- (1.) THIS petition has been filed by the petitioner, NTPC Tamil Nadu Energy Company Limited (NTECL), seeking permission of the Commission for injection of infirm power into the grid during testing including full load testing beyond the period of 6 months form the date of first synchronization up to declaration of commercial operation of unit 3 of the Vallur thermal power project (generating station) (3x500 MW) (hereinafter referred to as 'the project') in terms of Clause (7) of Regulation 8 of the Central Electricity Regulatory Commission (Grant of Connectivity, Long -term Access and Medium -term Open Access in inter -State Transmission and related matters) Regulations, 2009 as amended from time to time (Connectivity Regulations).
(2.) THE petitioner has submitted that the 1st and 2nd units of the generating station have already been declared commercial on 29.11.2012 and 25.8.2013 respectively. The third unit of the generating station (Unit) was synchronized on 28.2.2014, which was expected to be declared under commercial operation by 28.8.2014. The various systems/works required for declaration of commercial operation are in advanced stage of completion.
(3.) THE Commission by its order dated 25.8.2014 in Petition No. 129/MP/2014 had allowed injection of infirm power from the Unit of the project for testing including full load testing till 15.10.2014 or upto the declaration of commercial operation of unit, whichever is earlier. The petitioner has submitted that COD of the Unit could not be achieved by 15.10.2014 due to technical issue relating to failure of CW pump. The petitioner in this petition, while praying for extension of time for testing and full load testing and consequent injection of infirm power, has mainly submitted as under: (a) Boiler was lighted up to 12.9.2014 for start trial operation. Steam dumping has been carried out to achieve the desired parameter for turbine rolling. The turbine rolling was about to be started after achieving the desired steam parameters. However, unexpected heavy leakages in pipe lines of HVAC (AC and Ventilation) system, led to tripping of air conditioning system of Unit control room. Unit was stopped on advice of M/s. BHEL to prevent the failure of electronic cards in UCB due to insufficient cooling. However, HVAC leakages were attended and in addition, tower ACs were also provided for the control room as a standby cooling system. (b) During the period one of CW Pumps tripped on very high vibration. After inspection, catastrophic failure observed in the CW Pump. Sea water with IDCT is envisaged for the project as circulating water for condenser cooling system. The project has been provided with 6 nos. of CW Pumps for three units (2 per unit). Since the pumps are of vertical wet pit and impeller pull out type pumps manufactured by M/s. WPIL in collaboration with MHI (Japan), stand by pumps are not envisaged in the scheme. The petitioner has been facing problems with the availability of pumps owing to high pump vibration and high motor thrust bearing temperature. (c) The problems associated with pumps have taken up with WPIL (manufacturer), reviewed the causes of failures and revised several engineering aspects to overcome the vibration problem. The pump has under several modifications such as modification at site and WPIL Works and redesign/design ratification by WPIL in association with MHI (Japan). The modifications carried out at site reduced the failure rates. However, the manufacturer proposed to change the design of impeller such as introduction of additional shells in the suction bell, flow stream liner in the bowl guide, provision of leather gaskets between the taper seating surface of the bowl and bowl guide to address the vibration problem. All the above modifications have been made in one of the pumps. (d) On 2.9.2014, WPIL was requested to perform inspection and root cause analysis. In response, WPIL vide its letter dated 3.9.2014 informed the petitioner that components required for modification in the failed pump will be procured at their works and necessary modification and repair will be made at the earliest. (e) The petitioner vide its letter dated 10.9.2014 addressed to WPIL expressed serious concern over sustained high vibration level and repeated failure of pumps and motors and insisted on the requirement of all 6 pumps in proper working condition for declaration of commercial operation of the Unit by September 2014. (f) On 19.9.2014 a meeting was convened with Original Equipment Manufacturer i.e. WPIL regarding problems in CW pumps and the petitioner requested WPIL to take necessary action to bring down the vibration to acceptable limits. ;