Data Flow Analysis, Network Management and Security Assessment for Digital Substations

  • Zhihao Wu

Student thesis: Phd


The growing demand for functionality in electrical substations has made the operation and management of substation communication networks much more complicated than ever before. At present, thanks to the standard IEC 61850, power system protection automation and control can become more agile and flexible, allowing power utilities to perform complex tasks like remote monitoring and control. The standard addresses issues such as communications, interoperability and compliance. However, there are still many challenges to overcome, including performance assessment of substation communication networks, substation network configuration and management, and cybersecurity, etc. Therefore, it is necessary to develop an advanced data flow analysis and network management strategy for the IEC 61850-based substation communication network. This thesis firstly assesses the message exchanges performance among protection, automation and control (PAC) equipment for an IEC 61850 based digital substation PAC communication system. There are two important system performance indices: (i) the maximum number of PAC bays to be installed for a given data service rate, and (ii) the maximum packet delay of event-driven stochastic message Tp. To study the system performance, two queuing models, D/M/1 and M/M/1, are used. The former uses the D/M/1 model to determine the service rate µ1 for the time-driven cyclic messages exchanges. The latter considers M/M/1 model to determine the service rate µ2 for event-driven stochastic messages exchanges. A typical UK 400kV substation is used for the studies. Results are compared and discussed, confirming that it is necessary to consider the combined queuing models to determine IEC 61850 digital substation data exchange capacity and delay for implementing substation PAC communication system. Secondly, the thesis implements novel software-defined networking (SDN) technology to replace the traditional switches for managing substation communication network with flexible programmability. Considering that a substation configuration language (SCL) file contains the necessary information needed for the configuration of a substation, this research utilises it to simplify the manual, repetitive and tedious SDN configuration process. The research demonstrates how SDN can help utilities to achieve flexible, scalable, agile and secure communication networks though several test cases, and show the benefits of using SCL to simply the SDN configuration process. Finally, the thesis carries out cyber risk assessment of the substation communication network based on Markov decision process model. The research uses Purdue Model to represent the substation. And then it uses Markov decision process model to evaluate cyber risk for the Purdue Model-based substations. The results are compared between traditional switch-based network and SDN-based network. The results show that the use of SDN can effectively can help improve the cybersecurity of substation, and reduce potential loss for power utilities.
Date of Award1 Aug 2024
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorHaiyu Li (Supervisor)


  • power substations
  • substation communication network
  • data flow
  • network management
  • IEC 61850
  • digital substations
  • cybersecurity

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