Distribution System Protection Research Articles

Qualitative and Quantitative Evaluation of Overcurrent Protection in Active Distribution Systems

Greenhouse gas emissions are considered a global problem, which is why interest in implementing renewable distributed energy resources (DER) is increasing worldwide. However, despite the contributions to the reduction of fossil primary energy sources, the connection of DERs to power grids often gives rise to new problems in control, operation and protection systems that need to be analyzed and solved. The objective of this paper was to compare a conventional overcurrent protection scheme and several adaptive schemes for active distribution networks (ADN). The proposed methodology consisted of performing an analysis of the adaptive protection approaches for ADN. From this evaluation, the most relevant documents were classified according to the main requirements, contributions, and conclusions. Additionally, some of these proposals were tested with conventional overcurrent protection, using the ATP simulator and Python software. Finally, a quantitative and qualitative analysis of the proposed protection approaches was performed in order to identify limitations to be considered in future research work. The results obtained, when considering different faults and modes of operation of the DNA, showed that the conventional protection coordination approach is highly vulnerable to faults when DERs are connected, mainly due to the change in current magnitudes and direction. The adaptive schemes analyzed have adequate performance, however, several application issues need to be analyzed in the future.

A protection scheme based on conditional generative adversarial network and convolutional classifier for high impedance fault detection in distribution networks

• Combination of Conditional GAN with Convolutional classifier is proposed for fault detection. • Third Harmonic Angel (THA) of fault current is used as an effective feature. • Little amount of training data is used to train CGAN. • High performance of the CGAN in generation of pseudo-real data in large scale. Low level current and similarity of High Impedance Faults (HIF) in respect of characteristics to other transient events have posed a critical challenge to the protection of distribution systems. In addition, the dependency of previous methods on large amounts of training data increases the simulation error rate, and preparing this amount of data is time-consuming. In this paper, a novel scheme based on conditional generative adversarial network (CGAN) and convolutional neural network (CNN) classifier techniques is proposed, that reduces this dependency and leads to acceptable classification accuracy . In the proposed method, a small amount of data is extracted from the under-study network as the real data. Then, the third harmonic angle of the current is extracted from the real data by an adaptive linear neuron (ADALINE) as an effective feature. The CGAN is performed to produce a large amount of pseudo data. At last, the fault data is separated from other transient network events via the CNN classifier. Five different scenarios are used to evaluate the proposed method on a 13-bus IEEE network. The simulation results show that the Precision and Recall of distinguishing HIFs from other transient events is greater than 98% in all the scenarios. These results verify that the proposed scheme is very accurate despite the low dependency on input training data.

High speed protection of medium voltage DC distribution system using modified mathematical morphology

One of the challenging issues in the realization of medium-voltage DC (MVDC) distribution system is high-speed protection scheme design against quickly rising short circuit fault-DC current. This paper proposes a high-speed protection scheme based on the processing of energy signals through mathematical morphology (MM). The voltage and current signals measured at a distribution line section (DLS) are used to obtain the energy signal. The proposed scheme develops a modified MM-based filter to extract the transient information in the energy signal rapidly and distinctly in the form of positive/negative polarity. The polarity detection of any disturbance in the analysed energy signal indicates the occurrence of a sudden disturbance in the system. The sudden disturbance occurrence confirmation triggers the faulty DLS identification and classification algorithms of the proposed scheme. The faulty DLS identification and classification algorithms are based on the detected polarities of the energy signal. The protection scheme requires low bandwidth communication. The proposed protection scheme is evaluated by using a ±2.5 kV radial distribution network containing 4 feeders under different fault conditions in MATLAB/SIMULINK software. Simulation results verify that the proposed scheme can isolate the faulty portion within a few milliseconds after fault inception under a variety of fault cases.

Over current protection of distribution system with impact of solar and wind generation using DIgSIlent power factory

The utilization of renewable resources has been growing very fast worldwide recently to manage the increasing energy gap, but it also raises some challenges like protection issues, transient stability issues and security issues in the power system operation. Mainly, wind and solar photovoltaic renewable power generation sources are account for bulky renewable energy share. The transients in power systems including renewables are reduced and have recently attracted wide attention. The impact of renewables generation on power system transients should be effectively analyzed and evaluated to improve power system reliability, stability, operation and security. DIgSILENT Power Factory software is more powerful and useful for providing phasor of fundamental power frequency components better than other existing software’s; therefore, DIgSILENT Power Factory is proposed for modeling and analysis of the system.

A High-Impedance Fault Detection Method for Distribution Systems Based on Empirical Wavelet Transform and Differential Faulty Energy

High-impedance faults (HIFs) pose the greatest challenge for distribution system protection, especially for microgrids and distribution networks with distributed generators (DGs) that have flexible operation modes. This paper analyzes the faulty features of HIFs and proposes a HIF detection method that uses empirical wavelet transform (EWT) and differential faulty energy. The proposed method is as follows. First, the various time-frequency components are obtained by utilizing the EWT to decompose the differential faulty energy and adaptively select the feature component with the largest permutation entropy. Second, the permutation variance index is constructed based on the sample point number and feature component energy, and then it is employed to detect HIFs. Finally, low voltage microgrid simulation tests, medium voltage distribution system integrated by DG simulation tests, and field tests show that the proposed method can correctly distinguish HIFs from normal disturbances, including operation mode switches, load switches, capacitor switches, and DG switches. The advantages of the proposed method are also elaborated in detail, from signal preprocessing and feature extraction.

Increment of Fault Current due to integration of Distributed Generation and its impact on Distribution Network protection

One of the new technologies in generating power near the distribution system is called distributed generation which has supportive and destructive characteristics to the power system protection. One of the destructive characteristics of distributed generation is increasing the level of fault current to the protective equipment of the power system that affects the existing time intermission coordination of the protective overcurrent relay. In addition to increment of fault, it also alters the radial nature of the power distribution system and cause the power bidirectional rather than unidirectional. Integration of distributed generation to the distribution network causes increment of fault current effect, reliability drop, and affects security of protection system. The level of failure of protection be contingent on type, size, location and number of distributed generation. This fault current can cause a great damage to the electrical equipment with the miss operations of protective devices. The main aim of this paper is analysis of the fault current level to the protection of distribution network due to the integration of distributed generation which concerns on solar distributed generation, wind distributed generation and combination of solar and wind distributed generations at a time. This paper conducts the increment of fault current by the integration of distributed generation to the distribution system and its impact on distribution network protection. The analysis and the modeling are conducted on the 15KV distribution network of the radial feeder in Debre Markos town. This paper has covered the ling to ground, line to line and three phase fault analysis and their impact on the protection of distribution system for the wind and solar distributed generation types. After the integration of the distributed generation the fault current is increased by 0.529KA for three phase, 0.74KA for line to ground, 0.467KA for line to line and 0.523KA for line to line to ground. This paper confirms designing distribution network without forecasting the future demand of electric power users give the protection equipment additional requirement. As the result, the fault current after the integration of distributed generation to the distribution network have great value in terms of power system protection.

A Real-Time Simulation-Based Practical on Overcurrent Protection for Undergraduate Electrical Engineering Students

From prior studies, it is evident that computer-aided education can be beneficial in various ways. It has also been observed that class sizes are becoming larger in engineering disciplines as the importance of engineering education is realized more by the communities. Concurrently, in an outcome-based learning environment, practical classes have become more important to better facilitate student learning, preparing them to the relevant requirements of real-life tasks. This study aimed at developing a simulation-based practical for electrical engineering students with an improved educational process while addressing issues of large class sizes vis-à-vis expansion of physical laboratories and noted that it can be as effective as a traditional practical and accommodating large class sizes efficiently. In this tutorial paper, an industry-standard software is used to educate students on distribution system protection through a practical together with a standard assessment method with a model of feedback for evaluation. The paper contributes with an improved educational process through the practical in providing the students with experiences similar to industry work to meet the requirements of professional bodies and industries considering primary teaching and learning outcomes as the focus of outcome-based education system. Also, it delivers as a better platform for the students connecting lectures and practical sessions more effectively with the adopted methodology and approach. Further, it can provide the students exciting opportunity to best practice on systems that are highly related to industry applications in addition to encouraging them for advancing their education in the related niche areas of power systems protection.

Implementation of Human Electrocution Prevention Protection in Low-Voltage Distribution Systems with Declared Load of 12 Kva

Implementation of Human Electrocution Prevention Protection in Low-Voltage Distribution Systems with Declared Load of 12 Kva

Control of parameters of electrochemical protection of gas distribution systems against corrosion using wireless data transmission technology of short range

Control of parameters of electrochemical protection of gas distribution systems against corrosion using wireless data transmission technology of short range

Zonal Machine Learning-Based Protection for Distribution Systems

Adaptive protection is defined as a real-time system that can modify the protective actions according to the changes in the system condition. An adaptive protection system (APS) is conventionally coordinated through a central management system located at the distribution system substation. An APS depends significantly on the communication infrastructure to monitor the latest status of the electric power grid and send appropriate settings to all of the protection relays existing in the grid. This makes an APS highly vulnerable to communication system failures (e.g., broken communication links due to natural disasters as well as wide-range cyber-attacks). To this end, this paper presents the addition of local adaptive modular protection (LAMP) units to the protection system to guarantee its reliable operation under extreme events when the operation of the APS is compromised. LAMP units operate in parallel with the conventional APS. As a backup, if APS fails to operate because of an issue in the communication system, LAMP units can accommodate a reliable fault detection and location on behalf of the protection relay. The performance of the proposed APS is verified using IEEE 123 node test system.

Islanding Detection Strategy for Wind Farm Based on Performance Analysis of Passive Indices Having Negligible NDZ

Distributed generation (DG) resources integration into power system results in environmental and economic benefits. However, technical challenges may create many problems for the distribution system. Islanding detection is the topmost technical perspective regarding distribution system protection. This paper devised a passive islanding detection strategy that employed voltage phase angle (VPA). The VPA is selected after the performance assessment of 6 passive indices. Comparative study proves that VPA has the best accuracy and sensitivity compared to other indices parameters. The proposed technique is employed on a generic system that easily distinguished islanding situations from non-islanding cases such as load increment, load decrement, capacitor energization, capacitor de-energization, motor starting, motor unloading and various types of faults switching scenarios. The protective method is simple and has a quick interpretation algorithm as compared to other existing methods. The study is carried out on IEEE 1547 general test system in MATLAB/SIMULINK environment. The proposed strategy has nearly zero non-detection zone.

Integration Analysis of Electric Vehicle Charging Station Equipped with Solar Power Plant to Distribution Network and Protection System Design

The improvements and implementation of new generation equipment to the conventional grids are increasing along with the increase of the number of renewable energy power plants and smart grid components. The existing grid infrastructure is required to be modified and upgraded as a result of the increasing integration of the renewables and new generation consumers where the availability of the existing networks has to be analyzed for integration as well. In order to keep the grid stable and integrate the renewables to the grid optimally, necessary analyses have to be realized including the investigation of the optimal integration criteria. During the integration phase of the new generation consumers and producers, two ways power flows and variable power production of renewables have to be considered for system design. In this study, analysis for optimal sizing and integration studies are performed for electric vehicle parking lot and solar power plants located on the campus distribution network considering optimal sizing criteria and the aim of stabilization of voltage regulation during day time operation of solar power plant and random charging profile of electric vehicles. The proposed network is equipped with adaptive protection system to ensure stability and the reliability of the distribution network in the concept of smart grid.

Hybrid optimization algorithm applied to adaptive protection in distribution systems with distributed generation

The expansion of distributed generation (DG) to supply the energy demand is a reality in the modern electricity sector. However, it may cause changes in the load current and short-circuit current levels of feeders and transmission lines, among other undesirable impacts, which impair the coordination of protection schemes that were formerly designed for a radial configuration. This work proposes a method for optimizing the coordination of overcurrent relays based on computational intelligence techniques applied to adaptive protection in the context of DG. The proposed hybrid algorithm uses fuzzy logic to control the setting currents and genetic algorithms (GAs) to obtain the time dials and curves of the relay. In order to validate the proposed technique, a case study based on a 13-bus test distribution system is analyzed to compare the proposed method with two other protection methods widely known in the literature. ATPDraw software is used for the system simulation and MATLAB software allows implementing the protection algorithms. By using the proposed solution, it is possible to obtain a protection system with improved response with respect to the power system dynamics, thus enabling improvements in sensitivity and minimizing the trip times of the relays without violating the selectivity criteria.

Protection of Power Semiconductors in Inverters, using Fuses and their Coordination with the Protection Schemes of the Distribution System

The integration of Distributed Energy Resources (DER) implies an important challenge for the protection of the distribution network, due to the incorporation of devices with less capacity to withstand normal disturbances in distribution systems, particularly for overcurrents and overvoltages. The increasingly widespread use of power electronics, incorporated in rectifiers and inverters, which due to its weakness requires highspeed protection devices, complicates coordination with the traditional protection of distribution systems. Converters (rectifiers and inverters) require ultra-fast protection against high current faults, conditions that currently only meet high breaking capacity fuses. The response characteristics of these ultra-fast fuses, oblige the professional in charge of the protection of the distribution system to have a deep knowledge about the behavior of the power electronics in the face of overcurrents, and to know also how the fuses, through the selection of its rated values and characteristic curves protects it. Coordination of the rating values and characteristics of these fuses with their counterparts (when they exist) of traditional protection devices is the main objective of this article. Particular terms are explained in detail, such as fault current asymmetry and its effect on the coordination of protections, specific energy, etc. It is concluded that deep knowledge of the dissimilar characteristics of power electronics devices and the usual devices of distribution networks, with regard to their protections, are essential to obtain a maximum use of the traditional scheme with the addition of DER.

Cost-Effective Design of IoT-Based Smart Household Distribution System

The Internet of Things (IoT) plays an indispensable role in present-day household electricity management. Nevertheless, practical development of cost-effective intelligent condition monitoring, protection, and control techniques for household distribution systems is still a challenging task. This paper is taking one step forward into a practical implementation of such techniques by developing an IoT Smart Household Distribution Board (ISHDB) to monitor and control various household smart appliances. The main function of the developed ISHDB is collecting and storing voltage, current, and power data and presenting them in a user-friendly way. The performance of the developed system is investigated under various residential electrical loads of different energy consumption profiles. In this regard, an Arduino-based working prototype is employed to gather the collected data into the ThingSpeak cloud through a Wi-Fi medium. Blynk mobile application is also implemented to facilitate real-time monitoring by individual consumers. Microprocessor technology is adopted to automate the process, and reduce hardware size and cost. Experimental results show that the developed system can be used effectively for real-time home energy management. It can also be used to detect any abnormal performance of the electrical appliances in real-time through monitoring their individual current and voltage waveforms. A comparison of the developed system and other existing techniques reveals the superiority of the proposed method in terms of the implementation cost and execution time.

New Infeed Correction Methods for Distance Protection in Distribution Systems

The reliability and security of power systems may be jeopardized by the increase in the amounts of renewable generation and the uncertainties produced by these devices. In particular, the protection schemes of traditional power systems have been challenged by the integration of distributed generation (DG) resources. Distance relays (DRs), which have been mainly employed to protect transmission systems, are increasingly proposed as one of the solutions to protect distribution systems with a heavy penetration of DGs. However, conventional distance protection faces several drawbacks that might lead to maloperation. One of those challenges is the “infeed effect”, which causes the impedance seen by the distance relay to be larger than the actual positive-sequence line impedance between the fault and relay location. This paper proposes three new methods to estimate the distance to the fault in the presence of infeeds, whether in a radial distribution feeder or the transmission line. Unlike other solution methodologies in the literature that require communication links to estimate the distance to the fault, the proposed methods only need the local measurement (i.e., the voltage and current measurements at the location of the distance relay) to do the same. The performance of the method is demonstrated with a radial distribution system model in PSCAD™/EMTDC™.

Distribution system protection by coordinated DC Reactor Fault Current Limiters (DCRFCL)

One of the most serious issues that requires special attention is the protection of distribution networks. Using the proper protective equipment improves the safety of the power distribution network during fault conditions. Fault current limiter (FCL) is a type of modern preservation system used to protect power networks and equipment. The voltage restoration of buses during faulty conditions is one of the main concerns of power networks. A group of coordinated DC reactor type fault current limiters are designed and tested in this study to protect the network and restore its bus voltage during the fault period. The proposed FCLs coordination strategy is modelled and simulated in the MATLAB platform, and the results are validated.

Reducing multiple estimation for fault location in medium voltage distribution networks

Short circuits are a matter of major concern in the protection of power distribution systems. They can lead to interruptions in energy supply, and consequently affect the quality of power delivered to consumers. In these situations, there is a need to determine a fault location to ensure that a technical crew can reestablish the system as fast as possible. However, in radial distribution networks, fault location is not a trivial task, as the presence of lateral branches will result in multiple estimations. In this context, the present article addresses the problem of multiple estimation, considering the response of an impedance-based fault locator. To validate the proposed analytical approach, the IEEE 34-node test feeder was used. Moreover, the approach was analyzed in terms of: (a) the percentage reduction of the multiple estimation regions (R%); (b) the number of meters allocated in the feeder; and (c) the distance errors estimated by the fault locator. The results demonstrate that the proposed formulation allowed a minor influence of errors deriving from the impedance-based fault locator and a good trade-off between the number of meters (investment) and the R%.

An offline three-level protection coordination scheme for distribution systems considering transient stability of synchronous distributed generation

The growing penetration of synchronous distributed generation (SDG) affects the protection and stability of power distribution systems. The connection of SDG to distribution network may lead to change in the amplitude and direction of the current of feeders during the fault conditions and thus disturb the coordination of protection devices (PDs). On the other hand, the transient stability of SDGs as low-inertia machines after fault occurrence strictly depends on the fault clearing time which relies on the performance of the protection system. Therefore, an effective protection scheme should simultaneously consider both aspects of protection coordination of PDs and transient stability of SDGs. In this paper, an efficient and comprehensive offline three-level protection scheme is proposed to consider both protection coordination and transient stability indices. In the first level, the transient stability of SDGs is assessed in terms of critical clearing time (CCT) using offline simulations. In the second level, PDs are coordinated considering clearing time interval (CTI) of the main and backup PDs and CCT of SDGs. Finally, in the third level, the characteristic curves of PDs are modified if required by the transient stability of SDGs. The effectivity of the proposed method is demonstrated using the simulations on an active IEEE 33-bus distribution network in the ETAP software.

Protection philosophy for distribution grids with high penetration of distributed generation✰

Distributed Generation (DG) can cause several problems in electrical systems that are not prepared to deal with these new sources: situations such as bidirectional power flow and large variations in short-circuit current values. This article presents changes in the actual distribution systems protection philosophy that intend to make the protection system always work properly and reliably eliminate any short-circuit. Furthermore, it shows that the actual philosophy is inefficient in systems with high DG penetration level and, through modifications in the actual philosophy, using available functions in the protection devices, it is possible to increase the reliability and assertiveness of the protection system for any fault.