Study on Method for Determining the Buffer Size of Communication Module Inside SMU On Emergency

Current methods for determining the buffer size of communication module inside substation main unit (SMU) usually need engineers´ experiences, which could be inaccurate and burdensome. This paper introduces queuing theory, proposes a method to solve the problem of determining the buffer size, in which SMU and intelligent electronic devices (IEDs) is considered as a whole and makes a serial queuing network model of the SMU receiving IEDs on emergency. The exact formulas among the buffer size, the packet loss probability and the delay are deduced. The method for determining buffer size is given on the basis of meeting the requirement of packet loss probability and delay. Case studies on a 500 kV substation on emergency show that the method is effective