DESIGN, SUPPLY INSTALLATION AND COMMISSIONING OF GENERATOR TRANSFORMER COOLERS - T398

GENERAL DESCRIPTION OF WORKS

·           Eraring Power Station has four 660MW Turbo-generator units that are currently being up rated to 750 MW each. Each Unit feeds two Generator Transformers in parallel. For Units 1 and 2, the Generator Transformer ratings are each 390MVA with voltages 330kV/23kV. For Units 3 and 4 the Generator Transformer ratings are each 390MVA with voltages 500kV/23kV.  The power station has an 11kV auxiliary supply system fed by two 23kV/11kV Unit Auxiliary Transformers from each Unit.  These transformers are also operated in parallel & are rated at 45 MVA.

·           Units 1 & 2 Generator Transformers currently utilise an Oil Forced Directed Water Forced (OFDWF) cooling system and the Units 3 & 4 Generator Transformers utilise an Oil Forced Directed Air Forced (OFDAF) cooling system. It is required that the new cooling systems for all Generator Transformers be OFDAF and be capable of cooling the Transformers to match the Turbogenerator Units when up rated to 750 MW. This requires a combined transformer rating of 834 MVA at an ambient temperature of 40 deg Celsius. Therefore each Generator Transformer shall be capable of operating at a load of 417 MVA at an ambient air temperature of 40 deg Celsius, with the new cooling system in operation.

·           All the existing Unit Auxiliary Transformers utilise an Oil Forced Air Forced or Oil Natural Air Natural OFAF/ONAN system. The Transformers are rated for 45 MVA for OFAF and 25 MVA for ONAN. Due to the expected increase in auxiliary loads resulting from the Unit upgrades the Unit Auxiliary transformers are to be replaced with OFAF/ONAN cooling systems rated at 50 MVA for OFAF and 25 MVA for ONAN with the ambient air temperature of 40 deg Celsius.

·           Eraring Energy shall replace all the coolers associated with two Units (4 Generator Transformer Coolers & 4 Unit Auxiliary Transformer Coolers) during two separate upcoming major Unit outages. There is then an option for Eraring Energy to replace the remaining two Unit cooling systems at a later date.

KEY SCOPE OR DELIVERABLES OF WORKS

·           Evaluate the thermal performance & cooling requirements such that the transformers operate continuously with their new upgraded ratings.

·           Propose a number of modern modular type oil to air heat exchangers operating in parallel for each Generator Transformer such that each cooler bank consists of several independent coolers operating together. Each cooler will have its own individual oil pump, oil flow switch & associated isolation & non-return valves. The Contractor shall supply one additional modular cooler for each Generator Transformer, which may be used as a spare or may be used in parallel with the other coolers.

·           Remove existing transformer tank cooling systems. Remove all obsolete pipework, switchboards, control panels, instrumentation and cabling.

·           Design, supply, install & commission new cooling systems for each Generator & Unit Auxiliary Transformer, including new pipework, switchboards, control panels, instrumentation, alarms and remote I/O to the Station’s ICMS (Instrument Control & Management System).

·           Transfer existing OLTC control and alarm functions to the new switchboards then into the Station’s ICMS.

Provide in a written format a detailed functional specification that would allow Eraring Energy to program the control of the oil pumps and cooling fans as well as set alarms & trips.

Tenders MUST be submitted using DecisionMAX Lite software.