India’s electricity sector is among the world’s most active players in renewable energy utilization. It has recorded an estimated per capita total power consumption of 879 kWh in March 2012. When juxtaposed against conventional power generating systems, renewable energy projects often get affected by voltage dips due to irregular wind flow or grid faults, thus impeding the power quality. These voltage dips in turn create transient voltage instability that eventually abates the overall stability of the wind turbine grid. In order to avoid such cases it is necessary that wind and solar power plants should have control capabilities and protection mechanisms. Therefore the transmission system operators have established so-called grid codes with certain critical values and control characteristics that the generating plants have to fulfill. An important part of these requirements is the so-called LVRT capability of generating plants.
LVRT is short for Low Voltage Ride Through and describes the requirement that generating plants must continue to operate through short periods of low grid voltage and not disconnect from the grid.
To counteract voltage instabilities especially due to voltage dip, it is vital to leverage Low Voltage Ride Through (LVRT) testing specifications and processes that will help maintain grid integrity. In a country where variation of power frequency and poor power quality has plagued for many years, it is imperative for wind farming operators to utilize such advanced techniques to maintain grid stability. In India, CEA (Central Electricity Authority) has already issued ‘Connectivity Standards (2013) for wind and solar generating stations’ which stipulates that, the wind generating stations connected to the grid at 66 kV voltage level and above shall have the fault ride through (LVRT) capability.
Generally, the LVRT tests are conducted on prototypes and are referenced to International Electro technical Commission (IEC) standards and other national & international grid codes. So, it is crucial to validate LVRT capability of wind turbines and solar inverters from IEC accredited third party firms to ensure grid authenticity.
UL is accredited to ISO/IEC 17025, has been testing the LVRT capability of wind turbines, solar inverters and of other generation units/systems for several years. Specialized tests reveal the behavior of the generation unit during LVRT dips, and measure compliance with respective requirements, including local grid codes. As an institution accredited by the German accreditation body DAkkS (according to DIN EN ISO/IEC 17025:2005), we can conduct measurements and evaluations according to IEC 61400-21 for wind turbines and FGW TR3 for solar inverters/plants, to reveal the behavior of the generation unit during voltage dips and measure compliance with the corresponding grid codes such as CEA and BDEW guidelines. To further exemplify our competency, we acquired new mobile LVRT systems last year that can test generating plants up to 3.5MVA (in grids up to 20kV) and generating plants up to 10MVA (in grids up to 35kV) at any desired location.
In addition to LVRT test capabilities, we are poised to help Indian renewable energy sector with other professional services too, such as design evaluation, type testing and certification, wind measurements, energy yield assessment, technical due diligence, site classification and others.