While Solar Energy is a relatively new sector in India, the other high potential sector – Wind energy, has been around for a while. Wind Energy has an installed capacity of about 13 GW and this constitutes about 70% of the total renewables installed capacity. Interestingly, India’s wind power potential is estimated at 45GW.
With the increase in wind energy penetration, the interaction between the grid and the wind farms generating electricity becomes more and more critical. In this interview with EAI, Mr. Jayateerth Managoli, Country Sales Manager, American Superconductor Corporation, talks about the status of current technology in the electric power infrastructure, advances in technology, grid codes and shares his views about what the Government of India should do about grid codes.
EAI: Please provide a brief introduction and background to your company.
Jayateerth Managoli (JM): American Superconductor (AMSC) offers an array of proprietary technologies and solutions spanning the electric power infrastructure – from generation to delivery to end use. The company is a leader in renewable energy, providing proven, megawatt-scale wind turbine designs and electrical control systems. The company also offers a host of Smart Grid technologies for power grid operators that enhance the reliability, efficiency and capacity of the grid, and seamlessly integrate renewable energy sources into the power infrastructure. These include superconductor power cable systems, grid-level surge protectors and power electronics-based voltage stabilization systems. AMSC’s technologies are protected by a broad and deep intellectual property portfolio consisting of hundreds of patents and licenses worldwide.
AMSC is offering its complete range products and technologies to customers in India.
EAI: As power generation from wind farms increase, if not connected properly, they can potentially have negative ramifications for the electricity grid. Please describe how your product solves this problem.
JM: AMSC’s D-VAR STATCOM systems and D-VAR RT are used to seamlessly integrate wind energy to the grid. Our products enable wind farms to look more like conventional power plants from the power grid’s perspective. This means that the voltage provided to the grid is always steady even when the wind slows. AMSC products offer additional benefits to wind farm owners in terms of longer life of the wind turbines, reduced maintenance requirements and maximized power outputs.
AMSC’s D-VAR system is deployed in more than 100 locations around the world, including over 70 wind and solar farms. In many instances, local requirements dictate the use of such devices due to the unique nature of their grid systems. As wind power – and the use of other renewables increase – we expect more countries and regions to adopt similar requirements.
AMSC also provides advanced power electronics and control systems for individual wind turbines. A dozen manufacturers around the world – including two of the world’s 10 largest wind turbine manufacturers – are using these electrical control systems to maximize the power output, efficiency and reliability of their wind turbines.
EAI:What are the key benefits AMSC products have over the capacitors that are being currently used in wind farms?
JM: Wind is, by nature, a variable source of energy. The reactive support required by induction generators also varies continuously. Capacitors come in predefined steps and need to be switched off and on several times during the day to handle these variations. In most cases capacitors are not designed to operate in this mode. This recurring switching function puts pressure on the capacitor banks, switches and the life of the capacitors.
Operation of capacitor banks in large enough steps introduces step voltage in the system which can affect the equipment connected to the grid. For induction machine wind generators, a large and frequent step voltage change introduces a torque or a twisting force on the gear box of the wind turbine, which increases wear and tear with every capacitor bank switching event.
There are many instances when the grid voltage rises higher than the limit and needs to be brought back down to the limit. Instead of reducing the voltages at these instances, capacitors increase the voltages causing further harm. This, then, requires inductive support to ensure continuity of operation.
Alternatively, the D-VAR system also aids in restoring the grid during extreme low voltage events such as fault situations.
Additionally, the transformers and other equipment connected to the grid consume reactive power from the grid, which is not always offset by just the capacitors.
By providing continuously variable capacitive and inductive support as needed and acting as a smooth integrator, AMSC’s D-VAR system offers solutions to these issues.
EAI: How can wind farms that do not have equipments similar to your products affect the grid?
JM : During a grid high voltage situation (which are common in India), the wind farms with only capacitors are likely to increase the voltage further, making the situation worse.
Additionally, the availability of the wind farms to the grid reduces as the turbines require more maintenance. During the grid faults, wind farms without a dynamic reactive compensation device disconnect from the grid. This can wreak havoc on the grid and can cause a very weak grid to collapse. Or, the turbine will require a larger amount of costly spinning reserve to be maintained, to account for the lack of dynamic performance.
EAI: What are the current wind farms using in order to reduce the amount of fluctuations and reactive power draw in their supplies to the grid?
JM: Many of the current wind farms use conventional capacitors to reduce the reactive power draw from the grid. The capacitors, though economical, cannot provide a robust and flexible performance.
EAI: What innovations do you foresee happening in the wind farm to grid connectivity stage?
JM: As the penetration of wind energy is increasing, grid operators all over the world are putting in place appropriate Grid Interconnection Codes. These codes address the potential issues that larger amounts of wind will cause in their system.
Wind turbine manufacturers are trying to upgrade or develop the turbine systems to meet the requirements. Many power electronics experts have developed systems independent of turbines which can be used for this interconnection.
EAI: Tell us something about grid codes, their status in India and how you see them evolving in the next few years.
JM: Higher penetration of renewables will have higher impact on the grid. Since the output of the wind and solar power is varying in nature, it poses integration challenges.
The grid operators would like to see the wind and solar farms operate as conventional power plants, meaning that they provide a steady state of power without any intermittencies or fluctuations. Since wind and solar (as well as other renewables) are intermittent sources of energy, technology needs to be used to for them to “look like” fossil fuels.
Many regions have adopted special interconnection standards called “grid codes” to integrate renewables into the grid. The grid codes help in establishing a standard operating practice to minimize the impacts on the grid while providing a platform for uniform requirement that maximizes benefits for the grid and the developers alike.
In India, renewable energy – with installed capacity of 18.15 gigawatts (GW) – accounts for 10.9% of India’s total installed power generation capacity. Wind energy – with installed capacity of 12.8 GW – constitutes 70% of the total renewables (as on 30.9.2010 according to MNRE). This figure is only expected to increase as the government continues to focus on and encourage renewable energy generation.
However, as the use of renewable energy increases, it becomes imperative on the part of the government and regulatory boards to introduce standards that ensure a safe and reliable connection. Without these standards, India’s grid cannot be improved. The good news is that this could happen within the next 6-8 months, as efforts have already been initiated by the appropriate parties.
EAI:Are grid codes applicable to wind farms today, and if not, why not?
JM: The present grid codes do not cover the wind farms. However, when the new grid codes come into effect, logically they will need to cover wind farms.
The reason current grid codes do not cover the requirements of the wind farms yet is because the penetration of wind generation had been very low and usually restricted to small pockets of the grids. In most cases the wind farms have been small enough that the loss has not been considered crucial to the grid operations.
But as the level renewable energy generation increases, grid operators will need to refocus their attention to the reliability of their system. In addition to increasing the safety and reliability of the grid, a uniform and comprehensive grid code will serve as a platform to encourage seamless integration process and advance of the nation’s renewable energy policies.
EAI: As and when grid codes come into practice, how can wind farms satisfy the policies laid down by these grid codes?
JM: As and when the grid codes come into practice, the wind farms will need to be able to comply through an improved set of performance criteria. In some cases the turbines will need to be adapted to be able to meet the requirements. However, AMSC’s D-VAR system offers an easy solution to two of the important requirements of the expected grid code – namely dynamic reactive power compensation and fault ride through capabilities. AMSC’s D-VAR STATCOM systems are an ideal solution to improve the capabilities of older wind farms.
EAI: What would be your recommendations to the government of India in order to ensure seamless connectivity for wind farms to electricity grids?
JM: Because the penetration of the wind energy is already substantial in India, there is an urgent need for a grid code that is in line with countries that have already have a high level of penetration of wind power like Spain, the UK and Australia.
Simultaneously as solar energy generation will be the next big wave in India, it is logical to prepare for the future and appropriately plan all renewables into the Grid Code so that the grid operators can maintain a safe and reliable electricity supply throughout India.
American Superconductor also has developed solutions for the Solar PV Plants like SolarTie™ Grid Interconnection Solution . The company is participating the Intersolar Exhibition in Mumbai between 14-16 December 2010. Visitors to the Exhibition can learn more about American Superconductor by meeting their representatives at Booth #6169.
A similar interview with L&T is available at http://eai.in/blog/2011/03/captive-solar-pv-systems-%E2%80%93-lt%E2%80%99s-experience.html