Outage Time Research Articles

Consideration of Evaluating Method for Domestic Water Supply Potential by Agricultural Water Facilities at the Time of Water Outage

Consideration of Evaluating Method for Domestic Water Supply Potential by Agricultural Water Facilities at the Time of Water Outage

Improving the Reliability of Pumping Equipment at Production Plants

The most reliable diagnostic signs of the limit state of the pumping equipment at production plants are established to minimize the outage time.

Protective Device and Switch Allocation for Reliability Optimization With Distributed Generators

The location of protective devices, such as circuit breakers, reclosers, sectionalizers, and fuses, along with isolating switches in a distribution network is a key factor impacting the reliability performance. Furthermore, automatic restoration from intentional islanding with renewable-based distributed generators (DGs) or from alternate feeders can reduce outage times. In this paper, a mixed-integer linear program (MILP) formulation is proposed for protective device and switch allocation considering intentional islanding with distributed generation in distribution systems. The specific impact of each protective device type and isolating switch is modeled, e.g., momentary interruptions caused by reclosers. Efficient graph search algorithms combined with a directed graph representation of the distribution system allows for preprocessing of the network data and facilitates the formulation of an MILP. The formulation is able to efficiently compute optimal device allocations for multiple scenarios, revealing key insights, e.g., the location and capacity of DGs providing the greatest reliability benefit for a fixed protection budget. Numerical tests on realistic feeders and comparison with prior solutions show improved device allocations and lower objective function values.

Development and Application of Live Replacement of Insulator Suspension Tool Components for Transmission Lines

Transmission line insulators will reduce the insulation level and become low-value insulators because of lightning flashover. Toughened glass insulators are used in 500kV Tongfeng 1 and 2 lines in Tonghua area. Most umbrella skirts will break and fall off after lightning flashover, which greatly reduces the insulation performance. It needs to be replaced in time, but frequent blackouts will bring great losses and reduce the reliability of power supply. Aiming at the frequent lightning hazards and lightning strikes on transmission lines in Tonghua area, a tool assembly for live replacement of insulators for transmission lines is developed. Through the application of this tool, the live operation mode is adopted to eliminate such defects. The operation time can be arranged and implemented in a very timely manner, which avoids the threat of long-term defects, effectively reduces the outage time of equipment, enhances the stability of power grid, and greatly improves the reliability of power supply of lines. Finally, taking the live line insulator suspension tool as an example, the economic benefit analysis is given, and the feasibility and correctness of the tool are verified..

GNSS signals ionospheric propagation characteristics in space service volume

In recent years, Global Navigation Satellite System (GNSS) showed a remarkable capability to serve for medium and high earth orbit spacecraft, called space service volume (SSV). However, SSV users face a critical problem of insufficient GNSS signal visibility. In previous studies, the ionospheric signals are usually discarded, which results in a large discrepancy in mission design and system optimisation. In this paper, a three-dimensional ray-tracing method is adopted to analyse signal propagation through the ionosphere. Taking GPS constellation and a GEO user as an example, the principles are validated with a careful simulation. The results show an interesting phenomenon that the bending angle of the signal path and the ionospheric attenuation are very small, and the ionospheric delay is large but eliminable. If the ionospheric signals are considered, the signal visibility and availability will significantly increase, which leads to a shortened maximum outage time for SSV users.

Precise Fault Location on Transmission Lines Using Ensemble Kalman Filter

Accurate pin-pointing of faults on transmission lines minimizes outage time, labor, and costs. This letter proposes a simple yet effective ensemble Kalman filter (EnKF) approach to accurately locating the faults on transmission lines within half-cycle time. The approach is easy to implement and does not require foreknowledge of either the fault type or an approximate guess of the fault location. Extensive results validate the effectiveness and accuracy of the EnKF-based fault location approach.

Reduction of Forced Outages in Islanded Microgrids by Compensating Model Uncertainties in PV Rating and Battery Capacity

Energy management systems for islanded microgrids often rely on predictions of energy availability and usage. Such predictions can be used to plan actions, such as shedding non-essential loads, so that critical loads continue to be served. However, uncertainties in the prediction models may lead to incorrect decisions, and subsequently jeopardize reliable operation of the microgrid. For a photovoltaic (PV) and battery based microgrid, uncertainties in the PV rating and the battery capacity model parameters can lead to otherwise avoidable outages. In this paper, techniques have been developed to identify and compensate for such model uncertainties. The approach uses differences between the actual and predicted data sequences to determine compensation factors to improve prediction accuracy. The developed techniques account for operating condition changes automatically, and no additional sensors are needed for their implementation. The method has been evaluated using data from rooftop irradiance and temperature sensors and the corresponding forecasts. It has been shown that the proposed techniques can improve the accuracy of the predictions and hence lead to more effective energy management decisions. Together with a pre-emptive load shedding strategy, the total outage time of the microgrid can be shortened by as much as 11% for the chosen scenario.

Shunt Capacitor Banks Online Monitoring Using a Superimposed Reactance Method

A new indicating quantity, named superimposed reactance (SR), is presented in this paper to determine failed capacitor elements’ involved phase and number in shunt capacitor banks (SCBs). The proposed quantity is estimated using available measurements to the unbalance protection function of SCBs numerical protective relays. The proposed SR adopts calibrating factors for element failures online monitoring and can provide live report of the number of failed capacitor elements. The proposed method applications are: faster identifying SCBs faulty units, for fuseless and internally fused designs, and planning preventive/scheduled maintenance for all types of unit designs including externally fused units. With integration of these applications into protection intelligent electronic devices that provide captured and time-tagged event records via communication protocols for HMIs and SCADA systems, outage times would be reduced and smart grids reliability would be improved. The developed algorithm supports three different grounding arrangements, Wye-ungrounded, Wye-grounded via a low ratio current transformer, and Wye-grounded via a grounding capacitor at the SCB neutral point. Comprehensive simulation and fault-location sensing in PSCAD and MATLAB have verified the proposed algorithm performance. Advantages of the proposed method reports over conventional unbalance relaying alarms are also demonstrated using a commercial relay test results comparison.

Fault section locating method and recovery strategy of pole‐to‐ground fault for medium voltage direct current (MVDC) distribution network

High-resistance clamping grounding is a common grounding mode of modular multilevel converter (MMC) based DC distribution network. Due to the current limiting function of grounding resistor, pole-to-ground fault can only cause limited steady-state fault current. Consequently, it is very difficult to locate fault section. Besides, there are a few research works on pole-to-ground fault recovery strategy of a DC distribution system. This study purposes a fault criterion based on DC pole-to-ground voltage amplitude and changing rate. Then, by extracting polarities of a DC feeder current travelling wave using the method of wavelet transform modulus maximum, a rapid fault section locating method is presented. Furthermore, a feasible pole-to-ground fault recovery strategy is introduced, which can reduce outage range and time on the premise of guaranteeing system stability. The performances of the proposed methodologies were validated by numerical simulation.

Predictive analytics tools to adjust and monitor performance metrics for the ATLAS Production System

Having information such as an estimation of the processing time or possibility of system outage (abnormal behaviour) helps to assist to monitor system performance and to predict its next state. The current cyber-infrastructure of the ATLAS Production System presents computing conditions in which contention for resources among high-priority data analyses happens routinely, that might lead to significant workload and data handling interruptions. The lack of the possibility to monitor and to predict the behaviour of the analysis process (its duration) and system’s state itself provides motivation for a focus on design of the built-in situational awareness analytic tools.

Impact of Distributed Generation Integration on Distribution System Reliability

Objectives: To study the impact of Distributed Generation (DG) integration and automation on distribution system (DS) reliability. Impact of switch operational failures is to be studied. Methods/Statistical Analysis: The system reliability is estimated using time sequential Monte Carlo Simulation (MCS) considering time varying load models. The uncertainties of wind and solar powers are modelled by using Weibull and Beta probability distribution functions respectively. The concept of expectation is used for fuse and switch operational failures to determine the average outage time. System equipment is modelled using two state continues Markov modelling. Findings: The impact of DGs and system automation on distribution system reliability is estimated. The impact analysis is done on a practical Indian distribution system. The impact on system reliability due to operational failures of the fuses and switches is analysed. The failures of substation equipment and DGs are also included for reliability evaluation. The load transfer restrictions are applied on feeders and load transfer capacity is evaluated based on the instantaneous loading of the feeder. Both system reliability and load point reliability is evaluated for impact analysis and results are compared. Application/Improvements: The results contribute the generic observations regarding the impact of DG integration and operational failures of switches. Keywords: Distribution Automation, Distributed Generation, Monte Carlo Simulation, Probability Distributions, Solar Power, Wind Power

A Simple and Reliable Submental Intubation Technique for Maxillofacial Fractures.

In 1986, Altemir first reported the use of submental intubation to avoid tracheotomy in patients with panfacial and midfacial fractures for whom intermaxillary fixation is necessary, but orotracheal and nasotracheal intubations are not recommended. This novel technique allowed intraoperative access to perform dental occlusion and reconstruction of the nasal pyramid in patients with skull base fractures. Herein, we describe a refined technique based on Altemir's original procedure. Seven male patients with panfacial fractures underwent submental intubation using our refined technique. The technique was developed after encountering a technical error with Altemir's original procedure. In this new technique, we employed a 2-0 silk suture guide to allow the passage of both the endotracheal and cuff-inflation tubes through the same tunnel created from the oral cavity to the submental area. The success rate of the refined technique was 100%, and there were no intraoperative or postoperative complications. There was 20 seconds of ventilation outage time in total. Endotracheal and cuff-inflation tubes were easily and quickly passed through the same submental tunnel. Our refined technique is simple, easy, safe, fast, inexpensive, and does not require specific materials. Submental scars were smaller and relatively inconspicuous in this study, compared to those reportedly associated with other modified techniques.

FAULT DETECTION IN UNDERGROUND CABLES BY USING WAVELET TECHNIQUE (WT)

This paper describes a novel fault-detection technique of high voltage underground cables. Electric power systems have rapidly grown for the past fifty years. Speedy and precise fault location plays an important role in accelerating system restoration, reducing outage time, reducing great financial loss and significantly improving system reliability. Therefore, this paper presents a fault detection, classification and fault location estimation method based on Discrete Wavelet Transform for medium voltage 11kV underground cable. Different faults (Lg, LLg, and LLLg) and at different locations 2km, 4km and 6km of 10km length are simulated by Mat Lab, and then certain selected features of the wavelet transformed signals are used as an input. From the results, it was found that the percentage error in wavelet Transform output is very less. Hence, it can be concluded that the proposed technique is able to offer high accuracy in both of the fault classification and fault location.

A full-wave rectified alternating current wireless electrocoagulation strategy for the oxidative remediation of As(III) in simulated anoxic groundwater

The application of conventional DC electrocoagulation for remedying the anoxic As(III)-contaminated groundwater normally suffers from the external introduction of O2 and the vulnerability of the ohmic contact between iron electrode and conductive wire. To address these limitations, a novel full-wave rectified alternating current wireless electrocoagulation (FWAC-WEC) technology for the oxidative immobilization of As(III) from anoxic groundwater was developed in this study. The FWAC-WEC process produced Fe(II) and O2 simultaneously when utilizing iron bipolar electrodes (Fe-BPEs) and two Ti plate coated mixed IrO2/Ta2O5 (MMO) driving electrodes. The increase in Fe-BPEs number (1–3) and outage time (0–6 s) and the decrease in the angle for Fe-BPEs to electric field line separately benefited As(tot) removal. Besides, As(tot) removal was enhanced with increasing pH value but deteriorated by the presence of HCO3− and PO43−. In the FWAC-WEC process, As(III) was initially oxidized to ionic As(V) by intermediate Fe(IV) species. Thus, As(tot) removal was significantly promoted by adsorption and/or co-precipitation of As(V) with the fresh Fe(III) (oxyhydr)oxides, which appreciably obeyed the Langmuir isotherm and the second-order kinetics. Notably, the FWAC-WEC technology can effectively eliminate the passivation of Fe-BPEs and thereby increase the utilization of Fe-BPEs due to the periodic exchange of driving electrodes polarity. This strategy could remarkably reduce the energy consumption to 0.101 kW·h/m3 for As(III) removal, which was much less than 0.167 KW·h/m3 in the DC counterpart. Generally, the FWAC-WEC technology is energy-efficient and has the potential of being a sustainable treatment option to improve access to safe groundwater for millions of people.

Research on New Scheme Based on Secondary Reclosing Distribution Network Protection

The research on the rapid secondary reclosing technology proposed by Shandong Electric Power Grid (short delay primary reclosing + long delay secondary reclosing) and boundary switch reclosing and fixed value matching system within the framework of the grid is introduced in this paper. The different distribution network structure identifies the selection of relevant matching principle and secondary reclosing scheme, which changes the current mode which puts emphasis on the safe operation of the system side. The secondary reclosing shortens the user power outage time, achieves the reliability of the user's power supply, improves the quality of power, and provides a high quality distribution network for the users. By continuously optimizing the reclosing strategy and the corresponding protection configuration setting principles, the system to respond to the actual user needs is fully coordinated to improve the reliability of power supply of distribution network.

Fault Location in Double Circuit Medium Power Distribution Networks Using an Impedance-Based Method

The distribution network is extended throughout cities, towns, and villages. Because of the increase in loads and the decrease in power passageways and public corridor reduction, double circuit lines are increasingly being used instead of single circuit lines. Fault location in double circuit power networks is very important because it decreases the repair time and consequently the power outage time. In this paper, a new improved method for fault location in double circuit medium power distribution lines is proposed. The suggested impedance-based fault location method takes into account the mutual effect of double circuit lines on each other. To the best of our knowledge, the proposed method is the first of its kind which supports double circuit distribution networks. In the proposed method, a new quadratic equation for locating fault in power distribution networks is obtained using recorded voltage and current at the beginning of feeder. In this method, the π line model is used for improving the accuracy of the suggested method. The proposed method is supported by mathematical proofs and derivation. To evaluate the accuracy of the proposed method, the proposed method is tested on a thirteen-node network in different conditions, such as instrument error, various fault resistances, and different fault inception angles in various distances and fault types. The numerical results confirm the high accuracy and validity of the proposed method.

Novel Method for Identifying Fault Location of Mixed Lines

The identification and localization of a fault are a basic requirement for optimal operation of a modern power system. An effective fault identification method significantly reduces outage time, improves the electrical supply reliability, and enhances the speed of protection control. This paper proposes a novel method based on the theory of the two-terminal traveling wave range to identify the fault location in a voltage source converter based high voltage direct current (VSC-HVDC) system containing mixed cable and overhead line segments. It uses variational mode decomposition (VMD) and the Teager energy operator (TEO) as a new method to detect the traveling wave fault through a fault signal. The effectiveness of the proposed method is verified via time domain simulation of the hybrid VSC-HVDC transmission system using PSCAD/EMTDC and MATLAB software. Simulation results show that the proposed method demonstrates high fault location accuracy and excellent robustness with a slight effect on transient resistance and fault types, and that it performs better than the existing transient detection techniques, such as wavelet transform and ensemble empirical mode decomposition.

Substation Reliability Evaluation Considering the Failure Events

In this paper, bus and breaker structures of typical two substations were modelled by graph circuit to evaluate each reliability considering the various failure events and compare them each other. Passive failure event, active failure events, breaker stuck conditions and overlapping failure events in substation were conceptually explained and the reliability equations were presented to calculate the failure rate, repair rate and unavailability of each failure events. Also, deduction algorithms were implemented as a software programming to find the minimal cut sets for passive failure events and active minimal cut sets for active failure events. In the case study, reliability indices of each failure events and entire reliability indices (failure rate, annual outage time and MTTR) of typical two substations were calculated and quantitatively compared.

The Role of Preventive Major Maintenance in the Costs of Electric Energy Distribution Companies

Objectives: The unwanted and unplanned outages due to faults occurred in electrical energy distribution systems are one of the main concerns of distribution companies. This paper examines this concerning. Methods/Statistical Analysis: This paper examines about ninety outages in related to the medium pressure power lines in second region of Bushehr over twomonth period. Findings: It has identified faults caused by power outages, and the time of outage for each fault is extracted in all regions of the primary data obtained from the power events. Then, by determining the cost function with the purely economic factors, are obtained the costs of each fault individually. In the following, for each fault are provided a series of preventive overhauls or preventive recommendations. Until increasing the system’s trustworthiness, the operating costs of unwanted faults are completely eliminated or minimized. Application/Improvements: The application of this paper is that examines the roles of preventive major maintenance in the costs of electric energy distribution companies. Keywords: Cost Function, Electric Energy Distribution Companies, Energy Not Served (ENS), Preventive Maintenance, Unplanned Outage

Rancang Bangun Kontrol Pemadaman Listrik Rumah Via SMS Dengan Lampu Emergency Inverter

Electricity is the main source of energy that humans need for everyday life, without electricity a human can not turn on the television, the fridge, and which is sure to be dark because it can not turn on the lights at night. Therefore electricity is very important and can be a major requirement in this life, recently there are frequent blackouts in turn by PLN. The problem is that during the night there is a blackout the house will be dark because the lights will also die, and that's when it takes a tool to turn on the house lights to be able to illuminate the house when there is a power outage. The tool is an inverter run by batteries with 12 volt DC voltage that replaces 220 volt voltage from PLN and also can control via SMS if at any time of power outage. The inverter circuit will be active when there is a power outage and the arduino as a microcontroller triggers the SIM 900 sms module to send a message to the homeowner to confirm the inverter is activated or not, if the inverter is active then the lamp will turn on and if the inverter is off then the lamp will stay off. So that will be generated appliance control of house electricity blackout by sms with emergency lamp run by DC to AC inverter.