Parallel Feeders Research Articles

Zero power mismatch islanding detection algorithm for hybrid distributed generating system

Distributed generation is essential for both keeping up with the rising power demand and reducing the amount of money spent on fossil fuels. There is widespread agreement that the world should prioritize the development of renewable energy systems such as wind and solar energy. This study describes the design and utility-grid integration of a hybrid distributed generating system that utilizes photovoltaic and wind-driven permanent magnet synchronous generators (hybrid PMSG-PV systems). To prevent damage to the grid, hybrid distributed generation systems, consumer devices, and line workers must be protected from islanding. Detection of islanding in hybrid DG systems has been suggested using passive islanding and time-spectral analysis. Measuring and amplifying the ripple content present in voltage at point of common coupling (PCC) about 0.4 seconds after the permissible delay time after the circuit breaker opens on the utility grid side is how islanding is discovered using this method. Compared to other methods, the proposed method has smoother islanding detection waveforms owing to increases in both the window size and threshold limit. The suggested method detects islanding in 40 ms and is verified in a variety of non-islanding scenarios, such as fault occurrence, parallel feeder loss, and load shift. In addition, the cost is reduced, the response time is rapid, and there is no non-detection zone (NDZ) when using these methods. Unlike active islanding detection methods, their function is unaffected by the size, quantity, or type of distributed generators linked to the utility grid; hence, there are no power quality concerns.

Efficiency Analysis for Inductive Power Transfer Using Segmented Parallel Line Feeder

Parallel line feeder (PLF) consisting of a two-wire transmission line operating in the MHz band has been proposed as a wide-coverage short-distance wireless charging. In the MHz band, a PLF of several meters suffers from standing wave effect, resulting in fluctuation in power transfer efficiency accordingly to the receiver's position. This paper studies a modified version of the system, where the PLF is divided into individually compensated segments to mitigate the standing wave effect. Modelling the PLF as a lossy transmission line, this paper theoretically shows that if the segments' lengths are properly determined, it is able to improve and stabilize the efficiency for all positions. Experimental results at 27.12 MHz confirm the theoretical analysis and show that a fairly high efficiency of 70% can be achieved.

Modal Aggregation Technique to Check the Accuracy of the Model Reduction of Array Cable Systems in Offshore Wind Farms

The need for a verification method for aggregation techniques for passive electrical systems is necessary as power systems increase in complexity. Model reduction is crucial to increase the number of simulations necessary to ensure a stable and reliable design of power systems. This paper presents a novel modal domain-based technique to identify the best aggregation technique for a given system and to indicate the validity of the aggregation. This is done by benchmarking different aggregation techniques and using the dominant contribution factor ratio as a validity parameter. The different aggregation techniques are compared via time-domain simulations against the full detailed model. It is found that (1) the power loss aggregation technique is the most precise when it weighs the equivalent impedances of the parallel feeders, (2) unequal current generation does not impact the aggregation accuracy, (3) individual string aggregation provides the best results for dynamic simulations, and (4) the validity of aggregation decreases as frequency or cable length increases.

Current Breaking Test of the Superconducting Feeder on Tram-Train Running

To introduce the superconducting feeder cable for commercial operation of a railway system, it is required to establish technologies for safety and reliability. The behavior of the superconducting cable must be determined for the case in which the superconducting cable fails in the feeder system for railways. The superconducting cable can be introduced so that it is installed along with the existing feeder cable or so that only the superconducting cable is installed to be used as the feeder line. For this time, at first only, the superconducting cable was used to establish a circuit for feeder to the electric railcar without using the existing feeder circuit to conduct the power-transmission test and current breaking test. Then, the superconducting cable was installed along the existing feeder line to establish a circuit that is capable of feeder via both feeder lines to conduct the same tests. In both tests, it is confirmed that no problem occurs in the train and the superconducting cable system when it encounters the current breaking. For the parallel feeder system, it is found that the current path is transferred to the existing feeder line and the system is continuously capable of operating the train stably when the current is broken in the superconducting cable.

Adaptive optimum coordination of overcurrent relays for deregulated distribution system considering parallel feeders

This paper proposes an adaptive optimum overcurrent protection for deregulated distribution networks containing parallel feeders. The proposed adaptive coordination eliminates the maloperation of conventional overcurrent protection under different fault scenarios. These scenarios take place when faults occur close to the end of the parallel feeders specially when faults are associated with significant fault resistances. Under these faults, the current at the backup relay is almost double that at the corresponding primary. Thus, adaptive pickup setting is recommended. However, this problem is complicated remarkably when distributed generation units feed the upstream source side faults or under the removal of the power source due to the interruption of a source side breaker. Simultaneously, the proposed coordination approach enhances the sensitivity and keeps on the optimum speed by automatically identifying the faulted zone. The faulted zone is identified by monitoring both the status concerning a single feeder or two parallel feeders in service and the faulted phase current direction of each pair of relays. Thus, a new fault direction identification method is presented. This method is based on comparing the angle of the post-fault current and that of the pre-fault current. Three optimization algorithms (genetic, harmony search, and water cycle algorithms) have competed to find the optimal settings of the installed overcurrent relays for each faulted zone. The reliability of the proposed method is examined as compared to conventional coordination concepts based on a detailed simulation of an actual 11-kV cascaded parallel series distribution feeder in the Egyptian distribution network. Sample results are examined.

Clearing Break Points of Overcurrent Protection Coordination for Parallel Distribution Feeder

This paper presents a modified overcurrent protection system to overcome the break points of a parallel distribution feeder protection. For realizing an appropriate protection setting, two concepts are introduced, and their performance is evaluated. These concepts are the adaptive coordination exploiting smart grid information and the modified coordination methods. The modified coordination is adjusted with changing of the contemporary worst fault point. A comparative study is done between the adaptive, modified, and conventional coordination concepts. For investigation purposes, a 11 kV distribution feeder is modelled using the Matlab/Simulink package. The results provide evidence of the efficacy of the proposed modified coordination concept for parallel distribution feeders.

The control of preexisting faults on the distribution, morphology, and volume of monogenetic volcanism in the Michoacán-Guanajuato Volcanic Field

AbstractInteractions between volcanic and tectonic processes affect the distribution, morphology, and volume of eruptive products in space and time. The Queréndaro area in the eastern Michoacán-Guanajuato Volcanic Field affords an exceptional opportunity to understand these relationships. Here, a Pleistocene lava plateau and 20 monogenetic volcanoes are vented from an active ENE-striking segment of the Morelia-Acambay fault system. Thirteen scoria cones are aligned along this structure, vented from an extensional gap in between two rotated hanging wall blocks of a listric fault. A new geological map, volcanic stratigraphy, and 40Ar/39Ar dating indicate that this lava plateau and volcanic cluster were emplaced from 0.81 to 0.25 Ma by 11 intermittent eruptive epochs separated by ca. 0.05 Ma, emplacing a total magma volume of 5 km3. Petrography and chemistry of rocks suggest that all volcanic structures were fed by three different magma batches but vented from independent feeder dikes. Our results indicate that preexisting faults exert a strong influence on volcanic spatial and temporal distribution, volcanic morphology, magma volume, and eruptive dynamics in this area. ENE-breached and ENE-elongated scoria cones indicate parallel subsurface fissure and feeder dikes. Additionally, points of maximum fault dilation at depth related to a transtensive state of stress coincide with less fragmented deposits and larger magma volumes. Furthermore, this study raises important questions on the geodynamics of volcano-tectonic interactions possible in similar monogenetic volcanic alignments worldwide.

Analysis and improvement on reliability of 66/11 kV distribution substation and its associated feeders: A case study of Lainchour substation in Nepal

Electric power interruption is becoming a day to day phenomenon in our distribution system. For distribution system to be effective there should be less outage in the system and if fault occur these faults should be cleared as soon as possible. Sustained power interruption occurs several times a day from few minutes to hours. Interruptions may be due to failure of substation equipment or failure of distribution network elements. This paper attempts to identify different causes of interruption and problems that customers in Nepal have been facing due to frequent planned and unplanned sustained interruptions by evaluating various reliability indices and parameters of Lainchaur distribution substation and its associated feeders operated under Nepal Electricity Authority. First, reliability analysis of substation configuration only is done followed by analysis of reliability improvement measures like use of double bus bar, parallel distribution feeders and underground cables in DIgSILENT PowerFactory only considering sustained failures of equipment and feeders. Calculated reliability indices like System Average interruption Duration Index (SAIDI), System Average Interruption Frequency Index (SAIFI), Energy Not Served (ENS) are compared for different cases so that it will be easy to make choice between options to the utility to upgrade/improve the system. Considering all feeders, result shows that main cause of interruption in the distribution system is failure of distribution lines showing 104 interruptions for total duration of 107 hours per annum in the system, followed by failure of distribution transformers indicating 19 interruptions for total duration of 47 hours per annum. Simulation result in DIgSILENT shows yearly total ENS of distribution system is high due to present configuration, and can be reduced by the use of parallel feeders and underground cables respectively. It is seen that ENS due to failure of substation components only is very low and huge revenues can be saved if auto-reclosures are used or a provision of charging feeders as soon as possible is made.

A Novel Protection Algorithm for Medium Voltage Collector Feeder In Wind Farm Based On Quadrature Directional Algorithm With Laboratory Investigation

A protection scheme for medium voltage wind farm collector feeder has been presented in this paper. The scheme is based on quadrature directional angle. This scheme is convenient for small WTG with capacity less than 1MVA. It uses the voltage signal at the collector bus and the current signals at each WTG zone to calculate the quadrature directional angle of each zone which connected to protected feeder, any fault occurs at any parallel feeder or at power grid is considered as an external fault. A part of Zafarana wind farm which is connected to 220 kV system of the Egyptian network is simulated by using MATLAB package to verify the proposed protection algorithms. The results covered a wide variety of fault scenarios; these results proved the ability of the proposed algorithm to differentiate between in-zone and out-of-zone faults. To verify the effectiveness of the proposed scheme it is tested in the laboratory by using induction machine, synchronous generator and DC Motor to simulate the power system, the current and voltage transformer are used to transfer the current and voltage signals respectively of the power system to the data acquisition system connected to pc by sampling frequency of 10 kHz. Lab- View package is used as software. The experimental results indicate that they are compatible with the simulated results and the proposed technique is stable, reliable, and fast during the discrimination between internal and external faults.

An Adaptive Virtual Impedance Control Scheme Based on Small-AC-Signal Injection for Unbalanced and Harmonic Power Sharing in Islanded Microgrids

To address the unbalanced and harmonic power sharing issue among parallel inverters caused by feeder impedance mismatch in islanded microgrids, an adaptive virtual impedance control method is proposed based on the injection of an extra small ac signal (SACS) in the output voltage of each inverter. Similar to the principle of active power–frequency droop, the frequency of the injected signal droops with the output unbalanced and harmonic power, while the active power produced by the injected SACS is detected to adjust the virtual impedance at the fundamental negative sequence and selected harmonic frequencies, which will tune the distribution of unbalanced and harmonic power in the system. When the injected SACSs of each inverter synchronize with each other and reach a common frequency in steady state, the virtual impedance of each inverter will be matched to each other for evenly sharing the unbalanced and harmonic power. This proposed method requires neither communication links among parallel inverters nor feeder impedance information. Furthermore, the control parameter design method based on modeling and stability analysis of the proposed control structure is discussed in detail. Finally, simulation and experimental results are provided to validate the effectiveness of the proposed scheme.

Positioning using hybrid inductively‐capacitively coupled parallel line feeder

AbstractIn this article, we propose a one‐dimensional positioning technique using hybrid inductively–capacitively coupled parallel line feeder, suitable for indoor industrial applications. The proposed system enables a tag to detect its own position by sensing the standing wave pattern along the elongated feeder. If the tag measures only the magnetic field via inductive coupling, the detectable range of this approach is limited to approximately a quarter wavelength as the magnetic field strength repeats beyond this distance. To increase the detectable range, we use a special coupler to observe the standing wave patterns of both electric and magnetic fields and compare them with the reference patterns. Simulation and experiment results show that our method is capable of positioning in approximately a half wavelength. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Effective Photovoltaic Integration and Power Quality Improvement on Parallel Feeders using Dynamic Multi Converter Controller

Growing phase of industry and living standards in modern world brings drastic changes in modern utility structure and control. Gradually, green sources takes place of traditional sources and aids the current utility power delivery for consumer loads. Green source and more sensitive loads integration to grid demands effective controller and reliable grid structure. In this paper, an effective grid structure with dynamic multi converter controller is proposed to alleviate disturbances in current and voltage on parallel feeders simultaneously. Soft computing based controller effectively integrates the photovoltaic green source and utilizes the power generated to aid the controlling action and to provide the desired power required on lines. Dynamic multi converter controller takes care of current and voltage disturbance alleviation, green source power integration and harmonics suppression on parallel lines under distorted & balanced and distorted & unbalanced source conditions. Performance of proposed Dynamic Multi Converter Controller with traditional and soft computing techniques is studied and compared in MATLAB/SIMULINK platform.

Parallel Switching Regulatory Control of Iron Ore Flowrate from Multiple Feeders with Time Delay

The suitable performance of an industrial process needs regulatory control loops to adjust the main process variables to their especified reference values (set-points), and to compensate eventual load disturbances on the process. Regulatory control is fundamentally used in the industry for stabilizing process variables, and it’s generally implemented through the SCADA architeture of the plantwide control system. The absence or inefficiency of control in an industrial process generally implies in losses of productivity so that regulatory control is a key issue for improving process performance. In this context, this article presents the development and implementation of a control strategy for regulating the output mass flow (in t/h) of a crushing plant in the Carajás Iron Ore Processing Factory. The plant has eight feeders in parallel, and the goal was to control such feeders so that the resulting output flow matches a specified production set-point (in t/h). The article first explains the process, the control problem, and the transfer function model of the process. Subsequently, one’s presented the control strategy, which was based on a switching between a constant and a PI control action. The suitability of the strategy was investigated through computational simulations. Finally, the results and conclusions are discussed

Low-Voltage Shore Connection Power Systems: Optional Designs and a Safety Loop Circuit

This article reviews low-voltage shore connection (LVSC) power systems for ships with up to 1,500 kVA and voltage of 400-690 V. The design concept for these systems is contained in the current LVSC draft standard, International Electrotechnical Commission (IEC)/IEEE 80005-3. Here, we attempt to clarify that an LVSC design concept using multiple parallel feeder circuit breakers does not violate National Electric Code (NEC) National Fire Protection Association (NFPA) 70 Section 240.8. We also attempt to clarify the optional design for an ungrounded shore power system, as required by certain ships and included in the draft standard [1]. In addition, we review the safety loop circuit that enhances operator safety both onshore and onboard a ship.

Impacts of the representation of mutual coupling between feeders in distribution systems

The mutual coupling between parallel feeders affects the power flow solution for distribution systems. By analyzing these effects, the unbalanced operation of distribution systems is better understood and the analyses are useful for distribution planning. This paper presents analytical evaluations of the impacts of mutual coupling between feeders in multiphase power flow analysis. Detailed explanations are presented, and several tests are performed to prove the results. The impacts of the mutual coupling representation are tested in relation to the distance between feeders, current intensity, unbalanced load, feeder geometry, parallel section size, and other sensitivities. The impacts considering the presence of voltage regulators are also studied. Tests were performed on a modified IEEE 13 system, a modified IEEE 34 system, and a neutral-to-earth-voltage (NEV) test feeder.

Energy efficiency analysis of two-sided feed scheme of DC traction network with high asymmetry of feeders parameters

In a given research using the example of traction network area with high asymmetry of power supply parameters, the sequence of comparative assessment of power losses in DC traction network with parallel and traditional separated operating modes of traction substation feeders was shown. Experimental measurements were carried out under these modes of operation. The calculation data results based on statistic processing showed the power losses decrease in contact network and the increase in feeders. The changes proved to be critical ones and this demonstrates the significance of potential effects when converting traction network areas into parallel feeder operation. An analytical method of calculation the average power losses for different feed schemes of the traction network was developed. On its basis, the dependences of the relative losses were obtained by varying the difference in feeder voltages. The calculation results showed unreasonableness transition to a two-sided feed scheme for the considered traction network area. A larger reduction in the total power loss can be obtained with a smaller difference of the feeders’ resistance and / or a more symmetrical sectioning scheme of contact network.

PERFORMANCE ANALYSIS OF DIGITAL OVER CURRENT RELAYS UNDER DIFFERENT FAULT CONDITIONS IN RADIAL AND PARALLEL FEEDERS

The conventional relays like electromechanical relays, static and microprocessor based digital relays are having their own disadvantages. Digital/ numeric relays are replacing to overcome these drawbacks. Digital protection devices are built with integrated functions and operated using digital binary values. Fast operation, high sensitivity, self-monitoring, low maintenance are the characteristics of the digital/ numeric relays and their cost is also relatively low. Accuracy, flexibility, reliability, multi-functional capability, and working under wide range of temperatures are the advantages of these relays. They have few limitations such as complexity, short life time due to the new technological developments, and susceptibility to power system transients. Digital over Current relays modeling for power system protection has been proposed in this paper. The performance of the proposed relays was tested by applying different types of fault conditions in radial and parallel feeders and results were analyzed. MatLab/Simulink software was used to simulate the proposed protection scheme due to its features like design flexibility and exploration of any physical module. Article DOI: https://dx.doi.org/10.20319/mijst.2017.s31.146158 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Earth fault location determination independent of fault impedance for distribution networks

Summary This article introduces a new earth fault location algorithm for both single and parallel feeders in distribution networks with single end measurements. The proposed algorithm depends on using the equality between the computed sequence components of the current at the fault point. The algorithm is independent of the dynamic arcing or static fault impedances. Then the faulted network can be decomposed into a prefault network and a pure fault network. The different types of connections of load transformer are considered in the study. This is because of their known influence on the direction of earth fault current in the faulty network. Moreover, the existence of distributed generation is considered during formulating the mathematical core of the proposed algorithm. Hence, the sequence current components at the faulty point can be derived without the need to measure the distributed generation current contribution or its terminal voltage with all varieties of load transformer connection. The proposed algorithm is tested via simulating a real 11 kV cascaded parallel-radial earthed distribution feeder from the Egyptian distribution network using Matlab. Different test cases are examined to visualize the performance of the proposed algorithm with a variety of fault conditions, including the fault impedance, loading, load transformer connection, and existence of distributed generations. All applied simulation tests ensure the efficacy of the proposed algorithm for estimating the fault distance in distribution systems with considerable distributed generation insertion and considering all possibilities of load transformer connection.

Dynamic charging using parallel line feeder with hybrid inductive-capacitive coupling and receiver-side load control

Dynamic charging using parallel line feeder with hybrid inductive-capacitive coupling and receiver-side load control

A methodology for real time analysis of parallelism of distribution networks

The parallelism of distribution networks can be used to transfer loads between feeders without the need of disconnection of consumers during the switching. In the context of the Smart Grid, the parallelism of feeders can be used in automatic reconfiguration of networks for the improvement of power quality and voltage levels, and reduction of energy losses. However, the switching for parallelism must be preceded by studies to verify its technical and operational feasibility. This paper presents a methodology to analyze aspects of loading, protection, and voltage levels related to parallelism of distribution networks, in transient and steady-state operation. The validation of the developed methodology was carried out by comparison with simulation results from the ATP program. The study aims to be suitable for real time application in reconfiguration of distribution networks, allowing, for instance, the integration with remote controlled switches, so that the network reconfiguration can be done automatically. The results here presented are based on a real model of a distribution network of a power utility. The developed methodology has as main result a reliable indication of the technical feasibility of connecting feeders in parallel.