A Report on Grid Tech Exhibition

A

REPORT

ON

GRIDTECH 2011 EXHIBITION

PRAGATI MAIDAN, NEW DELHI

20 th APRIL 2011

THEME:

NEW TECHNOLOGIES IN TRANSMISSION DISTRIBUTION, LOAD DESPATCH & COMMUNICATION

On the 20th of April 2011 the EDI (Electrical) and T&D Team from Isolux Corsan India visited the GRIDTECH 2011 exhibition to familiarize the team with the latest equipments and emerging technologies used in the field of Power , Transmission and Distribution. It is always required for the growing Electrical Engineers to expose themselves to the latest advancements in the industry. For example being introduced to the highest voltage level in the world i.e. 1200kV. All the international manufacturers like ABB, Areva / Alstom, Siemens and Crompton Greeves etc. had displayed their 1200kV equipments in their original Sizes. Also getting in touch with the worldwide suppliers and vendors for power products will definitely be helpful to the engineers.

ABOUT GRIDTECH

An international forum to convert concept into reality in Power and T&D sector, is basically a platform to the International and National manufacturers/ suppliers to showcase their State-of-the-Art products & technologies in the field of Transmission, Distribution, and Load Dispatch & Communication. It is a biennial event of international exhibition and conference .The exhibition provides a unique opportunity for the power utilities , Manufacturers , Research Institutions, Academicians , Consultants etc. in this field to get exposed to new technologies in substation, Transmission line , HVDC system , Grid management , Distribution , Smart Grid , telecommunication etc. The conference provides atmosphere for candid exchange of ideas /experience with international / national manufacturers, planners, policy makers, regulators, experts on new technologies in this field.

While the power sector in India has witnessed manifold growth in the past, the road that lies ahead of us is dotted with innumerable challenges that result from the gaps that exist between what’s planned versus what the power sector has been able to deliver. With focus on increasing generation capacity over the next 7-8 years, the corresponding investment in the transmission sector is also expected to be augmented. The govt. of India plans to establish a strong integrated national grid by 2012 with close to 200,000MW generation capacity and about 32,000 MW of inter-regional power transfer capacity.

The Highlights Of The Exhibition are:

1. High capacity ±800kV 6000MW HVDC system

POWERGRID has developed in-house expertise in implementation of HVDC systems. They have commissioned ± 500kV 2000 MW HVDC bipole between Talcher & Kolar, Asia’s longest HVDC bipole (about 1400 kms). Further ± 500kV, 2500MW Balia-Bhiwadi HVDC Bi-pole is under advance stage of implementation. POWERGRID now is in the process of implementing ± 800kV, 6000 MW HVDC Bi-pole line from North eastern region (Biswanath Chariali) to Northern Region (Agra).

This shall be the first ±800kV HVDC line in the world having largest power carrying capacity of the order of 6000MW and transferring power over more than 2000 Kms.

Bharat Heavy Electricals Limited (BHEL) has won a breakthrough order from Power Grid Corporation of India Ltd. for ±800 kV 6,000 MW HVDC Multi-Terminal System Package associated with the NE/ER-N/WR Interconnector-1 project, in consortium with ABB, Sweden. The order value for BHEL is Rs 1590 Crores. This is the largest order for BHEL in T&D sector.

2. 1200kV UHVAC system

1200 kV AC system is being envisaged as next transmission voltage to meet the long term power transfer requirement in the country. Ultra High Voltage (UHV) transmission schemes are driven by the need to transfer large amounts of electrical power from the generation resources to major load centers. This need is typical of large geographical regions with strongly growing electrical power consumption in one part of the region and natural resources that are far away from the major load centers.

Power grid is establishing a 1200 KV National Test station at Bina. It is unique collaborative efforts where leading manufacturers have joined hands with Power grid for indigenously developing the technology for transmitting power at 1200kV. 35 Electrical Equipment manufacturers in the ultra high voltage segment including 25 IEEMA members have activity collaborated with Power grid for design and development of the required 1200 KV equipment indigenously.

3. High temperature low sag conductor lines

Efforts to reduce right-of-way are complemented with the use of high temperature endurance conductor for select transmission corridor to increase the current rating. Presently the technology to use high temperature and low sag conductor is becoming more important. Maximum temperature limit of the Aluminum Conductor Steel Reinforced (ACSR) conductors is about 100°C and it may not be possible to go beyond this limit as galvanization of the wire would be tampered and secondly there may be a creep in the conductor. However, in special situations anyone can use high temperature endurance conductors which can withstand temperature up to 230°C like Invar. This type of conductor is designed with max. Operating temperature of 210°C for ACSR conductor. It gives matching thermal rating and also has been found to be economical due to considerable savings on structure. POWERGRID has already

implemented twin INVAR conductor line for LlLO portion (15kms stretch) of 400kV Dadri-Ballabgarh quad conductor line at Maharanibagh substation. Apart from increasing the power flow capacity, there was considerable reduction in special pile foundations in the river Yamuna. Further, after implementation of Tala transmission system, two nos. of 400kV D/C lines between Siliguri and Purnia, one with twin Moose conductor and other with quad Moose conductor are running in parallel. This not only creates unbalanced power flow condition but also restricts total transfer capacity of the corridor. In order to address above issues, Siliguri – Purnia, twin Moose conductor line is being re-conductor with high temperature low sag (HTLS) conductor. This type of conductor also has high potential in urban/city areas which is being implemented in metros like Mumbai.

4. High surge impedance loading line (HSIL)

In order to increase the loadability of lines, development of HSIL technology is gaining momentum. By suitably spacing the bundle conductor, surge impedance can be reduced. POWERGRID is building up one HSIL line viz. 400kV Meerut – Kaithal D/C where SIL is about 750 MW as against nominal 650MW for a normal quad bundle conductor line.

For example - SIL = V 2 / Z

Voltage Level (kV) Conventional Line (MW) HSIL Line (MW)

69 9-12 10-40

138 40-50 50-120

203 120-130 130-440

500 900-1020 950-2000

Hence basic advantages of a HSIL Line:-

Enhanced Power Transfer Capacity

Improved voltage regulation of high stressed Transmission Lines

Improved Power Systems Transient Stability Limits

Reduced Environmental Impact, for the Same Power Transmission Level

Maximum Utilization of Existing Right-of-Ways

5. High strength Polymer Insulators

Polymer insulators also known as composite insulators are proliferating on transmission and distribution systems due to their ease of handling, resistance to vandalism, impact and seismic performance and relatively low cost. The polymer materials have high elasticity which will compensate the different expansions of the end fittings due to material temperature variations and mechanical loading and thus there will be no critical forces acting at the interfaces. The polymer insulators basically consists of fiber reinforced plastic core which will provide the necessary mechanical and load handling capabilities and this core is covered with polymer materials which will provide necessary electrical creepage and protects the core against the environmental stresses. The polymer insulators have high strength to weight ratio than the porcelain insulators, which provides easy installation and maintenance. The picture below gives a comparison of the porcelain insulator string versus the polymer insulator string.

6. Controlled series and shunt compensation (FACTS)

To enhance controllability and increase power transfer capability of the network Flexible Alternating Current Transmission System (FACTS) were on display. The two major problems that the modern power systems are

facing are voltage and angle stabilities. A power network is mostly reactive. A synchronous generator usually generates active power that is specified by the mechanical power input. The reactive power supplied by the generator is dictated by the network and load requirements. A generator usually does not have any control over it. However the lack of reactive power can cause voltage collapse in a system. It is therefore important to supply/absorb excess reactive power to/from the network. Shunt compensation is one possible approach of providing reactive power support. A device that is connected in parallel with a transmission line is called a shunt compensator, while a device that is connected in series with the transmission line is called a series compensator. These are referred to as compensators since they compensate for the reactive power in the ac system. We shall assume that the shunt compensator is always connected at the midpoint of transmission system, while the series compensator can be connected at any point in the line. FACTS devices can be connected to a transmission line in various ways, For example, the static VAR compensator (SVC) and static synchronous compensator (STATCOM) are connected in shunt; static synchronous series compensator (SSSC) and thyristor controlled series capacitor (TCSC) are connected in series; thyristor controlled phase shifting transformer (TCPST) and unified power flow controller (UPFC) are connected in a series and shunt combination. In series compensation, the FACTS is connected in series with the power system. It works as a controllable voltage source. Series inductance occurs in long transmission lines, and when a large current flow causes a large voltage drop. To compensate, series capacitors are connected. In shunt compensation, power system is connected in shunt with the FACTS. It works as a controllable current source.

7. GIS and Substation compaction

With scarce land availability there is a growing need for reduction of land use for setting up of transmission systems, particularly in Metros, hilly and other urban areas. POWERGRID has established State-of-the-art Gas Insulated Substations (GIS), which requires less space (about 80% reduction) i.e. 5-6 acres as compared to conventional substation which generally requires 30-40 acres area. POWERGRID has already commissioned 400/220kV GIS at Maharanibagh in Delhi, Kayankulam in Kerala.

8. Short circuit current limiter

Short circuit current limiters are used in power lines to limit the short circuit level in the event of a short-circuit fault on power lines. Different technologies have been employed to

design such as turn-off of a solid state switch to using superconductors that respond with increasing resistance in the event of fault current.

There is a high interest in SC current limiter as it reduces the expected SC current without affecting the steady state power flow. There are different techniques to reducing the short circuit levels using current limiters. The differences between these techniques include the type and location of different elements (reactor, thyristor controlled series inductor, superconductors, etc.) to limit the current. It also varies according to the network voltage level. The majority of the current limiters are installed in the tie circuits such as the bus tie and utility tie circuits in which the current limiters could perform effectively.

9. Super Conductor Technology

Superconductivity is a phenomenon observed in specific materials at very low temperatures. A primary feature of superconductivity is the complete absence of dc electrical resistance.  Promising future applications include ultra-efficient power lines and electric motors, high-performance transformers, power storage devices, and fault current limiters. High temperature superconductivity (HTS) technology enables extremely efficient power transmission by replacing copper wires with a ceramic superconductor alternative that has 5x higher capacity while reducing resistive losses. HTS wire is expected to lose only about one-half of a percent of the power that it transmits, compared to the five to eight percent lost by traditional power cables. 

The cable requires a cooling system to refrigerate the HTS wire to a temperature at which resistance is minimized, about –321°F.  In the cooling system, liquid nitrogen is circulated within a thermal envelope (cryostat) to cool the superconducting wire through which electricity flows. The superconducting tapes, which are wrapped around the core of the cable, make up the phase conductor, replacing the copper or aluminum in conventional cables.

10.Submarine DC cable system

Submarine cables have been increasingly used for power transmission in recent decades. Requirements are increasing regarding more effective use of available energy resources, for very long-distance power transmission, only Solid (mass-impregnated (MI) type or non-draining (ND) type) DC cable can be used because it is impossible to feed

insulating oil into the cable from its both ends. Therefore, oil of very high viscosity has been used for conventional Kraft paper Solid DC cable under a relatively low permissible conductor temperature (T max), such as around 50°C, in order to prevent oil-migration.

11.Live line maintenance techniques

Co-habiting with UHV transmission lines has mostly been for the birds. Techniques have been developed, however, for humans to safely work on the ultra high voltage transmission lines - when live. The ability to provide maintenance services without shutting down the line has many benefits to the network owner such as fewer requirements for line redundancy and no discontinuity in the electricity supply

Live Line Maintenance or Hot Line works can be classified into two types as follows:

a) Hot Stick Method

Using hot-stick methods, direct human contact with live components is avoided. Line workers use tools fastened to insulated fiberglass poles to carry out the work, and always keep themselves at a safe distance from the live components.

b) Bare Hand Method

The work can be attended directly on EHV lines by Bare Hand suits, conductive shoes, socks and gloves from insulated ladders. For EHV Line 220 KV and above up to 765 KV this procedure is being used. This technique is in use in Nasik Unit.

12. . Thermo vision scanning

Thermo-vision scanning is prevalent in power sector for more than two decades.  However, during past two years development in this technology has been unbelievable.  Presently, precision wide lenses thermo-vision equipments are available, which facilitate large area scanning even  in day light and also provide a comparison of pre and post scanned object.  Temperatures are recorded in the microprocessor, which facilitate use of equipment at a stretch for scanning of more than 100 joints.  In MP Transco, extensive use of this equipment is being made not only for the purpose of scanning of weak joints alone, but also efforts have been

made to compare the operating temperature of CTs and VTs in the same bay.  In few substations, it was found that one of the CT/PT (out of set of three) was operating at a high temperature compared to the others.  The equipment was taken out for maintenance and it was found that oil characteristics in the equipment have lowered down and also loose connections were found therein.  Maintenance was done to save the equipment.  Thermo-vision scanning, therefore, will write its own history in the power sector, if full advantage of the facilities provided by the technology is taken.  For this equipment as well as critical equipments of this nature, MP Transco has developed a system of maintaining equipment-wise log book to record history of each operation as also utilization schedule for the equipment.

13.Smart Grid – WAMS, PMUs, adaptive islanding, self healing grid

Smart Grid - A smart grid is a form of electricity network using digital technology. A smart grid delivers electricity from suppliers to consumers using two-way digital communications to control appliances at consumers' homes; this could save energy, reduce costs and increase reliability and transparency if the risks inherent in executing massive information technology projects are avoided. The "Smart Grid" is envisioned to overlay the ordinary electrical grid with an information and net metering system, that includes smart meters. Smart grids are being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues.

Advantages of Smart Grids:

1. Better energy management.

2. Proactive management of electrical network during emergency situations.

3. Better demand supply / demand response management.

4. Better power quality

5. Reduce carbon emissions.

WAMS - Wide area management systems are software systems that acquire, manage, analyze, monitor and store phasor data from network infrastructures over a wide area.

PMUs - A phasor measurement unit (PMU) measures the electrical waves on an electricity grid to determine the health of the system. In power engineering, these are also commonly referred to as synchro phasors and are considered one of the most important measuring devices in the future of power systems. A PMU can be a dedicated device or the PMU function can be incorporated into a protective relay or other device. PMUs with GPS system to be installed at four substations of Northern Region

and PDC at NRLDC, Delhi. (PMU locations: Moga – 400 kV, Kanpur – 400 kV S/s, Vindhyachal – HVDC, Dadri – HVDC).

Basic advantages:

1. Power system automation, as in smart grids2. Load shedding and other load control techniques such as demand response

mechanisms to manage a power system. (i.e. Directing power where it is needed in real-time)

3. Increase the reliability of the power grid by detecting faults early, allowing for isolation of operative system, and the prevention of power outages.

4. Increase power quality by precise analysis and automated correction of sources of system degradation.

5. Wide Area measurement and control, in very wide area super grids, regional transmission networks, and local distribution grids.

Adaptive Islanding –

When a fault occurs in an energy distribution network, adaptive islanding is initiated to supply energy to customers who are disconnected from the primary source of energy on the network. The customers are selectively connected to secondary energy resources that are distributed within the network. The selected customers are chosen in accordance with a profile that takes into account the amount of energy available from the distributed resources, the expected length of time to repair the fault, the recent energy demands of the customers, and levels of priority that are assigned to respective customers. These factors are monitored, and the selected customers who are connected to the distributed resources are dynamically adjusted during the time that the fault exists

Self Healing Grid –

A system that uses information, sensing, control and communication technologies to allow it to deal with unforeseen events and minimize their adverse impact. A secure “architected” sensing, communications, automation (control), and energy overlaid infrastructure as an integrated, reconfigurable, and electronically controlled system that will offer unprecedented flexibility and functionality, and improve system availability, security, quality, resilience and robustness.

S. Silberman, July 2001. He said:

“ The best minds of electricity R&D have a plan: Every node in the power network of the future will be awake, responsive, adaptive, price-smart, eco sensitive, real-time, flexible, humming-and interconnected with everything else .”

14.DC Micro Grid, Distribution Management System

DC Micro Grid

Our electric power system was designed to move central station alternating current (AC) power, via high-voltage transmission lines and lower voltage distribution lines, to households and businesses that used the power in incandescent lights, AC motors, and other AC equipment. Today’s consumer equipment and tomorrow’s distributed renewable generation requires us to rethink this model. Electronic devices (such as computers, florescent lights, variable speed drives, and many other household and business appliances and equipment) need direct current (DC) input. However, all of these DC devices require conversion of the building’s AC power into DC for use, and that conversion typically uses inefficient rectifiers. Moreover, distributed renewable generation (such as rooftop solar) produces DC power but must be converted to AC to tie into the building’s electric system, only later to be re-converted to DC for many end uses. These AC-DC conversions (or DC-AC-DC in the case of rooftop solar) result in substantial energy losses. One possible solution is a DC Micro Grid, which is a DC grid within a building (or serving several buildings) that minimizes or eliminates entirely these conversion losses. In the DC microgrid system, AC power converts to DC when entering the DC grid using a high-efficiency rectifier, which then distributes the power directly to DC equipment served by the DC grid. On average, this system reduces AC to DC conversion losses from an average loss of about 32% down to 10%.2 In addition, roof top photovoltaic (PV) and other distributed DC generation can be fed directly to DC equipment, via the DC microgrid, without the double conversion loss (DC to AC to DC), which would be required if the DC generation output was fed into an AC system. Barriers to deployment, and policy measures that could accelerate this deployment.

Distribution Management System

Unbalanced distribution power flow, loss and contingency analysis, and switch order management are essential functions of electric system operations. DMS helps Utilities existing assets more effectively, utilize the full capacity of the system, defer capital expenditure wherever possible, and at the same time reduce outages and increase customer service levels.

Feedback:

1. Ravi Goyal

It was the first time when 1200kV equipments displayed by Crompton Greaves, ABB and other participants. Power grid displayed the 1200kV Bina substation which is working on trial basis. Model of 132kV underground substation was displayed by Hyosung. This substation is working in Korea under a commercial complex.

2. Dinesh Kumar Kushwaha

GRIDTECH 2011 EXIBITION IN PRAGATI MADAN was Excellent informative experience in all kind of product/company presentations like Gas Insulated Switchgear up to 245Kv, SF6-Gas Circuit Breakers110kV-245kV, Modular substation computers, HV Power Disconnectors up to 1200 kV, Aluminum conductors up to 500mm, 1200 kV CTs, UHV 1200 kV AC Transmission, Solar Energy and wind Energy System, Hollow Insulators in single piece up to 2300mm. It was great visit.

Extremely thankful to Mr. Sanjib Banerjee and the people who coordinated to organize this visit.

3. Arjun Uberoi

The visit to GRIDTECH 2011 was a highly informative and exhilarating experience. To learn about the world’s highest system voltage i.e. 1200kV and to see the equipments of this scale made us aware of the in-depth engineering development and technical growth in our industry. From this it becomes evident that there is a rapid increase in the efficiency of the power generation, transmission & distribution. Coming face to face with concepts like underground GIS substations and Smart Grids was a good learning experience .I am grateful to my seniors and mentors for giving an opportunity to keep in stride with the advancements in our industry.

4. Ashwini Kumar Pandey

The visit to the exhibition was great in term of the on field knowledge of the job we are doing in office. Watching the equipment sizes that we just rated on the paper gives the on field idea of the switchyard. Talking to the experts of the equipment also gives the confidence about the technology we are using and also to gain knowledge from their experience.

5. Vaibhav Pisal

The exhibition was having plenty of stalls with all major equipment manufacturers in field of electrical engineering. It was very informative as all manufacturers were displaying cutting edge technologies that were still in testing phase like 1200 kV transmission lines, ±800 kV HVDC transmission lines. The exhibition was also suitable place for collecting brochures and catalogues for various products from manufacturers. The exhibition was well worth my time.