Power Supply Restoration Research Articles

Resolution and Analysis of Transmission Line Fault Types Based on Recording Type Data and Deep Learning

The reliable identification of fault types in transmission lines is essential for restoring power supply swiftly and minimizing economic losses during outages, thereby ensuring the safe and efficient functioning of the power system. This paper addresses the challenge of low recognition accuracy in existing transmission line fault diagnosis methods and presents a novel approach based on fault recording data collected from both ends of the line. This method distinguishes between lightning-strike and non-lightning-strike faults, utilizing a deep learning network architecture to analyze time-domain information from recorded data, using the initial and terminal waveforms as inputs. The proposed fault identification model integrates fault current phase mode transformation, Local Mean Decomposition (LMD) decomposition, and spectral entropy analysis, applying deep learning principles to enhance fault detection precision. This comprehensive approach enables the effective identification of various fault types on transmission lines. Extensive simulation tests were conducted using a sophisticated fault simulation model developed within simulation software to validate the proposed algorithm’s efficacy. The results demonstrate the algorithm’s high accuracy and efficiency in recognizing various fault types on transmission lines.

Unmanned Aerial Vehicle Based Power Pole Localization Using Image Stitching

When facing natural disasters, power transmission and distribution towers are prone to tilting, collapsing, and other situations, which can easily lead to line faults and subsequently cause power outage incidents. In order to quickly and accurately locate abnormal towers and restore power supply promptly, the power maintenance department typically employs unmanned aerial vehicles (UAVs) for post-disaster inspections of power line towers. Traditional methods for UAV ground target localization mainly rely on the UAV’s own position, attitude, and onboard sensor information to indirectly calculate the target’s position. This method is influenced by the Global Positioning System (GPS) and Inertial Navigation System (INS), relying on high-precision sensors. To achieve precise positioning of power line towers with simplified equipment on UAVs, this paper proposes a visual passive localization method based on ground control points. Addressing the sparse distribution of ground control points, a solution based on image stitching is introduced to overcome difficulties in localization caused by insufficient ground control points.

МЕТОДЫ ОПРЕДЕЛЕНИЯ КОЛИЧЕСТВА И СОСТАВА РЕМОНТНЫХ БРИГАД ПРИ ВОССТАНОВЛЕНИИ ТЕХНИКИ

Energy resources (ES) that are part of the machine and tractor fleet, agricultural enterprise (Agricultural Enterprise), subject to intensive use, constantly need to maintain their working condition. The main problems of maintenance and repair of electrical systems and methods for solving them have been identified. A scheme for planning repairs at agricultural storage facilities has been determined. In conditions of limited time, medium and major repairs are proposed to be carried out by reassembly or by the aggregate-sectional method. It has been established that the main technical characteristics of the quality of repair bodies are the following indicators: the complexity of performing a certain type of repair on a given type of electrical system; repair cycle; repair intensity; working time fund. They are determined analytically and make it possible to evaluate the quality characteristics of repair bodies, determine the number and composition of repair teams at the enterprise, the list of repair work, etc. The norms for time expenditure (labor intensity) for performing each individual repair operation, which are also the norms for the production of repairmen, are determined in the process of repairing equipment by timing. When statistically processing the results of timing the time of repair work, the estimated norms of labor costs for individual types of work and the total costs of performing current, medium and major repairs for each type of electrical system are determined. Then the following is determined: lists of necessary equipment, instrumentation, equipment, tools and spare parts; technology of repair work; the required number of repair teams, workshops, workshops, sites, work areas and repair specialists; duration of the repair cycle; production standards for repair specialists; intensity of repairs; list of specialties, qualification level and productivity of each repairman. The implementation of theoretically based methods for determining the number and composition of repair teams when restoring power supply systems will expand the capabilities of the enterprise's repair bodies to restore equipment with faults of various types.

Power supply restoration strategy of distribution system considering load demand response

The fluctuation of new energy output decreases distribution system reliability and increases the risk of a power outage. Based on this, considering the participation of new energy sources, the influence of load participation demand response on the distribution system is analyzed, the load demand response model is established, and the corresponding unit capacity compensation cost model is proposed. Considering the recovery income, operation cost, demand response compensation cost, and risk, a bi-level optimization model is established to solve the maximum recovery net income of the system. The upper layer aims at maximizing the expected net recovery income of the entire distribution system and proposes a distribution system partition scheme that takes into account the participation of new energy sources and mobile sources. The lower layer aims at maximizing the net recovery income of each partition and solves the recovery time and recovery amount of the load in each partition or the response time and response amount of the load participating in demand response under the condition of limited resources. Finally, the effectiveness of the power supply recovery optimization strategy of the distribution system proposed in this paper is verified by an example.

Assessment of topological boundaries for microgrids in an active power distribution network during emergencies

Microgrid (MG) operation has become an intriguing possibility to enhance the sustainability, reliability, and resilience of electricity distribution systems in emergencies. However, identifying suitable physical boundaries of MGs from an active power delivery infrastructure is a highly challenging task. This study describes a novel approach for determining the topological boundary of multiple MGs to restore power supply in a power distribution system during the unavailability of grid power supply. This method tries to enhance the self-adequacy of the MGs by increasing power flow within the MG boundaries. In this context, possible demand at the nodes of the power delivery infrastructure during an emergency is anticipated by an autoregressive integrated moving average (ARIMA) and long short-term memory (LSTM) network-based time series forecast models. A modified backward-forward sweep (MBFS) power flow analysis, tailored for islanded mode, is employed to assess the power flow status in the MGs during emergencies. The MGs are supplied with locally available dispatchable distributed generators (DDGs). A particle swarm optimization (PSO) algorithm intertwined with the MBFS power flow method has been employed to determine the boundary of MGs by identifying minimum power flow line in the shortest path between the consecutive DDGs. Further, this study demonstrates the evaluation of the shortest path between paths between the consecutive DDGs with the help of a breadth-first search (BFS) algorithm. The proposed strategy has been tested on a modified 33-bus, 69-bus and 118-bus power distribution test systems. The experimented results are verified with the results obtained from similar existing approaches to explore the opportunities in the proposed methodology.

Optimization Method of Photovoltaic Microgrid Energy Storage System Based on Price-based DR

Extreme events lead to an increasing number of power outages in the distribution network. It is currently the most effective method to restore power supply after distribution network failure to connect distributed photovoltaic to the distribution network in the form of microgrids. However, the randomness of distributed PV output and load is the biggest obstacle limiting its development. Therefore, an optimization method of photovoltaic microgrid energy storage system (ESS) based on price-based demand response (DR) is proposed in this paper. Firstly, based on the influence of the uncertainty of the time of use (TOU) and load on the price-based DR, a price-based DR model is built. Then, taking the minimum difference between photovoltaic output and load demand as the optimization objective, the optimal operation model of price-based DR based on the fuzzy chance constrained program (FCCP) is established, and an optimization model of photovoltaic microgrid ESS based on FCCP is obtained. Finally, the fuzzy chance optimization problem is converted into a deterministic optimization problem through constraint equivalent treatment. The proposed method is verified by numerical simulations.

Performance of 420 kV Instrument Transformers under Earthquake

Seismic performance of substation equipment during past earthquakes is poor. In addition, requirement of electric power during post-earthquake led to an increased focus on the earthquake survivability of substation equipment. Equipment installed in the substation is vulnerable to earthquakes by virtue of its geometry and configuration. Interconnection between equipment further aggravates the problem. Failure of substation equipment results in financial loss and considerable time is required to repair/replace the equipment to restore power supply. Earthquake vibration level can be evaluated based on site/location but predicting time of occurrence of earthquake is not possible. High voltage substation equipment shall be designed for seismic loading. Foundation, anchoring, installation and interconnection between equipment also need to be engineered according to the seismic load based on location of installation of equipment. Seismic qualification of various substation equipment as per National and International standard is performed using tri-axial shake table facility of Earthquake Engineering and Vibration Research Centre. Performance of 420kV instrument transformers under earthquake environment is presented in this paper.

Emergency Power Supply Restoration Strategy for Distribution Network Considering Support of Microgrids with High-Dimensional Dynamic Correlations

With the rapid development of renewable energy, microgrids are becoming more and more essential in distribution networks. However, uncertainties brought by new energy sources have posed great challenges to the energy safety and stability of distribution networks, especially in the process of fault restoration. To address these issues, this paper investigates an emergency power supply recovery strategy for distribution networks by considering the support capability of microgrids and the high-dimensional dynamic correlations of uncertainty. Firstly, the structure of distribution networks including microgrids is analyzed. Then, the high-dimensional dynamic vine copula model is proposed to model the joint output uncertainty process. Next, island partition and operation models are established, including the objective function and constraint conditions, and the model solving methods are also presented. Finally, an example analysis is conducted to verify the effectiveness of the proposed strategy. The results show that the proposed strategy is able to deal with the uncertainties brought by renewable energy sources in distribution networks with microgrid support, improving energy safety and stability. This research provides valuable insights for the development of emergency power supply strategies in distribution networks.

Co-simulation platform for the assessment of transactive energy systems

The integration of distributed energy resources (DERs) into smart grids provides great flexibility in terms of ancillary services like the restoration of power supply, regulation of voltage levels, and reactive power support, among others. In this context, this work introduces a simulation model applied in the conception of a transactive energy system (TES) architecture. The proposed approach allows for the integration of distinct domains associated with smart grids considering the joint use of simulation tools that constitute a multidomain system, thus enabling the assessment of control actions, optimization algorithms, load flow, and communication infrastructure. The Simulation Model for Transactive Energy Systems (SIMTES) framework relies on a multiagent system (MAS) and consists of two main stages: operation scheduling and real-time operation. The obtained results demonstrate the applicability of SIMTES, showing that the use of DERs associated with the grid and prosumers clearly influences energy pricing in electricity markets.

СОВЕРШЕНСТВОВАНИЕ ИНФОРМАЦИОННОЙ СИСТЕМЫ ВЗАИМОДЕЙСТВИЯ ПОТРЕБИТЕЛЬ-ДИСПЕТЧЕР ПРИ ЛИКВИДАЦИИ АВАРИЙ В РАСПРЕДЕЛИТЕЛЬНЫХ ЭЛЕКТРИЧЕСКИХ СЕТЯХ

. The need of power grid companies to quickly detect emergency power outages and identify damaged areas when solving the problem of restoring power supply in low-voltage networks leads to the need to improve the information system for consumer-dispatcher interaction. This work performed a critical analysis of the traditional system of interaction between the consumer and the dispatcher through contact centers customer service energy companies. Technical requirements to mobile system of consumer-dispatcher interaction are formed

A Statistical Study of Failures in the 10 kV Distribution Network of the Moscow Region

The dependence of distribution electrical network outages on various factors is statistically studied, and the network reliability is analyzed based on the emergency log entries. The emergency log data are analyzed, put in a systematic order, and checked for correctness and completeness. The faults are combined into groups, outliers are considered, and anomalies are excluded from the sample using a statistical and qualitative method. Based on the processed statistical information, a correlation analysis is performed with the formulation and testing of statistical hypotheses; the sample numerical characteristics are calculated, and a theoretical law for distribution of the number of outages in the network as a function of the power supply restoration time is selected. Conclusions about the influence of the time of day and climatic factors on the faults in various distribution network facilities in the Moscow region have been drawn; the least reliable network equipment items have been defined, and a probabilistic mathematical model describing the probability distribution function of the power supply restoration time has been developed.

Research on power supply recovery control technology of distribution network embedding with DC links

The flexible interconnection device (FID) enables multiple distribution feeders in closed-loop mode to support a higher proportion of distributed generation (DG) and large-scale new loads connected to the distribution network (DN). Moreover, the closed-loop operation mode based on FIDs provides an effective technology roadmap for high-quality and highly reliable power users, especially the quick restoration of power supply after the failure of DN. This paper proposes a new supply shape in which the multi-terminal DC links are flexibly embedded in the AC DN (EDC-DN) to realize closed-loop operation, achieving lower investment costs than the existing mode that replaces tie switches with soft open points (SOPs). Meanwhile, a two-stage power supply quick recovery control technology is proposed for the EDC-DN, including the fast power supply recovery stage based on EDC and the optimizing restoration stage based on network reconfiguration. Firstly, the role of EDC in the process of power supply restoration of three different faults on AC feeder is analyzed. Secondly, a detailed power supply recovery process is proposed, which is based on a distribution automation system (DAS) and the real-time control capability of EDC. Thirdly, the power supply restoration second stage is implemented, which is based on network reconfiguration with switch combination and EDC continuous variable optimization. Finally, a 58-node DN with an EDC system was constructed using PSCAD/MTDC simulation software to verify the effectiveness of the two-stage strategy for EDC-DN power restoration.© 2017 Elsevier Inc. All rights reserved.

Post-emergency reconfiguration of a distribution network as a method for restoring power supply to consumers

The work is aimed at solving the problem of using reconfiguration and additional reactive power sources to restore power to consumers of the medium-voltage distribution network in the case of emergency disconnections of connections by bus section circuit breakers. The reconfiguration problem for a 118-node test distribution network is solved using a high-speed algorithm involving the construction of a maximum spanning tree on a network graph as the basis for determining information about the composition of branches and chords of independent circuits necessary to restore power following disconnection. To ensure acceptable voltage levels following power restoration, additional reactive power sources determined using singular Jacobian matrix analysis methods are installed in the sensor nodes of the network. For the test circuit, the modes for single disconnections of individual sectional switches, including in dead-end sections, are analysed. By optimally reconfiguring the network in the normal mode, it is possible to reduce voltage deviations from 13% to 7%. For the modes caused by disconnections of individual bus section circuit breakers that lead to unacceptable voltage deviations, the set-down locations and reactive power of additional sources are selected. In the most severe of the considered disconnection scenarios, the installation of additional sources provided a reduction in voltage deviations from 18 to 8%. Thus, the methods proposed by the authors make it possible to restore the test network mode following emergency disconnections and ensure that the voltages in the network nodes are maintained within acceptable limits, both in normal and in post-emergency modes.

Disaster Damage Assessment of Distribution Systems With Incomplete and Incorrect Information

Motivated by the increasing frequency and intensity of extreme weather events, this article aims to effectively assess the scope of zones damaged by natural disasters in distribution systems, which can help for rapid restoration of power supply. Multiple-branch faults and the uncertainty of monitoring information pose huge challenges to Disaster Damage Assessment (DDA). This paper proposes a multiple hypothesis based DDA method to solve this problem. In the proposed method, the novel external environment information is used by updating the objective function with Pre-disaster Prediction Matching Index (PPMI). The reasonable weighting factor of PPMI is theoretically derived. Multiple disaster scenarios are simulated and the DDA results show that the proposed method is more effective. The introduction of PPMI can help to rectify the assessment of zones in high disaster risk zones, thereby improving the overall performance of DDA. Therefore, the proposed DDA method breaks through the assessment bottleneck under limited internal monitoring information. In addition, new technology is proposed to speed up the DDA by setting an effective initial value of optimization, making DDA more efficient.

Restoration Strategy of Distributed Power Supply in Distribution Network Based on Genetic Algorithm

Nowadays, the penetration of distributed power in distribution network increases the complexity of power supply restoration. For the recovery of the traditional method in the field of distributed power supply system restore deficiency, the improving measures are put forward based on the many kinds of operation constraints, proposes the mathematical model of multi-objective optimization. In addition to conventional constraints in the mathematical model, will also be the network structure and branch power flow constraints into consideration. In view of the model, using the rough set theory, a multi-objective optimization problem into a single objective problem, and on this basis, considering the characteristic of radial network and the characteristics of the different load, by using genetic algorithm to reconstruct network, finally through the corresponding example recovery strategy is feasible and efficient.

Research on Electric Boiler Auxiliary Thermal Power Unit Operation in Isolated Grid

An electric boiler is widely used in the research and application of thermal power flexibility transformation because of its fast regulation and strong energy storage capacity. However, as an electrical load with high flexibility, the value of isolated operation of auxiliary units in case of grid line failures has not been fully recognized. This paper studies the unit load balance system, unit isolated network operation decision-making, unit load switching, steam turbine control, and boiler control of live boiler operation, so as to realize the control function of an electric boiler assisting the isolated network operation of the thermal power unit, ensure that the unit can stably turn into the isolated network operation state in case of grid failure, and effectively ensure the heating of residents and the rapid restoration of grid power supply.

Coordinated Post-Disaster Recovery and Assessment Method for Integrated Electricity-Gas-Transportation System

Extreme disasters may cause damage to energy system’s components and transportation networks. How to achieve a rapid restoration of power supply is crucial. A coordinated post-disaster recovery and assessment method for the integrated electricity-gas-transportation system is proposed in this paper, and a repair sequence assessment model for the damaged road in transportation network based on topology and operational metrics is also established. Then, considering the dynamic changeability of the transportation network status, a rolling-updated model for dynamic road restoration and repair crew scheduling is proposed. Finally, we propose the coordinated post-disaster recovery and assessment model of electricity-gas-transportation system, in which the modified alternating direction multiplier of method is applied to solve. The impact of the transportation network repair process on system load recovery under different perspectives is verified by arithmetic examples.

Risk assessment in distribution networks considering cyber coupling

With the continuous development of information and communication technologies and their wide application in distribution networks, which have evolved into cyber-physical distribution systems (CPDS). Yet, interactions between cyber and physical systems mean power systems face a greater potential risk. Since feeder automation (FA) systems in a CPDS can quickly isolate faults and restore services, to reduce customer outage times, the potential effect of cyberattacks on FA systems is massive. This paper proposes a risk assessment method for cyberattacks in distribution networks considering cyber coupling. The proposed method takes into account the impacts of cyber systems on power systems, and vice versa. Regarding the cyberattack, an attack method to mislead the judgment of FA systems by tampering with monitoring data of remote terminal units (RTUs) is analyzed, and a Bayesian attack graph (BAG) model is adopted to quantify the successful probability of RTUs. To calculate the attack consequences, a power supply restoration model considering the interdependence of cyber and physical systems is developed, which is measured in scale and in duration to full restoration. The proposed methodology is tested and validated using the modified IEEE 33-node and CPS 62-node test systems. This study highlights the importance of assessing distribution network security from the cyber-physical point of view.

Research on high voltage cable fault location technology based on neural network

At present, high voltage cables are widely used in urban transmission system. When cable fault occurs, the speed of locating fault point and the accuracy of locating fault point play a decisive factor for power system to restore power supply quickly. This article adopted the method of neural network model based on the traveling wave ranging method. It could judge the fault location of 35kV~500kV high-voltage cable more quickly and accurately. Then, we have designed a portable high volt cable fault location device, which has been tested in the domestic power plant. The experiment showed that it could quickly determine the nature and location of power cable faults, shorten the time of blackouts and reduce the loss caused by blackouts.

THE STUDY OF A MAJOR 2008 SUBSTATION INCIDENT IN THE EPS OF CRETE

A major incident in the Electric Power System (EPS) of Crete resulting in extensive damages in the SS Iraklio 3, 150/15 kV is studied. The accident originated from a medium voltage fault at the substation. This fault was not cleared due to the coincident destruction of the protection and control circuits resulting in large shortcircuit currents for 16 minutes, fires of materiel and extensive damage in high voltage, medium voltage as well as DC voltage hardware of the substation in addition to significant loss of load. This paper begins with an assessment of the power system condition at the time of the incident. Then the sequence of events for this accident will be described. The ensuing measures that include the restoration of interrupted power supply, the partial return to service as well as the final completion of repairs at the substation facility are detailed. The analysis of the incident is presented. Conclusions of practical importance are drawn as well as recommendations regarding improvements in hardware and protection system and in the available technical support that can be crucial in avoiding and/or limiting damage in future incident.