System Integrity Protection Schemes Research Articles

Local and Wide-Area PMU-Based Decentralized Dynamic State Estimation in Multi-Machine Power Systems

Accurate measurement of the rotor angle and speed of synchronous generators is instrumental in developing powerful local or wide-area control and monitoring systems to enhance power grid stability and reliability. Exogenous input signals such as field voltage and mechanical torque are critical information in this context, but obtaining them raises significant logistical challenges, which in turn complicates the estimation of the generator dynamic states from easily available terminal phasor measurement unit (PMU) signals only. To overcome these issues, the authors of this paper employ the extended Kalman filter with unknown inputs, referred to as the EKF-UI technique, for decentralized dynamic state estimation of a synchronous machine states using terminal active and reactive powers, voltage phasor and frequency measurements. The formulation is fully decentralized without single-machine infinite bus (SMIB) or excitation model assumption so that only local information is required. It is demonstrated that using the decentralized EKF-UI scheme, synchronous machine states can be estimated accurately enough to enable wide-area power system stabilizers (WA-PSS) and system integrity protection schemes (SIPS). Simulation results on New-England test system, Hydro-Quebec simplified system, and Kundur network highlight the efficiency of the proposed method under fault conditions with electromagnetic transients and full-order generator models in realistic multi-machine setups.

Design of dependable and secure system integrity protection schemes

System Integrity Protection Schemes (SIPS) are traditionally designed with an emphasis on dependability. This ensures they operate when required to preserve system integrity and as a result, most SIPS are implemented as fully duplicated schemes. However, as the complexity and uncertainty of power systems increase, enhancing the security of SIPS becomes vitally important. This prevents spurious operations, which have a detrimental impact on system reliability. A procedure for designing SIPS that achieve an effective tradeoff between dependability and security is proposed in this paper. The proposed method uses fault tree analysis and the theory of minimal cut sets to break down the reliability analysis of the complete SIPS into the analysis of the individual operational phases of SIPS, which simplifies the analysis. Then, this study determines the minimum reliability requirements of each component, i.e. Mean Time To Failure (MTTF) and Mean Time To Fail Spurious (MTTFspurious) and the optimum design of SIPS for realizing the desired level of dependability and security. It is illustrated using the Dinorwig Intertrip Scheme, which is located in North Wales and operated by National Grid (Great Britain transmission system operator).

Quantifying the reliability level of system integrity protection schemes

System integrity protection schemes (SIPS) are a widely used solution to the challenges in operating electrical power transmission systems during the last few decades. Since these protection schemes have become an integral part of the system, it must be ensured that their performance satisfies the reliability requirements of electrical utilities, when expressed in terms of dependability and security. This study proposes a method based on Markov modelling and fault tree analysis for assessing the reliability of a generic SIPS, but it is illustrated using the Dinorwig intertrip scheme, located in North Wales and operated by National Grid (Great Britain system operator). In addition, two reliability indices, widely used in the process control industry, are suggested for quantifying the reliability level of SIPS: (i) safety integrity level and (ii) spurious trip level. Many operators tend to have SIPS permanently in service; this reduces the probability of a `failure to operate' because of a problem in the arming software or an error by a human operator that prevented the scheme being armed when required. Therefore, the impact of having SIPS always armed on SIPS reliability is compared with the impact of switching IN the scheme only when the arming conditions are fulfilled.

System Simulation and Implementation of SIPS in Taiwan

This study describes the system simulation and implementation of the system integrity protection schemes (SIPS) in an independent, intensive, and island-type power system. It also elucidates a smart grid plan to provide grid security in this power grid. The proposed SIPS can prevent blackouts that could otherwise result from the transient instability of N-3 contingencies and has been fully implemented and operated. The entire SIPS installation comprises two stages. The first-stage SIPS takes generator tripping system simulation and the second-stage SIPS involves generator tripping, load rejection, and bus-tie switching countermeasures. The proposed SIPS can prevent isolated power system blackout from extreme contingencies system and provide a valuable system simulation experience for similar independent power grids.

Wide‐area monitoring and control using the real time digital simulator and a synchrophasor vector processor

AbstractSeveral major blackouts in the past have shown the need for advanced wide‐area monitoring and control (WAMC) techniques. Advanced synchrophasor visualization and monitoring can be realized with time‐referenced power system data that are collected by phasor measurement units (PMUs) using synchronized clocks. Presently, PMUs are being deployed around the world at a rapid rate for various power system applications. When a necessary number of PMUs are installed at optimal locations throughout the network, the complete state of the system can be observed. PMUs take real‐time measurements to determine the state of the power system and can be used to enhance state estimation efficiency. With PMUs in place, there are many control and protection schemes that can be implemented successfully to take preventive and corrective actions. These remedial action schemes (RASs) are classified by the IEEE Power System Relaying Committee (PSRC) as system integrity protection schemes (SIPSs). This work involved the development of a real‐time hardware test bed in order to analyze the transient stability of a simulated power system by using synchrophasors to visualize system stress across a transmission line with and without load‐shedding schemes. The real time digital simulator (RTDS®) was used to model the power system in real time. PMUs, a satellite‐synchronized clock, and a synchrophasor vector processor (SVP) were used to test the synchrophasor application. Copyright © 2010 John Wiley & Sons, Ltd.

IEEE PSRC Report on Global Industry Experiences With System Integrity Protection Schemes (SIPS)

This paper is a summary of the IEEE Power System Relaying Committee report on the System Integrity Protection Schemes (SIPS) survey. The SIPS role is to counteract system instability, maintaining overall system connectivity, and/or to avoid serious equipment damage during major system events. The survey describes industry experiences with this category of protection schemes applied to protect the integrity of the power system. It is designed to provide guidance for SIPS users and implementers based on surveyed operating practices and lessons learned. The survey includes a global participation through the comprehensive effort of IEEE and CIGRE.