Relay Protection Research Articles

Mono-pole blocking accident analysis caused by inaccurate measurement of optical CT in ±800 kV UHVDC transmission system under lightning strike

The ultra-high voltage direct current (UHVDC) power transmission systems usually transmit a capacity of 6-8 GW, their stability and reliability are of vital importance to the large power grid. This paper analyses a mono-pole blocking accident caused by the inaccurate measurement of optical current transformer (OCT) when the pole line of Shaanbei-Wuhan ±800 kV UHVDC transmission system was struck by lightning. Combined with electromagnetic transient simulation of the UHVDC transmission system, digital simulation and in-plant testing of the optical CT, a comprehensive understanding of the factors contributing to the accident is achieved. It reveals that optical CT measurement anomalies were significant contributors to the misoperation of protective relays, which led to the mono-pole blocking accident. Based on the simulations of optical CT under high peak currents and high di/dt conditions caused by lightning strike, the importance of proper setting of demodulation algorithm parameters in optical CT to avoid inaccurate measurements is emphasized. Through in-plant testing and steady state current accuracy verification, the reasonableness of demodulation parameters is verified. Simulation results illustrate the challenges in measuring very fast transient current accurately, which are the premise and guarantee of stable operation of UHVDC transmission systems under lightning strike.

Analysis of War Optimization Algorithm in a Multi-Loop Power System Based on Directional Overcurrent Relays

In electrical power systems, ensuring a reliable, precise, and efficient relay strategy is crucial for safe and trustworthy operation, especially in multi-loop distribution systems. Overcurrent relays (OCRs) have emerged as effective solutions for these challenges. This study focuses on optimizing the coordination of OCRs to minimize the overall operational time of main relays, thereby reducing power outages. The optimization problem is addressed by adjusting the time multiplier setting (TMS) using the War Strategy Optimization (WSO) algorithm, which efficiently solves this constrained problem. This algorithm mimics ancient warfare strategies of attack and defense to solve complex optimization problems efficiently. The results show that WSO provides superior performance in minimizing total operating time and achieving global optimum solutions with reduced computational effort, outperforming traditional optimization methods (i.e., SM, HPSO, GA, RTO, and JAYA). The proposed algorithm shows a net time gains of 7.77 s, 2.57 s, and 0.8484 s when compared to GA, RTO, and JAYA respectively. This robust protection coordination ensures better reliability and efficiency in multi-loop power systems.

An adaptive distance protection scheme considering fault resistance, injected current, and structural changes in the power system

AbstractFaults in power systems occur for various reasons, such as aging or natural disasters. Detecting, locating, and promptly clearing these faults is crucial for maintaining the safety and reliability of transmission lines (TLs). Distance relays (DRs), which protect TLs, detect faults, estimate their location, and send the required commands. However, these relays may experience mis‐detection due to manipulated impedance arising from both internal and external factors. These factors include measurement device errors, network topology changes, the presence of fault resistance (FR), and injected currents from remote line terminals. To address this challenge, an innovative adaptive protection scheme that considers FR, changes in network topology, and injected current from the opposite end of the line is proposed. By estimating the equivalent circuit impedances (ECIs) of the network connected to the terminal of the TL, this protection scheme utilizes impedance estimation techniques at the line terminals and offline network information. Simulation studies (tested on the IEEE 39‐bus standard network) show that the proposed scheme accurately estimates fault location (FL) and FR with high precision. The simulation results demonstrate its effectiveness in improving the performance of conventional distance protection relays in both the first and second protection zones ( and ).

Identification of characteristics of conceptual prototype of microprocessor resource-saving relay protection system

The object of the study is the conceptual prototype of a microprocessor resource-saving relay protection system. Currently, relay protection ensures electrical networks reliable and efficient work, however, the traditional architecture is proprietary, not allowing to fix and replace damaged parts without a company specialist. Therefore, the open-architecture relay protection is a very pressing issue, but the problem lies in meeting the relay protection requirements. The data transmission protocols nRF and ESP-NOW, Hall sensors evaluation for AC current measurement determination and sensor accuracy improvement was implemented. Experimental validation demonstrated that nRF and ESP-NOW protocols meet the delay and reliability requirements, however, the nRF protocol is more suitable due to its flexibility and obstacle penetration. The data demonstrated that the most effective conditions are without obstacles at 15 meters from the modem and with obstacles 5 meters from the modem. The experiment of Hall sensors characteristics determination demonstrated the accuracy of current measurement with the set values of the opening and closing currents. Nevertheless, it is not accurate (12.45 %) for the relay protection application. Therefore, the application of the changing values of the opening and closing currents is more effective and accuracy reaches 6.92 %. As a result, the service life of the Hall sensor was determined, and even after 10 million openings, the open state time remained unchanged. Therefore, the approximation function for current amplitude determination depending on open state time was found. On the other hand, Hall sensors may suffer from temperature drift and require further optimization to be fully reliable. The study limitation is the current range from 0 to 800 A

Perancangan Time Synchronization Sebagai Alat Bantu Pengujian Intertrip Relay Distance

At the company PT. PLN (Persero) ULTG Madiun carried out many tests relay, one of which is intertrip testing relay distance. Intertrip testing relay distance is a test carried out between 2 (two) relay distance conducting bays in main substations that face each other. Intertrip testing relay distance must be done if replacement occursrelay, replacement of teleprotection equipment, changes to protection schemes, and changes to logic circuitsrelay which is related to the send or receive signal from the opposite substation. However, this test requires synchronization between two intertrip test tools relay distance at each substation. In this final project, it will be designed Time Syncronization As A Tool For Intertrip Relay Distance Testing, to make things easier for PT employees. PLN (Persero) ULTG Madiun when synchronizing two intertrip test equipment relay distance. All process control of this tool uses ESP32 Devkit V1. Meanwhile for displaying setting time for testing can be seen on the web assisted by GPS NEO-6M. The results obtained when testing the Dolopo by Ponorogo R and S phase distance intertrip relay were carried out at 12.00.00, experiencing a delay time of 0.0553 seconds when the PMT tripped. Meanwhile, the Dolopo by Ponorogo T phase distance intertrip relay test was carried out on 12.09.00 and experienced a delay of 0.0529 seconds when the PMT tripped. From two intertrip relay distance tests, the trip time delay is no more than 0.1 second.

A crucial remark on the importance of considering transient configurations on the optimal coordination of directional overcurrent relays in power systems with high penetration of inverter-based generation resources

A crucial remark on the importance of considering transient configurations on the optimal coordination of directional overcurrent relays in power systems with high penetration of inverter-based generation resources

Internal faults in stator winding of synchronous generator: Modelling, detecting and protecting

AbstractProtection of synchronous generators (SGs) against internal faults, such as stator earth fault (SEF) and turn‐to‐turn fault (TTF), is crucial for ensuring the stability and security of the power system. This paper presents a phase domain model for simulating SEF and TTF in SGs, requiring only nameplate data and avoiding the need for complex geometric data or lengthy simulations typical of FEM models. The stator winding is divided into three sections, allowing for the calculation of magnetic field distribution in both healthy and faulty conditions. The model is capable of simulating short‐circuit turns at various locations within the stator winding with high accuracy and speed. The dynamic response of the generator is also incorporated into the model. The model's accuracy is validated through comparison with results from multiphysics simulation software. Furthermore, this study addresses the limitations of conventional protection methods in detecting TTF and proposes a novel, simple, fast, and accurate protection logic that can be implemented in digital protection relays and is effective across a wide range of TTF scenarios.

Ensuring Stable Operation of Wind Farms Connected to Distribution Networks

Wind farms with type IV wind turbines from various manufacturers are being massively put into operation. These wind turbines comply with the requirements of the grid codes of the countries where they are designed and/or manufactured, but do not factor in the specific features of the distribution networks of other countries to which they are connected. The study at issue involves a comparative analysis of the requirements of grid codes of different countries for the stable operation of wind turbines under standard disturbances. The low voltage ride through (LVRT) characteristic makes it possible to prevent wind turbine shutdowns in case of short-term voltage dips of a given depth and duration. The calculations of transient processes indicate that wind turbines may not meet the requirements of the grid code of a particular country for their stable operation. As a result, standard disturbances will block the reactive current injection and the wind turbine will be switched off. This is often caused by the relay protection devices with a time delay of 1–2 s, which are used in distribution networks and implement the functions of long-range redundancy. Excessive shutdowns of wind turbines lead to emergency rises in the loads for the generating units of conventional power plants, aggravating the post-accident conditions and disconnecting consumers of electricity. This article presents a method for checking the LVRT characteristic settings for compliance with the technical requirements for wind turbines. To prevent wind turbine outages, one should either change the configuration of the LVRT characteristic, upgrade the relay protection devices in the distribution network adjacent to the wind farm, or implement group or individual technical solutions at the wind farm. The performance of the proposed technical solutions is confirmed by the calculations of transient processes.

A low-cost strategy for systematically removing DC short-circuit currents in AC/DC-HDN

For any practically applied AC/DC hybrid distribution network (AC/DC-HDN), the hard issue of removing DC short-circuit currents must be solved by a cost-effective scheme. However, up to now, in the most published achievements of AC/DC-HDN, the systematic scheme to address the above issue is rarely found. This paper proposes a novel strategy with a low cost for solving this problem. The proposed strategy can: (i) greatly decrease the DC short-circuit current components flowing from the AC/DC converters to the fault point, (ii) fast switch off the paths of DC short-circuit current components from DG branches to the fault point, (iii) completely block the DC short-circuit current components that feed into the fault point from the capacitors paralleled on the DC ports of load branches. Also, in this paper, a new topology of DC/DC converter with a controlled zero-current output function is proposed for fast switching off the paths of DC short-circuit current components from DG branches to the fault point. The scheme of relay protection and automatic control matching with the proposed strategy is designed. The principles of the scheme and design are explained in detail. The simulation results verified the effectiveness of the proposed strategy are given.

Joint optimal PMU and DULR placement in distribution network considering fault reconstruction and state estimation accuracy

Due to the rapid development of the distribution network, there is an urgent need for high-precision state estimation and safe and stable operation, this paper proposes a joint optimal placement method for Phasor Measurement Unit (PMU) and Dual Use Line Relay (DULR) in distribution networks considering fault reconstruction and state estimation accuracy. The proposed method aims to minimize the cost of PMU and DULR configuration. Based on the known pseudo-measurements and Supervisory Control and Data Acquisition (SCADA) measurements, we use the E-optimal standard design of the state estimation error covariance matrix to form the state estimation accuracy index and take the relay protection function of Feeder Terminal Unit (FTU) device and DULR device into consideration of the fault reconstruction. By solving the mixed integer semidefinite programming (MISDP) model, the optimal placement result is obtained, so that the network under normal condition and the network after multiple fault reconstruction can meet the constraints of state estimation accuracy and load loss rate respectively. The proposed method is tested on IEEE 33-node, 123-node systems as an example. The experimental results show that the proposed method is effective and practical.Note to Practitioners—This study is stimulated by the need for optimizing the placement of Micro-PMU (µPMU) in distribution network. Since the new µPMU device DULR has the same relay protection function as FTU, and distributed generation can supply power to the island after failure, this paper adds the load loss rate to the constraint conditions to study the influence of fault reconstruction on the placement scheme. A new two-step SE method considering mixed measurements was used in this paper to improve the computational efficiency of real-time SE of large-scale system while ensuring the accuracy of the calculation results. We have conducted tests in IEEE-33 and IEEE-123 systems. After preliminary verification, compared with the single fault scenario, we find that the placement scheme considering multiple fault scenarios can effectively improve the accuracy of state estimation and reduce the load loss rate of each fault scenario and only increase the cost a little. The increase in the number of DG and contact lines in the network will also effectively improve the feasibility of the placement scheme. The increase of the number of FTU configurations can effectively reduce the configuration of DULR by adding a small amount of µPMU, reduce the total cost as a result. In future studies, we will further consider the integrated configuration of µPMU, DULR and FTU, to meet more failure scenarios while reducing costs.

Retraction Note: Feeder segment switch-based relay protection for a multilayer differential defense-oriented distribution network

Retraction Note: Feeder segment switch-based relay protection for a multilayer differential defense-oriented distribution network

Combination of Implementation of Antiphase and Overcurrent Relays for Protection of 0.75 kW Three-Phase Induction Motor in Industry

Three-phase induction motors are the most widely used type of motor in industry. These motor operations are generally susceptible to unbalanced voltage disturbances. This interference is caused by the loss of one or two phases on the input side of the motor. This source voltage disturbance then causes an unbalanced current which flows to the coil, causing a phase shift, overheating the coil, and if left for a long time, it causes the motor to burn out. The research aims to design and implement a combination of antiphase relay (APR) and overcurrent relay (OCR) to prevent voltage drops due to failure of one or two phases and overcurrent to prevent overheating and fires in three-phase induction motor coils. Motor testing is carried out by adjusting the magnitude of the three-phase motor source voltage in three testing stages, i.e., tests A, B, and C, under no-fault conditions, 1-phase open and 2-phase open conditions respectively. The direct test results are then validated with ETAP simulations. In direct testing, A, B, and C can produce a current and relay working time of 6 A-31.04 s, 7.1 A-20.98 s, and 8.3 A-14.93, respectively. Meanwhile, testing using ETAP simulation can produce current and relay working times of 6A-31.366 s, 7A-20.599 s, and 8A-14.822 s respectively. The combination of an APR and an OCR can detect and interrupt voltage drops and overload currents in systems connected to 0.75 kW three-phase induction motors in the industry.

OUT–OF–STEP protection in rotating generation networks for hydrogen fuel production. Modeling conditions to test its algorithms

The testing of relay protection devices is an extremely important task on which the stable and safe operation of the power systems depends. One of the most complex and responsible kinds of protection in networks with rotating generation, which includes hydrogen fuel generation, is protection against loss-of-synchronism. Integration of heterogeneous generating electrical devices based on renewable energy sources and based on a hydrogen fuel cell is associated with the need for reliable relay protection. It disconnects tie-lines between the systems in out-of-step conditions. And it is a challenging task to simulate input signals corresponding to the exact settings of the out-of-step protection to make sure it operates correctly. This is because one has to simulate exact parameters of impedance locus (its radius, coordinates of the center in the impedance plane, spin direction, speed, etc.) while available tools embedded in testing devices often don’t support such parameters directly. To deal with the problem, the authors present the approach to simulate instantaneous values of line currents and phase-to-ground voltages during the out-of-step operation. These electrical signals form the locus of the impedance vector with the desired parameters to test the operation of the out-of-step protection devices. The software based on the proposed algorithm also provides a graphical representation of the simulation results. All the proposed solutions proved to reduce the time required for commissioning of out-of-step protection and thereby increase tests quality and speed.

Maintenance of RZA equipment according to technical condition

Subject of research: methods of maintenance and adjustment of relay protection and automation devices (RPA) in electrical power systems. Purpose of research: analysis of existing maintenance and adjustment methods, development of proposals for their optimization to increase the efficiency and reliability of electrical power systems. Methods of research: the research used methods of analysis of regulatory documents, survey of specialists and analysis of publications. Main results of research: identification of a lack of standardization of procedures, problems with personnel qualifications and the discrepancy of some devices with the declared characteristics. The findings highlight the need to develop unified approaches to maintenance and commissioning, as well as improve the professional training of specialists. The results of the study can be used to improve the practices of maintenance and adjustment of relay protection and automation systems, which helps to increase the reliability of electric power systems.

Resonance Suppression Method Based on Hybrid Damping Linear Active Disturbance Rejection Control for Multi-Parallel Converters

The parallel operation of multiple LCL-type converters will result in a deviation of the resonant frequency and resonance phenomena. The occurrence of harmonic resonance can cause problems such as an increase in harmonic voltage and current. This can lead to the malfunction of relay protection and automatic devices, causing damage to system equipment. In severe cases, it can cause accidents and threaten the safe operation of the power system. A hybrid damping active disturbance rejection control (HD-ADRC) method is proposed in this paper to suppress the harmonic resonance of parallel LCL-type converters. First, a third-order linear disturbance rejection controller (LADRC) including the linear extended-state observer and the error-feedback control rate is designed based on LCL-type converter model analysis. The proposed method considers the resonance couplings caused by both internal and external disturbances as the total disturbance, thus improving the anti-disturbance capabilities as well as the operational stability of converters in parallel. Then, a hybrid damping control is proposed to reconstruct the damping characteristics of converters to suppress the parallel resonance spike and reduce the resonance frequency offset. And the parameter selection of the control system is optimized through a stability analysis of the tracking performance and anti-disturbance performance of the HD-ADRC controller. Finally, all the theoretical considerations are verified by simulation and experimental results based on the Matlab/Simulink 2018B and dSpace platform. The simulation and experimental results show that the PI controller gives a THD of 5.33%, which is reduced to 4.66% by employing the HD-LADRC, indicating an improved decoupling between the converters working in parallel with the proposed control scheme.

Design and Development of Overcurrent Protection Relay Inverse Definite Minimum Time Type Based on Arduino Uno

An overcurrent protection relay is an essential component in electrical system to protect devices from damage due to excessive current. The Inverse Definite Minimum Time (IDMT) type has a trip time that depends on the magnitude of the overcurrent, with faster trip times for higher overcurrent levels. Arduino Uno can be used as a microcontroller platform to build an IDMT with relatively low cost and ease of implementation. This research aims to design and construct an Arduino Uno-based IDMT. The system consists of a current sensor, Arduino Uno, and a relay. The current sensor is used to detect the current flowing through the load. The Arduino Uno processes the data from the current sensor and determines if the current exceeds a predefined limit. If the current exceeds the limit, the Arduino Uno will activate the relay to cut off the current flow to the load. The IDMT trip time is implemented using an algorithm that considers the magnitude of the overcurrent and the minimum trip time. The system is tested using a simulator and actual load. Test results show that the Arduino Uno-based IDMT system works well and can protect the load from damage due to overcurrent.

Application of the percentage differential relay and stator earth fault protection in synchronous generators

Abstract Synchronous generators play a vital role in the power system. The relay protection distributed in the system can quickly remove the fault, effectively respond to it, and solve the problem. In this paper, the characteristics of a synchronous generator neutral ungrounded are analyzed when various unsymmetrical and symmetrical faults occur in the internal and external areas, and the percentage differential relay is used to solve the problem of short circuit faults. For the single line-to-ground fault, the stator earth fault protection is also introduced to compensate for the shortcomings of the generator neutral ungrounded. The simulation software MATLAB/Simulink is applied for modeling and analysis, and the strategy of composite protection solves the problem of unsymmetrical failure for the neutral point ungrounding generator.

Analysis of Relay Coordination in Electrical Distribution Networks with Optimally Positioned Distributed Generation Units

As power demand increases and transmission and distribution capacity is limited, Distributed Generation (DG) units are gradually being incorporated into electrical power distribution networks. However, this integration may result in a significant impact on the coordination of protective relays, potentially generating issues such as blindness of protection and false tripping of overcurrent relays. To overcome these issues, an adaptive protection method is presented that adjusts relay sensitivity in response to changes in network design. The suggested technique dynamically modifies relay settings based on the line current, which fluctuates depending on the system design. Digital relays are needed for this method in order to save operational data in real time. Based on periodic observations, the Plug Multiplier Setting (PMS) and Time Multiplier Setting (TMS) parameters are optimized using a Fuzzy Inference System (FIS). Fuzzy rules are used by the adaptive algorithm for every relay. These rules are produced using the fuzzy editor using the inputs provided. An initial investigation was carried out to evaluate the effect of DG on the coordination of relay protection., as well as the optimal placement of DG to reduce losses and improve voltage profiles, using two base distribution networks. The algorithm was further tested on various configurations of IEEE distribution networks, and its effectiveness in achieving optimal relay coordination with adaptive settings was validated through the relay coordination module in ETAP.

Adaptable Ground Fault Relay Protection for Neutral Grounding Resistor in Transformers and Generator: A Study in Indonesian Context

Adaptable Ground Fault Relay Protection for Neutral Grounding Resistor in Transformers and Generator: A Study in Indonesian Context

Performance Evaluation of Distance Relay Operation in Distribution Systems with Integrated Distributed Energy Resources

This article presents the evaluation of the performance of the distance relay (ANSI function 21) when integrating Distributed Energy Resources (DERs) in a Local Distribution System (LDS). The aim is to understand the impacts of and the necessary modifications required in the operation of distance relays, considering different levels of DER aggregation, and identifying any threshold levels before issues arise. To achieve this, first, a comprehensive review was carried out to analyze the impacts generated in the protection systems. Second, by using the DigSilent Power Factory software, the implementation of the distance relay using a IEEE 13 Node Test Feeder was validated. The aggregation of the three fundamental types of DG, synchronous machines, solar panels, and wind turbines, was evaluated. The threshold at which distributed generation power injection begins to compromise distance protection performance was identified. This study compares the outcomes of using mho and quadrilateral protection schemes.