Wide Area Monitoring, Protection And Control Research Articles

Fast and Reliable Sending of Generic Object Oriented Substation Event Frames between Remote Locations over Loss-Prone Networks.

WAMPAC (Wide Area Monitoring Protection and Control) applications are becoming crucial for granting a stable operation of the electricity transmission grid. These systems use a set of sensors distributed between different electrical substations to gather real-time measurements from the field. These sensors are called Phasor Measurement Units (PMUs). Using the gathered data, different monitoring, protection, and control algorithms are run in a Phasor Data Concentrator (PDC) located in a central location. These algorithms close the loop via the generation of remedial commands, which are sent back to the field level with stringent delay, security, and reliability requirements. GOOSE (Generic Object Oriented Substation Events) protocol, defined by IEC 61850 (IEC stands for International Electrotechnical Commission), is used for that aim and also considers the option of sending these commands over IP networks (this option is called Routed-GOOSE). The present article proposes two alternatives for the tunneling of GOOSE frames over IP. Both options allow the decoupling of the transmission and the security aspects, thus increasing flexibility and allowing for easier deployment. The first option, called VX-GOOSE, is a combination of standard protocols, allowing the sending of these frames over UDP/IP tunnels. The tests that have been carried out demonstrate that, under certain network conditions, the transmission of GOOSE frames over UDP may fail, and in some extreme cases, even a whole burst of GOOSEs could be lost. This may have very bad consequences for a distributed electrical system. It should be noted that this limitation affects both VX-GOOSE and Routed-GOOSE. To overcome these limitations, the second option, called Simplemux blast mode, includes a novel mechanism that provides delivery guarantees and a reduced delay, with the counterpart of a certain degree of redundancy. As shown in the experiments, the incurred delays can be significantly reduced when remote locations are connected via unreliable networks, whereas the bandwidth increase caused by redundancy can be kept at reasonable levels. Finally, it should be remarked that although GOOSE is a relevant example use case, this approach can be applied in other fields where flows require very low delay and delivery guarantees.

A Graph-Theoretic Approach for Optimal Phasor Measurement Units Placement Using Binary Firefly Algorithm

The pursuit of achieving total power network observability in smart grids using Phasor Measurement Units (PMUs) carries a significant promise of real-time Wide-Area Monitoring, Protection, and Control (WAMPAC). PMU applications eliminate periodical measurements, thereby increasing accuracy through a high sampling rate of the measured power systems quantities. The high costs of installation of PMUs for total power system observability presents a challenge in the implementation of PMUs. This is due to the expensive costs of PMU devices. This has led to a prominent optimal PMU placement (OPP) problem that researchers tirelessly aim to solve by ensuring a complete power network observability while using the least installed PMU devices possible. In this paper, a novel Binary Firefly Algorithm (BFA) based on the node degree centrality scores of each bus is proposed to minimize PMU installations. The BFA solves the OPP problem in consideration of the effect of Zero Injection Buses (ZIBs) under normal operation and single PMU outage (SPO). The robustness and efficiency of the proposed algorithm is tested on IEEE-approved test systems and visualized with a force-directed technique on an undirected power network graph. The proposed BFA yields the same but better optimal PMU numbers, obtained by existing meta-heuristic optimization techniques found in the literature for each of the IEEE test cases, as well as highlighting the cost–benefit of having a robust system against single PMU loss while considering the ZIB effect for an improved system measurement availability.

Assessing Hardware in the Loop Approaches for Wide-Area Monitoring Control and Protection Devices

Wide-area monitoring, protection, and control (WAMPAC) systems are expected to support the transmission system operators in maintaining stability and security of supply in the future power systems. The WAMPAC solutions heavily rely on deployment and use of phasor measurement units (PMU) and related communication technologies. Laboratory testing in a realistic environment utilizing hardware in the loop (HIL) approaches can be successfully used to evaluate WAMPAC functionalities algorithms and to accelerate proofs of concept. However, different implementations of the HIL testing can be adopted and their inherent characteristics affect both the accuracy of the results and the overall testing capabilities. The objective of this paper is to provide a comparative assessment of three HIL approaches for laboratory testing of WAMPAC systems and devices. These testing approaches have been implemented in a laboratory configuration and applied to characterize WAMPAC devices. Moreover, methodologies to quantify the error introduced by these testing approaches in static and dynamic conditions are presented and applied to this laboratory configuration.

Security of Wide-Area Monitoring, Protection, and Control (WAMPAC) Systems of the Smart Grid: A Survey on Challenges and Opportunities

The evolution of power generation systems, along with their related increase in complexity, led to the critical necessity of Wide-Area Monitoring, Protection, and Control (WAMPAC) systems in today’s smart grid. Recent developments in smart measurement devices coupled with data communication technologies allow for significant improvements in power systems’ reliability, efficiency, and security. These technological advancements make WAMPAC systems of significant practical interest. However, the geographically distributed nature of such systems increases the potential attack surface and the risk of critical vulnerabilities. Thus, it is of paramount importance to identify the related threats and vulnerabilities as well as the prominent solutions relevant to WAMPAC systems. Consequently, this paper aims to provide a comprehensive review of WAMPAC security aspects along with the state-of-the-art research initiatives addressing such aspects. Specifically, this paper provides critical taxonomies of the cyber-security scope of WAMPAC that guide the accompanying survey of the recent studies on the WAMPAC security domain. As such, this article aims to pave the way for prospective researchers to pursue further studies in areas that require in-depth investigation into the security, reliability, and efficiency of WAMPAC as the backbone of smart grids.

Time Synchronization for Smart Grids Applications: Requirements and Uncertainty Issues

Smart grid implementation requires that multiple distributed systems are synchronized within and between substations. This is needed to coordinate the Intelligent Electronic Devices (IEDs) as well as to align in time the measurement data associated with the same event, but collected in different points of a broad geographical area. The time synchronization accuracy requirements in power systems are application-specific and are classified in the IEC Standard 61850-5:2013. Depending on such requirements, alternative solutions can be used. For instance, sub-microsecond time synchronization is essential for the implementation of Wide Area Monitoring, Protection, and Control (WAMPAC) systems. In fact, time synchronization directly and indirectly affects Phasor Measurement Units (PMUs) accuracy. The PMUs can measure the magnitude, the phase, the fundamental frequency and the Rate of Change of Frequency (ROCOF) of ac voltage and current waveforms at times synchronized to the Universal Coordinated Time (UTC). Among such quantities, the phase data are those most strongly affected by time synchronization. If time synchronization accuracy is within ±1 µs, its impact on synchrophasor phase measurement is in the order of a fraction of mrad, i.e., low enough to have a negligible impact on the state estimation uncertainty of most of transmission and distribution systems. However, the need to interpolate the missing phasor values when data from PMUs with a different reporting rate are collected and aligned in time may unexpectedly boost synchrophasor phase estimation uncertainty.

On the use of Real-Time transformer temperature estimation for improving transformer operational tripping Schemes

During each summer, the super grid transformers (SGTs) inside GB transmission network are maintained according to the schedule which is determined by the asset management strategies. The outage of selected transformer often results in an increased loading on the rest of transformers in the adjacent circuits. Any type of faults occurring on circuits or other elements during this period of time is likely to cause overloads on the remaining transformers which could lead to a breach of the Security and Quality of Supply Standards (SQSS). The transformer operational tripping scheme (OTS) is a technique for protecting transformers from overloading by tripping pre-selected groups of generations so that the loading on the monitored transformers can be relieved during the contingencies. An event-based transformer OTS has been constantly armed in the GB network. This paper presents a novel technique to integrate the real time transformer temperature estimation into an existing transformer OTS. This technique improves the OTS by reducing the number of unnecessary generation tripping, which is initiated from the overly conservative transformer ratings. This novel scheme will generate enormous economic benefits as well as provide significant flexibility to the GB system operator – National Grid Electricity System Operator (NGESO). The new scheme is an example of a Wide Area Monitoring, Protection and Control (WAMPAC) application.

Real-Time Testing of Synchrophasor-Based Wide-Area Monitoring System Applications Acknowledging the Potential Use of a Prototyping Software Toolchain

This article presents a study on real-time testing of synchrophasor-based “wide-area monitoring system’s applications (WAMS application).” Considering the growing demand of real-time testing of “wide-area monitoring, protection, and control (WAMPAC)” applications, a systematic real-time testing methodology is formulated and delineated in diagrams. The diagrams propose several stages through which an application needs to be assessed (sequentially) for its acceptance prior to implementation into a production system. However, only one stage is demonstrated in this article which comprises the use of a prototyping software toolchain and whose potential is assessed as sufficient for preliminary real-time testing (PRTT) of WAMS applications. The software toolchain is composed of two components: the MATLAB software for application prototyping and other open-source software that allows ingesting prerecorded phasor measurement unit (PMU) signals. With this software toolchain, a PRTT study is presented for two WAMS applications: “testing of the PMU/phasor data concentrator (PDC)” and “testing of wide-area forced oscillation (FO) monitoring application.”

Construction and Evaluation of an Optical Medium Voltage Transducer Module Aimed at a 132 kV Optical Voltage Sensor for WAMPAC Systems.

This paper reports on the construction and characterization of an optical voltage transducer module for applications in the field of wide-area monitoring, protection, and control (WAMPAC). The optical medium voltage transducer (MVT) module was designed to be combined with a capacitive voltage divider (CVD) to form a voltage sensor intended for 132 kV high voltage (HV) networks. The MVT module comprises a combination of a piezoelectric transducer (PZT) and a fiber Bragg grating (FBG) as a core optical sensing element. Changes in the input voltage across the PZT translate into strain being detected by the FBG. The resultant FBG peak wavelength can be calibrated in terms of the input voltage to obtain a precise voltage measurement. The module was experimentally evaluated in the laboratory, and its performance was assessed based on the requirements specified by the IEC standards for electronic voltage transformers and low power voltage transformers. The results of accuracy tests demonstrate that the MVT module is free from hysteresis, within the experimental error, and is capable of simultaneously meeting the requirements for 0.1 metering and 1P protection classes specified by the IEC 60044-7 and IEC 61869-11 standards.

Cyber–physical testbed for Wide Area Measurement System employing IEC 61850 and IEEE C37.118 based communication

Wide Area Measurement Systems (WAMS) are well known for enhancing situational awareness of the grid using IEEE C37.118 phasors from Phasor Measurement Units (PMUs). Recently introduced IEC 61850-90-5 Routable Sample Values (R-SV) have proven promising to communicate timestamped synchrophasors to the control center, fulfilling the purpose. In wide area protection and control schemes, the communication of synchrophasors to the control center is also followed by sending back a supervisory decision signal (based on synchrophasor data) to the physical devices in the field. Development of WAMS testbeds for implementation and assessment of such schemes have often been addressed only from IEEE C37.118 PMU phasors’ perspective alone. This paper presents a comprehensive cyber–physical WAMS testbed capable of real-time communication of synchrophasors using both IEEE C37.118 PMU phasors and IEC 61850-90-5 R-SV. It also facilitates status and feedback signal communication between the control center and substations using IEC 61850-90-5 Routable GOOSE (R-GOOSE). The developed testbed integrates a real-time digital simulator (RTDS), industry-standard hardware devices such as PMUs, Phasor Data Concentrator (PDC), IEDs, Global Positioning System (GPS) synchronization clock, network components, and software components such as IEC 61850 emulator tools. It can be used for end-to-end implementation of a myriad of wide area monitoring protection and control (WAMPAC) applications. It can further facilitate vulnerability analysis of WAMS components, analyze the impact of cyber-attacks on critical applications, and then test and validate various security solutions for cyber resiliency of WAMPAC applications.

Application of IIA Method and Virtual Bus Theory for Backup Protection of a Zone Using PMU Data in a WAMPAC System

Many wide area monitoring, protection, and control (WAMPAC) systems are being deployed by grid operators to deal with critical operational conditions that may occur in power systems. Thanks to the real-time measurements provided by a set of distributed phasor measurement units (PMUs), different protection algorithms can be run in a central location. In this context, this article presents and validates a novel method that can be used as a backup protection for a selected area in a power system. It merges the integrated impedance angle (IIA) protection method with the theory of virtual buses in wide area electrical power systems. The backup protection works this way: once a fault is detected (pickup time), another delay (added to the pickup time) is defined in order to wait for the primary protection to act. If this does not happen, the algorithm generates its backup trip. The proposed method has been called the zone integrated impedance angle (Zone IIA). A real-time PMU laboratory has been used to test the proposed algorithm using a real-time digital simulator (RTDS). The algorithm has been programmed in a real-time automation controller (RTAC). It has been tested in two different simulated setups: first, a 400 kV transmission system, with and without the use of renewable energy sources (RES); second, a 150 kV submarine line between the Greece mainland and an island, which is currently the longest submarine alternating current connection in the world. The results obtained during the tests have yielded tripping times for area protection in the order of 48 ms, if no time delay is used between the fault detection and the trip order. According to the test results, the proposed method is stable, reliable, obedient, and secure, also with RES installed in the power system. Additionally, the method is selective, i.e., during the tests no trip was executed for external faults, no trip was executed in no-fault condition, and all the applied internal faults were detected and tripped correctly. Finally, the protection method is easy to implement. The method is also applicable to protection against short circuits in distribution systems. According to the trip times observed during the tests, it is clear that these algorithms are well suited to implement backup protections in transmission grids, even in scenarios with high penetration of renewable energies. Considering that backup trip times in transmission grids are usually set between 400 and 1000 ms, and that the actuation times obtained by the proposed algorithm are under 100 ms, the method is suitable for its use as a backup protection.

Operational planning steps in smart electric power delivery system

This paper presents a comprehensive review of advanced technologies with various control approaches in terms of their respective merits and outcomes for power grids. Distributed energy storage control is classified into automatic voltage regulator and load frequency control according to corresponding functionalities. These control strategies maintain a power balance between generation and demand. Besides, three basic electric vehicle charging technologies can be distinguished, i.e. stationary, quasi-dynamic and dynamic control. For realizing charge-sustaining operation at minimum cost quasi-dynamic and dynamic strategies are adopted for in-route charging, while stationary control can only be utilized when the electric vehicle is in stationary mode. Moreover, power system frequency stability and stabilization techniques in non-synchronous generator systems are reviewed in the paper. Specifically, a synchronverter can damp power system oscillations and ensure stability by providing virtual inertia. Furthermore, it is crucial to manage the massive information and ensure its security in the smart grid. Therefore, several attack detection and mitigation schemes against cyber-attacks are further presented to achieve reliable, resilient, and stable operation of the cyber-physical power system. Thus, bidirectional electrical power flows with two-way digital control and communication capabilities have poised the energy producers and utilities to restructure the conventional power system into a robust smart distribution grid. These new functionalities and applications provide a pathway for clean energy technology. Finally, future research trends on smart grids such as IoT-based communication infrastructure, distributed demand-response with artificial intelligence and machine learning solutions, and synchrophasor-based wide-area monitoring protection and control (WAMPC) are examined in the present study.

Wide area monitoring, protection, and control application in islanding detection for grid integrated distributed generation: A review

The assimilation of Distributed Generation (DG) into the electric power system (EPS) has become more attractive as the world is following a trend to reduce greenhouse gas emissions by introducing more renewable energy forms resulting in high penetration scenarios. This high penetration of DGs brings several challenges to the protection philosophy of the EPS which compromises its reliability, availability, and efficiency. Under high DG penetration scenarios, conventional islanding detection methods (Idms) fail to detect an island as the grid loses its inertia to leverage a significant frequency and voltage mismatch necessary for Idms to effectively detect an islanding event. This has given rise to the birth of Artificial Intelligent (AI) methods that are found to perform better in islanding detection. AI Idms are computationally intensive and require a lot of data to operate accurately. Because the computational burden of these methods requires fast computing hardware, the current trend of AI Idms are integrated with Wide Area Monitoring, Protection, and Control (WAMPAC) system. This paper aims at reviewing all these Idms and the WAMPAC’s system latency when hosting AI Idms which are currently the best in islanding detection. This is done to determine if the WAMPAC system latency plus Idms computational time meet the islanding detection time specified by the IEEE Standard 1547 framework.

A network design algorithm for multicast communication architectures in smart transmission grids

In future smart transmission grids, there are distributed applications that will benefit from the deployment of Internet Protocol (IP) multicast technology for communication. Sharing of Routable-Sample Values (R-SV) and Routable-GOOSE among the digital substations for wide-area monitoring, protection, and control (WAMPAC) applications will be needed. Using multicast for distribution of R-SVs is resource-efficient and offers a simpler configuration with only the interested substations needing reconfiguration. However, the demands for such concurrent delivery of R-SV data will put constraints on the underlying supporting networking infrastructure. For example, it must be ensured that the paths taken to route data traffic are within the bounds of delay to achieve the aims of the WAMPAC application. In this paper, we look at the problem of network topology augmentation through link additions. We present a heuristic algorithm that finds a set of links to be added to a network topology such that the multicast distribution tree for a multicast configuration is bounded by latency, which is set as the hop-count threshold. Our results show that by adding a few new links to the network topology, the delay incurred by the multicast traffic from sources to destinations can be reduced.

Real‐time data‐assisted replay attack detection in wide‐area protection system

The cyber-attack surface in the power grid has widened with the deployment of the wide-area monitoring, protection, and control (WAMPAC) system. Replay attacks are one of the most challenging attacks to detect in a WAMPAC system. The authors aim to address the problem of identification and repercussions of continuous replay attacks on wide-area backup protection schemes. The continuous replay attacks introduce a permanent lag in the phasor measurement unit (PMU) data. The authors classify such attacks into small, medium, and wide-scale based on the number of compromised substations. Furthermore, the signature of a replay attack is derived using a one-step-ahead prediction of PMU data. The resulting forecast error distributions are subsequently analysed using the Kullback–Leibler divergence metric. Results using field PMU data show that this method successfully distinguishes replay attacks from normal system operation and faults in the system. Therefore, the proposed scheme can be used to detect and mitigate the effects of replay attacks on wide-area protection schemes.

PRIME: a real‐time cyber‐physical systems testbed: from wide‐area monitoring, protection, and control prototyping to operator training and beyond

As the power grid continues to evolve with advanced wide-area monitoring, protection, and control (WAMPAC) algorithms, there is an increasing need for realistic testbed environments with industry-grade software and hardware-in-the-loop (HIL) to perform verification and validation studies. Such testbed environments serve as ideal platforms to perform WAMPAC prototyping, operator training, and also to study the impacts of different types of cyberattack scenarios on the operation of the grid. In this study, the authors introduce pacific northwest national laboratory(PNNL) cyber-physical systems testbed (PRIME): the testbed that integrates real-time transmission system simulator with commercial industry-grade energy management system software and remote HIL (RHIL). PRIME is an end-to-end, modular testbed that allows high-fidelity RHIL experimentation of a power system. We present two detailed case studies (fault location and clearing in the transmission system and operator training) to show the capabilities of their PRIME testbed. Finally, we briefly discuss some of the potential limitations of their testbed in terms of scalability and flexibility to set up larger test systems and identify directions for future work to address these limitations.

PMU-Based ROCOF Measurements: Uncertainty Limits and Metrological Significance in Power System Applications

In modern power systems, the Rate-of-Change-of-Frequency (ROCOF) may be largely employed in Wide Area Monitoring, Protection, and Control (WAMPAC) applications. However, a standard approach toward ROCOF measurements is still missing. In this paper, we investigate the feasibility of Phasor Measurement Units (PMUs) deployment in ROCOF-based applications, with a specific focus on Under-Frequency Load-Shedding (UFLS). For this analysis, we select three state-of-the-art window-based synchrophasor estimation algorithms and compare different signal models, ROCOF estimation techniques, and window lengths in datasets inspired by real-world acquisitions. In this sense, we are able to carry out a sensitivity analysis of the behavior of a PMU-based UFLS control scheme. Based on the proposed results, PMUs prove to be accurate ROCOF meters, as long as the harmonic and interharmonic distortion within the measurement pass-bandwidth is scarce. In the presence of transient events, the synchrophasor model loses its appropriateness as the signal energy spreads over the entire spectrum and cannot be approximated as a sequence of narrow-band components. Finally, we validate the actual feasibility of PMU-based UFLS in a real-time simulated scenario where we compare two different ROCOF estimation techniques with a frequency-based control scheme, and we show their impact on the successful grid restoration.

System Integrity Protection Scheme (SIPS) Development and an Optimal Bus-Splitting Scheme Supported by Phasor Measurement Units (PMUs)

System integrity protection schemes (SIPS) are schemes that can, under potentially hazardous conditions, prevent a complete blackout of endangered parts of an electrical power system (EPS). The main objective of SIPS is to monitor the state of the power transmission network in real time and to react in emergency cases. This paper explores the use of phasor measurement unit (PMU) technology for the development of SIPS as a part of wide-area monitoring, protection, and control (WAMPAC) systems. A new SIPS development method is described using the experience from the real-time operation. The developed optimal bus-splitting scheme identifies potential actions that can eliminate or reduce power system overloads and protect the integrity of the power system. An optimal bus-splitting scheme based on a DC power flow model and PMU measurements is given as an example and is explained and tested on an IEEE 14 bus test system. Conducted simulations indicate that the described SIPS methodology supported by the PMU measurements can mitigate potential overloads of the observed network part.

Wide area monitoring system for an electrical grid

Power Sector is the back bone of the economy of a nation. In the day to day scenario power plays a vital role and it is the basic amenity of any sector. The power supply should be of good quality, highly reliable, cheap etc. Modern Power System is close to the stability operation, as the Distributed Generations have increased widely, and the Power Network has been extended by laying newer Transmission Lines etc., which has eventually led to the complexity in the operation and control of the Power Network. The lack of monitoring and appropriate control may lead to catastrophic failure of the network known as blackout. It occurs due to a series of outage in the system. The trend in the power network sees advanced longer paths to meet the existing demand and one such trend is the WAMPAC systems. The congestion and complexity in the network have pushed the grid to enhance for proper monitoring and control by Wide Area Monitoring Protection and Control (WAMPAC), an enabler of the Smart Grid which is a bidirectional network that can heal itself in case of any failure.

Real-time multi-state classification of short-term voltage stability based on multivariate time series machine learning

The analysis of the significant amount of data collected by PMU devices in wide-area monitoring, protection and control (WAMPAC) applications has been a great challenge for assessing power system fast phenomena. This paper presents a novel methodology for real-time assessment of short-term voltage stability (STVS) under large disturbances with an approach based on data mining and machine learning. This methodology classifies off-line the power system stability in multiple operating states through the calculation of the maximal Lyapunov exponent and dynamic voltage indices. This allows identifying not only fast voltage collapses (FVC) but also fault-induced delayed voltage recovery (FIDVR) events. The multivariate time series data of the power system dynamic response are processed and transformed with a symbolic representation technique. This together with the operating state classification are used to train an intelligent machine based on Random Forest proposed for applying in real time to classify the post-disturbance operating state. This methodology is tested in the New England 39-bus system. The performance of the methodology to classify the STVS in real time was verified, obtaining a classification error less than 2% using a post-contingency data window of 0.58 s and less than one-third of all the bus voltage measurements. Results show the ability of the methodology to predict voltage stability problems, having enough time to carry out automatic control actions to prevent or mitigate problems.

RELEVANCE OF ADAPTIVE PROTECTION SCHEME USING PHASOR MEASUREMENT UNIT IN INDIAN POWER GRID

The configuration of the power system is constantly changing due to renewable integration, changing loads, network switching operations or faults. The relays settings based on pre-determined static system conditions that are in general maximum or minimum, may not suffice, leading to inaccurate relay operation for a dynamic power system. Malfunction of conventional protection system has been one of the main causes of cascading catastrophes in power grid. Selection of suitable relay characteristics that will be an appropriate compromise for all loading conditions and contingencies is a matter of concern. The relevance of adaptive relay settings in wide area monitoring, protection, and control (WAMPAC) using synchrophasor is brought out in this paper. The significance of new wide area adaptive protection system (WAAPS) in improving the reliability and safety of power transmission through Indian grid, with a high level of operational uncertainties, is analysed and an architecture is suggested.