Electrical Distribution Circuits Research Articles

Modeling and Simulation of Distribution Networks with High Renewable Penetration in Open-Source Software: QGIS and OpenDSS

There are important challenges in modeling large electrical distribution circuits, especially with the presence of distributed renewable generation. Constructing simulations to assess the effect of the penetration of distributed generation on electrical distribution networks has become of great importance for Distribution Network Operators (DNOs). This paper proposes a simulation strategy based on open-source platforms and the integration of scripting tools for the rapid modeling of large-scale electrical distribution circuits with distributed renewable generation. The implementation is based on the adaptation of a tool called QGIS2OpenDSS, which creates OpenDSS distribution network models directly from an open-source geographic information system, QGIS. The plugin’s capabilities are demonstrated using a real distribution feeder with more than 60% penetration of renewable generation based on photovoltaic systems. These simulations are carried out using real data from a circuit provided by a DNO in the Dominican Republic, which is used to demonstrate how this approach provides a more accessible and flexible way to simulate and assess the effect of Distributed Energy Resources (DERs) in medium voltage (MV) and low voltage (LV) networks, enabling utilities to evaluate system performance and identify potential issues. The integration of this open-source tool within the DNO software stack enables users to apply it according to specific project needs, enhancing their capability to analyze and manage high DER penetration levels, aiding in better planning, operation, and decision-making processes related to renewable energy projects.

A transparent broadband flexible metamaterial absorber for radar infrared-compatible stealth

The iterative upgrading of the means of warfare has promoted the development of detection technology, and military activities are increasingly demanding target stealth. In this paper, a multifunctional metamaterial absorber is recommended, which simultaneously realizes the integrated stealth functions of ultra-wideband radar wave absorption, low infrared emission, and optically transparent. The structure is composed of an infrared shield, a radar-absorbing layer, and a reflective layer. Simulation results indicate that the absorption bandwidth in the radar band (1.81–20.4 GHz) is more than 90%, and the infrared emissivity is as low as 0.271 in the IR band (3–14 μm). Moreover, it has the features of flexibility, angle stability (0–45°), polarization insensitivity (0–90°), and so on. Furthermore, the electric field current distribution and equivalent circuit model of the structure are analyzed, and a 180 mm*180 mm sample is built and tested; the results show that the simulated and actual measurements are in agreement, and it is expected that such absorbers will be used in areas such as aircraft.

A Novel Shield Gate 4H-SiC MOSFET with Reduced Reverse Recovery Losses

In this work, a novel integrated shield gate 4H-SiC MOSFET structure, which is mainly used to reduce the reverse recovery losses of the device, is proposed. Compared with integrating Schottky barrier diode or heterojunction diode in the device to reduce reverse recovery losses, the technology of introducing field plates in MOSFETs is more mature and economical. At the same time, the new structure studied ensures the gate oxide reliability of the 4H-SiC trench gate. According to the simulation of the electrical characteristics of the source-contacted shield gate device, the effects of multiple factors such as electric field distribution, carrier concentration, and peripheral circuit are comprehensively discussed, the phenomenon of smaller reverse recovery losses caused by the shield gate explained in detail. Compared with the conventional structure device, the peak reverse current, the peak overshoot voltage, and the reverse recovery losses for the source-contacted shield gate MOSFETs are reduced by 81.4%, 77.1%, and 65.1%, respectively.

Distribution Transformer Loading: Probabilistic Modeling and Diversity Factor

For planning purposes, the loading of assets in electric power distribution circuits is often modelled in terms of a diversified load. The temporal and probabilistic nature of the load is a sum of several individual loads of various levels and characteristics. The diversity factor of such circuits is the ratio of the sum of the individual non-simultaneous load asset ratings energized by that circuit to the total peak simultaneous demand. The diversity factor is temporal and probabilistic in nature. In this paper, the probability density of the load factor is described and modelled for power distribution loads. The model used is the ratio of two dependent bivariate normal random variables. The resulting probability density is termed a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ratio density</i> and a recent algebraic formulation of the ratio density is used. The probabilistic model is compared to results obtained by others. The potential impact of electric vehicle charging loads is applied to the sizing of distribution power supply assets using diversity loading strategies for Level 1 and single phase Level 2 EV chargers. The probabilistic method is offered as an added tool to the conventional, fixed diversity factor method in distribution engineering.

Analysis of design and structural features of the external insulation materials of high-voltage devices

In the article, the authors have analysed the design and structural features of various materials for external insulation of high-voltage apparatuses, namely, high-voltage equipment of stations and substations. The operational reliability of the external insulation is determined mainly by the electrical load, which is characterized by the local values of the field strength. The field strength along the insulating cover is distributed very unevenly and has a maximum value near the electrode with high voltage. Electrical isolators are used in all high-voltage apparatus of electrical transmission and distribution circuits to separate the voltage from the ground. The materials used in the development and production of electrical insulators have certain unique characteristics. These materials prevent the free passage of internal electric charges in the material, which makes it practically impossible to conduct an electric current. The ability of a material to prevent electrical conductivity is characterized by its dielectric strength. Polymer insulators allow you to combine high mechanical strength with satisfactory electrical characteristics. In such combined structures, fiberglass rods or cylinders are used as an element that withstands mechanical load. Also, the design of the internal insulation of the capacitor type, impregnated and filled with hardened epoxy resin, allows for particularly precise winding of the synthetic material and the placement of aluminium foils, which provide the capacitive levelling of the graduation and are necessary for the control and formation of the electric field. Such a field is controlled in such a way as to optimize the dimensions, mass and electrical characteristics of the high-voltage apparatus depending on the voltage class and other parameters. The protective polymer coating provides high electrical characteristics of insulators under operating conditions. It is known that during the operation of the high-voltage device, the aging rate of the external insulation is additionally enhanced due to the complex and heterogeneous structure of the insulating cover itself, as well as the influence of the surrounding environment and weather conditions. The main element of external insulation is the supporting insulating cover, in the middle of which the elements of the active part of a certain electrical device are placed. Its basis is usually a glass-epoxy cylinder (this ensures the mechanical stability of the structure), on which ribs made of organosilicon rubber are placed, which in turn ensures the electrical strength of the external insulation.

Two-Stage Distribution Circuit Design Framework for High Levels of Photovoltaic Generation

Present-day radial electric power distribution circuit faces multiple challenges due to the increased photovoltaic (PV) generation. This paper aims to examine and design modern distribution circuit topologies for accommodating high PV penetration, while addressing power quality concerns. The central hypothesis of the proposed design approach is that by decreasing the Thevenin impedance at the buses where PVs are connected, the impacts on feeder voltages due to PV generation become less pronounced thereby additional PV capacity can be integrated at the corresponding buses. A novel two-stage optimization framework is proposed. The first stage is a mixed-integer linear programing based formulation to design new optimal configuration for any given distribution circuit. The formulation allows the possibility that the circuit can be operated in either a radial or loop configuration. The second stage, a nonlinear programing based formulation, then finds PV hosting capacity for the identified optimal configuration. The proposed two-stage framework is evaluated for IEEE 123-bus test feeder. It is demonstrated that the PV hosting capacity of the feeder can be increased by 53% by optimally adding two new distribution lines with tie-switches.

Availability-Based Distribution Circuit Design for Shipboard Power System

The electric distribution circuit design problem has been primarily approached from the perspective of minimizing circuit losses. Motivated by the requirement for higher service continuity, we propose a graph theory based approach for the distribution circuit design problem. A mathematical formulation for designing a resilient circuit topology aiming to minimize the number of conductors while satisfying a given network availability constraint is developed first. A computationally efficient algorithm, termed successive minpath generation to solve the formulated topology design problem is proposed next. The proposed algorithm reduces the double exponential search space for the resilient circuit topology to polynomial time allowing a tractable solution for the topology design problem. The algorithm is applied to design the circuit topology for the zonal electric distribution (ZED) circuit of an all-electric ship supplied by single as well as multiple power sources. Compared with grid topology, the proposed approach results in circuit topologies with network availability more than 0.99 by using 3 fewer and 12 fewer conductors for a 15-node and a 30-node ZED, respectively.

Design of High-Rise Building’s Monitoring System for Electric Fire Base on CAN Bus

This paper accomplished a system of high-rise building’s fire monitoring system based on CAN bus. It is applied in avoiding the harm of leakage current , over current and short circuit, and protecting electric power distribution circuits and electrical equipment, thus to prevent the occurrence of electrical fire. The monitoring system can detect phase current signal and the leakage current signal, and can display real-time and alarm. It also can proceed network service and complete the distributed remote control and fault diagnosis. Practice shows that the system the characteristics of high precision, safe and reliable, low rate of false positives, easy operation and maintenance, etc .It can satisfy the demand of large high-rise building electrical fire.

Options for Control of Reactive Power by Distributed Photovoltaic Generators

High-penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit present several challenges and opportunities for distribution utilities. Rapidly varying irradiance conditions may cause voltage sags and swells that cannot be compensated by slowly responding utility equipment resulting in a degradation of power quality. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g., by minimizing thermal losses. We discuss and compare via simulation various design options for control systems to manage the reactive power generated by these inverters. An important design decision that weighs on the speed and quality of communication required is whether the control should be centralized or distributed (i.e., local). In general, we find that local control schemes are able to maintain voltage within acceptable bounds. We consider the benefits of choosing different local variables on which to control and how the control system can be continuously tuned between robust voltage control, suitable for daytime operation when circuit conditions can change rapidly, and loss minimization better suited for nighttime operation.

NOVEL PLANAR MULTIMODE BANDPASS FILTERS WITH RADIAL-LINE STUBS

This paper presents a novel approach for designing planar multimode wideband bandpass fllters with good selectivity. The multimode resonator is composed of an open-ended microstrip line with length of half-wavelength (‚=2) and several radial-line stubs. By using difierent kinds of radial-line loaded stubs, difierent kinds of responses including three-pole and four-pole bandpass fllters can be realized. Depending on electric fleld distribution and equivalent circuit model, the characteristics of the fllter are analyzed. To verify the proposed method, two fllters are implemented. The measured results exhibit good agreement with the simulation.

Power factor and your electrical utility bill in egypt

Beside being a good neighbor and not causing harmonic voltage for others that are connected to your electrical distribution circuit, complying with the legal requirements of IEEE standards 519, and maintaining safe and economical operating environments for electrical equipment within your physical load, there is another very good reason to maintain a good power factor: saving money on your electrical utility bill. Utilities often encourage consumers to maintain a high PF by applying tariff clauses, which penalize consumers for low PF. This letter discusses the topic.

Standard levels of energy losses in primary distribution circuits for SCADA application

The reduction of energy losses in distribution systems is an important issue during planning and operation with important technical and economical implications. The standard or normal level of energy losses in primary distribution circuits represents an important indicator for the planning and operation of electrical distribution circuits. It depends upon a number of parameters and variables such as the nominal circuit voltage, the installed transformer capacity, the number of transformation points, the load level, etc. In this article the application of a statistical procedure for the determination of the standard levels of energy losses in primary distribution circuits is proposed. The methodology is applied to a subset of 312 primary distribution circuits out of the total of 819 circuits of the electrical distribution network that serves the city of Caracas and its surroundings. The resultant standard upper and lower levels of energy losses are presented for the 15 different groups of circuits that were formed by the statistical procedure. These limits are used online for the identifleation of those distribution feeders with an operating level of energy losses out of the standard levels of its correspondent statistical group, as candidates for the application of energy losses reduction measures. The developed application software is presently running on-line at the distribution energy management system of the of C.A. La Electricidad de Caracas-AES Venezuela.

Standard Levels of Energy Losses in Primary Distribution Circuits for SCADA Application

The reduction of energy losses in distribution systems is an important issue during planning and operation with important technical and economical implications. The standard or normal level of energy losses in primary distribution circuits represents an important indicator for the planning and operation of electrical distribution circuits. It depends upon a number of parameters and variables such as the nominal circuit voltage, the installed transformer capacity, the number of transformation points, the load level, etc. In this article the application of a statistical procedure for the determination of the standard levels of energy losses in primary distribution circuits is proposed. The methodology is applied to a subset of 312 primary distribution circuits out of the total of 819 circuits of the electrical distribution network that serves the city of Caracas and its surroundings. The resultant standard upper and lower levels of energy losses are presented for the 15 different groups of circuits that were formed by the statistical procedure. These limits are used online for the identifleation of those distribution feeders with an operating level of energy losses out of the standard levels of its correspondent statistical group, as candidates for the application of energy losses reduction measures. The developed application software is presently running on-line at the distribution energy management system of the of C.A. La Electricidad de Caracas-AES Venezuela.

Field results for a distribution circuit state estimator implementation

Distribution automation encompasses functions that rely on knowledge of the state of the distribution circuit in real-time. This paper presents field results for a distribution circuit state estimator that was implemented on an electric utility distribution circuit. The state estimation algorithm is based on a probabilistic radial power flow approach that incorporates real-time measurements as solution constraints. A load modeling technique based on using customer billing information and daily load profiles is used to provide needed load estimates. This paper provides an assessment of how accurately the developed state estimation algorithm is able to predict circuit states. The improvement in circuit estimates as a function of available feeder measurements is illustrated as well. Finally, difficulties encountered with implementing an actual distribution state estimator are discussed.

Twenty-five years of progress in vacuum arc research and utilization

Progress in understanding and applying vacuum arcs is reviewed. Laser diagnostics have demonstrated the existence of micron-sized regions in the cathode spot plasma having electron densities exceeding 10/sup 26/ m/sup -3/. The expanding plasma produces a highly ionized jet whose ions typically have charge states of 1-3 and energies of 50-150 eV. Gas dynamic and explosive emission models have been formulated to explain cathode spot operation. In cases where the arc is constricted at the anode, forming an anode spot, or the anode is thermally isolated, forming a hot anode vacuum arc, material emitted from the anode may dominate the interelectrode plasma. Evaporation from liquid droplets may also provide a substantial component of the plasma, and the presence of these droplets can have deleterious consequences in applications. The vacuum arc has been extensively utilized as a plasma source, particularly for the deposition of protective coatings and thin films, and as a switching medium in electrical distribution circuit breakers.

Tree-Caused Electric Outages

In 1995, Eastern Utilities was among 14 utilities in the United States and Canada participating in a study to collect and evaluate data about the phenomena of how trees cause outages. Results indicate that failure of trees accounted for 40% of the preventable tree-caused outages in the Brockton territory of Eastern Utilities. Even though line clearance tree trimming continues to be the primary strategy, programmatic changes were made in Eastern Utilities' Tree Management Program. A Danger Tree Project was initiated to identify and mitigate trees with structural weaknesses along the 3-phase portion of the electrical distribution circuits. Approximately 4% of the trees in the portion of the urban forest managed by Eastern Utilities will either be removed or stormproof pruned. Reliability has improved by 20% to 30% along the circuits where hazardous trees have been removed or storm-proof pruning has been done. Proactive communication within the community and participation in communitybased tree planting has accompanied this project.

Communication Using Pseudonoise Modulation on Electric Power Distribution Circuits

Localized communication networks for office automation, security monitoring, environmental management of buildings, computer communications, and other applications enjoy every increasing demand. This paper considers communication of data and analog message signals over electric power distribution circuits for such applications, using pseudonoise (PN) modulation. Advantages of power distribution circuits include reasonably universal coverage and easy access via a standard wall plug. Disadvantages include limited communication bandwidth, relatively high noise levels, and varying levels of impedance, noise, and attenuation. PN (spread-spectrum) signaling provides immunity to narrow-band signal impairments and casual eavesdropping, multiplexing capability, addressing capability, and easily implemented error rate versus data rate tradeoffs. The primary disadvantage is synchronization delay and hardware cost normally associated with PN code synchronization at the receiver. Our prototype modem avoids these difficulties by using the 60 Hz power line frequency for carrier, code, and data-bit synchronization. Design issues discussed include processing gain optimization, modem impedance specification, carrier frequency selection, and PN code selection. Prototype modem circuitry costing less than $30.00 is described. Measurements on actual power distribution circuits indicate a bit-error probability p = 10^{-4} or less at data rate R_{B} = 6 kbits/s for single users or at R_{B} = 60 bits/s for M \simeq 22 simultaneous users. Performance calculations for analog message signals are included.

Portable Power Supply for High-Speed Cameras

A new portable power supply has been designed for operation of high-speed cameras in temporary locations. Objective was to have a mobile operational unit which could be taken to test site and placed in service quickly, with all necessary electrical power obtained from the plant's 3-phase power systems. An enclosed trailer contains a permanent installation of transformers, electrical distribution systems and circuit controls, and provides storage space for cameras and accessories. The cameraman's remote panel which controls operation of lights, cameras and test event can also function as control center for complete test program and all instrumentation.

Discharge currents in distribution arresters

With a view to augmenting the meager data available on the discharge currents through lightning arresters on electric power distribution circuits, the investigation reported in this paper, which covered 4 power systems of various voltages and in different sections of the country, was undertaken. Over the range of circuit voltages involved in this investigation (4 to 24 kv) voltage rating seemed to have no definite influence on the discharges. More negative than positive discharges were recorded, the ratio increasing as the discharge current increased. The maximum current recorded was 17,000 amperes.

Discharge Currents in Distribution Arresters

With a view to augmenting the meager data available on the discharge currents through lightning arresters on electric power distribution circuits, the investigation reported in this paper, which covered 4 power systems of various voltages and in different sections of the country, was undertaken. Over the range of circuit voltages involved rating seemed to have(4 to 24 kv) voltage on the discharges. More negative than positive discharges were recorded, the ratio increasing as the discharge current increased. The maximum current recorded was 17,000 amperes.