Power System Protection Research Articles

Zero Crossing Point Detection in a Distorted Sinusoidal Signal Using Decision Tree Classifier

Zero-crossing point detection in a sinusoidal signal is essential in the case of various power systems and power electronics applications like power system protection and power converters controller design. In this paper, 96 data sets are created from a distorted sinusoidal signal based on MATLAB simulation. Distorted sinusoidal signals are generated in MATLAB with various noise and harmonic levels. In this paper, a decision tree classifier is used to predict the zero crossing point in a distorted signal based on input features like slope, intercept, correlation and Root Mean Square Error (RMSE). Decision tree classifier model is trained and tested in the Google Colab environment. As per simulation results, it is observed that decision tree classifier is able to predict the zero-crossing points in a distorted signal with maximum accuracy of 98.3 % for noise signals and 100 % for harmonic distorted signals.

Development of a Low-Cost Relay Prototype for Real-Time Power Protection Functions

This paper presents a Raspberry Pi 3B+ based low-cost universal relay able to run power protection functions in real-time. The configurations necessary for this single-board computer to be able to provide real-time response are shown, as for latency tests to verify its response time. An experimental circuit was built to send three-phase fault signals from a Relay tester to the low-cost relay, in order to evaluate its response time to clear faults in comparison to a commercial relay. A neural networks algorithm was developed and executed in real-time by the proposed low-cost relay, which is able to differentiate three-phase faults from transient signals created from large load variations. The results show that the low-cost relay is capable of running simple and complex protection functions within a pre-defined runtime and acceptable precision, compared to a commercial protection relay. However, the sampling frequency the low-cost relay is able to handle is limited. The results have also shown that the low-cost relay meet the requirements for a soft real-time system, which is not ideal for practical power protection systems that require hard real-time systems.

Special issue on all‐electric and hybrid‐electric flight

Special issue on all‐electric and hybrid‐electric flight

Fast Detection of Current Transformer Saturation Using Stacked Denoising Autoencoders

Malfunctions in relay protection devices are predominantly caused by current transformer (CT) saturation which produces distortion in current measurements and disturbances in power system protection. The development of deep learning in power system protection is on the rise recently because of its robustness. This study presents a CT saturation detection where the secondary current becomes distorted. The proposed scheme offers a wide range of saturation detection and consists of a moving-window technique and stacked denoising autoencoders. Moreover, Bayesian optimization was used to minimize the difficulty of determining neural network structure for the proposed approach. The performance of the algorithm was evaluated for a-g faults on 154 kV and 345 kV overhead transmission line in South Korea. The waveform variation has been generated by PSCAD for different scenarios that heavily influence CT saturation. Moreover, a comparative analysis with other methods demonstrated the superiority of the proposed DNN method. With the proposed algorithm to detect CT saturation, it significantly yielded high accuracy and precision for CT saturation detection which were approximately 99.71% and 99.32%, respectively.

Multi-objective Optimization of Relay Protection Setting Based on MOAHA Algorithm

With the expansion of the power grid scale, more and more relay protection devices exist in the power system, and the optimization of node protection setting values has also begun to receive attention. Conventional genetic algorithm is mainly used in the current multi-objective optimization solution of relay protection fixed value, and its multi-objective optimization procedure is relatively complicated, resulting in low optimization solution efficiency. Therefore, applying the multi-objective artificial hummingbird algorithm (MOAHA) to the optimization process is proposed to obtain a new fixed-value multi-objective optimization method for relay protection. According to the set value requirements of the relay protection, a multi-objective optimization model of the set value of the relay protection is established, and the constraints are determined. Regarding the grid vulnerability coefficient, calculate the weighting factor corresponding to each constraint condition. Then, the multi-objective artificial hummingbird algorithm is applied to design a simple multi-objective optimization mode, including two stages of self-search and guided search to obtain fixed-value optimization results. The results of the example analysis show that the proposed optimization method only needs 20 iterations to output the optimal solution, and the average time spent to obtain the optimal solution is 17.6s. It can play a prominent role in the global optimization and tuning of relay protection in large power systems.

Design and implementation of an innovative wind power system for beach erosion protection and nourishment

Beach erosion phenomena have become increasingly frequent and devastating with serious economic damage on tourism. A relatively recent technique of beach protection and nourishment is based on the creation along the shoreline of an unsaturated sandy zone, in which the level of the phreatic surface is lowered by means of buried drains connected to electric suction pumps. The main problem encountered in this solution is the need to guarantee the drainage when the erosive activity is maximum in the presence of intense thunderstorms that often produce malfunction and outage problems of the power supply. This paper shows the realization of a “green” solution based on a totally mechanical design and construction approach, achieved by connecting a 3.5-meter single-bladed wind turbine to a submerged axial pump with optimized volute by means of a vertical shaft placed inside the tower. The system is managed by a mechanical pitch controller studied for starting and limiting power in exceptional winds.

A Communication-less adaptive protection scheme for Self-Healing distribution systems

Network reconfiguration has allowed supply restoration to disrupted areas after fault events. However, changes in network topology can alter the direction and magnitude of fault currents and jeopardize the coordination of overcurrent relays. Adaptive protection schemes using system-wide communications have been developed to solve this issue by performing dynamic relay recalibration. Unfortunately, system-wide communications are also associated with huge economic costs, data integrity issues, and limitations of infrastructures. Moreover, in less developed communities, such schemes are less applicable. Although various communication-less schemes have been proposed, they mainly focused on adapting overcurrent relay protection for different distributed generation penetrations and microgrid islanding statuses. Currently, no communications-less adaptive protection method has been proposed to address the miscoordination of protection relays caused by network reconfiguration for supply restoration. Thus, this paper presents a communication-less adaptive protection scheme to maintain relay coordination in a reconfigurable distribution network that performs supply restoration. The scheme deploys microcontroller units to predict the correct relay settings by monitoring load flows through the relays. The scheme is demonstrated on the IEEE 33-bus and 69-bus test distribution systems using two different relay placement strategies, non-directional and directional relays. The proposed scheme achieved up to 10.8 times lower disruptions than the existing system in N-1–1 contingency scenarios. Overall, the scheme provides a simple and low-cost alternative to improve the effectiveness of power system protection in a reconfigurable network.© 2017 Elsevier Inc. All rights reserved.

Fault Detection and Protection of Power Transformer Using Fuzzy Logic

Abstract: Power transformer malfunctions cause significant power outages and, as a result, material damage. This critical issue must be resolved. Power transformers must be protected from various fault conditions and power system failure. Fuzzy logic is used in this study to detect and protect power system transformer faults. In the simulation system that diagnoses transformer faults and monitors its operating conditions, the fuzzy logic (FL) toolbox in MATLAB/ SIMULINK software was used. The input variables, current and rate of change of current with time, have been identified as "Error" and "Error-Dot" in the programme. The study's findings show that when the output response is zero, the current in the transformer is normal. This is obtained by injecting [0] and [0] input values into the system, resulting in a response of "6e(-017)," which is close to zero. If the output response is greater than zero, the transformer current is rising above normal and the protection scheme should be notified. This condition is achieved by giving the system input values of [-1.5] and [5] and expecting a response of "+5". If the response is less than zero, the transformer current is less than normal, and the protection scheme should be notified. The study concluded that electrical faults and mechanical failures in power transformers can be quickly identified using Fuzzy logic. Thus, power transformer damage is avoided by controlling relays more effectively and quickly. This has resulted in significant savings in maintenance and repair costs. It is assumed that the study was a success.

Real-time low-carbon scheduling for the wind–thermal–hydro-storage resilient power system using linear stochastic robust optimization

With the large-scale wind power integration, power systems have to address not only the conventional power demand fluctuations but also the wind uncertainty. To improve the economical effectiveness, resilience, and environmental protection of power systems in the source-load uncertainty, a real-time low-carbon scheduling for the wind–thermal–hydro-storage integrated system is proposed. The power imbalance caused by the uncertainty is neutralized by the synergetic linear decision of multiple resources. To address the source-load uncertainty, a stochastic robust optimization is introduced, which establishes the system constraints by robust optimization for the resilience operation, while optimizing the expected operation cost in the empirical uncertainty distribution for economic efficiency. Moreover, a multi-point estimation is applied to formulate the expected operation cost precisely and quickly. By using the dual theory, the proposed real-time power scheduling is derived as a mixed integer bilinear constrained programming. A multi-step sequential convexified solution is developed to solve the complex scheduling problem, which linearizes the bilinear constraints with alternate optimization and relaxes the state variables of energy storages with an “estimation–correction” strategy. Finally, case studies show the superiority of the proposed scheduling method and convexified solution.

FAULT DETECTION AND PROTECTION OF POWER TRANSFORMER USING FUZZY LOGIC

Power transformer malfunctions cause significant power outages and, as a result, material damage. This critical issue must be resolved. Power transformers must be protected from various fault conditions and power system failure. Fuzzy logic is used in this study to detect and protect power system transformer faults. In the simulation system that diagnoses transformer faults and monitors its operating conditions, the fuzzy logic (FL) toolbox in MATLAB/ SIMULINK software was used. The input variables, current and rate of change of current with time, have been identified as "Error" and "Error-Dot" in the programme. The study's findings show that when the output response is zero, the current in the transformer is normal. This is obtained by injecting [0] and [0] input values into the system, resulting in a response of "6e(-017)," which is close to zero. If the output response is greater than zero, the transformer current is rising above normal and the protection scheme should be notified. This condition is achieved by giving the system input values of [-1.5] and [5] and expecting a response of "+5". If the response is less than zero, the transformer current is less than normal, and the protection scheme should be notified. The study concluded that electrical faults and mechanical failures in power transformers can be quickly identified using Fuzzy logic. Thus, power transformer damage is avoided by controlling relays more effectively and quickly. This has resulted in significant savings in maintenance and repair costs. It is assumed that the study was a success. Keywords: Fuzzy logic, Transformer, fault, Detection, Current, Protection

Innovative Higher Education Approaches for Power System Courses

Higher education plays a crucial role in modern society and in emerging energy systems, due to the rising complexity of the phenomena and the interplay among various layers (physical, cyber, social and economic). To cope with this context, universities need to develop new visions and tools for education and training. Real-time simulation (RTS) is emerging as a novel and effective approach to analyzing power system aspects, and this characteristic can be effectively used in power system courses. Hence, after the presentation of the basics about the RTS, the paper will show the advantages of employing RTS for teaching activities. Finally, two examples of didactic activities involving RTS at Politecnico di Torino will be presented. In fact, RTS is part of both multi-disciplinary projects (where students with different backgrounds can face the issues affecting the protection and control of power systems) and the course “Electrical systems and safety”, where RTS is used to study the behavior of voltage transformers in saturation.

Passive anti-Islanding protection for Three-Phase Grid-Connected photovoltaic power systems

This paper presents the performances of a new passive anti-islanding protection with minimal switching losses for three-phase grid-connected photovoltaic power systems. The novelty of the proposed strategy consists of five conventional passive relays, which are as follows: over/under current, over/under voltage, over/under frequency, rate of change of frequency, and dc-link voltage-based anti-islanding methods. Integrating these methods in a synergistic way reduces the limitations of each method, while combining the strengths and benefits of each method in islanding detection. As such, the dc-link voltage-based method consists in supervising the dc-link voltage in voltage source converters to reduce the voltage stress and increase performance. The performance in islanding prevention is determined by the detection time of islanding operation mode. The proposed anti-islanding protection was simulated under complete disconnection of the photovoltaic inverter from the electrical power system, as well as under grid faults as required by new grid codes.

A New Method of Fault Localization for 500 kV Transmission Lines Based on FRFT-SVD and Curve Fitting

The paper presents the Fractional Fourier Transform-Singular Value Decomposition (FRFT-SVD) method for the localization of various power system faults in a 200 km long, 500 kV Egyptian transmission line using sent end-line current signals. Transient simulations are carried out using Alternating Transient Program/Electromagnetic Transient Program (ATP-EMTP), and the outcomes are then examined in MATLAB to carry out a sensitivity analysis against measurement noises, sampling frequency, and fault characteristics. The proposed work employs current fault signals of five distinct kinds at nineteen intermediate points throughout the length of the line. The approach utilized to construct the localizer model is FRFT-SVD. It is much more effortless, precise, and effective. The FRFT-SVD is utilized in this technique to calculate 19 sets of indices of the greatest S value throughout the length of the line. The FRFT-SVD localizer model is also designed to be realistic, with power system noise corrupting fault signals. To generate fault curves, the curve fitting technique is applied to these 19 sets of indices. Reduced chi-squared and modified R-squared criteria are used to choose the best-suited curve. The proposed work results in a very precise localization, with only a 0.0016% average percentage error for fault localization and a maximum percentage error of 0.002% for the 200 km Egyptian transmission line. Finally, this work can be employed as a proper link between the nuclear power plant and the grid. The proposed method is an efficient fault distance estimation method that might contribute to creating a dependable transient-based approach to power system protection.

A Negative Sequence Admittance Based Algorithm for Identifying Fault Direction in the Presence of Inverter Based Resources

Ever increasing integration of renewable resources into contemporary power systems has imposed a unique set of challenges for system protection. Effectiveness of techniques based on conventional system protection theory has long been questionable in protecting power systems with higher penetration of inverter-based resources (IBRs). Fault direction identification is one of the commonly affected protection functions in the presence of IBRs. This paper presents a novel algorithm to correctly identify fault direction using negative sequence admittance measurements. The proposed technique is robust and reliable and yields better results in comparison to conversional techniques in presence of IBRs. In addition, its operation is simple and can be conveniently incorporated into a modern digital relay.

Preventive protection of autonomous electric power systems from reverse power on the basis of preventive control

Preventive protection of autonomous electric power systems from reverse power on the basis of preventive control

New Motor Protection Standard IEEE 3004.8: Getting Up to Speed

IEEE Standard (STD) 3004.8-2016 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Recommended Practice for Motor Protection in Industrial and Commercial Power Systems</i> <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> is the first industrial-based standard providing detailed protection setting tables with companion single-line and three-line diagrams of recommended protection schemes for multifunction motor protection relays. Comprehensive motor protection information and diagrams are included for adjustable speed drive (ASD) applications. The content triples and deepens the information from its predecessor: IEEE Std 242-2001 (Buff Book), Chapter 10. Contributions were incorporated from end users, manufacturers, and consultants from across the world, capturing advancements in protection technologies, including field experiences. Updates include motor protection for hazardous (classified) locations. This article covers a brief standard overview and deep dives into material that is most applicable to the petrochemical industry.

A DC Solid-State Current Limiter With Adaptive Current-Limiting Ability

The proportion of DC power generation, transmission, and distribution in power systems is continuously increasing. Currently, fault protection in DC power systems is an attractive yet difficult research topic. In this paper, a DC solid-state current limiter with adaptive current-limiting ability is proposed. The basic topology and the working principle of the proposed current limiter are presented. Then, an improved topology with bidirectional current-limiting and reactor self-bypass capacity is realized. In order to achieve adaptive current-limiting, a multi-stage cascaded structure of the proposed current limiter is studied. The single-stage current-limiting ability and multi-stage adaptive current-limiting ability of the current limiter in DC power systems are verified by simulations. Furthermore, the proposed current limiter topology is verified by hardware-in-the-loop test bench. Corresponding results show that the proposed current limiter can reduce the influence of reactor on the dynamic characteristics in DC power systems, and effectively suppress the rapid rise of DC fault currents at fault time.

Transient Stability and Active Protection of Power Systems With Grid-Forming PV Power Plants

Photovoltaic (PV) power plants with grid-forming technology must withstand severe disturbances and remain operational. To address this challenge, this paper sets forth a grid-forming strategy for PV solar power plants so that they can ride through power system faults. This capability is accomplished by leveraging two-axis proportional-integral regulators with anti-windup functionality. This paper also demonstrates that fluctuations of solar irradiance can cause significant dc-link voltage variations and loss of synchronism of grid-forming PV plants. Hence, we develop an active dc-link protection method which depends on estimation of solar irradiance. The contributions of this paper are demonstrated via positive-sequence simulations of modified versions of the WSCC 9- and IEEE 39-bus grids.

A Novel Method of Vector Shift Criterion Utilization in Power System Automation

The article describes the new application of a well-known protection criterion - Vector Shift (VS). In the paper, technical problems related to the utilization of this criterion have been described. Additionally, the authors conducted laboratory tests of a digital protection relay. The impact of different disturbances occurring in the power systems on the operation of the Vector Shift criterion has been examined. The obtained results have proved the validity of banning the Vector Shift criterion in some countries. Furthermore, a novel application of the Vector Shift criterion has been presented. This criterion could be utilized to determine the degree of balance of a separated island. This information may be helpful in novel power system protection devices used in Smart Grids or microgrids.

A Systematic Review on Cascading Failures Models in Renewable Power Systems with Dynamics Perspective and Protections Modeling

• Complex probabilistic techniques reduce the cascade data needed to generate the dynamic failure model. • Implementing the correct renewable power systems protection scheme and the dynamics of renewable power systems improves cascading failure modeling. • High penetration of renewable power systems significantly impacts cascading failure due to low inertia, rapid frequency and voltage fluctuation. • Grid-forming technology is the solution to mitigate cascading failures in renewable power systems. • Investigating a power system's reliability with complex dynamics driven by its upgrade process help reduce the blackout risks. Cascading failure in renewable power systems is a hot topic that attracts most researchers worldwide. This paper discusses the phenomena of blackout and cascading failure in terms of definition, causes, and past events worldwide. This paper also compares the models in terms of features, limitations, computational speed, and test bus for assisting the tradeoff analysis. Benchmarking among the models and potential test buses to be utilized for cascading failure analysis considering the high penetration of renewable power systems, are also included in this paper. The authors propose tradeoffs between the existing cascading failure models and solutions to achieve high accuracy and reduce computational complexity. Furthermore, this paper also compares the statics versus dynamics model methodology and the parameters involved during the simulation, corresponding to the latest challenges in protection systems. This paper also discusses the emerging challenges of cascading failure with an emphasis on the aspect of dynamic models, renewable energy, and the reliability of power systems. Due to the emerging problems that arise with the high penetration of renewable energy, grid-forming technology is the solution to study the impact of renewable energy on cascading failure. Researchers must develop a sophisticated dynamic model with high-speed computational time to realize online monitoring, prediction, and mitigation of blackouts becomes possible.