Feeding Substations Research Articles

Evaluating distribution network optimal structure with respect to solar hosting capacity

Optimal design of distribution networks has become an important topic for analysis due to the growing share of photovoltaics (PV). Low and medium voltage networks should undergo structural changes to accommodate widespread PV generation and optimal operation. In this paper, the impact of the network structure on the solar hosting capacity (HC) is analyzed with respect to the role of low and medium voltage networks in power delivery. A given set of load nodes is simulated with multiple feeding substations and varying peak power and number of PV plants. The slime mold algorithm is utilized for numerous topology generations and measured load time series represent regions ranging from rural to urban. The results reveal that networks should go through significant structural changes to cope with larger PV generation and even more so to increase the HC. On the other hand, voltage control measures, such as on-load tap changers, PV reactive power control and curtailment, provide a competitive solution to varying size of distribution networks in hosting solar power. Finally, the analysis in this study provides evidence to a possible need in the change of residential PV policies in order to sustain the current pace of adopting PV plants in Finland.

Studi Penambahan OCR dan GFR Gardu Hubung Gondol untuk Mengurangi Gangguan Meluas Penyulang Banyupoh

At the Banyupoh Feeder there is a Gondol Hubung Substation, which has 2 outgoings, the first line goes to the Banyuwedang Feeder and the second line goes to Penyabangan. However, because there is no protection on the outgoing side, if there is a disturbance in the first section on one of the outgoing sides, it will cause 1 feeder with a total of 49 transformers to experience a blackout. To overcome this condition, it is necessary to add relays at the substation. After the addition of relays at the substation, the impedance and short-circuit current are recalculated which can be used to determine the timing of the OCR and GFR relays at the new substation for each outgoing. The calculation results are then converted into a curve to determine the coordination of the protection with the existing protection relays on incoming, outgoing and recloser in anticipating disturbances in the first section at the Banyupoh Feeding Substation. After setting the protection relay on the outgoing side of the substation, the outage area due to interference can be minimized. When section 1 of the Banyuwedang Feeder is disturbed, the relay on the outgoing Gondol Substation will work so that the Energy Not Served (ENS) which was previously 40.008 kWh becomes 20.511 kWh. If section 1 of the Feeding Feeder is disturbed, then the relay on the outgoing Substation Hubung Gondol will work so that the ENS which was previously 40.008 kWh becomes 19,497 kWh, so that the amount of energy that is not channeled is reduced by 50% and this makes the service better.

SCADA based intake monitoring for improving energy management plan: Case study

Intake is one of the most important pumping stations in water treatment plant (WTP) and greatly effects the overall plant efficiency. Intake mainly consist of high-tension (HT) motor pump such as vertical turbine pump and submersible pump. The required power supply for intake is generally fed from the main grid through distribution company/department. At the same time, high operational cost of the diesel generator (DG) power back up source results in a huge burden. Also, internet of things (IoT) and Supervisory control and data acquisition (SCADA) based system is widely used nowadays. Therefore, study regarding monitoring strategies of intake is very important and is rarely to be found. In this paper, monitoring strategies of Greater Aizawl Water Supply Schemes phase II is studied. The main objectives are; to study and analyze pump energy consumption (viz. Feeder Current, Frequency etc.); to implement ladder logic for monitoring energy parameters using MOVEREAL. The study shows monitoring of intake energy parameters as well as the feeding substation, showing that SCADA can be efficiently used as an energy management plan.

Studi Penambahan OCR dan GFR Gardu Hubung Gondol untuk Mengurangi Gangguan Meluas Penyulang Banyupoh

At the Banyupoh Feeder there is a Gondol Hubung Substation, which has 2 outgoings, the first line goes to the Banyuwedang Feeder and the second line goes to Penyabangan. However, because there is no protection on the outgoing side, if there is a disturbance in the first section on one of the outgoing sides, it will cause 1 feeder with a total of 49 transformers to experience a blackout. To overcome this condition, it is necessary to add relays at the substation. After the addition of relays at the substation, the impedance and short-circuit current are recalculated which can be used to determine the timing of the OCR and GFR relays at the new substation for each outgoing. The calculation results are then converted into a curve to determine the coordination of the protection with the existing protection relays on incoming, outgoing and recloser in anticipating disturbances in the first section at the Banyupoh Feeding Substation. After setting the protection relay on the outgoing side of the substation, the outage area due to interference can be minimized. When section 1 of the Banyuwedang Feeder is disturbed, the relay on the outgoing Gondol Substation will work so that the Energy Not Served (ENS) which was previously 40.008 kWh becomes 20.511 kWh. If section 1 of the Feeding Feeder is disturbed, then the relay on the outgoing Substation Hubung Gondol will work so that the ENS which was previously 40.008 kWh becomes 19,497 kWh, so that the amount of energy that is not channeled is reduced by 50% and this makes the service better.

Use of AMT Transformers and Distributed Storage Systems to Enhance Electrical Feeding Systems for Tramways

Tramway systems are more and more diffused today, to reduce pollution and greenhouse emissions. However, their electrical feeding substations can have significant margin for improvement. Therefore, it is questionable which kind of changes can be introduced, by changing their main features. First of all, transformer technology can be enhanced, by moving from the standard transformer to the amorphous metal one; thus, guaranteeing a significant reduction in losses. Then, by installing one dedicated storage systems for each substation. This solution can help to increase the energy efficiency; thus, recovering the tram braking energy and reducing the delivered energy from the grid, and also the reliability of the system; thus, guarantee different levels of services, in the case of failure of a feeding substation. This paper investigates in a systematic approach the two proposed solutions. In particular an amorphous metal transformer has been properly designed, and performance compared to the standard one. Then, evaluation of distributed storage installation was performed, and the aspects of reliability for these systems evaluated. Results have shown the general feasibility of the proposed solutions, showing a significant energy saving with respect to the conventional ones.

Improvement of the Method of Calculation of Steady-State Modes of Urban Electric Networks Taking into Account Consumer Energy Sources

The method of calculation of the steady-state mode of the open city distribution electric network with small generation sources is offered. It is shown that the city electric network consists of passive and active physical elements. Passive elements include power transformers and linear regulators, overhead and cable power lines, current-limiting reactors, etc. Active elements of networks are power sources (transformer inputs of low voltage of feeding substations and distributed small generation sources) and loads, mathematical models of which can be various. Power sources in urban distribution networks of 10 kV and below are classified by type and power and can be of two kinds, viz. power feeding centers of the network and small generation sources. Consumer loads are modeled by current sources connected to network nodes. The parameters of the current sources are usually graphs of the change of the module of the actual current value and the power factor in time. The values of these parameters in single-line substitution schemes of 6–10 kV distribution networks with isolated neutral are assumed to be average for three phases. The power centers are transformer inputs of low voltage power substations of the main electric networks of 35 kV and above, equipped with digital devices of the account of the electric power connected to the automated system of control and accounting of power resources. The developed technique allows receiving the refined balanced calculation model of the steady mode of the open city network for the set time of the daily schedule. It includes the sequential distribution of the specified power of each network power supply between its loads, followed by clarification of flows and power losses in the sections, as well as voltages and actual loads in the nodes of the scheme by the overlay method.

Modelling and Simulation of Tramway Transportation Systems

Electrified guided vehicles typically face routes having a large number of acceleration and braking phases. The braking energy, since the feeding line presents nonreversible electrical feeding substations, can be recovered in the presence of other nearby vehicles. To improve braking energy recovery, one or more storage systems can be positioned along the track. Analysis of effectiveness for the considered solution requires time-domain simulation models, to be created through suitable simulation general-purpose languages or specialised languages/software. In this paper, three different tools for the considered existing tramway were developed, and the main examined characteristics have been compared to each other. Then, analysis of output results was also performed, demonstrating the real cost-effectiveness of introducing one storage device on the considered tramline in operation.

Locating lightning strikes and flashovers along overhead power transmission lines using electromagnetic time reversal

The paper presents a method to identify the location of direct lightning strikes to overhead transmission lines and potential subsequent flashover(s). The method is based on the electromagnetic time reversal theory and relies on the use of a single measurement point to record voltage transient signals originated by a direct lightning strike either on the phase conductors or shielding wires, and possible flashovers. The measurement system is supposed to be installed on the secondary winding of the transformer located at the line feeding substation. The performance of the proposed method, applicable for different power network topologies, is validated by using different numerical simulations applied to various case studies. The paper also discusses the impact of the grounding system model, high-frequency transformer model, presence of surge arresters as well as soil electrical parameters.

A new impedance-based fault location scheme for overhead unbalanced radial distribution networks

This paper proposes an analytical impedance-based fault location scheme for distribution systems. The approach is based on voltage and current measurements extracted at only one-end feeding substation. Modal transformation is implemented to decompose the coupled three phase equations due to mutual effects into decoupled ones, and hence directly calculating fault distance in each section without iterative processes. The proposed approach considers various aspects of distribution systems: intermediate loads along the feeder, tapped laterals and sub-laterals at various nodes, time varying loads, and unbalanced operations. The proposed algorithm is extensively investigated on a typical real 11kV distribution system, South Delta electricity sector, Egypt using MATLAB environment. Different cases are studied considering various loading conditions, varied fault resistance values and different fault types. The achieved results ensure the effectiveness of the proposed fault locator irrespective to fault conditions. Besides, the robustness of the proposed scheme against unbalanced loading, network topology change and non-homogenous network sections is also confirmed.

Optimal power flow with storage in DC electrified railways

Purpose Due to the increase of the traffic, issues are appearing on DC electrified railway feeding systems. One candidate solution to solve these issues and to improve their performances is to add storage systems in the railway DC electrical network. The paper presents a method based on an Optimal Power Flow (OPF) for the analysis and design of DC railway feeding systems with storage. Design/methodology/approach The paper describes a new methodology based on optimization to study DC electrified railways, including storage systems. A load flow model of a DC 1500V railway electrification system is presented, including the mobility of the train sets. Then, an Optimal Power Flow model of the DC network, including energy storage systems and feeding substation rectifiers has been developed. Finally, the OPF model has been tested on a real application case showing its benefits while searching solutions in order to improve the network performances. Findings An OPF model suitable for analysis of DC networks with storage is presented. It shows its ability to solve large scale problems. Research limitations/implications The paper focuses on the physical model of the network. The optimization model will have to be extended with application constraints. Originality/value The hypothesis presented in this paper allows to remove the discontinuities of the system in order to use a continuous optimization approach.

A bi-objective maintenance scheduling for power feeding substations in electrified railways

Railway infrastructure is characterized by intensive capital investment, long lifecycle and low return. It is crucial to attain a reasonable system reliability while keeping the recurrent cost manageable throughout the asset lifecycle. Power feeding substations are the key assets on electrified rail lines. As they are subject to various adverse operating conditions, maintenance works of different levels are scheduled to ensure reliability and extend the asset life time if possible. Maintenance scheduling is often regarded as a trade-off between reliability and cost. This study incorporates considerations of different levels of maintenance activities to balance between reliability and cost. In establishing the system reliability model, the contribution of individual component reliability toward the overall system reliability is extracted from the functional relationship among the components. Solution methodologies to this scheduling problem are also proposed here. Evaluation of the scheduling model and the proposed solution is discussed and analyzed through simulation. To cater for the operating conditions in different systems, the impact of weighting factors between reliability and cost on the variations of resulting schedules will be investigated.

절연구간 자동통과 열차검지시스템 개발 및 성능시험

A neutral section is installed around feeding substation(SS) and sectioning post(SP) that M phase and T phase are isolated in AC feeding system. Electric Train under Notch-OFF is operated by inertia within the neutral section. It causes disturbing the operation of electric trains for speed drop and driver`s mistakes. A automatic changeover system with thyristor recently have taken under development. In the paper, it is introduced the configuration of train detection system and performance testing on automatic changeover system..

Technology Trend in DC Feeding Substation of Private Railways

Technology Trend in DC Feeding Substation of Private Railways

Electronic Frequency Converter Feeding Single-Phase Circuit and Controlling Feeder Voltage With Fixed Power Factor Method for Shinkansen

In the Tokaido Shinkansen, the instantaneous feeding power of substations has increased because of the high-density train schedule and the improved acceleration performance of the rolling stock. If the load power of feeding substations increases any further, it will not be possible to maintain the feeder voltage when the power converter supplies only reactive power. In consideration of such a situation in the frequency conversion section, an electronic frequency converter that controls the ac voltage using a fixed power factor method was developed. The superiority of the proposed control method is confirmed with electromagnetic transient program calculations and field test results. The electronic frequency converter has been in operation since February 2009 with good performance, showing the success of the system development described in this paper.

Preliminary evaluation of the energy-saving effects of the introduction of superconducting cables in the power feeding network for DC electric railways using the multi-train power network simulator

Thanks to the recent developments, the superconducting cables using high-temperature superconducting (HTS) materials are now expected to reduce feeding losses in the power supply network for DC electric railways. However, by connecting the HTS cables with the normal conducting wires electrically, heat intrusion is inevitable; to suppress heat intrusion to an acceptable level, interconnection becomes a large and costly installation. This means that the use of HTS cables as the replacement for normal conducting feeder wires in the DC railway feeding network is unrealistic because of the need for frequent interconnections between the feeder and contact wires. By combining the results obtained by a number of cases of multi-train simulation and a preliminary estimate of the refrigeration losses, the author shows that, by using HTS cables to replace some of the feeding substations, rather than the feeder wires, the introduction of HTS cables in the feeding network of DC electric railways may have positive effects of saving energy.

Modelling the magnetic field caused by a dc-electrified railway with linearly changing leakage currents

Magnetic fields produced by dc railways can disturb operations at geomagnetic observatories. These magnetic fields consist of two parts: the ideal “full-loop” field due to the traction current in an overhead wire and in the rails, and the “leakage” field due to currents leaking from the track into the ground. Pirjola et al. (2007) present formulas with numerical examples for the magnetic field assuming a constant leakage current density between the train and the feeding substation. Lowes (2009) considers this assumption questionable. In this paper, we derive exact formulas for the magnetic field assuming that the leakage current density changes linearly being largest at the train and decreasing to zero at the substation. The Earth is considered layered. Computer codes enable calculations of the magnetic fields due to any number and configuration of the train-substation pairs at any points of observation. Numerical examples show that the value of 10 pT can easily be exceeded. An important conclusion is that the magnetic fields in the cases of a linearly changing and a constant leakage current density do not differ much. Particular attention is paid to the temporal behaviour of the magnetic field when one or two trains travel along a railway.

Electronic Frequency Converter Controls A. C. Voltage Using Fixed Power Factor Method

In Tokaido Shinkansen, the power of a feeding substation increases in a short time because the train schedule is of high density and the acceleration performance of the rolling stock has improved. If the load power of the feeding substation increases further, the feeder voltage cannot be maintained when the power converter supplies only the reactive power. Because such a case was assumed in the frequency conversion section, we developed the Electronic Frequency Converter controls the A. C. voltage using the fixed power factor method. The Electronic Frequency Converter is under construction in the Numazu frequency conversion substation. We describe the domination of A. C. voltage control using the fixed power factor method.

Modelling the disturbance caused by a dc-electrified railway to geomagnetic measurements

Abstract Magnetic fields created by a dc-electrified railway are a nuisance to the operation of a geomagnetic observatory and also disturb other electromagnetic studies. Theoretical formulas that enable quantitative estimates of the magnetic effect of a dc railway including leakage currents in the ground are presented in this paper. They are illustrated by numerical examples. The validity of the theoretical model was verified by measurements carried out in the vicinity of a nearly north-south railway in Calgary, Canada. The earth structure in that area is approximately layered, which is an assumption included in the theoretical model. The agreement between the measured magnetic fields due to trains and the theoretical values is good. Numerical computations indicate that magnetic fields larger than the maximum allowable noise level (assumed to be about 10 pT) at today’s magnetic observatories may extend to distances of tens of kilometres from a railway. We have prepared computer programs based on the theoretical formulas in the MatLab, Octave, FORTRAN and IDL languages, in which the locations (i.e. the latitudes and the longitudes) of the point of observation, of the feeding substations and of the trains, together with the feeding and leakage currents and the heights of the feeding lines, can be given as inputs.

전기철도 급전시스템의 순시전압강하 보상을 위한 단상 배전 STATCOM의 적용

AC 전기철도 시스템은 동적 단상부하가 빠르게 변화하고, 전철 급전변전소에서 3상 전력을 단상 전력으로 변환한다. 이것은 일반 배전 시스템과 비교해서 AC 전기철도 시스템의 전기적인 현상들이 다르다는 것을 나타낸다. AC전기철도 열차부하의 전기적인 특성은 동적부하의 운영과 운행 스케쥴, 트랙의 구배 등에 따라 연속적인 변화를 받고 있다. 이와 같은 열차부하의 운영에 따른 급전거리가 길어 전압강하, 전압 불평형 및 고조파 왜곡현상 등의 전력품질 저하요인이 발생하게 된다. 이러한 문제점은 상위계통인 송전시스템의 안정도에 악영향을 줄뿐만 아니라, 전기철도 급전시스템의 전력품질 저하, 전기철도차량의 통신장비, 운행 및 수송량 제한에도 영향을 미치게 된다. 따라서 본 논문에서는 전기철도시스템의 과도상태 평가를 위해 PSCAD/EMTDC를 이용한 평가모델을 제시하고, 전압 강하에 주안점을 두어, 전기철도 급전시스템의 말단 분기점(Sectioning Post)에 정지형 무효전력 보상장치인 단상 배전 STATCOM(Single-phase Static Synchronous Compensator)을 설치하여 그 작용에 따른 전압강하 보상을 평가하였다.

인천 국제공항청사 경전철 도입에 따른 고조파 영향 분석

최근 전기철도에 고속화 기술이 적용되고 열차 구동장치 및 제어계통에 전력용 반도체 소자가 사용되고 있으며, 전기철도 구동시스템의 주요 구성장치인 인버터와 컨버터의 동작을 제어하는 전력전자 소자의 이용은 고조파를 발생의 원인이 된다. 이러한 고조파는 통신장해 및 전류, 전압의 전력품질 저하 등 여러 가지 문제를 발생시킨다. 따라서 본 논문에서는 인천 국제공항에 설치되고 있는 경전철 전력설계의 전력시스템 평가 및 개발을 통해 상위 계통에 미치는 영향 및 전력시스템에서 발생할 수 있는 장애 요인을 사전에 예측 계산하여 이에 대한 대책을 마련하여 전력품질 향상에 목적이 있다. 인천 국제공항청사 내의 전력시스템의 전력품질 문제 접근에 있어 경전철이 운행될 경우 발생할 수 있는 여러 문제 중 특히 전압강하 및 전압불평형에 영향을 미치는 고조파 발생에 대해 분석하였다. 고조파 분석은 IEEE 519-1992(IEEE 141-1993과 동일) 기준에 의거하여 행하였다. 또한 인천 공항청사의 운행되는 경전철은 동적 전력시스템 해석 프로그램인 PSCAD/EMTDC 모델링하고 이의 시뮬레이션 결과를 이용하여 고조파 분석을 하였다.