Installation of electromechanical equipment for large cascade power stations engineering construction organization design
1.1.1 Overview A hydropower station is located in the middle and lower reaches of the XX River in the upper reaches of the main stream of the Yuan River, in XX County of XX Miao and Dong Autonomous Prefecture, XX Province. It is 80km away from the county seat of XX and 25km away from the county seat of XX. It is the second stage of the 15 cascade hydropower stations in the main stream of the Yuan River, and the only Longtou hydropower station on the Yuan River with multi-year regulation performance. The power station is a Class I project with a large scale (I). The hydroproject layout is as follows: the main dam is arranged on the riverbed, and the auxiliary dam is arranged on the left bank. The dam type is concrete faced rockfill dam, and the underground water diversion and power generation system is arranged on the right bank. The normal pool level of the reservoir is 475m, the corresponding storage capacity is 3.748 billion m3, and the effective storage capacity is 2.616 billion m3. The water diversion and power generation system is composed of three systems: water diversion system, powerhouse system and tailrace system. It is mainly composed of underground buildings such as headrace tunnel, main and auxiliary power houses, bus tunnel, main transformer switch tunnel, tailrace surge shaft, tailrace tunnel, cable shaft, tailrace gate shaft, construction adit, access tunnel to the plant, main exhaust wind tunnel, bus duct wind tunnel and shaft, drainage gallery, and ground buildings such as water inlet, tailrace outlet, outlet platform. The underground powerhouse is equipped with four vertical shaft mixed flow water turbine generator units with a unit capacity of 250MW. The layout of one unit and one tunnel is adopted for water diversion. The tailrace system adopts the layout of two units sharing one surge shaft and one tailrace tunnel. The guaranteed output of the power station is 234.9MW, and the average annual power generation is about 2428 million kW · h. The power station is connected to XX substation of XX power grid at a 500kV voltage level. The power station serves as peak shaving, frequency modulation and emergency standby in the system. The underground powerhouse area is equipped with main and auxiliary powerhouse and installation yard, with main dimensions of 147.20m × 22.70m × 60.01m (length, width and height), and the bottom is equipped with maintenance drainage gallery (elevation 291.24m). A six storey central control building is arranged at the end of the main power house near 4 # unit. The main transformer switch tunnel is located at the downstream of the main power house and parallel to it. The rock wall between the caverns is 31.50m thick. The size of the main transformer switch tunnel is 111.00m × 23.00m × 30.80m. There are four bus tunnels between the main transformer switch tunnel and the main power house. The tunnel is 7m wide and the ground elevation is 322.70m. The tailrace system is composed of four 8.9m × 11.5m tailrace adits, two circular impedance surge shafts, two "2-in-1" bifurcated tunnels, two circular tailrace tunnels, tailrace outlets and other structures. The gate shaft of the tailrace adit is located at the downstream side wall of the main transformer switch tunnel, with an orifice size of 8.90m × 3.0m. The generator and transformer unit are connected by joint unit, and the generator circuit breaker is installed at the generator outlet. The generator to main transformer room is connected with 15.75kV isolated phase enclosed bus, and the main transformer is directly connected with 500kV GIS through oil/SF6 bushing and tube bus (GIB). GIS is connected to outdoor outgoing platform equipment through 500kV extruded insulated cable. The power station adopts an open and fully distributed computer monitoring system. The power station is equipped with a central control room, which is responsible for the operation, control and monitoring of the plant equipment. Each unit is equipped with unit excitation, governor, auxiliary equipment control panel and protection panel, local control unit of computer monitoring system, etc. 1.1.2 The natural conditions of the project and the ambient temperature of the external traffic project site vary from the lowest - 8.4 ℃ to the highest 38.3 ℃, with the lowest monthly average temperature of 2.2 ℃, the highest monthly average temperature of 32.4 ℃, the multi-year average relative humidity of 84%, and the multi-year average river flow of 240m3/s. The basic earthquake intensity in the area where the power station is located is less than 6 degrees on the Richter scale. The external road of XX power station is connected from Xiangshui Dam of National Highway 309 in XX Jingzhou County to XX River Bridge downstream of the dam, about 82km long, with concrete pavement and 6.5m wide. The load standards of bridges and culverts along the highway are steam - 20 and hanging - 300. The concrete pavement in the plant is 10.5m wide, and the bridge load standard is steam 60 and hanging 200. The nearest railway station is Genshankou Station in Jingzhou County, about 88.6km away from the construction site. The size of the access tunnel to the plant is 7.0m × (7m straight section+2m crown), and the size of the lifting hole for equipment in the plant is 4.8m × 3.0m for the generator floor; Bus layer 3.0m × 2.5m; 2.5m × 2.5m below the turbine floor. 1.2 Scope of work The items and work contents of the electromechanical installation works under this contract include the arrival, unloading, on-site acceptance, warehousing, secondary transportation, installation, commissioning, startup, trial run, maintenance of the following equipment, and all the work from warranty to handover to the Employer during the warranty period (including temporary facilities required to complete the contract): (1) 4 sets of francis turbine generator units (including francis turbine and its microcomputer governor oil pressure device; 250 MW turbine generator and microcomputer silicon controlled static excitation equipment; control, protection and measurement panel cabinet of water turbine generator unit; oil, gas, water, measurement, fire fighting system pipeline and equipment in unit unit). (2) 2 sets of 400/100/10t bridge crane body and its supporting equipment, 1 set of 10t bridge crane and its supporting equipment, and installation of bridge crane track and slide line.
