The
required materials were transported in the above plane which At one place, three towers were destroyed on the double
made several trips between Jammu and Srinagar to circuit 220kV transmission lines from Panandru thermal
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Disaster Advances Vol. 12 (6) June (2019)
power station to Anjar route. These lines were rapidly circuit on the 18/06/1998 using four ERS towers while the
restored using cranes and other heavy equipment along with second circuit was restored on the 23/06/1998 using another
Powergrid’s ERS towers. Power was restored on the first four ERS towers (Figure 11).
Figure 7: Odisha Power Demand met during Super Cyclone Phailin
Figure 8: Erection of the 400kV single circuit 15-degree
tension ERS tower using manpower to pull the two Figure 9: Two views of the almost completed 400kV
conductors of the bottom phase. ERS tension tower showing the span over the double
circuit 220kV line
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Disaster Advances Vol. 12 (6) June (2019)
Figure 10: ERS towers used to restore power after the Orissa cyclone
Figure 11: Tower damaged during Gujarat cyclone and ERS Tower
Heavy Wind and Rainstorms in West Bengal, 1997: On quickly as possible. The closest emergency restoration
28/05/1997, heavy wind and rainstorms caused five double system was located in Itarsi, which was 1500km away from
circuit 400kV suspension towers on the Maithon- site, therefore, it took 3 days to transport the material to the
Jamdeshbur transmission line in West Bengal State to fail. restoration site. During this time engineers from Powergrid
The five suspension towers were located between two surveyed the site and decided to restore one circuit of the
tension towers in that location. All five suspension towers 400kV with the emergency restoration system (ERS) and
collapsed and the resulting collapse caused cross-arms on followed other locations to restore complete line.
both tension towers to damage them. The terrain was
relatively flat and rolling terrain. Failure of these towers did Challenges faced and Possible Solutions: As we have
not cause any outages but due to the increasing loads on observed from the above case studies, even after carrying out
other redundant lines, it was critical to restore these lines as condition monitoring and preventive maintenance, the
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Disaster Advances Vol. 12 (6) June (2019)
break-down of transmission lines cannot be ruled out. This power outages. Examples of structural, foundation and
is mainly because natural calamities are unpredictable events hardware failures on high voltage transmission lines in India
and ranging various severity. Because of this Powergrid has and restorative processes adopted were of help for better
deployed the IEEE Standard 1070 Emergency Restoration planning and restoration work.
System for restoration of collapsed towers as we have seen.
Manual transportation and erection of the ERS tower takes The effective emergency restoration procedures capable of
minimum 3-4 days when restoring a collapsed tower. But, if being activated at short notice must be in place with all
we use hydraulic cranes or if helicopters can be deployed, utility companies. These procedures must be based on the
the restoration work can be done in 2-3 days-time. knowledge of stock materials in storage, trained workforce,
available equipment and resource mobilization, while
We observed from above studies that the restoration process responding to power blackouts caused by natural disasters.
consisted of determining the cause of failure as due to Since new materials and techniques are constantly being
galloping, replacing the hardware fittings and adding more developed, these ERS systems and procedures require
vibration dampers to the conductors to increase damping. periodic review with updated technologies. So, it is very
These three restoration activities discussed highlights and much necessary for the transmission line utilities to take
the importance of utilizing available inventory, devising precautionary actions to avoid and reduce these disruptions.
quick construction methods and deployment of temporary Hence it is extremely important to restore the line as quickly
structures. as possible after failure whether it is planned or due to the
natural disaster.
Powergrid has used these ERS systems many times for either
emergency restoration on transmission line or its References
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their expectations. As a result of Powergrid’s pre-planning reduce restoration time for damaged transmission lines in India,
for potential emergencies on their transmission grid, Lindsey ERS Reference Materials, White Papers (2000)
significant savings have been realized by them. From the
experience to date, Powergrid has modified their emergency 2. IEEE, IEEE Guide for the Design and Testing of Transmission
Modular Restoration Structure Components, IEEE Std 1070-1995
restoration program in many ways as emergency restoration
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materials have been made more decentralized through-out
India in order to reduce deployment time. Also, they have 3. Mukhopadhyay Subrata, Soonee Sushil K., Agrawal Vinod K.,
reduced inventory of permanent emergency towers from 5% Narasimhan S.R. and Saxena Samir C., Impact of Super-Cyclone
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At National Harbor, MD, USA (2014)
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elevation-offset formats that designers have traditionally Porwal Rajiv K., An Indian Experience of Defense Against
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surveying the affected area in some form of three- 5. NDMA, National Disaster Management Guidelines, published
dimensional geographical information system (GIS) type by National Disaster Management Authority Government of India
representation. Data are usually collected in electronic (2012)
format or quick planning and the transmission line software
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Conclusion
From this study, we can conclude that the sever natural 8. Vadivel Karthi K., Emergency Restoration of High Voltage
disasters are always un-predictable and result in various Transmission Lines, The Open Civil Engineering Journal,
challenges for the utility companies. So, it emerges of having 11(Suppl-2 M6), 778-785 (2017).
an effective Emergency Restoration plan, which can help
control the financial impact of losses due to weather-related (Received 06th April 2019, accepted 23rd April 2019)
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