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Showing papers on "Blackout published in 2019"


Journal ArticleDOI
20 Feb 2019-Energies
TL;DR: A comprehensive review on the major blackouts and cascading events that have occurred in the last decade is introduced in this article, where a particular focus is given on the US power system outages and their causes since it is one of the leading power producers in the world.
Abstract: Power systems are the most complex systems and have great importance in modern life. They have direct impacts on the modernization, economic, political and social aspects. To operate such systems in a stable mode, several control and protection techniques are required. However, modern systems are equipped with several protection schemes with the aim of avoiding the unpredicted events and power outages, power systems are still encountering emergency and mal-operation situations. The most severe emergencies put the whole or at least a part of the system in danger. If the emergency is not well managed, the power system is likely to have cascading failures that might lead to a blackout. Due to the consequences, many countries around the world have research and expert teams who work to avoid blackouts on their systems. In this paper, a comprehensive review on the major blackouts and cascading events that have occurred in the last decade are introduced. A particular focus is given on the US power system outages and their causes since it is one of the leading power producers in the world and it is also due to the ready availability of data for the past events. The paper also highlights the root causes of different blackouts around the globe. Furthermore, blackout and cascading analysis methods and the consequences of blackouts are surveyed. Moreover, the challenges in the existing protective schemes and research gaps in the topic of power system blackout and cascading events are marked out. Research directions and issues to be considered in future power system blackout studies are also proposed.

348 citations


Journal ArticleDOI
TL;DR: A method for energy management in microgrids with stochastic load is proposed, which is performed through solving a nonlinear optimization problem and the efficiency of the proposed distributed EMS is depicted.
Abstract: The uncertainty of load is a challenging issue for power systems. These uncertainties can damage the power systems and even cause blackout. Therefore, it is necessary to handle this problem. In this paper, a method for energy management in microgrids with stochastic load is proposed. The design is performed through solving a nonlinear optimization problem. In the centralized optimization technique, high computational capabilities are needed and the customer's privacy might be infringed. On the contrary, in distributed techniques, the power network and its constraints are neglected since it is assumed that all loads and generations are connected to one bus. Consequently, in the proposed distributed energy management strategy (EMS), the optimization problem is decomposed into two optimization levels, which consist of the microgrid centralized controller and local controllers and the distribution network and the corresponding constraints are taken into account. Since the precise prediction of the load is not accessible, the load is assumed stochastic. The proposed distributed EMS is integrated with diesel generators, wind turbines, photovoltaics, and a battery storage system. The simulation results depict the efficiency of the proposed distributed EMS.

51 citations


Proceedings Article
01 Jan 2019
TL;DR: The results show that MadIoT attacks can cause a partition of the bulk power system, and can also result in controlled load shedding, but the protections embedded in the operation of the transmission grid can allow the system to withstand a large variety of MadIeT attacks and can avoid a system blackout.
Abstract: Author(s): Huang, B; Cardenas, AA; Baldick, R | Abstract: Devices with high energy consumption such as air conditioners, water heaters, and electric vehicles are increasingly becoming Internet-connected. This new connectivity exposes the control of new electric loads to attackers in what is known as Manipulation of demand via IoT (MadIoT) attacks. In this paper we investigate the impact of MadIoT attacks on power transmission grids. Our analysis leverages a novel cascading outage analysis tool that focuses on how the protection equipment in the power grid as well as how protection algorithms react to cascading events that can lead to a power blackout. In particular, we apply our tool to a large North American regional transmission interconnection system consisting of more than 5,000 buses, and study how MadIoT attacks can affect this power system. To help assess the effects of such cyber attacks, we develop numerical experiments and define new and stronger types of IoT demand attacks to study cascading failures on transmission lines and their effects on the system frequency. Our results show that MadIoT attacks can cause a partition of the bulk power system, and can also result in controlled load shedding, but the protections embedded in the operation of the transmission grid can allow the system to withstand a large variety of MadIoT attacks and can avoid a system blackout.

49 citations


Journal ArticleDOI
TL;DR: A real-time ICI and restoration scheme that consists of an ICI algorithm that finds islanding solutions with minimal power-flow disruption while considering power system restoration constraints, a real- time state estimator that monitors the system before and after the islanding, and a restoration process.
Abstract: Power system operators are facing major challenges today to keep the system operating at the admissible limits. Recent blackouts demonstrated the need for a systematic study and design of a comprehensive system control strategy. Intentional controlled islanding (ICI) has been proposed as an effective corrective control action of final resort to save the system from a partial or a complete blackout. ICI limits the occurrence and consequences of blackouts by splitting the power system into a group of smaller, stable, and sustainable subsystems, also called islands. After a controlled system separation, power system operators should resynchronize and reconnect each island to restore the system. In this sense, real-time knowledge of the operating condition of the islands is required. In this paper, a real-time ICI and restoration scheme is proposed. The proposed scheme consists of an ICI algorithm that finds islanding solutions with minimal power-flow disruption while considering power system restoration constraints (e.g., blackstart availability, sufficient generation capacity, and observability), a real-time state estimator that monitors the system before and after the islanding, and a restoration process. The proposed ICI and restoration scheme is tested using the dynamic IEEE 39- and 118-bus test systems.

41 citations


Journal ArticleDOI
TL;DR: An integrated control and protection scheme that has the ability to prevent the blackouts caused by cascading fault using transmission capacity enhancement of the ac line and load-shedding in the inverter ac system and a thyristor-controlled series compensator.
Abstract: Cascading fault is one of the serious challenges in hybrid ac/dc power grids, which initiates from a dc or a severe inverter ac fault and leads to a blackout in the inverter ac side. However, owing to the fact that dc faults do not cause commutation failure, the existing commutation failure inhibition approaches are not effective in the prevention of cascading faults caused by dc fault. In order to resolve the challenge, this paper first develops a hybrid ac/dc relay (HADR) based on the positive-sequence component, which can detect and locate the fault events in hybrid ac/dc networks. Subsequently, an integrated control and protection scheme is presented using the developed HADR and a thyristor-controlled series compensator. The proposed scheme has the ability to prevent the blackouts caused by cascading fault using transmission capacity enhancement of the ac line and load-shedding in the inverter ac system. The salient feature of the proposed scheme is that it provides a very economical way to compensate for the loss of power caused by HVdc line outage. In addition, it does not require communications among the relays. The practical performance and feasibility of the proposed scheme is validated by laboratory testing, using the real-time Opal-RT hardware prototyping platform. The experimental results demonstrate that the proposed strategy can effectively inhibit the blackouts caused by cascading fault in hybrid ac/dc networks.

35 citations


Journal ArticleDOI
TL;DR: Event-level findings of this study document that events leading to alcohol-induced memory loss are associated with other adverse experiences relative to drinking events that do not result in blackout, and offer potentially motivational levers for preventive interventions.
Abstract: Background Prior research identifies a range of potential predictors of blackouts and suggests that blackouts increase risk for additional negative consequences. However, these studies are based on epidemiological work that allows us to draw conclusions about groups of people but not within-person processes. The present study examined within-person, event-level correlates of blackouts. Methods Ninety-six heavy drinking college students (52% female) completed 28 days of daily reports of alcohol use and consequences, including blackouts. Thirty-three participants reported 56 blackouts. Hierarchical linear modeling compared morning reports of drinking events on which participants did versus did not report a blackout, controlling for total drinks at the event. Results Blackout likelihood increased as a function of total drinks consumed and of crossing thresholds for heavy episodic drinking (4+/5+ drinks for women/men) and high-intensity drinking (8+/10+). Participants reported a higher total number of additional negative consequences on blackout events. Specific consequences that were more likely included embarrassing oneself and hangover. Blackouts were associated with morning ratings of less positive mood and a less favorable drinking event. Motives for drinking and simultaneous use of marijuana were not associated with blackouts. Conclusions Event-level findings of this study document that events leading to alcohol-induced memory loss are associated with other adverse experiences relative to drinking events that do not result in blackout, and offer potentially motivational levers for preventive interventions.

34 citations


Journal ArticleDOI
TL;DR: This review summarizes and updates the important aspects ofUVLS and provides principle understanding of UVLS, which are critical in planning such defense schemes and will serve as one‐stop information for power system engineers, designers, and researches.
Abstract: A blackout is usually the result of increasing load beyond the transmission capacity of the power system. One of the main reasons for power blackouts is voltage collapse. To avoid this problem, the proper corrective measures called load shedding is required. In critical and extreme emergencies, under voltage load shedding (UVLS) is performed as a final remedy to avoid a larger scale voltage collapse. Therefore, UVLS is considered state of the art to achieve voltage stability. This review summarizes and updates the important aspects of UVLS; it also provides principle understanding of UVLS, which are critical in planning such defense schemes. Moreover, this article provides a discussion on recent state-of-art UVLS schemes applied in various power industries. Additionally, the pros and cons of the conventional and computational intelligence techniques are discussed. It is envisioned that this work will serve as one-stop information for power system engineers, designers, and researches.

32 citations


Journal ArticleDOI
TL;DR: Results show that for having almost the same resilience enhancement in both systems, the second system, which is a grid-connected microgrid, indicates lower NPC and COE compared to the first system.
Abstract: Extreme weather events lead to electrical network failures, damages, and long-lasting blackouts. Therefore, enhancement of the resiliency of electrical systems during emergency situations is essential. By using the concept of standby redundancy, this paper proposes two different energy systems for increasing load resiliency during a random blackout. The main contribution of this paper is the techno-economic and environmental comparison of two different resilient energy systems. The first energy system utilizes a typical traditional generator (TG) as a standby component for providing electricity during the blackouts and the second energy system is a grid-connected microgrid consisting of photovoltaic (PV) and battery energy storage (BES) as a standby component. Sensitivity analyses are conducted to investigate the survivability of both energy systems during the blackouts. The objective function minimizes total net present cost (NPC) and cost of energy (COE) by considering the defined constraints of the system for increasing the resiliency. Simulations are performed by HOMER, and results show that for having almost the same resilience enhancement in both systems, the second system, which is a grid-connected microgrid, indicates lower NPC and COE compared to the first system. More comparison details are shown in this paper to highlight the effectiveness and weakness of each resilient energy system.

32 citations


Journal ArticleDOI
TL;DR: A distributed strategy for integrated transmission and distribution systems restoration (ITDSR) has been developed based on the alternating direction method of multipliers (ADMM), able to provide the coordinated restoration for both TSOs and DSOs by sharing limited information of boundary buses in an iterative procedure.
Abstract: A resilient power system is capable of providing fast and efficient recovery from outages caused by natural or man-made attacks. After a major blackout, transmission, and distribution system operators (TSOs and DSOs) coordinate to restore the system in a timely and reliable manner. However, these two systems are usually operated separately without considering capabilities and limitations of each individual network, or their mutual impacts. This could prolong the restoration process and lead to unpractical outcomes. Therefore, a distributed strategy for integrated transmission and distribution systems restoration (ITDSR) has been developed in this paper. Based on the alternating direction method of multipliers (ADMM), the distributed algorithm is able to provide the coordinated restoration for both TSOs and DSOs by sharing limited information of boundary buses in an iterative procedure. The ADMM-ITDSR model includes convex ac power flow model and three-phase unbalanced branch flow model. The ITDSR strategy coordinates the operation of distributed energy resources in terms of serving high priority loads across different networks. The effectiveness and advantage of developed models and algorithms are validated and demonstrated through testing of the integrated IEEE test cases, such as 14-bus transmission with 13-node distribution systems, and 39-bus transmission with 123-node distribution systems.

30 citations


Journal ArticleDOI
TL;DR: The findings suggest that Twitter users express intentions to blackout due to celebration or coping reasons, and future research should consider the link between blackout intentions, blackout motives, and alcohol-related harm.
Abstract: Background Alcohol-related blackouts are associated with a range of negative consequences and are common among social drinkers. Discussing alcohol use on social networking platforms (e.g., Twitter) is common and related to higher alcohol consumption levels. Due to the widespread nature of alcohol-related social networking posts and alcohol-related blackouts, we examined the content of alcohol-related blackouts posts/"Tweets" on Twitter, with a focus on intentions to blackout and specific motivations for blacking out. Methods A set of Tweets containing "blackout," "blackout," "blacking out," "blacked out," or "blacks out" were collected from April 26, 2018, and April 29, 2018. Using NVivo software, we coded all preblackout Tweets (i.e., before the blackout experience) for intentions and motives to blackout. Results Most Tweets that we collected expressed an intention to blackout and these intentions ranged in strength (i.e., will blackout vs. might blackout). With respect to specific motives for blacking out, celebration motives were identified. For example, Tweets addressed blacking out to celebrate one's birthday, someone else's birthday, a school or work accomplishment, a sports win, during a vacation, or a holiday. Another endorsed motive for blacking out was loss or coping motives. For example, the Tweets commented on blacking out to deal with stress or a bad day. Conclusion Our findings suggest that Twitter users express intentions to blackout due to celebration or coping reasons. Given the consequences associated with blackout drinking, future research should consider the link between blackout intentions, blackout motives, and alcohol-related harm.

23 citations


Journal ArticleDOI
TL;DR: The proposed methodology uses real-time information to estimate the rotor angles of generators, which serve to define the suitable number of coherent generators and the actual coherent groups, and adopts the concept of area-based center of inertia-referred rotor angle index to determine the actual time of islanding.
Abstract: Cascading outages leading to large-area blackouts can be mitigated using intentional controlled islanding (ICI). An ICI scheme must define the most suitable time to split the system after a severe contingency (i.e., when to island), as well as to quickly determine the set of branches to be disconnected to create stable islands (i.e., where to island). Most of the works in the literature, however, focus on the latter and little has been done to address the “ when to island ” problem. To fill this gap, this paper proposes a unified methodology to determine the most suitable moment for islanding. First, the proposed methodology uses real-time information to estimate the rotor angles of generators, which, in turn, serve to define the suitable number of coherent generators and the actual coherent groups. It then adopts the concept of area-based center of inertia-referred rotor angle index to determine the actual time of islanding. The unified methodology for determining the number of islands to be created, the coherent generators, and the time for islanding is tested using the IEEE 39- and 118-bus test systems. Multiple case studies are presented to demonstrate the adaptability and effectiveness of the proposed unified methodology to different system conditions.

Journal ArticleDOI
TL;DR: In this article, the authors estimate the effects of outages on small firms using original firm-level panel data and find evidence of differential effects by firm size, where firms without employees experience large reductions in revenues and profits.
Abstract: Entrepreneurs in developing countries report that unreliable electricity imposes a serious constraint, yet little evidence exists on how blackouts impact the micro firms that account for the majority of employment. This paper estimates the effects of outages on small firms using original firm-level panel data and finds evidence of differential effects by firm size. Firms without employees experience large reductions in revenues and profits. Outages have no measurable effect on the output of firms with employees, where worker hours increase, weekly wages paid decrease, and the analysis fails to reject that blackouts have no effect on (average firm-level) worker hourly wages.

Journal ArticleDOI
TL;DR: A cooperative control based algorithm using a vehicle to grid (V2G) technology based on a fuzzy logic approach is proposed to prevent cascading failures without loss incurrence to improve the accuracy of taking necessary actions to compensate these CFEs.
Abstract: The previously proposed algorithms for preventing cascading failures, which lead to a blackout event, involve specific load shedding schemes, which introduce incurring losses in the power system network. In this paper, a cooperative control based algorithm using a vehicle to grid (V2G) technology based on a fuzzy logic approach is proposed to prevent cascading failures without loss incurrence. The algorithm is implemented on a standard IEEE-30 bus system, and it uses mathematical combinations heuristically to identify the critical nodes through the use of a self-propagation graph to dispatch the optimum power from V2G. For the enhancement of computational speed, a network operator considers only those vulnerable nodes, which are identified by a self-propagating graph. Through this, a network operator can easily detect critical nodes by rooting straight to the vulnerable transmission lines in the IEEE-30 bus network. The probabilistic modeling in this paper is performed in such a way that network operators will mitigate cascading failures events (CFEs) after the occurrence of (N -1) and (N -1-1) contingencies/blackout events without performing load shedding. The detailed experimental analysis provides better visualization of the impact of CFEs on power grids to the power network operators and therefore significantly improves the accuracy of taking necessary actions to compensate these CFEs.

Journal ArticleDOI
TL;DR: As JTEC increases, the parameters of the average and standard deviation of electricity demand, power supply rate, length of lead time, capacities of power plant and transmission substation increase, and the cost decreases as the blackout ratio and distribution substation capacity increase.
Abstract: We propose an integrated distribution system model for electricity supply chain The distribution system consists of a power plant, a transmission substation, a distribution substation and multi-customers The electricity generated by the power plant is transmitted to the submission and distribution substations, and finally consumed by the customers We apply the inventory theory to the distribution system model and assume the electricity demand is normally distributed The objective is to minimize the joint total expected cost (JTEC) incurred by the power plant, transmission substation, distribution substation and multi-customers The JTEC includes the transmission and the distribution costs, the blackout cost, the energy storage cost, setup/ordering cost, and the production cost We develop a procedure to derive the optimal solution and the decision variables using differential calculus The model is tested with an artificially generated data The results in Fig 5 show that as JTEC increases, the parameters of the average and standard deviation of electricity demand, power supply rate, length of lead time, capacities of power plant and transmission substation increase The cost decreases as the blackout ratio and distribution substation capacity increase The cost is insensitive to the changing electricity consumption time

Proceedings ArticleDOI
Ge Shaoyun1, Li Jifeng1, Liu Hong1, Cao Yuchen1, Yang Zan1, Yan Jun1 
01 Aug 2019
TL;DR: An accurate fragility model of the overhead system under extreme weather conditions is built to reflect the wind's impacts on failure rate, and a resilience evaluation method is proposed based on loss of load.
Abstract: Distribution networks often have blackouts because of natural disasters like typhoon. Resilience describes the ability of a distribution network to withstand extreme weather. To perfect the resilience assessment and analysis method of distribution systems, an accurate fragility model of the overhead system under extreme weather conditions is built to reflect the wind's impacts on failure rate. Failure scenarios are selected based on Shannon entropy and the level of blackout is determined. Second, resilience evaluation method is proposed based on loss of load. Third, the contribution of a traditional hardening method and distributed generation access to a distribution network resilience are compared. Finally, a simulation verifies the validity and accuracy of the proposed approach in this article.

Proceedings ArticleDOI
17 Apr 2019
TL;DR: This article is focused on determining the frequency of UFLS scheme to ensure the optimal sequence of switching off consumers and uses the optimization method to prove that proposed method is an effective approach to improve power system reliability.
Abstract: There is a significant risk of instability, which may lead to wide-spread blackout if power system is stressed towards their stability limit under any unexpected serious disturbances. Frequency is a reliable indicator for identification of power system instability. Therefore, under-frequency load shedding technique is used to stable the power system by reduce the load. This article is focused on determining the frequency of UFLS scheme to ensure the optimal sequence of switching off consumers. For this goal it is proposed to use the optimization method. A developed method upgrades the UFLS model for assessment of optimal load capacity and load disconnection sequence during a power system emergency. The simulation results prove that proposed method is an effective approach to improve power system reliability.

Journal ArticleDOI
TL;DR: Simulations carried out on a simplified model of the Hydro-Quebec network show that the proposed control strategy for HVDC systems to increase their contribution to system security can greatly improve system security during emergency situations.

Proceedings ArticleDOI
01 Sep 2019
TL;DR: The general situation of Brazilian power grid is introduced, the occurrence and propagation of the blackout are retrospected, and the main reason of the blackouts are analyzed in this article.
Abstract: Brazil ±800kV Xingu convertor station’s technical defects lead to chain reaction in Brazil that a Brazilian nationwide blackout accident happened on March 21st, 2018. This blackout severely impact the north and northeast of Brazil including 14 states. In this paper, the general situation of Brazilian power grid is introduced. And the occurrence and propagation of the blackout are retrospected. Furthermore, the main reason of the blackouts are analyzed in this article. According to the Brazilian blackout, Qishao DC is evaluated from the relay protection, configuration of security and stability equipment and strategy analysis of power plants’ primary frequency regulation. Combined with the reality of Hunan power grid, this paper sum up experience and lessons of Brazilian blackout.

Proceedings ArticleDOI
01 Sep 2019
TL;DR: The results obtained that the UPS can work in the event of a blackout with a maximum power of 450 watts, by maintaining the output voltage in 215 V with PI control.
Abstract: Electricity is the main requirement nowadays, but blackouts still occur frequently, this is caused by several things, one of which is the transmission and distribution disorders, especially when it rains badly. Some houses use backup resources such as generator sets that operated during a blackout. This research proposes a temporary backup resource source that is Uninterruptible power supply (UPS) , by using fullbridge inverter with battery 12 volts as a source. This system using Solid State Relay (SSR) as switch so the displacement switches between PLN and the UPS has no delay time. Inverter using SPWM switching techniques to produce a sinusoidal wave output approaching. There is a proportional integrator (PI) control to maintain the value of the inverter output voltage by changing the value of magnitude amplitude (ma). The results obtained that the UPS can work in the event of a blackout with a maximum power of 450 watts, by maintaining the output voltage in 215 V with PI control.

Proceedings ArticleDOI
08 Jan 2019
TL;DR: This work validates OPA on a detailed 19402 bus network model of the Western Electricity Coordinating Council (WECC) interconnection with publicly available data, and examines scalings on a series of WECC interconnection models with increasing detail.
Abstract: The OPA model calculates the long-term risk of cascading blackouts by simulating cascading outages and the slow process of network upgrade in response to blackouts. We validate OPA on a detailed 19402 bus network model of the Western Electricity Coordinating Council (WECC) interconnection with publicly available data. To do this, we examine scalings on a series of WECC interconnection models with increasing detail. The most detailed, 19402 bus network has more tree structures at the edges of the main mesh structure, and we extend the OPA model to account for this. The higher-risk cascading outages are the large cascades that extend across interconnections, so validating cascading models on large networks is crucial to understanding how the real grid behaves. Finally, exploring networks with mixed mesh and tree like structure has implications for the risk analysis for both the transmission grid and other network infrastructures. Disciplines Electrical and Computer Engineering | Power and Energy Comments This is a pre-print of the proceeding Carreras, Benjamin A., B. A. C. V. Solutions, José M. Reynolds-Barredo, Ian Dobson, David E. Newman, and A. K. Fairbanks. "Validating the OPA cascading blackout model on a 19402 bus transmission network with both mesh and tree structures." 52nd Hawaii International Conference on System Sciences (HICSS). 2019. This conference proceeding is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ece_conf/64 preprint; to appear at 52th Hawaii International Conference on System Sciences, January 2019, Maui, Hawaii. Validating the OPA cascading blackout model on a 19402 bus transmission network with both mesh and tree structures Benjamin A. Carreras BACV Solutions Mohawk Drive Oak Ridge TN USA bacarreras@gmail.com José M. Reynolds-Barredo Departamento de Fı́sica Universidad Carlos III Madrid, Spain jmrb2002@gmail.com Ian Dobson ECpE Department Iowa State University Ames Iowa USA dobson@iastate.edu David E. Newman Physics Department University of Alaska Fairbanks AK USA denewman@alaska.edu

Journal ArticleDOI
TL;DR: The lack of monitoring and appropriate control may lead to catastrophic failure of the power network known as blackout as mentioned in this paper, which occurs due to a series of outage in the system, which is the back bone of the economy of a nation.

Journal ArticleDOI
TL;DR: Evaluations of blackouts were primarily negative, with some notable positive, neutral and mixed reactions, and insight into why some students are not necessarily concerned with blackout experiences is provided.

Journal ArticleDOI
TL;DR: The Alcohol-Induced Blackout Measure (ABOM) is a brief and reliable, self-report measure that quantifies the frequency of a range of blackout experiences in the past 30 days and predicted alcohol-related consequences at baseline and one-month follow-up.

Proceedings ArticleDOI
01 Nov 2019
TL;DR: The operation status of the power grid before the accident, the cause, process and recovery of the accident are introduced, and the main causes are the lack of necessary stability analysis, the defects of the safety control, the wrong operation of the protection and the unreasonable configuration of the "third line of defense".
Abstract: On June 16 and July 13, 2019, two major power outages occurred in Argentina and Manhattan, New York. This paper introduces the operation status of the power grid before the accident, the cause, process and recovery of the accident, and points out that the main causes of the accident are the lack of necessary stability analysis, the defects of the safety control, the wrong operation of the protection and the unreasonable configuration of the "third line of defense". In combination with the actual situation of China’s power grid, some suggestions are put forward, such as attaching importance to the protection, setting and operation maintenance of safety and control devices, to ensure the safe and stable operation of power grid and prevent the occurrence of major power failure.

Journal ArticleDOI
TL;DR: This study proposes a modified logic scheme for blocking/de-blocking of distance relays i.e. change the existing scheme with ‘ block all zones except Zone-1’ to ‘block all zones on power swing detection’ and derives rate of change of DPC, which aids in differentiating stable and unstable power swings.
Abstract: System Integrity Protection Scheme (SIPS) aids the normal protection scheme in case of certain special contingencies like tripping of important corridors/flow gates etc. to mitigate the voltage or angular instability, load generation imbalance and finally large-scale cascading catastrophes. A recent blackout incident in an ultra-mega-power project (UMPP) in India has motivated the authors to ponder upon a SIPS as a solution. As part of designing the SIPS, an efficient solution is formulated using synchrophasors for a well-known issue nonetheless an issue which still disturbs the Indian power system network with blackouts – i.e. unintended distance relay operation in the event of power swing. Here, real-time voltage and current phasors and the angular separation between the buses connecting faulted line, acquired by phasor measurement unit is utilised to derive a differential power coefficient (DPC). This study proposes a modified logic scheme for blocking/de-blocking of distance relays i.e. change the existing scheme with ‘block all zones except Zone-1’ to ‘block all zones on power swing detection’. Rate of change of DPC is derived here which aids in differentiating stable and unstable power swings. A special protection scheme is finally formulated based on the modified logic.

Journal ArticleDOI
TL;DR: A precise optimization-based load recovery tool that intends to determine the optimal location and amount of load pickup through modeling the governor of generators as well as loads’ dynamic behaviors is proposed.
Abstract: A self-healing power grid can mitigate the impact of power outages and recover the affected area swiftly. To properly size the optimal amount and location of de-energized loads in the presence of both conventional and renewable sources, a precise optimization-based load recovery tool is proposed in this paper. The steady-state and transient behaviors of loads have been taken into account. The proposed tool contains three separate problems that interact with each other during the restoration period. The first-level problem determines the dispatching of generation units. The second-level problem comprises the non-linear algebraic equations, whose task is to provide the initial conditions for the third-level problem. Finally, the third-level problem intends to determine the optimal location and amount of load pickup through modeling the governor of generators as well as loads’ dynamic behaviors. To examine the effectiveness of the proposed tool, a modified IEEE 39-system under a partial blackout condition has been tested. The results are verified by a commercial time-domain simulation software (PSS/E) to demonstrate the accuracy of the proposed approach. Ultimately, the impact of wind turbine frequency control on the load recovery process has been studied under different penetration levels.

Proceedings ArticleDOI
01 Aug 2019
TL;DR: The Shandong AC/DC hybrid power system in China is used to demonstrate the feasibility and effectiveness of the cascading failures propagation model and the blackout risk quantification method proposed in this paper.
Abstract: With the operation of substantial HVDC lines, the blackout risk analysis based on cascading failures becomes more complex. A complete cascading failures propagation model (CFPM) in large-scale AC/DC systems is established. The model includes AC cascading failures search and DC block fast judgement, of which two parts are alternate. AC lines failure probabilities are defined which is used as the failure lines selection. DC faults fast judgement considers several reasons of DC faults across the board. Multi-infeed short-circuits ratio (MISCR) is used as criterion to estimate DC block fast, which avoids a lot of time-domain simulations. A quantitative risk analysis method based on spectral risk measure (SRM) is proposed, which can quantify blackout risk effectively. Finally, the Shandong AC/DC hybrid power system in China is used to demonstrate the feasibility and effectiveness of the cascading failures propagation model and the blackout risk quantification method proposed in this paper.

Book ChapterDOI
01 Jan 2019
TL;DR: Improving the cybersecurity of electrical power grids is the focus of the research.
Abstract: Historically, control systems have primarily depended upon their isolation from the Internet and from traditional information technology (IT) networks as a means of maintaining secure operation in the face of potential remote attacks over computer networks. However, these networks are incrementally being upgraded and are becoming more interconnected with external networks so they can be effectively managed and configured remotely. Examples of control systems include the electrical power grid, smart grid networks, microgrid networks, oil and natural gas refineries, water pipelines, and nuclear power plants. Given that these systems are becoming increasingly connected, computer security is an essential requirement as compromises can result in consequences that translate into physical actions and significant economic impacts that threaten public health and safety. Moreover, because the potential consequences are so great and these systems are remotely accessible due to increased interconnectivity, they become attractive targets for adversaries to exploit via computer networks. Several examples of attacks on such systems that have received a significant amount of attention include the Stuxnet attack, the US-Canadian blackout of 2003, the Ukraine blackout in 2015, and attacks that target control system data itself. Improving the cybersecurity of electrical power grids is the focus of our research.

Journal ArticleDOI
TL;DR: A robust estimation procedure for the power-law distribution based on the minimum distance estimation method is proposed and it is found that the proposed method outperforms the existing maximum likelihood method in the presence of contaminated data.

Journal ArticleDOI
TL;DR: A decision tree algorithm is proposed to capture the characteristics of electricity consumers and to recognize the crowd who is power blackout sensitive, and a comparison with other intelligent algorithms shows that the decision tree has a good recognition performance over that of others, and the characteristics used to identify the blackout-sensitive crowd is various.
Abstract: With the further liberalization of the electricity market of China, customers’ requirements, characteristics, and distribution, as well as the quality, security, and reliability of power supplies without interruption, have received considerable attention from power companies, policymakers, and researchers. How to deeply explore the distribution characteristics of electricity customers and analyze their sensitivities to electricity blackouts has become an especially important problem. This paper takes over 0.1 billion data, collected by various smart devices of the Internet of Things in the power system of China, such as smart meters, intelligent power consumption interactive terminals, data concentrators, and other cross-platform data, for example, 95 598 telephone records, complaint information, user bills, user information, and maintenance records, as study objects, to analyze the consumption characteristics of power users. It has been found that there is a wide range of power users who pay different electricity bills; a long-tail distribution following a power law lies in the number of users versus their paid electricity bills. Meanwhile, there are two Pareto effects (2-8 rule): the number of residents and non-residents versus their electricity bills, and the number of large industrial users and general industry (business users) versus in their electricity consumption and bills. Then, a decision tree algorithm is proposed to capture the characteristics of electricity consumers and to recognize the crowd who is power blackout sensitive. The evaluation indexes and parameters of the decision tree are discussed in detail, and a comparison with other intelligent algorithms shows that the decision tree has a good recognition performance over that of others, and the characteristics used to identify the blackout-sensitive crowd is various. All the results state that except for economic factors, positive social effects should also be considered. Various marketing strategies to satisfy different requirements of power users should be provided to promote long-term relationships between the power companies and power customers.