Research On Transmission Power Limit Between The Regions Of Xinjiang Power Grid Based On Transient Stability

With the promotion of electric power Market Mechanism, new problems emerge power system, one of which is the regional transmission power limit (TTC) calculation. Since the southern and northern power grid load characteristics and differences, runoff of hydropower generating units, as well as the seasonal distribution of wind power, power exchange between the regions of Xinjiang grid grows frequently. Especially with the wind power capacity growing under the weak conditions, the stability of Xinjiang Grid becomes more prominent. However, the traditional transmission power limit based on static stability often difficult circumstances to ensure the system dynamic stability, and the expectations are too optimistic. Therefore, this paper does some comprehensive analysis and argument, calculating available transfer between the four major regions from the perspective of transient stability.Firstly, paper summarizes the research and methods of the transmission power limit, wind farm output forecasting and the dynamic equivalent. Then, the methods with wind farm output prediction and dynamic equivalent are proposed, and results show the methodvalidity and accuracy. Use the methods on Turpan grid two large wind farms for grid-based output prediction and the corresponding equivalent. Finally, paper introduces the power flow calculation software PSAT, and the transient stability assessment software TSAT with its main functions and use in details.Research is started based on the summer of 2009, Xinjiang Power Grid mode.The basic trend of the N-1 cases of transient stability is analyzed in detail, while the transmission capacity between the East Xinjiang, southern, northern, north western regions and the main gateway and related stability margindegree indicators are comprehensively analysed based on transient stability.Finally, the transient stability problems arise in Turpan region of Xinjiang grid. Paper conducts scanning according to stabilize the first standard line fault, scan results: Three phase permanent fault in He-Lou line near Loulan side is the most serious in transient voltage stability. Taking the appropriate measures for the reactive power compensation can improve the transient voltage stability, especially SVC device is better. In addition, this paper also studied the impact of the Turpan wind disturbance on the weak power grid, results show that: in normal manner, wind speed fluctuation in the system does not constitute a threat to stability. Even if the wind speed is too high or too low, fan protection device also moves in the cutting machine, or any event of a wind farm outlet when the removal of a permanent fault, transient stability index of the region has dropped, but the power angle, voltage, damping, and frequency stability criteria are met. Proposed to increase a few lines between Turpan and the main network to strengthen Turpan and Urumqi grid, Turpan and Hami grid electrical connection, short the distance while failure of the region and improve the system transient stability level.