| In the recent years, with the fast building of interconnected power grid, network structure has becoming more and more complex. With the parallel operation on ultra high voltage DC transmission and AC transmission, and configuration on the devices utilizing new technology widely, the operation of modern power system presents very complex and shows serious stable problem. Today security and stability control system (SSCS) has been applied to power grid widely in order to safeguard the reserve defense line of power system and to ensure the emergency control measures trigger in time. Fast evaluating, confirming and optimizing emergency control method are of great importance to the improvement on power grid security and the loss reduction in case of faults.Currently transient stability-constrained emergency control and optimization have been under intensive investigation, with some progress being made on these research fields. As yet few scheme has reached a practical level due to the inherent discreteness and widely engineering related. In this thesis, several control performance index and its sensitivity based on transient energy have been proposed, considering the background of engineering technology. Moreover, many research methods previous reported have been discussed and reviewed. The contents and creative points of this thesis are as follow1. As the implementation platform of emergency control, the security and stability control systems are introduced in detail. The working modes of SSCS are enlightened according to different power system scale and size. In addition, the decision-making modes of offline, on-line preventive and real time are also discussed and prospected from the point of view of the development of data sources in power system.2. The transient energy based control theory is proposed, and the control measures are discussed from this theory. And the energy-type performance and sensitivity are defined. Furthermore, the application methods based on the novel index are also presented.3. The control performance index and sensitivity for generator tripping are defined. The case examples on New England test power system show the basic properties of the novel indices. On the background of DC and AC power transmissions on South China Power Grid, the transient voltage problem following synchronism stability problem are investigated intensively. Furthermore, the interaction of AC and DC transmissions is discovered clearly. Then the effectiveness and practicality of the generator tripping control are discussed and emphasized.4. Compared with angle index, the more effective generation drop measures or the least drop power can be obtained by the energy-type sensitivity index, which can obtain the better transient stability constrained emergency control measures and get the loss reduction in case of faults. The case examples on South China Power Grid show that the proposed approach is practical and effective.5. Based on the properties of the operation mode on regional power network, the feasibility and foundations of Corrected Transient Energy Function are explained in order to apply the CTEF method to regional power grid. A new stability margin by different drop power has been defined, considering the constant of corrected transient energy function (CTEF). The definition of stability margin for the stable case of the first swing is discussed in detail. From the definition procedure and regularity of stability margin, the estimated drop power by generation tripping control can be obtained from only two simulation process. The case examples on the MeiZhou power grid in GuangDong show that the proposed approach reduces the heavy workload using the traditional method of trials and errors to find a suitable unit combination to drop.
|
PDF Full Text Request