Feeder Head Research Articles

Research on Data-Driven Fault Scenario Simulation Model of Distributed Network

Distribution lines are critical components of today's power system, and can directly impact on power supply security and stability. An effective power system protection system should detect any faults as soon as they occur. There are two steps in fault diagnosis. One is defect classification, which has already achieved excellent accuracy rates. As a result, this study concentrates on the opposite objective, which is fault location. This research introduces a War Strategy Water Wave Optimization (WSWWO) based Deep Q Network for radial distribution networks using synchronous generators for Distributed Generation (DG). The algorithm estimates the fault site by analyzing voltage and current samples at the main feeder head, and scheduled active and reactive power injections by network synchronous generators. A full-order synchronous machine model was utilized to analyze the dynamic behavior of DG plants during fault transients. Here, the Deep Q Network is trained by WSWWO, and hybridized by two optimization algorithms, War Strategy Optimization (WSO) and Water Wave Optimization (WWO). Furthermore, the experimental results revealed that the WSWWO-Deep Q Network outperformed state-of-the-art models in terms of Accuracy and Error, with values of 0.997 and 0.141, respectively.

Thermal-Electric Modeling: A New Approach for Evaluating the Impact of Conservation Voltage Reduction on Cooling Equipment

It has been suggested in the literature that by reducing the incoming voltage at a distribution feeder head or at the supply side of buildings, significant electricity savings can be achieved. This technique is called Conservation Voltage Reduction (CVR). Data-based analysis with and without CVR is primarily used to support such assertions, which does not explain the physics behind reduction in energy consumption with CVR. This paper presents a new approach for evaluating the impact of CVR on cooling equipment. In this approach, a thermal-electric model of the cooling process is developed in MATLAB’s SIMSCAPE toolbox that can be used to explain the physics behind energy reduction with CVR. This model includes an accurate model of a compressor coupled to an induction motor whose supply voltage can be varied to simulate CVR. Simulations performed using this model show that the Coefficient of Performance (COP) of cooling equipment improves with a reduction in supply voltage. However, the energy lost in the motor windings may nullify the impact of the improvement in the COP and render the CVR programs ineffective if the range of speed change is small over the allowable voltage change. The simulation results show an increase in energy consumption of 4% at 90% rated voltage compared to the energy consumed at the rated voltage. However, if variable frequency drives-based cooling equipment is appropriately controlled, it is possible to reduce their net energy consumption using CVR. Simulations performed keeping the ratio of the supply voltage and the frequency constant showed a reduction in energy consumption of 2.5% at 90% rated voltage compared to the energy consumed at the rated voltage. Thermal-electric modeling of building cooling equipment is, therefore, vital to accurately evaluating the benefits of CVR as smart, power electronics-based end-use equipment is globally adopted.

Detailed Primary and Secondary Distribution System Model Enhancement Using AMI Data

Reliable and accurate distribution system modeling, including the secondary network, is essential in examining distribution system performance with high penetration of distributed energy resources (DERs). This paper presents a highly automated, novel method to enhance the accuracy of utility distribution feeder models to capture their performance by matching simulation results with corresponding field measurements. The method is demonstrated using an actual feeder from an electrical utility with high penetration of DERs. The method proposed uses advanced metering infrastructure (AMI) voltage and derived active power measurements at the customer level, and data acquisition systems (DAS) measurements at the feeder-head, in conjunction with an AC optimal power flow (ACOPF) to estimate customer active and reactive power consumption over a time horizon, while accounting for unmetered loads. The ACOPF uses the measured voltage magnitudes, derived active power measurements, and the feeder head measurements to obtain a complete active power and reactive power capture of the feeder loads. Additionally, the method proposed estimates both voltage magnitude and angle for each phase at the unbalanced distribution substation. The accuracy of the method developed is verified in two stages: by comparing the time-series power flow results obtained from the enhancement algorithm with OpenDSS results and with the field measurements available. The proposed approach seamlessly manages the data available from the optimization procedure through the final model verification automatically.

State Estimation for Medium- and Low-Voltage Distribution Systems Considering Measurement Characteristics and Grounded Slack Bus

The medium voltage (MV) and low voltage (LV) distribution systems are usually built in a mixed three-phase three-wire and three-phase four-wire pattern, in which the conventional measurements are obtained through the two-wattmeter method (TWM) and three-wattmeter method (HWM). The existing three-phase state estimation (SE) models only involve the measurement characteristics of the HWM. Instead, a set of new and improved measurement equations are formulated in this paper for such buses measured by TWM, and the measurements include line-to-line complex power and virtual zero-sequence current. Along with the increasing underground cable, the neutral point of MV feeder head is normally grounded through a small resistance, and its voltage magnitude is not equal to zero. Accordingly, an accurate model for the slack bus together with its measurement equations is proposed herein, based on the conventional measurements and neutral point virtual measurement. Moreover, this work presents a three-phase SE model for MV and LV distribution systems that incorporates the constraints of zero-sequence current and zero injection, in combination with the exponentially weighted least squares method. The test results of the IEEE 34 bus system and IEEE 123 bus system verify that the proposed formulation takes full advantage of the measurements and structural characteristics of practical distribution networks, and simultaneously boosts the estimation accuracy.

An efficient fault diagnostic approach for active distribution networks considering adaptive detection thresholds

As support to fault location algorithms, this paper presents a new method for detecting and classifying faults in active distribution networks using the energy moving averages of the current signals measured at the feeder head. A proposal for updating the energy thresholds for fault detection is introduced, aiming to achieve higher sensitivity in fault detection, especially for scenarios with high penetration levels of distributed generation (DG). Since the power injected by DG can rapidly change, this proposal is essential for maintaining the fault detection method’s reliability. Also, the fault classification is based on an analytical approach, making it possible to be easily applied to different operating scenarios of a distribution system. Thus, its potential for real-world implementation is higher when compared to classifiers based on supervised learning algorithms. Performance tests on the IEEE 34-node test feeder showed that this method is reliable for detecting and classifying different fault types, with diverse generation-load scenarios and noisy signals.

A framework to measure the technical, economic, and rate impacts of distributed solar, electric vehicles, and storage

This study explores the joint impacts across the power system of distributed energy resources (DER) that could be deployed in utility distribution systems through an analysis of generation, transmission, and distribution expansion and costs driven by DER adoption. We identify six adoption scenarios that combine deployment levels of rooftop solar photovoltaic modules (PV), electric vehicle charging (EV), and battery storage in residential and commercial customers connected to representative feeders in Indiana by 2025 and 2040. Indiana is a good proxy for many U.S. states with low current DER adoption but potentially high future growth. The economic value of DER is assessed by developing capacity expansion and power flow analysis of the generation and distribution segments, respectively, under future hourly demand assumptions based on each adoption scenarios. Results for the distribution system power flow simulations show that voltage violations are relatively rare. Voltage violations can be mitigated at a very low cost using a combination of smart inverters in future rooftop PV systems and voltage adjustments in the feeder heads. Line loading issues are minimal, with only 0.2% of simulation hours showing loading levels above 100% of capacity. Generation capacity impacts are driven by unmanaged EV charging and could be mitigated with charging management. We estimate that the incremental rate impact from power system investment and operation of increased DER adoption in Indiana will be between −1.6% to + 2% in 2025 and + 0.2% to + 15% in 2040 relative to the base case.

Interphase Power Flow Control via Single-Phase Elements in Distribution Systems

The capability of routing power from one phase to another, interphase power flow (IPPF) control, has the potential to improve power systems efficiency, stability, and operation. To date, existing works on IPPF control focus on unbalanced compensation using three-phase devices. An IPPF model is proposed for capturing the general power flow caused by single-phase elements. The model reveals that the presence of a power quantity in line-to-line single-phase elements causes an IPPF of the opposite quantity; line-to-line reactive power consumption causes real power flow from leading to lagging phase while real power consumption causes reactive power flow from lagging to leading phase. Based on the model, the IPPF control is proposed for line-to-line single-phase power electronic interfaces and static var compensators (SVCs). In addition, the control is also applicable for the line-to-neutral single-phase elements connected at the wye side of delta-wye transformers. Two simulations on a multimicrogrid system and a utility feeder are provided for verification and demonstration. The application of IPPF control allows single-phase elements to route active power between phases, improving system operation and flexibility. A simple IPPF control for active power balancing at the feeder head shows reductions in both voltage unbalances and system losses.

A Data-Driven Pivot-Point-Based Time-Series Feeder Load Disaggregation Method

The load profile at a feeder-head is usually known to utility engineers while the nodal load profiles are not. However, the nodal load profiles are increasingly important for conducting time-series analysis in distribution systems. Therefore, in this paper, we present a pivot-point based, two-stage feeder load disaggregation algorithm using smart meter data. The two stages are load profile selection (LPS) and load profile allocation (LPA). In the LPS stage, a random load profile selection process is first executed to meet the load diversity requirement. Then, a few pairs of pivot points are selected as the matching targets. After that, a matching algorithm will run repetitively to select one load profile at a time for matching the reference load profile at the pivot points. In the LPA stage, the LPS selected load profiles are allocated to each load node on the feeder considering distribution transformer loading limits, load composition, and square-footage. The proposed method is validated using actual data collected in a North Carolina service area. Simulation results show that the proposed method can generate a unique load shape for each load node while match the shape of their aggregated profile with the actual feeder head load profile.

Separating Feeder Demand Into Components Using Substation, Feeder, and Smart Meter Measurements

Real-time, feeder-level energy disaggregation seeks to separate the measured total demand of a distribution feeder into components (e.g., into the aggregate demand-responsive load and remaining demand on the feeder, or into the aggregate generation and demand on the feeder). It can benefit distribution system operators and demand response providers by providing real-time information about balancing reserve requirements or the aggregate demand-responsive load, among other applications. In this work, we develop a feeder-level energy disaggregation algorithm that uses measurements from multiple sources that are available on different timescales. The algorithm is based on online learning and uses sensor fusion to incorporate output equations associated with disparate active and reactive power flow measurements, complex bus voltage measurements, and residential smart meter measurements. The algorithm also uses distribution substation measurements. Case studies simulate a three-phase distribution feeder model with unbalanced loads, where the active and reactive demand of the loads are modeled as a function of voltage and temperature. These models are parameterized using real-world active power demand data at each time-step. Results indicate that disaggregating three demand components is possible using feeder head active power measurements, that including feeder head reactive power measurements improves disaggregation accuracy by 32% on average, and that including intermittent real-time smart meter measurements further improves disaggregation accuracy.

Distributed Photovoltaic Generation and Impact on Voltage Profiles of Distribution Feeders

Distributed Photovoltaic applications bring considerable benefits to the distribution network, especially in regions with high irradiation levels. This work contributes to the efforts of adapting Distributed Photovoltaic applications in Iraq, as it has high irradiation levels. The development of a Photovoltaic physical model for Distributed Photovoltaic installations under actual weather conditions has been presented. Additionally, the impact of Distributed Photovoltaic installations connected at downstream points of distribution feeders on the voltage profile along those feeders has been discussed. Based on that, a suitable procedure to assess this impact has been developed under four different scenarios. A case study of the existing 11 kV feeder in Baghdad has been used to apply the developed procedure by considering different scenarios of Distributed Photovoltaic integration. The case study concluded no over-voltage issues along the feeder, even with the extreme conditions of applied scenarios, related to voltage level at the feeder head, capacity and location of the Distributed Photovoltaic plant, and load/ Distributed Photovoltaic profiles of summer and winter.

An Investigation of Ingots Teemed under Different Thermal and Physical Solidification Conditions and the Analysis of Metal Quality of the Hollow Forgings Produced

Optical and electron microscopy are used in the paper to analyze the quality of the cast metal of a 1.53 ton ingot of steel 38ХН3МФАteemed with a cooling feeder head. In addition, the analysis of the metal of hollow forgings produced from ingots with “cooled” and thermally insulated feeders is performed. A metallographic study reveals that if the ingot top is cooled down, it results in an accelerated solidification throughout the entire mass of the ingot; in addition, the thermal centre shifts to the ingot central axial area.

Optimizing Power–Frequency Droop Characteristics of Distributed Energy Resources

This paper outlines a procedure to design power–frequency droop slopes for distributed energy resources (DERs) installed in distribution networks to optimally participate in primary frequency response. In particular, the droop slopes are engineered such that DERs respond in proportion to their power ratings and they are not unfairly penalized in power provisioning based on their location in the distribution network. The main contribution of our approach is that a guaranteed level of frequency regulation can be obtained at the feeder head, while ensuring that the outputs of individual DERs conform to some well-defined notion of fairness. The approach we adopt leverages an optimization-based perspective and suitable linearizations of the power-flow equations to embed notions of fairness and information regarding the physics of the power flows within the distribution network into the droop slopes. Time-domain simulations from a differential algebraic equation model of the 39-bus New England test-case system augmented with three instances of the IEEE 37-node distribution network with frequency-sensitive DERs are provided to validate our approach.

Model-Free Optimal Coordination of Distributed Energy Resources for Provisioning Transmission-Level Services

Collective control of distributed energy resources (DER)—such as photovoltaic (PV) inverters or battery storage—have the potential to provide regulation services to the bulk electric grid. While optimal power flow techniques may be used to coordinate DER for this purpose, these approaches typically rely on accurate network models and a large number of system measurements. In this paper, we consider an approach that alleviates these modeling and measurement requirements. Here, we consider a two-dimensional adaptive control scheme known as extremum seeking, or ES, to perform optimization without knowledge of a model of the distribution network. We apply this scheme to enable simultaneous feeder head active power and voltage magnitude reference tracking, as well as feeder voltage regulation. From the perspective of the transmission grid, this approach essentially transforms the distribution feeder into a controllable (P,V) bus. Simulation results confirm the ability of the approach to track substation real power and voltage reference signals while maintaining distribution system voltages within acceptable tolerances.

Power Factor Analysis in Distribution Network with Roof Photovoltaic Units

In last decade considerable efforts have been made in the study of impact of photovoltaicunits on the power system performance. Maintaining the power factor at the connection point of photovoltaicunits is important since it allows greater flexibility of supply and power quality demanded by consumers. In this paper a power factor analysis of group of fixed roof photovoltaic power plants (PVPPs) connected to the low voltage distribution network is presented. Power factor analysis was based on the extensive yearly measurement of electricity production of seven PVPPs, recording maximal mean 15-minutes power as well as one-minute power at the 20 kV feeder head and PVPPs connecting points. The correlation between power factor of the feeder and electricity production of the PVPPs for the specific period of day are obtained. Besides, the effects of the power factor of PVPPs on the voltage conditions in the low voltage network are analyzed. Discussions of the results and conclusions that may be of interest to improve the performance of small and medium size on-grid PVPPs, are presented.

Faulted Segment Identification in Multi-phase Distribution Systems Using Sequence Component Modeling

This article discusses the potential for identifying faulted segment(s) on multi-phase distribution primaries using sequence component modeling and standard three-phase short-circuit solvers. Identifying faulted segments in a timely manner speeds up fault isolation and restoration processes, contributing to greater feeder reliability. The methodology utilizes fundamental frequency current magnitudes from the feeder head in conjunction with an approximate sequence model of the multi-phase feeder including single-phase and double-phase line segments augmented with dummy lines. Under certain fault conditions, multiple faulted segments may be yielded for which a new faulted segment reduction method based on voltage sag data is proposed. The Saskpower network simulated in MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA) environment was used to evaluate the faulted segment identification and reduction methods. The evaluation studies show quite promising results in uniquely identifying the actual faulted segment with reduced measurement and modeling requirements.

Design and Strategy for the Deployment of Energy Storage Systems in a Distribution Feeder With Penetration of Renewable Resources

Integration of distributed energy resources has the potential to impact the operation of the distribution systems by affecting the equipment reliability and customer power quality. The stochastic nature of the distributed energy resources have been accommodated using the energy storage systems along with providing economical benefits to the distribution systems. This paper provides a generalized framework for strategic deployment of a lithium-ion-based energy storage system to increase the benefits in a distribution feeder. Convex optimization is specifically developed to exploit the energy price arbitrage along the optimization time horizon. A significant amount of work has been performed in this paper for detailed characterization of the life cycle costs of the battery energy storage system (BESS). A novel approach for effective utilization of the energy storage system to mitigate the intermittent nature of the photovoltaic (PV) generation has been presented in this paper. The objectives include reduction of the substation transformer losses, reduction of the life cycle cost of the battery storage system, and accommodate PV variability. A convex optimization with a quadratic objective has been formulated to calculate the charge/discharge schedule of the energy storage system. A field validated model of the distribution feeder in OpenDSS has been used to determine the impact of optimal scheduling of the BESS on the substation transformer losses and the feeder head voltage.

Multi-Agent Based Control Scheme for Electrical Distribution System Restoration

Continuity of the electric supply is considered one of the main power quality indices, and thus, it is essential to perform fast and efficient restoration of electricity following outages. However, this might not be always an easy task, especially in large distribution networks. In this paper, an efficient multi-agent based control scheme is introduced to restore the maximum possible out of service loads without violating any of the technical constraints of the electric network. The proposed scheme utilizes a number of agents distributed along the feeder to gather the necessary information and communicate it to the decision making agent at the faulted feeder head. The decision making agent first attempts to restore all the out of service loads through group restoration. However, if this is not possible due to violating any of the technical constrains, then the agent attempts to restore as much loads as possible through a zone restoration process. To validate the effectiveness of the proposed control scheme, two case studies are presented to show the group and zone restorations. The distribution system is simulated in the MATLAB environment to perform the required power flow calculations and provide the necessary information to the agents. On the other hand, the agents are implemented in JADE environment where the communication and decision making process occurs.

Investigation into Formation of Metallic Beads on Wheel Ingots

This paper discusses the results of investigation into the formation of metallic beads on the bottom-poured ingots manufactured in Durgapur Steel Plant. These beads were very hard and offered extreme resistance to the sawing operation. Frequently, the saw blades broke on encountering these beads. A metallographic investigation revealed formation of hard white iron material due to the interactions of the mould powder and the liquid steel in the feeder head. As a result of these findings the mould powder quantity could be rationalized.

An Accurate Synchrophasor Based Fault Location Method for Emerging Distribution Systems

The accurate knowledge of fault location in distribution systems can aid in the repair process, expedite system restoration, and, thus, reduce outage duration. This letter presents a new method for locating a fault in distribution systems using synchrophasor measurements, which are often provided by phasor measurement units (PMUs) with high accuracy and a timestamp. Using voltage and current phasor measurements at substations and/or feeder heads obtained through suitable communication schemes, candidate fault locations are identified by iterating every possible line segment. The measurements from remote devices are used to eliminate all nonfaulted cases. This method works effectively for active and passive networks, radial and looped topologies, high impedance faults, and is not constrained to a certain pattern of PMU locations. The proposed method has been tested in a real distribution system. Results show that it can identify faults within 1% accuracy of the line length.

A New Modular Coaxial Feeder Nozzle in Laser Cladding

The powder feeder head is studied, which is one of the key to laser cladding. In view of many coaxial nozzles that are used nowadays, we have found that while cladding is doing, most of the nozzles have poor affect on powder-gathering. So as have researched on the theoretical and experiments, we designed a new coaxial nozzle, which has a great affect on powder-gathering, and can be modular disassembled. We have researched on powder stream theoretically, shot the morphology of powder stream by using high-resolution CCD camera, and analyzed the parameters of powder stream. And this new coaxial nozzle has been used in laser cladding experiments.