A Cyber Physical Framework for Remedial Action Schemes in Large Power Networks

Abstract:

Despite the integration of advanced cyber technologies in monitoring and communication in electric power networks, design and development of control systems, and in particular, Remedial Action Schemes (RAS) tend to evolve at a very slow pace. The objective of this research is to study new distributed system modeling techniques to faithfully capture the physical and communication  system characteristics  as well as the "wave" like propagation of some disturbances. These new mathematical approaches lead us to propose new controls which seek to minimize the impact of disturbances.  As power networks are large-­‐scale systems, both computationally  and geographically, a centralized wide-­‐area controller  is practically  difficult  to implement.  Therefore,  our research  is mainly  focused  on  the design  of distributed   controllers   for   spatially   interconnected   cyber-­‐physical   systems.   The   idea   is   to   adapt   the distributed output feedback control method from network control theory to achieve high performance for an interconnected  power system. We have developed  a distributed  control framework,  which guarantees  local and  global  stability  of the  interconnected  subsystems,  using  a cyber-­‐physical  power  system  model  where dynamics  of each  module  is represented  in terms  of its local  variables  and  the  interconnection  variables. Simulation results on different test systems validate the effectiveness of the proposed controller in improving the ability of the system to mitigate electromechanical disturbances. To better explore the impact of power network topology on system stability, we have expanded the existing partial   differential   equation   (PDE)-­‐based   model  for  power   system   to  capture   both  angle  and   voltage dependence  to spatial  parameters.  The stability  analysis  of a continuum  system  for which  robust  methods have  been  developed  provides  an  alternative   to  overcome  the  extreme  difficulties   associated  with  the stability analysis of a large dimensional  discrete system. Considering  powerful mathematical  tools  for PDEs, our objective is also to apply distributed  control designs appropriate  to the wave equation to our  proposed continuum  model  and  gain  additional  insight  into  mechanisms  by  which  disturbance  propagations  in  the power  system  can be mitigated.  We have  recently  derived  an optimal  control  solution  for  this  PDE  based model.

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