Circuit Breaker Trip Research Articles

SF6 Dynamic Capacitance Measurement Methods for Breaks in the Breaking Process of Circuit Breakers

In order to effectively obtain the contact state without disassembling the interrupter chamber of the SF6 circuit breaker, a dynamic capacitance measurement method for the breakout process of the circuit breaker is proposed. The dynamic capacitance measurement is carried out by applying high-frequency excitation at both ends of the interrupter chamber, the dynamic capacitance measurement system that can meet the pF-level variation is designed, and the measurement method for correcting the stray capacitance of the wire is proposed. Based on the fundamental wave component method, a dynamic capacitance calculation method is proposed for the circuit breaker tripping process, and the optimal parameter combination for the dynamic capacitance calculation is determined through simulation analysis. The best combination of computational parameters for dynamic capacitance calculations was determined to be a triangular window, a window length of 480, and an overlap length of 0. The dynamic capacitance-travel curve of SF6 circuit breaker tripping process under different ablation states is obtained in the final test, and the results show that: with the increase in contact ablation, the overall shape of the dynamic capacitance-travel curve is basically unchanged, and the capacitance value at the starting point increases and the travel value decreases, which provides a new idea for the evaluation of circuit breaker interrupter chamber’s electric life. This provides a new idea for the electrical life assessment of circuit breaker interrupters.

PMSG-based wind farm high-voltage ride-through improvement for single-pole tripping of circuit breakers

For transient single phase-to-ground (SPG) faults in transmission lines, single-pole circuit breaker (SPCB) operation can improve system reliability. This issue is more critical in transmission lines emanating from wind farms (WFs). In the large-scale WFs, the grid codes necessitate that wind generation remains in operation during the transmission line faults. For this purpose, the grid codes focus on the development of fault-ride-through (FRT) requirements. In this paper, it is shown that after the SPCB operation, the terminal voltage of the permanent magnet synchronous generator (PMSG)-based wind turbine (WT) rapidly increases and may cross the high-voltage ride-through (HVRT) boundary. Therefore, the WT terminal overvoltage after the SPCB operation may result in undesirable tripping of the WT. The obtained results in this paper show that in most cases both the coupled and decoupled sequence controllers of the WT converter equipped with the FRT requirements are not able to improve the HVRT performance after the SPCB operation. To enhance the HVRT performance of PMSG-based wind turbines after the SPCB operation, a dc-link chopper controller is proposed. EMTP-RV simulation results on the IEEE 118-bus and 5-bus systems show the success and effectiveness of the proposed method.

Assessment of the Factors Affecting the National ICT Broadband Backbone (NICTBB) Systems Restoration Time

This study investigates the factors affecting the prolonged system restoration time when national ICT broadband backbone (NICTBB) services are affected by breakdown incidents. NICTBB is the government-owned backbone infrastructure constructed nationally by the Republic of Tanzania to increase the usage of ICT for equitable and sustainable socio-economic development and accelerate poverty reduction. This study utilised a mixture of exploratory and descriptive study approaches. The sample size determination was executed using purposing and simple random sampling, thus involving 289 respondents. The data reliability test was undertaken. It was followed by factor analysis, analysis of variances (ANOVA), linear regression analysis, and confirmed with confirmatory factor analysis (CFA) using IBM SPSS Amos 28 to test the model fitness. The study revealed that the maintenance centres are few and sparsely located, and the distance from maintenance centres increases travelling time, resulting in increased time to restore services. Some factors affecting the restoration time include initial infrastructure design not trenching to locate points of cut, absence of dedicated vehicles standby for NICTBB restoration, retirements of experienced and well-trained staff leaving behind untrained personnel for maintenance activities, and insufficient funds for maintenance. Lastly, power equipment is not looked upon as sometimes the services are down due to commercial power cuts, tripped circuit breakers, and batteries not being charged. Some recommendations include having proper maintenance processes, having enough restoration resources at all maintenance centres, and maintaining proper communication.

Reliability Evaluation of Cabled Active Distribution Network Considering Multiple Devices—A Generalized MILP Model

With the rapid development of power electronic equipment, the automation and intelligence level of active distribution networks (ADNs) continues to improve. Against this background, soft open points (SOPs) are gradually replacing traditional segmented switches and interconnection switches. The voltage support capability and fast response characteristics of SOPs can shorten power outage time and expand load recovery range. However, the widespread integration of distributed renewable energy and new power electronic devices has made the fault characteristics of ADNs more complex, significantly increasing the computational complexity of ADN reliability assessment. At present, there are few studies that comprehensively consider ADNs with multiple devices. Therefore, this paper proposes a reliability evaluation method for ADNs that considers multiple devices. Firstly, the impact of circuit breakers, SOPs, and segmented switches on the load recovery process is analyzed. Secondly, an improved virtual fault flow model based on the action mechanisms of circuit breakers, SOPs, and segmented switches is established. The virtual fault flow is represented by logical variables to simulate post fault network reconstruction strategies that include circuit breaker tripping, SOP power supply recovery, and segmented switch isolation actions. Then, with the goal of minimizing the system average outage time after network reconstruction, a generalized mixed integer linear programming (MILP) model is given. Finally, taking the IEEE 33-node testing system as a case, the effectiveness and feasibility of the proposed method are demonstrated.

Overvoltage Suppression and Energy Balancing for Sequential Tripping of Hybrid DC Circuit Breakers

During sequential tripping of dc hybrid circuit breakers (HCBs), the energy-absorbing metal-oxide varistors (MOVs) are inserted one after the other rather than simultaneously. This tripping scheme has been demonstrated to be effective in reducing the peak fault current and fault interruption time. However, the voltage overshoots during the sequential tripping process need to be suppressed and the fault energy among the MOVs needs to be balanced. Therefore, this paper proposes (i) a simple overvoltage suppression method and (ii) a modified sequential tripping algorithm for HCBs. The former method is realized by increasing the turn-off gate resistance of the semiconductor devices, for which an analytical expression relating the HCB peak overvoltage and the semiconductor switch's gate resistance is provided. The latter algorithm is able to evenly distribute the MOV energy absorption under different grid conditions with the least number of switching events via a predefined tripping scheme and an energy feedback loop. Verification results from both time-domain simulation and a 1.2 kV circuit breaker hardware corroborate the efficacies of the proposed strategies, which will improve the performance of the sequentially tripped HCBs.

A Method and an Algorithm for Implementing Relay Protection of 6(20)/0.4 kV Step-down Transformer Substations

The article discusses a method and an algorithm for implementing the protection system for a 6(20)/0.4 kV transformer substation, using which its reliable operation is secured regardless of the grid configuration and operation mode and the operation parameters of higher-level electrical installations. The proposed method makes it possible to clear any fault in the 0.4 kV network with minimal time delays. To this end, it is necessary to supplement the 0.4 kV network with current transformers (if they are not available) and forward the algorithm control output to the circuit breaker tripping coils. To ensure short-range backup protection, the circuit breakers protective functions remain in operation. Based on the existing electrical network, the approximate pickup parameters of the proposed method are pointed out, and recommendations for their optimization are given. Various contingencies in the 0.4 kV electrical network are considered to verify the correct functioning of the proposed relay protection method and algorithm.

Integration of Local and Central Control Empowers Cooperation among Prosumers and Distributors towards Safe, Efficient, and Cost-Effective Operation of Microgrids

The advent of energy communities will revolutionize the energy market. However, exploiting their full potential requires innovations in the structure and management of low-voltage grids. End users shall be aggregated within microgrids, where their physical interaction is possible and coordinated operation of power sources and energy storage systems can be achieved. Moreover, meshed network topologies will enable multiple paths for the power flow. The combination of smart control and meshed networks can dramatically improve microgrid performance in terms of power quality, efficiency, and resilience to transients and faults. Ubiquitous control of the power flow becomes possible, as well as active fault clearing and isolation of subgrids without tripping circuit breakers. This paper proposes a control approach that pursues such goals without requiring modification of control and communication hardware implemented in commercial inverters. Instead, a revision of control firmware, integrated with local measurements, allows retrofitting existing plants to improve microgrid operation. Further improvements may derive from the installation of community power sources and energy storage systems, which can extend microgrid operation to pursue demand response and islanding. The potential of the proposed control methods is demonstrated by simulation considering a standard microgrid under different operating conditions.

Study on switching overvoltage characteristics of VSC-HVDC grid with multiple topology

VSC-HVDC grid with multiple topology technology has broad application prospects in new energy grid connection. However, due to the various topologies, the overvoltage characteristics of DC line are quite different from the terminal-to-terminal DC systems. Based on the seven-terminal power grid of Zhangbei VSC-HVDC project in long-term planning and by combining theoretical analysis and simulation calculation methods, switching overvoltage characteristics of flexible MTDC grids with various topologies have been researched in this paper. The overvoltage amplitude generated on the fault line of the DC grid by DC circuit breaker tripping and clearing fault is relatively high. And, in the closed-loop topology, the overvoltage amplitude is lower than that in the open-loop topology. The overvoltage amplitude decreases when adding branch line. The overvoltage generated on fault-free pole line by single-pole grounding fault is less affected by the topology, and the overvoltage level of each line is not much different. In general, after the DC line is formed into a network, the switching overvoltage of DC line is lower and the distribution tends to be uniform, which is beneficial to insulation coordination of the DC line.

Backup protection method based on multi-interval information in low voltage distribution network of high proportion of renewable energy system

With the large number of renewable energy power sources such as wind power and photovoltaic power connected to the grid, the power system is becoming more electronic. The fault characteristics of renewable energy power sources and synchronous generators are obviously different, mainly manifested as the characteristics of short circuit current amplitude limitation and frequency offset, etc. The traditional protection based on the fault characteristics of synchronous generators may have adaptability problems. For a high proportion of renewable energy system, the short circuit current in the low voltage distribution network is greatly affected by the operation state of the renewable energy power sources after the short circuit fault occurs, which leads to the difficulty of the traditional three-stage overcurrent protection setting and coordination. In order to ensure the safe and stable operation of the system, this paper proposes a new backup protection method for low voltage distribution network. This method uses the information of the electric parameters on the high voltage side and low voltage side of the transformer. Firstly, the modulus sum of the voltage sampling value, the equivalent distance between the fault point and the protection installation place, and the modulus sum of the current sampling value are calculated. Secondly, the direction is judged by the criterion of the voltage direction element and the criterion of the distance protection element based on the multi-interval information. Finally, the maximum current branch of the low voltage distribution network is selected as the fault branch by the overcurrent element based on multi-interval information, so as to trigger the circuit breaker trip and isolate the fault. The low voltage distribution network model of the high proportion of renewable energy system is built on the PSCAD/EMTDC electromagnetic simulation platform. The simulation results show that the proposed protection method can reliably achieve fault removal by using multi-interval information, and has strong adaptability to the high proportion of renewable energy system.

Fault identification of high voltage circuit breaker trip mechanism based on PSR and SVM

AbstractThe trip mechanism is a weakness in circuit breakers. Traditional fault identification based on the coil current is difficult to report early mechanical defects such as coil‐plunger jam. Here, the vibration signal during the trip process was extracted. Based on the coil current signal and vibration signal, the characteristics of the trip mechanism are analyzed. The phase space reconstruction (PSR) method is used to extract features from the vibration signal. Combined with the features from the coil current waveform, the feature set representing the health condition of the trip mechanism is proposed. The fault simulation tests are carried out and the variation of current vibration characteristics under fault conditions is studied. The fault identification model based on a support vector machine (SVM) is proposed and compared with the identification results when features are extracted from a single signal. When the power supply voltage is dispersed, the prediction accuracy of fault identification is 83.3% considering only the features of the current waveform or vibration signal. And the identification accuracy rises to 96.7% while using the feature set of current and vibration signals. On basis of the current signal, the method further combines the vibration signal so that the robustness of defect identification improves.

Transients Caused by Sequential Circuit Breaker Tripping Issued by Busbar Protection

A study of transients in a high voltage substation 400/110 kV is presented in the paper. An analysis was carried out after a fault on the 110 kV busbar, which caused severe damage in the substation. Investigation was focused on a time frame of several sequential circuit breaker trippings. A first step of the study was collection of data from the primary and secondary system in the substation and the control centre. After numerous analyses of data an attempt was made to construct a precision model, which could be used in the computation. Appropriate models were developed for circuit breakers, voltage (potential) and current metering transformers, power transformers, surge arresters, overhead lines and an equivalent grid. The components of the power system can be modelled for the very particular purpose, which means that a different frequency model should be used and each element in this analysis has a specific frequency response. An attempt was made at very detailed modelling of a power transformer, air blast and SF6 circuit breakers. Computed results of fault currents were compared with measurements captured by the disturbance recorders in the field, mainly in differential numerical relays. Different switching schemes and different tripping sequences of several 110 kV circuit breakers were analysed with a constructed model in the millisecond range. Models of circuit breaker with different types of media, air blast and SF6 gas were used in the cases investigated. Modelling of the circuit breakers’ electrical arc was an important item in all cases in order to take into account the interaction between electrical arc and circuit current during the process of current interruption. The Schwarz/Avdonin equation is applied to model the dynamic behaviour of an electric arc. The fault studied was accompanied by a large short circuit current. For this particular case two types of circuit breaker, air blast and SF 6 were modelled. An important conclusion from those analyses was that sequential tripping of several circuit breakers does not cause superposition of overvoltages, because interruption the current happens when it is passing through the zero. Even the record from the substation and the disturbances recorder proves that each particular circuit breaker was successfully opened. On that basis, focus was put only on the final opening of the breaker and its arc extinction. The conclusion can be drawn that such a substation fault should have no influence on excessive overvoltages that can threaten the insulation of components in the substation.

Modeling and fault diagnosis of distribution networks cyber physical system based on IEC61850

In order to improve the fault tolerance and solution efficiency of power grid fault diagnosis model, a distribution network cyber physical system (CPS) fault diagnosis model based on advanced digital power system simulator (ADPSS) and IEC61850 is proposed. Firstly, the action rules and action status of CPS fault mode of distribution network from the whole correlation of fault element, protection action and circuit breaker trip, and the CPS grid topology of distribution network is constructed in ADPSS based on the topology and component characteristics of system. Secondly, according to the IEC61850 unified information model and modeling rules for the protection function of system equipment and operation function of circuit breaker, an information model with alarm, measurement, protection and fault recording logic is established. Then, the action status is obtained and used for the establishment of the distribution network fault diagnosis model by parsing the GOOSE message. Finally, the proposed modeling method and fault diagnosis strategy is validated through the test case.

Line to line DC fault protection strategy of AC/DC hybrid transmission system containing MMC-HVDC

In order to further analyze the fault characteristics of AC/DC hybrid transmission system containing MMC-HVDC,Based on the topology of AC/DC hybrid transmission system and modular multilevel converter(MMC), the mathematical model of MMC is derived ,The fault mechanism and characteristics of line to line DC fault are studied.Aiming at line to line DC fault of AC-DC hybrid transmission system with MMC-HVDC, a fault protection scheme combining current limiting circuit, locked-converter station and AC circuit breaker trip is designed.Based on Xiamen MMC-HVDC project,AC-DC hybrid system is built in PSCAD/EMTDC, and the protection scheme is simulated and verified.The results show that the proposed protection strategy can effectively reduce the fault current and improve the stability of the system.

Optimization of Substation Alarm Information Processing Based on BP Neural Network

When a fault occurs in the power grid, a large number of alarm messages will come out. In order to reduce the damage caused by power outages, the staff should find out the location and type of faults as soon as possible based on the alarm messages uploaded from the control center. However, we are currently facing problems in handling these alarm messages such as reliability of protection actions and circuit breaker tripping, correctness of received alarm messages, and the possibility of the existence of unreceived alarm messages. The fault tolerance of the BP neural network is studied in this paper, and the fault tolerance of the network corresponds to the size of the fuzzy zone formed by the test samples. The fault tolerance of the network is improved by eliminating the fuzzy zone, and a hierarchical causal rule reasoning network with a structure of four layers is established for each element in the station. An accessible path for the candidate cause of the fault is divided into two stages as follows: from the candidate cause to the protection operation and from the protection operation to the circuit breaker trip, which are assigned different credibility contribution rates. At the same time, the artificial bee colony algorithm is combined to identify the operation mode of the substation using its reasoning and judgment capacity and make the necessary corrections to get some output results of the neural network. The results of the examples suggest that the proposed evaluation method has a small workload of calculation and can identify the faulty components with high reliability and their causes, quickly and accurately.

Early fault identification for operating circuit breaker based on classifier model system

One of the most important switchgear in a substation is the circuit breaker (CB); it is used either in the transmission or distribution sections. Currently, the maintenance of a CB is done by capturing the trip time using a handheld device; the trip time is the time from trip initiation to the moment of current flow cessation in the load side of the CB. For the maintenance staff of the Iraqi National Power Board (INPB), their decision is mainly aimed to pinpoint the specific problem of the CB, the breaker parameters, such as latch, buffer, mcon, acon, and end which can be analysed using data mining methods such as K-means clustering and Sammon mapping (KCSM). The advantages of this approach include early identification of faults and saving more cost and time of repairing and replacing damaged CBs as the number of damaged CBs can be decreased. The problem with this method is the prolonged time of testing the conventional trip as it requires removing the CBs from service and planned outage. Furthermore, the CB may not capture the crucial information that causes slow tripping. Hence, the main objectives of this work are to analyse CB trip coil current data and study the effect and relationship between two different analytical approaches to analyse the data. The result of this technique showed excellent identification of the switch faults.

Data-Driven Anomaly Detection and Event Log Profiling of SCADA Alarms

Network human operators’ decision-making during grid outages requires significant attention and the ability to perceive real-time feedback from multiple information sources to minimize the number of control actions required to restore service, while maintaining the system and people safety. Data-driven event and alarm management have the potential to reduce human operator cognitive burden. However, the high complexity of events, the data semantics, and the large variety of equipment and technologies are key barriers for the application of artificial intelligence (ai) to raw scada data. In this context, this paper proposes a methodology to convert a large volume of alarm events into data mining terminology, creating the conditions for the application of modern ai techniques to alarm data. Moreover, this work also proposes two novel data-driven applications based on scada data: (i) identification of anomalous behaviors regarding the performance of the protection relays of primary substations, during circuit breaker tripping alarms in hv and mv lines; (ii) unsupervised learning to cluster similar events in hv line panels, classify new event logs based on the obtained clusters and membership grade with a control parameter that helps to identify rare events. Important aspects associated with data handling and pre-processing are also covered. The results for real data from a dso showed: (i) that the proposed method can detect unexpected relay pickup events, e.g., one substation with nearly 41% of the circuit breaker alarms had a ’atypical’ event in their context (revealed an overlooked problem on the electrification of a protection relay); (ii) capability to automatically detect and group issues into specific clusters, e.g., SF6 low-pressure alarms and blocks with abnormal profiles caused by event time-delay problems.

Prospects of regenerative current breaking in DC circuit breaker topology

Due to the stunning advancement of power electronics, DC power system is getting immense attention in the field of research. Protection and hereafter the protective devices for the DC power system application are two vital areas that need to be explored and developed further. Designing a protective device such as DC circuit breaker possesses a lot of challenges. The main challenge is to interrupt a current which does not have a natural zero crossing like AC current has. In addition, energy is stored in the network inductances during normal operation. Instantaneous current breaking is opposed by this stored energy during circuit breaker tripping, hence, all the DC circuit breaker topologies proposed in literature use snubber network, nonlinear resistor to dissipate this stored energy as heat during the current breaking operation. However, it is possible to store this energy momentarily and reuse it later by developing an improvised topology. In this paper, the prospects of energy recovery and reuse in a DC circuit breaker was studied and a new topology with regenerative current breaking capability had been proposed. This new topology can feed the stored energy of the network back into the same network after breaking the current and thus can improve the overall system efficiency.

Research on optimal reclosing time of AC/DC hybrid system based on dynamic energy

A method to calculate the optimal reclosing time of AC/DC hybrid system based on dynamic energy is proposed. First, in the whole fault process starting from fault initiation to accelerated tripping of circuit breakers after reclosing, the dynamic energy function that characterizes the stability degree of system is built. On this basis, the variation rate of dynamic energy is defined as the energy accumulation speed, which quantitatively characterizes the accumulation or consumption of dynamic energy in the fault duration. And detailed expressions of energy accumulation speed when single-phase fault and three-phase fault occur in the system are derived respectively. Then, with the accumulated dynamic energy of system being the minimum as the objective, the optimal reclosing time is searched, and the pattern in which the trajectory of operating points passes new equilibrium point when the system is reclosed at the optimal reclosing time is revealed. Finally, hardware-in-the-loop tests are conducted in RT-LAB for simulation verification. Simulation results demonstrate that, as reclosing time varies, total accumulated dynamic energy of system has multiple minimum points. Selecting the reclosing time calculated according to the method can improve stability of system.

Three zone detection and distance relay co-ordination of power system protection

To secure the transmission lines against power system faults, the distance relays are mostly used. Distance relay has its own Resistance (R)–Reactance (X) characteristics. Co-ordination of different distance relays is necessary for the fast operation of circuit breaker. Various distance relays which are being tripped with respect to circuit breakers which are attached at individual buses faraway from each other. These relays will be operated with respect to the distance between the occurred fault and relay location. In this paper, detection of three zones using relay characteristics, co-ordination of distance relays and circuit breakers are shown with the faults placed at different locations of an IEEE Nine bus system using MATLAB/Simulink GUI environment. A comparison also made between the relays performance and circuit breaker tripping operation with respect to severe faults at different locations on IEEE Nine bus system.

Fault Location Scheme for Cross-Country Faults in Dual-Circuit Line Using Optimized Regression Tree

In the double-circuit transmission line (DCTL), location of cross-country faults (CCFs) is more wearisome due to its intricate nature. The CCFs can occur at miscellaneous locations on dissimilar phases at the same fault inception time. Furthermore, the CCFs encompasses different fault locations which can mislead the line patrolling team and not only takes long hours to attend the fault location. Therefore, this may also cause electrical stress on the various power system components owing to tripping of circuit breaker repeatedly because of inappropriate fault clearance. In this context, an ensemble of regression tree (ERT) model-based fault location scheme is proposed using different regression trees such as Bagged Regression Trees (BGRT) and Boosted Regression Trees (BSRT). These regression tree modules have been trained with optimized hyper-parameters such as minimum leaf size, leaning cycles, and learning rate by using Bayesian optimization. A 400 kV, 50 Hz Chhattisgarh state power system (CSPS) network has been designed and simulated in MATLAB/Simulink to implement the proposed fault location scheme. Exclusive datasets have been designed at atypical fault scenarios thereby applying an exploratory signal processing technique such as Discrete Wavelet Transform (DWT). Additionally, the performance assessment has been done by comparing different error metrics. The simulation results reveal the applicability of the proposed ensemble regression tree (ERT) model for location of CCFs and it gives a research insight to adapt the same in the real power system network.