Stability and Reliability Issues of Smart Grid with Network Topology and Flow Controls
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abstract
Recently, multiple national and worldwide directives are called for the development of a smarter electrical grid. This includes, but not limited to, the development of advanced transmission technologies as well as optimizing the use of network topology and flow controls. Benefits of treating transmission lines as controllable assets and incorporating transmission switching into power system operations are manifold. It has been shown by researchers that by dispatching transmission lines together with generation, a 25% saving in dispatch cost can be achieved. It is also pointed out that corrective transmission switching can be used to improve the reliability of the grid as well as the operational efficiency. Moreover, it also shows that transmission switching is effective for load shedding recovery under emergency and contingency situations. The above studies that establish the merits of topology control through transmission line switching are based on steady state and optimization study. However, frequent transmission line switching increases big disturbances to large power systems that may cause stability problems. The potential stability and reliability issues can be classified into four categories. The first category is on the security margin of the switched systems: do the switched lines imply less transmission resources, which will make the resulting systems having less stability margin? And the second category is on the online stability issue: will line switching action itself cause system instability? And the third category is on how would power system conventional controls contribute to stabilize the system during online switching? And the fourth category is on the overall system reliability when line switching is routinely incorporated into system practice. In the overall approach we will determine if the switching practice can adverse effects. For example can this approach increase the probability of cascading failures? A framework for tradeoff between benefits and an adverse issues will be developed. In this proposal, we would like to investigate the feasibility of the flow controls and topological controls through line switching as a regular power system practice by looking into the above raised questions.
