Balraj also talked of incentives for wind development already in place, including facilities for banking and wheeling of power, and said a wind turbine test station was planned for Kayathar. It would be financed by the Ministry of Non Conventional Energy Sources (MNES) and the government of Denmark. Balraj, however, was unrelenting on the problem of reactive power drawn by the induction generators of most wind turbines. "We are insisting developers improve the power factor to 0.85. If the power falls below this, the turbine will be disconnected from the grid," he said.
TNEB has introduced a penalty of INR 0.10 per unit of reactive power drawn from the grid to act as a deterrent "As a system improvement, installation of 4.8 MVAR capacity of shunt capacitors in nine wind farm substations has been planned during 1996-97," assured Balraj. A strategy for improving the performance of wind plant, such as increasing the size of capacitors or looking at "synchronous types" of wind turbines is being explored, he added.
The potential of Tamil Nadu's wind resource is considerable. In three mountain passes alone, a wind tunnel effect would allow for 2000 MW of wind plant. The Palghat gap in the Coimbatore and Periyar district, with a potential for 1200 MW, is the fastest developing area for wind farms, with 258 MW installed there already. The potential of the Shencottah gap in the Tirunelveli, Kattabomman and Chidambaranar districts, is estimated at 500 MW, with 56 MW installed so far, while the Aralvoimozhi gap has space enough for 300 MW of wind plant, with 302 MW installed. Forty-five wind monitoring stations have been installed in these areas where annual wind speeds are 5-6 m/s.
Impressive six years
Indeed, Tamil Nadu has made great strides since the commissioning of its first private wind farm in 1990. A total of 396 wind farm developers have installed 617 MW of wind turbines in the state. Up until September, nearly 600 MW of this total was developed by private sector companies. With all the wind farms interfaced with existing substations at 33 kV, Balraj noted that no "insurmountable problem" had been encountered by developers in integrating wind power into the Tamil Nadu supply system. A 110 kV line between Nanguneri and Perungudy is now being built, for example, to solve problems of grid overloading, particularly in the peak wind season in the Tirunelveli area, he said.
Wind resource assessment formed a major part of the symposium. Dennis Elliott of the United States National Renewable Energy Laboratory (NREL), said the laboratory's goal was to improve the characterisation of wind resources in regions that had marketing opportunities for US wind technology. Major tasks included establishing new wind measurement programmes, gathering comprehensive meteorological and geographical data bases, and designing progressive wind mapping tools to facilitate products used in support of emerging markets.
Wind engineering consultant S.K. Tewari, stressed the importance of correct wind assessment and optimum turbine layout for any wind project, with particular reference to a project in complex terrain near Gadag in Karnataka that had used computerised wake decay models.
R. Ramanujam from M.P. Windfarms of Bhopal talked about interfacing wind turbines with the grid. To ensure grid stability, he said it was necessary that "wind farm capacity constitutes only a small percentage of the bus capacity of the grid substation." He felt the capacitor compensation provided by manufacturers was inadequate to maintain the power factor above specified levels, particularly in a low wind regime.
Another problem was raised by E Sreevaisan of the Agency for Non Conventional Energy and Rural Technology in Kerala. He felt that wind turbines now running in India were designed for European climatic conditions. "In India, the air density is around 0.981 kg/m3, while manufacturers are assuming a density of 1.23 kg/m3. Since the power output of a turbine depends on air density, a reduction in power output of 6-20% power compared with the design value is found in India," he said. He suggested that manufacturers should take this into account when designing turbines for India.
The general manager of the Indian Renewable Energy Development Agency (IREDA), B.S.K. Naidu talked about the role of international aid in Indian wind development. IREDA is currently administering a $78 million line of credit for wind farm projects. This includes $13 million from the World Bank's Global Environment Facility, $15 million from the Indian Development Administration, and $50 million from Denmark's overseas aid organisation, DANIDA. Together with the Asian Development Bank's package of $60 million, there is credit enough to finance 140 MW of wind farms in India.
Naidu said that though the favourable fiscal environment had inspired confidence in the private sector which was willing to enter a competitive electricity market, the stop-go investment pattern induced by India's tax credits was not beneficial. Tax credits become available each year in March and September, creating a wind development rush which ignores the "advance planning which is required for the appraisal and procurement process acceptable to international funding organisations," he said.
Naidu agreed that there were some "genuine problems faced in the World Bank's procurement procedures and some relaxation was required." He announced that the bank had now relaxed procedures for those procuring equipment costing less than or equal to $5 million.