作　　者： ; (舒廉甫）; (等）;

机构地区： 长江水利委员会湖北省武汉市430010

出　　处： 《电网技术》 2002年第12期37-40,共4页

摘　　要： 三峡水利枢纽工程地处花岗岩地带,电站装机数量多,单机容量大,500 kV发生单相接地故障时接地装置的入地电流可达33.3 kA。按规范要求接地装置电位不应超过2000 V,三峡电站的接地电阻应不超过0.06Ω。当电站接地装置处于等效电阻率为1000Ωm的地区时,按估算所需接地网面积为70 km2,这是不可能做到的。故立题进行研究。编制了计算电站复杂接地网和不同散流介质分布的接地电阻程序,建立三峡电站接地电阻计算模型,然后用边界元法计算电站接地电阻,同时对计算程序进行了沙池、电解槽和中型电站的实测验证,误差不超过10%。对三峡电站电阻率的选取是通过三峡临时船闸的测量计算得到的,三峡电站接地电阻为0.2W(初期)～0.168Ω(终期)。对于接地装置电位允许升高值问题,通过对电力、控制电缆和继电器的大量试验,认为接地装置的电位允许升高可到5000V。三峡左岸电站为一厂运行时,接地装置电位仍超过5000V,左岸电站一厂运行机组不超过11台和将其分为两厂运行才满足不超过5000 V的要求。接地装置电位超过2000V就要对接触、跨步电位差进行验算,并采取隔离电位的措施,以及防止对低压设备的反击等。 Three Gorges Project (TGP) is situated at the area of granite. Because there are 26 large capacity hydropower generators installed in the station, when single phase earth fault occurs the earthing current in 500 kV system can reach 33.3kA. According to the specification the potential of groundingdevices should not excess 2000 V and the grounding resistance of the grounding device should not excess 0.06W. When the grounding devices at the region where the equivalent resistivity is 1000W/m, the required area of earthing network bypreliminary estimation should be 70km2. This is impossible. To solve this problem, at first, the grounding resistance forcalculating the complicated grounding network of the powerstation with different kinds of discharging media distribution is programmed. The grounding resistance calculation model for Three Gorges Project is established and the groundingresistance is calculated by boundary element method. At thesame time the calculation program is verified by comparing the calculation result with actual measured value of sand pond,electric tank and medium scale electric power station. The error is less than 10%. Through the measurement and calculation for the temporary ship lock of TGP the calculated groundingresistance of Three Gorges Power Station in initial stage is 0.2W and that in final stage will be 0.168W. Secondly, thepermitted potential rise value of the earthing device isresearched. By means of a lot of tests for power cables, control cables and protective relays the permitted potential rise value of the earthing device is 5000V. When only the left bank station is put into operation and all its generating sets are running, the potential of the earthing device will be higher than 5000V. Under the condition that only not more than 11 generating sets in left bank station are running or the left bank station isseparated into two operating stations in parallel, the potential of earthing device can be not higher than 5000V. If the potential of earthing device is higher than 2000V, the

关 键 词： 接地 三峡水利枢纽工程 接地电阻 电力系统

领　　域： [水利工程]