Research On The Mechanism Analysis And Control Of A Novel Multi-Functional Solid State Fault Current Limiter

With the increasing expansion of the scale of power grid and continuous rising of the short circuit capacity, the short circuit fault occurs, which will cause a great impact on equipments in the grid and stability of grid itself, so the demand for short circuit fault current limiting will be more and more obvious; However, traditional current limiter usually has a single function,not only the time of use state compared to nonuse state is be negligible but also it is underutilized. Photovoltaic power, wind power and other power fluctuation energy constantly connect to the grid, highlighting the system voltage quality problems,especially investment on new energy continuing to increase since the twelfth five-year plan, voltage quality problems will deteriorate.Meanwhile, a lot of sophisticated equipments load connecting to grid demand for much better voltage quality. Based on the above two contradictories, it proposes a novel multi-functional solid state fault current limiter(MF-FCL) which has the capability of voltage quality compensation and short circuit fault current suppression and it has a theoretical significance and practical significance.For the problem of low utilization of traditional limiting device, and a combination of the presence of voltage quality problems and realities of compensation demand,it proposes the novel multi-functional solid state fault current limiter having the ability to compensate voltage and suppress short circuit current. It has a detailed description of the topological structure and working mechanism, analyzing the current limiting filter, series connection transformer,energy flow in the working process,the voltage quality compensation models and limiting models.It proposes a start/stop control,self-control in the grid,coordination control strategy with the power grid, deadtime effect characteristics in the control process and the switching control affecting MF-FCL itself.In order to fully explain the problems of the proposed MF-FCL in practical application, the article specifies a MF-FCL underlOkV voltage level and the need of cascaded structure, describes the determining ways of short circuit occurring and disappearing,puts forward different types of actions under different kinds of fault styles in10kV power grid and the control strategies in the working process.It bulids the simulation model of MF-FCL under10kV grid to prove the correctness and feasibility of topology,control strategy, switching methods and so It proves the actual validation of limiting way, detection methods, control methods and switching control through a MF-FCL experimental prototype built under a low-voltage test. Finally, it summaries the full text and presents some possible future research directions on MF-FCL.