Distribution Network Protection Research Articles

A high speed and sensitive protection for distribution network with DGs using ferrite rings as line boundary

AbstractThere exist problems of hard coordination and threshold setting as well as low sensitivity in overcurrent relay due to the bidirectional and small fault current when distributed generators are integrated into the distribution network. This paper introduces ferrite rings (FRs) to act as boundaries of distribution feeders, and a peak time of voltage traveling wave‐based protection is proposed. The characteristics of FRs are analyzed and their feasibility as line boundary is validated. The fault characteristics of internal and external faults are analyzed when FRs are installed at both ends of the protected feeder. The results show that the peak time of the voltage travelling wave of the internal fault is far smaller than that of the external faults. According to the difference, the fault detection method and the protection scheme are proposed. Simulations in PSCAD and experiment validate that the proposed protection principle can reliably distinguish between internal and external faults. Besides, the proposed protection scheme has higher sensitivity compared to ROCOV‐based protection.

Differential protection scheme for distribution network with distributed generation based on improved feature mode decomposition and derivative dynamic time warping

With the progress of communication technology, the cost of optical fiber and 5G continues to decrease, and data transmission becomes more convenient and fast, making it possible to realize differential protection of distribution network by various intelligent algorithms using signal waveforms. Aiming at the problem that the traditional relay protection device can not meet the actual demand when the single-phase ground fault occurs in the distribution network with distributed generation, this paper proposes a new differential protection scheme. The characteristic mode decomposition improved by the whale optimization algorithm is used to decompose the zero-sequence current waveform collected at both ends of the line. Based on the basic principle of current differential protection, the derivative dynamic time warping of the component with the largest fault feature can effectively solve the problem that the grounding current of the distribution network cannot meet the working requirements of the differential protection device, and ensure the safe and stable operation of the system. Finally, based on MATLAB software, the performance of this method is comprehensively evaluated by simulating different fault conditions, so as to ensure the feasibility and accuracy of this method in the case of diversified faults when the distributed generation is used as part of the power supply.

Influence of distributed generation on fault characteristics and relay protection of rural distribution network

High proportion distributed generation affect traditional rural distribution network. In the paper, a typical line model of rural distribution network with high proportion distributed generation was constructed, and the current and voltage characteristics of rural distribution network after fault were analyzed. At the same time, the compound voltage blocking element and autoreclosure strategy of current protection of rural distribution network were analyzed. The results showed that the short circuit current at the protection location was lower than that without distributed generation, and the voltage of the whole line after the fault was higher than that without distributed generation. In addition, if the autoreclosure strategy of the circuit breaker at the head of the line adopts the non-voltage detection mode, it may cause failure of the breaker reclosing.

Reference Phasor-Based Data Self-Synchronization Scheme for Line Current Differential Protection in Active Distribution Networks

Reference Phasor-Based Data Self-Synchronization Scheme for Line Current Differential Protection in Active Distribution Networks

Pilot protection based on novel comprehensive impedance of positive sequence fault component for distribution network

The integration of distributed power sources into the distribution network has changed the topology of traditional distribution networks, resulting in changes in fault characteristics, and brought severe challenges to conventional current protection of distribution network. This article proposes a protection method based on the comprehensive impedance of a new positive sequence fault component. Analyze the fault characteristics of positive sequence fault voltage and current during faults inside and outside the line area connected to different types of distributed power sources. The positive sequence fault components of voltage and current at both ends of the section are used to calculate the estimated line impedances. A novel comprehensive impedance is obtained by their subtraction. The ratio of comprehensive impedance to line impedance is constructed. The protection criterion for short circuit fault is given. The simulation experiments illustrate the effectiveness of proposed protection algorithm, not affected by the fault types, locations, permeabilities of distributed generations, has strong ability to withstand transition resistance.

Research and application of automatic mapping method of distribution network protection power supply based on knowledge graph and graph convolution network

Abstract This study aims to propose an automatic mapping method for distribution network protection based on knowledge graph (KG) and graph convolution network technology and applies it to power system. The relationship between physical entities in power grid is established by constructing KG, and multisource data fusion and analysis are realized by using graph convolution network technology, so as to realize one-click and automatic mapping of power diagram in power supply places. The distinctiveness of this study lies in the incorporation of KG and deep learning techniques into the field of power supply assurance for distribution networks, achieving automated and digitized generation of power supply assurance device diagrams with real-time dynamic updates capability. This innovation significantly enhances the level of digitization and intelligence in power supply assurance work, injecting new vitality into the field of power supply assurance for distribution networks. This method can provide a digital comprehensive and intuitive presentation for the power supply service and effectively improve the ability to grasp the equipment situation and risk situation awareness.

Enhanced Fault Detection and Localization Strategy for High-Speed Protection in Medium-Voltage DC Distribution Networks Using Extended Kalman Filtering Algorithm

Enhanced Fault Detection and Localization Strategy for High-Speed Protection in Medium-Voltage DC Distribution Networks Using Extended Kalman Filtering Algorithm

Energy-based Directional Pilot Protection for Distribution Networks with IBDGs Considering Unmeasured Load Switching

Energy-based Directional Pilot Protection for Distribution Networks with IBDGs Considering Unmeasured Load Switching

Retracted: Application of Artificial Intelligence Algorithm in Relay Protection of Distribution Network

Retracted: Application of Artificial Intelligence Algorithm in Relay Protection of Distribution Network

Adaptability Analysis of Distribution Network Protection Technology Considering Distributed Photovoltaic Power Generation Access

The integration of distributed power sources into the distribution network has transformed the traditional radial topology structure of the distribution network into a multi-source structure, which can lead to a series of problems, such as voltage violations and bidirectional power flow in the lines. This situation presents a significant challenge to traditional distribution network protection technology. Therefore, based on the electrical characteristics of random loads and distributed power sources, the impact of distributed power source integration on fault characteristics and protection is analyzed, and the adaptability of different distribution network protection methods to distributed power source integration is evaluated. Key factors for improving the protection action characteristics of the distribution network are proposed.

Enhancing Resilience and Reliability of Active Distribution Networks through Accurate Fault Location and Novel Pilot Protection Method

The integration of distributed generation (DG) into the decentralized access of the distribution network transforms the existing structure into an active distribution network. The alteration in fault characteristics poses significant challenges to the coordinated operation of relay protection. Fault location within the distribution network plays a vital role in facilitating fault recovery and enhancing the resilience of the power system. It proves instrumental in improving the network’s ability to withstand extreme disasters, thereby enhancing the reliability of power distribution. Therefore, this paper provides a detailed analysis of the voltage fault components occurring during various fault types within an active distribution network. Building upon the identified characteristics of voltage fault components, a novel approach for the longitudinal protection of active distribution networks is proposed. This method involves comparing the calculated values of voltage fault components with their actual values. The proposed approach is applicable to various fault scenarios, including short-circuit faults, line break faults, and recurring faults. It exhibits advantages such as insensitivity to the penetration of distributed power supplies and robustness in withstanding transition resistance. The simulation results validate the effectiveness of the proposed method, affirming its applicability to diverse protection requirements within active distribution networks.

Modeling and studying the impact of dynamic reactive current limiting in grid-following inverters for distribution network protection

Modeling and studying the impact of dynamic reactive current limiting in grid-following inverters for distribution network protection

Weighted Minkowski distance-based differential protection for active distribution networks considering the uncertainty of frequency-domain characteristics

With the increasing use of DGs (distributed generators) in the power system, the distribution network is becoming more and more complicated. The rapid change of DG output power and the diversity of DG location make the computing calculation of relay protection difficult, bringing severe challenges to the current protection based on single-end electrical volume. Therefore, double-end-based protection is a good choice in view of the DG uncertainty and the network complexity. However, the power frequency offset after fault and the uncertainty of DG fault current result in uncertainty in the frequency-domain characteristics, which can also negatively affect the differential protection. In view of this, a new differential protection method based on the weighted Minkowski distance algorithm is proposed in this paper. First, the Minkowski distance algorithm is used to describe the similarity of both currents considering the uncertainty in the frequency-domain characteristics. Second, each current similarity including the phase current, the positive current, and the negative current is calculated separately to increase the protection sensitivity. Through the weighted algorithm distribution, the weight is assigned. Furthermore, a high-performance protection mechanism is designed to improve the protection sensitivity. This method is suitable for the active distribution network with different penetration rates of DGs and different types of DGs. The simulations show that the proposed method has good feasibility and high superiority.

A proposed fault identification-based fuzzy approach for active distribution networks with photovoltaic systems

Recently, the issue of protection in active distribution networks has been greater than before due to mushrooming use of photovoltaic (PV) generation units. PV systems coupled to power electronics devices and their control strategies causes significant changes to fault current characteristics leading to maloperation of fault identification schemes. Therefore, this paper proposes a robust self-adaptive fault identification scheme that incorporates the presence of PV systems and considers the effect of uncertainty arising due to their high penetration levels. The real-time voltage and current measurements are captured locally by advanced one-end measuring facilities, considering the uncertain temperature and irradiation conditions, of solar generation units. First, the proposed scheme employs wavelet transform, statistical alienation concept, and fuzzy logic to identify the fault criteria. Then, it uses fuzzy concept-based the system features to obtain the optimal protection scheme setting. For simulation analysis, a 10 MW solar farm-connected to a real-world active distribution system is emulated in PSCAD-EMTDC simulator to create intensive study cases, and the proposed scheme is implemented in MATLAB software. Several fault parameters are examined in the scheme comprising different fault types, fault locations, and transition resistances. Also, the uncertainty arising from PV plants and different loading conditions are taken full consideration in the developed scheme. Simulation results have verified the validity of fault identification scheme; nonetheless, the computational burden is kept reasonable. The proposed scheme is investigated under white gaussian and impulsive noise. Furthermore, sensitivity analysis and comparative study are conducted in terms of accuracy, high decision speed, and sampling frequency variation. The proposed scheme succeeds to detect and classify internal faults for both on/off-grid operation modes and differentiate them from external ones in the case of on-grid mode. The proposed scheme has dominance performance including high speed fault detection within, a half cycle, and provides accuracy more than 98 %.

A new method for single‐phase high resistance grounding fault protection in low resistance grounded distribution networks

AbstractThe neutral point of the distribution network is grounded with low resistance, which can quickly remove single‐phase grounding fault and effectively suppress overvoltage. However, the existing zero‐sequence overcurrent protection has a high setting value. In the case of large fault resistance and weak fault current, the existing protection methods may refuse to operate. Based on the waveform characteristics of the zero‐sequence current of each outgoing line in the distribution network, this article proposes a new method for single‐phase high resistance grounding fault protection in low resistance grounded distribution network, which combines cosine distance and improved K‐means algorithm. First, the cosine distance between zero‐sequence current of every two outgoing lines is obtained, and the cosine distance matrix used to describe the fault characteristics is constructed. Then the improved K‐means algorithm is used to cluster the row vectors of the cosine distance matrix to obtain the convergent cluster center and cluster label, so that the fault line can be determined. This protection method does not need to set the threshold value manually, and has strong ability to handle large fault resistance. It can effectively deal with noise interference and intermittent arc grounding fault, and still has good adaptability in scenarios such as change of fault initial phase angle, change of fault location, access of distributed generations and occurrence of two outgoing lines in phase to grounding fault. Finally, a model is built, and the effectiveness of the proposed method is proved by the simulation of grounding fault.

Phase-angle adaptive current differential protection for active distribution network

With the distributed generator to be attached to the distribution network, the current differential protection scheme may have some problems, resulting in maloperation or rejection of protection. This paper investigates the current distribution properties of an active distribution network with branches of undetected load and draws the conclusion that undetected load may cause differential protection maloperation. The differences in fault properties of differential protection in transmission network scenarios and distribution networks containing distributed generator are evaluated, leading to the conclusion that differential protection applied to active distribution networks may have reduced resistance to transition resistance and that poor signal synchronization conditions in distribution networks may lead to larger synchronization errors. A phase-angle adaptive current differential protection is proposed. It adaptively adjusts the phase angle constraint using the magnitude of the power frequency full current component proportion at both sides of the line. It can accommodate the protection needs of various operation modes of distribution networks containing distributed generator, and has the characteristics of strong resistance to transition resistance and strong phase shift braking ability. The correctness of the suggested protection scheme was verified using the PSCAD platform.

Optimal Protection Coordination of Active Distribution Networks Using Smart Selection of Short Circuit Voltage-Based Relay Characteristics

Much attention has been paid to the optimized protection of microgrids (MGs) and active distribution networks (ADNs). However, the literature shows a research gap in proposing a hybrid scheme, utilizing the voltage-based and overcurrent-based relays, while the voltage relay characteristics are smartly selected. This study aims to address such a research gap. This article presents an optimal hybrid protection coordination method for ADNs and MGs. Considering that any system fault is associated with a voltage drop, a new protection method is formulated from voltage analysis under fault conditions. The proposed method is independent of the type, size, and location of distributed generation (DG) units, as well as the operation of the distribution system connected to the grid. This method uses only the local voltage to determine the relay’s tripping time and is a low-cost protection method, in addition to the directional overcurrent relays (DOCRs). Optimizing the voltage-based relay characteristics is one of the most important contributions, which leads to improving the protection system speed and its selectivity concerns. The effectiveness of the proposed method has been verified by several simulation tests performed on the medium voltage (MV) distribution system under different fault conditions and DG size and location. The simulation results show that the protection method has appropriate speed, and the protection settings could be independent of the operation modes/topologies and the locations of faults. The comparative results illustrate the advantages of the proposed hybrid protective scheme.

K-Nearest neighbour based approach for the protection of distribution network with renewable energy integration

k-Nearest neighbour based approach for the protection of distribution network with renewable energy integration

Исследование алгоритмов работы дистанционной защиты в системах распределенной генерации

Current trends in the development of power supply systems for industrial facilities when applying the principles of distributed generation consist in the implementation of power supply from several power sources of different types and characteristics (photovoltaic cells, wind power plants, microturbine plants, diesel power plants), the maximum approximation of power sources to electrical loads, the use of electricity storage. The availability of such installations near consumers reduces the quantitative energy consumption by reducing the technical losses of the ge¬nerated energy and reducing dependence on fossil fuels. However, with these advantages, distri¬buted generation has created technical problems, one of which is the complication of relay protection systems due to the possibility of powering the damage point from different sides. This circumstance requires the development of new algorithms and protection schemes to ensure selectivity and to increase the sensitivity of relay protection. The purpose of the study is to analyze the algorithms of remote protection in distributed generation systems. The methods used comprise an integrated approach, including scientific analysis, processing and analysis of the results of theoretical and experimental studies in the field of relay protection of electrical complexes in networks with distributed generation. The results obtained present the analysis of various algorithms for the implementation of protection, which were implemented as proposals for distribution networks. The system of remote protection in networks containing distributed generation systems is presented, and the algorithms of operation are compared to increase the sensitivity of remote protection devices to the occurrence of various emergency modes: single-phase and three-phase short circuits. Several algorithms for increasing the sensitivity of remote protection for distribution networks in the presence of several power sources are considered. The comparison of these algorithms according to the criteria of the implementation cost, the accuracy of implementation, the number of necessary input data is also carried out. Practical significance of the research the research results can be used to take into account the effect of changes in the parameters of protected connections under conditions of electrical complexes operation in a network with distributed ge¬neration on the effectiveness of remote protection. They make it possible to increase the sensitivity and selectivity of the remote protection operation in case of emergency situations.

Analysis of distribution network planning with distributed power supply based on ELM algorithm

Abstract With the development of the social economy, the importance of energy and environmental issues is becoming more and more prominent. Distributed power sources (DG) have the advantages of low carbon and environmental protection, flexible control, and low investment cost, but their nodes in the grid are random, which will increase the complexity and uncertainty of grid operation after grid connection. In this paper, we study the planning path of DGs in distribution networks and the protection technologies involved. Firstly, we focus on the impact of DG access on the protection of distribution networks and the impact of different access capacities and access locations of DG on the protection of distribution networks. Second, after studying the current status of the application of traditional genetic algorithms in distribution network fault location, a two-layer planning model based on the modified extreme learning machine algorithm (MPSO-ELM) is proposed, with the load demand guaranteed by the first layer of power allocation and the fault location incorporated into the distribution network protection scheme in the second layer. Finally, simulations are performed to compare and demonstrate the advantages of this MPSO-ELM algorithm. The simulation results show that the MPSOELM algorithm converges faster than the traditional genetic algorithm by 7s, the average operating speed of power nodes is 3.61ms faster than the traditional genetic algorithm by 5.59ms, and the accuracy in fault location is improved by 23.14%. The simulation results verify the comprehensiveness, accuracy, and high efficiency of the ELM algorithm for double-layer planning of distribution networks containing distributed power supplies, which is important for improving the level of power grid construction and avoiding the risk of power grid construction.