With over 35 GW of installed capacity, the Indian wind energy segment has matured significantly. Over the past two years, the market has also transitioned from a feed-in tariff (FiT) scenario to competitive bidding for wind power projects. The auction regime, introduced in 2017, has led to a significant decline in wind tariffs. This has, however, raised many questions on the quality of wind projects. The current installed capacity comprises a large number of projects set up in the early days and, therefore, based on old technology. Most of these projects came up at sites with flat terrain and high wind speeds. These projects now call for a relook from the perspective of repowering them using more efficient and advanced wind turbine technology. Already, the industry focus has shifted towards using innovative technology for optimum site selection, and increasing hub heights and wind turbine rotor diameters.
With project quality being called into question in a low-tariff regime and with the emergence of larger wind turbines, there is a need for updated standards and guidelines on the quality of turbines as well as the overall wind power project development.
Standards and guidelines
In 1995, the Ministry of New and Renewable Energy (MNRE) came up with the original guidelines for setting up wind projects under the Wind Power Programme in order to bring about balanced growth of wind energy. These guidelines related to the preparation of detailed project reports, micrositing, selection of wind turbine equipment, operations and maintenance, and performance evaluation. Since then, MNRE has been developing the basic infrastructure, institutions and resources for carrying out research and development (R&D) and large-scale demonstration projects.
As a step towards achieving these broad goals and to tackle the challenges in sustaining the development of the wind energy segment, the National Institute of Wind Energy (NIWE) was established as an autonomous R&D institution. NIWE was made the certifying agency for wind turbines and followed the IEC:61400 guidelines. It was also made responsible for issuing a list of certified turbines and empanelled manufacturers, called the Revised List of Models and Manufacturers (RLMM), on a quarterly basis. This listing has given stakeholders confidence regarding the quality of wind turbines offered by various manufacturers.
With the deployment of modern wind turbines with higher hub heights, capacity and capacity utilisation factor and larger rotor diameters, a need was felt for a comprehensive document providing the technical requirements to be complied with by all stakeholders including original equipment manufacturers, independent power producers, wind farm developers, financial institutions and utilities. To this end, the MNRE has prepared a draft certification scheme in consultation with the NIWE.
Indian Wind Turbine Certification Scheme
The Indian Wind Turbine Certification Scheme (IWTCS) is a consolidation of relevant national and international standards, technical regulations and requirements issued by the Central Electricity Authority, guidelines issued by the MNRE and other international guidelines. It incorporates best practices from other countries for ensuring the quality of wind energy projects. The scheme lists guidelines for the benefit of all stakeholders from concept to the lifetime of the wind turbine, and includes the Indian Type Approved Model (ITAM), the Indian Type Certification Scheme (ITCS), the Wind Farm Project Certification Scheme (WFPCS), and the Wind Turbine Safety and Performance Certification Scheme (WTSPCS).
ITAM: This procedure for listing wind turbine models has evolved from the earlier RLMM procedure. It has been further streamlined with an online mechanism with improved safeguards keeping in view the experience gained in implementing RLMM over two decades.
Prototype Certification Scheme: This ensures turbine safety during the testing of a new or improved turbine design. The scheme covers wind turbines installed at specific locations, which are not ready for production. It enables the testing of a new wind turbine type in order to obtain type certification or for R&D purposes.
ITCS: This covers certification of the wind turbine type, including the tower and the connection between the tower and the foundation. A type certificate is one of the mandatory requirements for the production of wind turbines by a manufacturer.
WFPCS: This outlines the process for the development of a wind farm, which may consist of one or more wind turbines, including the foundation for specific external conditions at an installation site. It streamlines the process of installation, commissioning and safe commercial operation of the wind farm.
WTSPCS: This defines the process for ensuring the safety and performance of the turbine during its operational lifetime. It covers failure reporting and analysis, safety and performance assessment and the decommissioning procedure. Under this, the catastrophic failure of all existing and upcoming wind turbines connected to the grid is evaluated. As per the requirement, all catastrophic failures of wind turbines have to be reported by the project owner to the accredited certification body and the NIWE. The NIWE then facilitates the evaluation of the failure and ensures safe operations of similar turbine installations in the country. Under the safety and performance assessment of installed wind turbines, an assessment of all the existing wind turbines connected to the grid, which have been in operation for more than 80 per cent of their design life, is carried out. As part of the decommissioning procedure, safe decommissioning of the turbine and its disposal as per the standards and guidelines are detailed.
Issues and challenges
The international standards are based on European site conditions, and the turbines installed in India have to undergo changes to suit domestic conditions. Therefore, the Indian standards cannot be completely based on international standards. Moreover, wind turbine manufacturers face various issues while complying with these standards. First, the entire testing process is extremely laborious and involves significant investment of time and capital. Any small improvements in wind turbine design need to be recertified through the entire process. This does not give manufacturers any incentive to invest in R&D.
The choice of site is a critical issue affecting the performance of wind projects. The choice of site requires an assessment of the likely impact of shadow areas (in the case of hybrid projects), terrain and obstructions that can affect generation from the system. Since most of the flat terrain has already been utilised to set up over 35 GW of capacity, developers now have to consider setting up plants in difficult terrain. Finding the optimum height of the installation is key. The increase in height has a twofold benefit – less obstruction and faster wind speeds. The air density, however, reduces with the increased height of the windmill. The blade design, the windswept area, the weight of the yaw and the rotor subsystem are also important aspects that impact the quality of wind projects.
Innovative technologies can help address the concerns related to the quality of wind projects. The use of drones, for example, can enable project developers to survey sites and perform soil and topographical analyses more efficiently and comprehensively. The use of 3D printing and augmented reality can help developers to test and modify the blade design in real time, and reduce manufacturing time and costs. The use of alternative and sustainable materials can not only improve turbine performance but also reduce the cost and weight of the turbine. For example, WiSH Energy, a manufacturer of small wind turbines, uses a composite polymer for the blades, which ensures good performance of the microwind turbines even in extreme climatic conditions. For small wind turbines, the use of direct drive generators rather than geared systems increases the mechanical and electrical efficiency. The use of alternative tower designs can address the issue of the height and weight of the system.
The way forward
Ensuring the quality of wind projects will be crucial for developers owing to the strict norms set by the MNRE and the regulations being issued by various state governments on forecasting, scheduling and the deviation settlement mechanism. According to the action plan proposed by the MNRE, if discrepancies are found in the compliance of a self-certified wind turbine model, the original equipment manufacturer would be barred from installing turbines in the country for five years, the turbines would be disconnected from the grid, and a penalty of Rs 20 million would be levied. Meanwhile, the state electricity regulatory commissions have started imposing deviation charges on developers for missing their power supply targets. Both over and underutilisation of generation capacity is penalised. As part of its future plans, the NIWE has proposed to set up a national offshore wind test centre at Dhanushkodi, Tamil Nadu, to test offshore wind turbines. The site will be equipped with four turbine test beds and serve as an exclusive wind testing centre for Southeast Asian countries.
However, considering the current target of 60 GW set for the wind energy segment, it will not be enough to just ensure the quality of products; more R&D labs also need to be set up across the country in a planned manner. Moreover, a quality control and checking mechanism is required for the entire life of the wind power project.