Reliability Assessment of a System Integrity Protection Scheme for Transmission Networks

  • Nan Liu

Student thesis: Phd


System Integrity Protection Schemes (SIPS) are being applied to power networks to minimize the probability of large system disturbances and to cope with the growing size and complexity of modern Power Systems. SIPS offer a timely and economical solution which enhances the transmission capability whilst postponing the need for new transmission facilities. However, recent SIPS related incidents reveal that SIPS maloperations could contribute to the spread of the system disturbance and expose the Power System to additional risks. In particular, the use of advanced Information and Communication Technologies (ICT) in SIPS, along with the continuously ageing protection assets used in the current GB National Grid, raises major concern in the reliable operation of SIPS. The aim of this thesis is to provide an insight into the reliability of the protection schemes in the transmission network and develop investigation methods to quantitatively assess the risk brought by SIPS. Probabilistic techniques have been developed to identify the optimal SIPS design in the ICT infrastructures and operational logic, which delivers the most reliable performance and the minimal risk to system operation. A method based on reliability block diagram is proposed to assess the impact of ICT failures on the communication services in an IEC 61850 based substation automation system. In addition, an investigation process based on function tests and invasive examination is developed to evaluate the operational condition of the commonly used electronic protection relay types that are approaching their predefined end of service life. The investigation results help ensure the reliable and fast automatic protection function against fast developing system incidents. The risks brought by SIPS operation is studied using both analytical and stochastic methods. A risk assessment platform based on Sequential Monte Carlo Simulation (SMCS) is developed to capture the time-series feature of the system conditions and assess the variation in SIPS operational risk. This thesis also describes a generic framework of using multi-level Markov models to quantify the probability of undesirable interactions between SIPS on the same or neighbouring systems. The simulations results indicate that, with a widespread proliferation of SIPS, uncoordinated SIPS operations lead to severe impact on Power System reliability. The use of adaptive SIPS, which adjust its protection logics to the increasingly variable system condition, could effectively mitigate the operational risk.
Date of Award1 Aug 2018
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorPeter Crossley (Supervisor) & Pierluigi Mancarella (Supervisor)

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