In order to facilitate the development, operation and maintenance of an efficient, coordinated and economical Gujarat power grid by specifying to STU/ transmission licensees and all the users connected to that system for their technical and procedural obligations, GERC has issued Draft Gujarat Electricity Grid Code. This Grid Code is applicable to Gujarat power grid only and for inter-state transmission, Indian Electricity Grid Code shall be applicable. The salient features of the Draft Grid Code relevant to renewable energy power plants are specified as under:
a) Connectivity Standards:
- Wind generating stations connected at 66 kV and above shall be capable of supplying dynamically varying reactive power support, so as to maintain power factor within limits of 0.95 lagging to 0.95 leading. Similarly, solar generating stations have to maintain power factor within limits of 0.90 lagging to 0.90 leading.
- Wind generating stations and solar generating stations shall have fault ride through capability of not less than 300 milli-seconds so that grid is not destabilized due to sudden outage of generation in the event of a grid disturbance.
- The total harmonic distortion for voltage at the connection point shall not exceed 5% with no individual harmonic higher than 3% and the total harmonic distortion for current drawn from the transmission system at the connection point shall not exceed 8%. The above measurement of Harmonics Distortion has to be carried out every six monthly and shall be reported to STUs/ Licensees.
b) Evacuation of wind generators
- SLDC shall make all efforts to evacuate the available solar and wind power and treat as a must-run station. However, the system operator may instruct the solar /wind generator to back down generation on consideration of grid security or safety of any equipment or personnel is endangered and solar/ wind generator shall comply with the same.
- SLDC/RLDC may direct a wind farm to curtail its VAr drawal/injection in case the security of grid or safety of any equipment or personnel is endangered.
- During the wind generator start-up, the wind generator shall ensure that the reactive power drawal (in-rush currents in case of induction generators) shall not affect the grid performance. For these, Data Acquisition System facility shall be provided for transfer of information to concerned SLDC and RLDC.
c) Scheduling/Dispatch Code:
- Scheduling of wind power generation plant would have to be done for the purpose of UI where the sum of generation capacity of such plants connected at the connection point to the transmission or distribution system is 10 MW and above and where PPA has not been signed before 3rd May, 2010. For capacity and voltage level below this, as well as for old wind farms (a wind farm is a collection of wind turbine generators that are connected to a common connection point), it could be mutually decided between the wind generator and the transmission and distribution utility, as the case may be, if there is no existing contractual agreement to the contrary. The schedule by wind power generating station(s) may be revised by giving advance notice to SLDC. Such revisions by wind power generation station(s) shall be effective from the 6th Time Block, the first being the Time Block in which notice was given. There may be a maximum of eight revisions for each three-hour time slot, starting from 00:00 hours during the day.
- The schedule of solar generation shall be given by the generator, based on availability of the generator, weather forecasting, solar insulation, season and normal solar generation curve and shall be vetted by the SLDC in which the generator is located and incorporated in the inter-state schedule. If SLDC is of the opinion that the schedule is not realistic, it may ask the solar generator to modify the schedule.
- Complementary Commercial Mechanism for wind and solar generators shall be according to the Indian Electricity Grid Code (IEGC), 2010 and as amended from time to time.