Application of Advanced Early Warning Systems with Adaptive Protection

This project developed and field-tested two methods of Adaptive Protection systems utilizing synchrophasor data. One method detects conditions of system stress that can lead to unintended relay operation, and initiates a supervisory signal to modify relay response in real time to avoid false trips. The second method detects the possibility of false trips of impedance relays as stable system swings “encroach” on the relays’ impedance zones, and produces an early warning so that relay engineers can re-evaluate relay settings. In addition, real-time synchrophasor data produced by this project was used to develop advanced visualization techniques for display of synchrophasor data to utility operators and engineers

An Assessment of PIER Electric Grid Research 2003-2014 White Paper

This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California’s California Institute for Energy and the Environment, from 2003-2014

Emergency response system for electric power systems

Complicated cascading disturbances do occur in power systems and cause extreme social and economic impacts. A new Emergency Response System (ERS) is developed to defend power systems against these severe situations. Compared with traditional System Protection Schemes (SPS), an ERS has the 4 significant advantages. (1) The remedial action designed by ERS is more adaptive to system configuration and operating conditions, since it conducts computation online and takes real-time operating conditions as input. (2) Its initiating event set is much larger than that in traditional SPS, because it uses Dynamic Decision Event Tree (DDET) technique and dynamically increases the number of initiating events to be analyzed. (3) It detects, by incorporating long-term simulation and protective relay modeling into the simulator, many power system failures that were \u27hidden\u27 during traditional SPS remedial action design process. (4) The optimal action identification process is adaptive to power market information---By communicating with power market database, the most up-to-date cost factor is used to determine the optimal action.;This work also generalized the basic remedial action design features in such a way so as to make what has heretofore been highly application-specific technology---the SPS action logic design---into an automated and intelligent decision process. This contribution is important, because it is the fundamental enabler for the ERS, making it effective in an emergency scenario where response must be very fast. This contribution is also important because it serves to encapsulate, in a formalized way, the SPS design process; as a result it will be useful to SPS designers in reflecting on and improving upon what they do.;A demonstration system for this generalized remedial action logic design process is developed for proof-of-concept. The results on a test power system show that this approaches is feasible and very effective. Out of 41 initiating events in the test system that would result in power system failure, only 3 can be detected thus prevented by traditional SPS. The rest would rely on the ERS for identifying effective remedial actions

Data Mining Framework for Monitoring Attacks In Power Systems

Vast deployment of Wide Area Measurement Systems (WAMS) has facilitated in increased understanding and intelligent management of the current complex power systems. Phasor Measurement Units (PMU\u27s), being the integral part of WAMS transmit high quality system information to the control centers every second. With the North American Synchro Phasor Initiative (NAPSI), the number of PMUs deployed across the system has been growing rapidly. With this increase in the number of PMU units, the amount of data accumulated is also growing in a tremendous manner. This increase in the data necessitates the use of sophisticated data processing, data reduction, data analysis and data mining techniques. WAMS is also closely associated with the information and communication technologies that are capable of implementing intelligent protection and control actions in order to improve the reliability and efficiency of the existing power systems. Along with the myriad of advantages that these measurements systems, informational and communication technologies bring, they also lead to a close synergy between heterogeneous physical and cyber components which unlocked access points for easy cyber intrusions. This easy access has resulted in various cyber attacks on control equipment consequently increasing the vulnerability of the power systems.;This research proposes a data mining based methodology that is capable of identifying attacks in the system using the real time data. The proposed methodology employs an online clustering technique to monitor only limited number of measuring units (PMU\u27s) deployed across the system. Two different classification algorithms are implemented to detect the occurrence of attacks along with its location. This research also proposes a methodology to differentiate physical attacks with malicious data attacks and declare attack severity and criticality. The proposed methodology is implemented on IEEE 24 Bus reliability Test System using data generated for attacks at different locations, under different system topologies and operating conditions. Different cross validation studies are performed to determine all the user defined variables involved in data mining studies. The performance of the proposed methodology is completely analyzed and results are demonstrated. Finally the strengths and limitations of the proposed approach are discussed

Probabilistic Framework for Online Identification of Dynamic Behavior of Power Systems with Renewable Generation

The paper introduces a probabilistic framework for online identification of post fault dynamic behavior of power systems with renewable generation. The framework is based on decision trees and hierarchical clustering and incorporates uncertainties associated with network operating conditions, topology changes, faults, and renewable generation. In addition to identifying unstable generator groups, the developed clustering methodology also facilitates identification of the sequence in which the groups lose synchronism. The framework is illustrated on a modified version of the IEEE 68 bus test network incorporating significant portion of renewable generation

Adaptive wide area protection of power systems

Studies of major blackouts reveal that power system protection devices have contributed to a majority of system disturbances. This leads to efforts of improving protection Philosophy;;Analysis shows that conventional protection relies on coordination among stand-alone relays to obtain a dependability-biased component-protection scheme. Whereas it is more desirable and also feasible nowadays for an integrated approach to both component and system protection, provided modern relays possessing the ability of sharing information and applying intelligence in decision-making.;This dissertation proposes the adaptive protection concept for wide area systems. The scope of the research includes identifying and developing the desired architecture, intelligent algorithms and communication needs that facilitate the protection system to avoid and reduce the impact of system emergencies.;The purpose of this research work is to conceptualize and nurture adaptive protection concept for wide area systems, and to conduct feasibility studies to make this concept practically viable. Several case studies are conducted to show the effectiveness of the proposed adaptive protection scheme. In addition, voltage stability, which is a classic wide area problem, can be alleviated with the proposed concept. Steady state and transient simulation studies provided encouraging results. The detailed decision-making algorithms are simulated in several examples for validation of the concept

Analytical Approaches for Identification and Representation of Critical Protection Systems in Transient Stability Studies

abstract: After a major disturbance, the power system response is highly dependent on protection schemes and system dynamics. Improving power systems situational awareness requires proper and simultaneous modeling of both protection schemes and dynamic characteristics in power systems analysis tools. Historical information and ex-post analysis of blackouts reaffirm the critical role of protective devices in cascading events, thereby confirming the necessity to represent protective functions in transient stability studies. This dissertation is aimed at studying the importance of representing protective relays in power system dynamic studies. Although modeling all of the protective relays within transient stability studies may result in a better estimation of system behavior, representing, updating, and maintaining the protection system data becomes an insurmountable task. Inappropriate or outdated representation of the relays may result in incorrect assessment of the system behavior. This dissertation presents a systematic method to determine essential relays to be modeled in transient stability studies. The desired approach should identify protective relays that are critical for various operating conditions and contingencies. The results of the transient stability studies confirm that modeling only the identified critical protective relays is sufficient to capture system behavior for various operating conditions and precludes the need to model all of the protective relays. Moreover, this dissertation proposes a method that can be implemented to determine the appropriate location of out-of-step blocking relays. During unstable power swings, a generator or group of generators may accelerate or decelerate leading to voltage depression at the electrical center along with generator tripping. This voltage depression may cause protective relay mis-operation and unintentional separation of the system. In order to avoid unintentional islanding, the potentially mis-operating relays should be blocked from tripping with the use of out-of-step blocking schemes. Blocking these mis-operating relays, combined with an appropriate islanding scheme, help avoid a system wide collapse. The proposed method is tested on data from the Western Electricity Coordinating Council. A triple line outage of the California-Oregon Intertie is studied. The results show that the proposed method is able to successfully identify proper locations of out-of-step blocking scheme.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

Impact Of Fault Current Limiters And Demand Response On Electric Utility Asset Management Programs

Over-currents are known to be the dominant cause of power system component failures or deterioration from full functionality. Some of these effects may remain unknown and could later result in catastrophic failures of the entire or large portions of the system. There are plenty of devices/methods available to limit the undesirable consequences of the over-current events. These devices/methods have great impact on system reliability by reducing stress on power system components and increasing their useful lifetime. Due to the importance of the subject, there is tremendous need to analyze and compare these devices/methods in terms of reliability. However, few researches have been reported on analyzing reliability impacts of these devices. Reported studies, in the meantime, appear to have investigated these effects qualitatively rather than quantitatively. This is mainly due to lack of a mathematical model to study the direct impacts of over-current values on system reliability. The main stream of reliability calculations are normally based on statistical measures of system outages rather than electrical parameters such as over-current values. Over-currents usually appear in two common forms of fault currents and overload currents. Fault Current Limiters (FCL) and protection devices are commonly used to limit the impact of fault currents. FCL’s limit the magnitude of fault currents and protection devices limit the exposure time of the component to the fault current and therefore have great impact on increasing the lifetime of the components. Overloads, on the other hand, have smaller magnitudes than those of fault currents but can still be destructive because of normally much longer exposure times. Overcoming overload problems usually requires control strategies such as generation rescheduling, and/or load shedding, and optimized usage of existing assets. Using Demand Response (DR) programs are one of the most effective ways of reducing overload burdens on the power system. In this dissertation, simulation models are developed and used to determine the effect of FCL on reducing the magnitude of fault currents. Various case studies will be performed to calculate the effectiveness of FCL’s in real power system applications. Then, security/dependability studies on the protection systems will be performed to analyze and calculate their effectiveness in reducing exposure times to fault currents. Based on the calculated indices, proper selection of protection schemes can be made based on the desired level of dependability/security. In the next part of the work, a mathematical model is developed to calculate the effect of fault current magnitude and duration on the reliability and asset management. Using the developed model and results of the earlier sections of this research work, the impact of protection systems and FCL devices on reliability and asset management programs are quantitatively calculated and compared. The results from such studies will assist in maintenance planning and in proper selection of the fault current limiting devices with regards to desired reliability and asset management programs. DR programs are introduced and modeled in this dissertation as an effective tool in reducing overload burdens on power system components. Using the developed mathematical model, DR programs are studied and compared in terms of reliability improvement that they provide by preventing unnecessary increase in the component failure rates

Dynamic security assessment processing system

The architecture of dynamic security assessment processing system (DSAPS) is proposed to address online dynamic security assessment (DSA) with focus of the dissertation on low-probability, high-consequence events. DSAPS upgrades current online DSA functions and adds new functions to fit into the modern power grid. Trajectory sensitivity analysis is introduced and its applications in power system are reviewed. An index is presented to assess transient voltage dips quantitatively using trajectory sensitivities. Then the framework of anticipatory computing system (ACS) for cascading defense is presented as an important function of DSAPS. ACS addresses various security problems and the uncertainties in cascading outages. Corrective control design is automated to mitigate the system stress in cascading progressions. The corrective controls introduced in the dissertation include corrective security constrained optimal power flow, a two-stage load control for severe under-frequency conditions, and transient stability constrained optimal power flow for cascading outages. With state-of-the-art computing facilities to perform high-speed extended-term time-domain simulation and optimization for large-scale systems, DSAPS/ACS efficiently addresses online DSA for low-probability, high-consequence events, which are not addressed by today\u27s industrial practice. Human interference is reduced in the computationally burdensome analysis