Stability Studies of the Nigerian 330 KV Integrated Power System

摘要

The Nigeria 330 KV integrated power network consisting of seventeen (17) generating stations, sixty four (64) transmission lines and fifty two (52) buses is studied, to investigate the time limits of stability before, during and after occurrence of a three phase (3-θ) fault on the largest generating station (Egbin) and to determine also the most affected generating stations and buses in the network.Theswing and torque equations expressed in time domain was used for the study and the network was modeled in ETAP transient analyzer environment. Transient stability time limit of the system was set to operate at maximum value of ten (10) seconds. Before the fault (between 0.000secs-0.0006secs), the system dynamics was not affected and the peak values of terminal current, rotor angle, frequency,mechanical and electrical power obtained were observed to be within stability region. However, as the fault occurred between 0.0006 secs-0.042 secs, the system dynamics changes, thus affecting the quadrature axis. This change in quadrature axis affected the individual generator’s exciter current, exciter voltage, electrical power, mechanical power, frequency, rotor angle and terminal current, though still remain within stability boundary. However, when the fault is cleared within this time, the system returns to its stability region. When the fault lasted beyond 0.042 secs, there is loss of system synchronism. Generating stations that were majorly affected are Omotosho, Sapele, AES and Delta stations. It was observed that the bus voltages connected to these stations deviated from the statutory limit of 313.45 KV-346.5 KV. Their bus voltage values were: Omotosho (361.42KV), Sapele (358.42 KV), AES (350.43 KV) and Delta (364.32 KV). The other buses connected to the other generating stations were however not affected. The province’s population is expected to grow by about 28 percent – or about 3.7 million people – by 2030 and become increasingly urbanized. The structure of the economy will also change as the high-tech and service sectors grow and demand from large industries is expected to grow moderately.