Analysis Of Power Distribution Systems Research Articles

A linear Distflow model considering line shunts for fast calculation and voltage control of power distribution systems

The line shunts are usually ignored by various linear power flow (PF) models in power distribution system analysis, planning and optimization. However, “charging effects” from line shunts of underground/submarine power cables would cause non-negligible model errors for these commonly used PF models. In this paper, we propose a modified Linear Distflow model (LinDist) with line shunts, i.e., LinDistS. We also further propose its extensions considering the ZIP load, weakly-meshed topology and unbalanced three-phase systems. Moreover, the linearization error of voltage component is theoretically analyzed. Case studies show that compared with other models, the proposed LinDistS achieves the descent calculation accuracy and efficiency. We also show the application scope of LinDistS by a Volt/VAr control (VVC) framework with distributed generators, mainly photovoltaic (PV), and the non-negligible “charging effect”. Simulation exhibits that with LinDistS, the VVC can optimally dispatch the shunt capacitors and also optimize the real-time reactive power output of PV. Moreover, with LinDistS, the VVC shows better solutions’ consistency and higher computing efficiency compared to traditional VVC methods.

Design and analysis of power distribution systems for optimum over-current relay coordination using voltage component of fault current limiters

Design and analysis of power distribution systems for optimum over-current relay coordination using voltage component of fault current limiters

Performance analysis of distribution system under different loading conditions using test bench

This paper presents performance analysis of power distribution system using distribution test bench. Distribution system is the part of power system in which significant portion of the power is utilized in it. The losses occur in distribution system mainly due to inherent characteristics of the number of components in the system. In this wok, we analyse the performance of distribution system having 4 feeders having different lengths supplying resistive and combination of resistive and inductive loads. The analysis includes the voltage regulation, power loss, efficiency for different loading conditions. Also shown are the improvement of terminal voltage of the feeders and receiving end power with compensation. Finally the inferences are drawn and suggestions are proposed to improve the performance.

Predictive Reliability Analysis of Power Distribution Systems Considering the Effects of Seasonal Factors on Outage Data Using Weibull Analysis Combined With Polynomial Regression

Predictive Reliability Analysis of Power Distribution Systems Considering the Effects of Seasonal Factors on Outage Data Using Weibull Analysis Combined With Polynomial Regression

Comparative Analysis of Power Distribution Systems with Individual Prosumers Owing Photovoltaic Installations and Solar Energy Communities in Terms of Profitability and Hosting Capacity

Future energy markets are foreseen to integrate multiple entities located mainly at the distribution level of the grid so that consumers can participate in energy trading while acting as individual prosumers or by forming energy communities. To ensure the smooth integration of prosumers and satisfy the effective operation of the power distribution systems (PDSs), it is important to fundamentally assess their performance for different grid development scenarios. This paper aims to estimate and compare the hosting capacity (HC) thresholds and profitability for two alternatives: (a) when the PDS experiences rapid growth of scattered individual prosumers with photovoltaic (PV) installations and (b) when prosumers intend to formulate a medium-scale energy community, which is a single source located in one node. Maximization of the profits of decision-makers and maximization of the capacity of the PV generation were set as the two objectives for the optimization tasks. It has been analyzed how the physical topology of the distribution network can be harmonized with the underlying bidirectional power flows for each alternative while satisfying system constraints. A typical distribution test feeder is employed to estimate the energy loss and voltage variations in the PDS, as well as the profitability for energy producers, for various penetration levels of prosumers, in comparison to the base case with no PV generation. The results indicate that improvements in terms of profitability and reduction of energy losses can be achieved in both alternatives, as long as the penetration of PV systems does not reach a certain threshold, which can be chosen by decision-makers and is limited by the HC. Comparing the results of the simulation, EComs demonstrate higher HC vs. individual prosumers, both in terms of technical and economic priorities.

Integrating dynamic Bayesian network and physics-based modeling for risk analysis of a time-dependent power distribution system during hurricanes

Hurricane is one of the major natural hazards that bring significant damages and failures to the power distribution system for many coastal regions. For better decision-making, pre-hazard maintenance and post-hazard restoration of the power distribution system can be improved through the risk analysis of the distribution system. However, as a natural material, wood deteriorates with time. Therefore, the performance of the power distribution system could vary significantly during their life cycles. To quantify the time-dependent nature of the existing power distribution system due to material deterioration, a dynamic Bayesian network (DBN) is implemented for the risk analysis of a power distribution system against hurricanes. To capture the failure probabilities of the poles in the power distribution system, fragility surfaces for the poles are generated through physics-based fragility analysis, incorporating physical properties of the pole-wire components and the pole-wire system topology. The failure rate of the distribution system is obtained through the Bayesian network (BN) at each time step. With the observed failure data of poles, the material properties and the fragility surfaces of the components in the power distribution system are updated through Bayesian inferring. More specifically, the particle filter (PF) algorithm is utilized. To efficiently save computational cost in BN reasoning, the Gaussian process (GP) algorithm is adopted to build surrogate models to predict poles’ behaviors. Predictors are selected from the feature space to further reduce computational time and to enhance the prediction performance of the surrogate models through the automatic relevance determination (ARD) method. The failure rate is underestimated by 11% when the system deterioration process is ignored given a ten-year interval of hurricane events.

Reliability-Based Assessment and Cost Analysis of Power Distribution Systems at Risk of Tornado Hazard

AbstractPower distribution systems are susceptible to significant damage when hit by a tornado. This damage can cause huge economic losses resulting from the cost of repairing failed distribution l...

Sparsity-Based Short-Circuit Analysis of Power Distribution Systems With Inverter Interfaced Distributed Generators

This paper proposes a method for calculating short-circuit current in distribution systems with inverter interfaced distributed generators (IIDG). It is capable of calculating the short circuit in a multi-phase distribution systems based on the symmetrical components without obtaining the complete impedance matrix. Furthermore, it considers the load effect and the pre-fault state of the system for the fault analysis and is able to handle unbalanced systems with mutually coupled phases. The problem is formulated as an iterative linear system calculation and is solved by generalized minimal residual (GMRES) approach. The validity of the proposed algorithm is verified through the simulation of IEEE 13-node, 123-node, 478-node, 954-node, and 1430-node distribution systems. Simulation results demonstrate the effectiveness of the proposed algorithm and the advantages of using the GMRES method to calculate the short circuit current in a distribution system with IIDG.

Individual Load Model Parameter Estimation in Distribution Systems Using Load Switching Events

There currently exists a mature literature on modeling the aggregate load of a distribution feeder by making use of measurements at its feeder-head at substation. The primary application of such feeder-aggregated load models is in sub-transmission or transmission system analysis. However, there is a growing need in practice also to model each individual load across the feeder. If available, such individual load models have applications in power distribution system analysis, e.g., to better integrate distributed energy resources or to improve power quality and reliability. Motivated by this observation, in this paper, we propose a new method for individual load modeling in power distribution systems. It works by using the measurements only at the feeder-head. It takes an innovative approach to analyzing the load switching events across the distribution feeder itself, instead of or in addition to relying on upstream voltage events that are commonly used in feeder-aggregated load modeling. By tracking the downstream load switching events, the proposed method can make a robust estimation of the ZIP load model parameters for all individual loads. The proposed method is examined on small illustrative test-feeders as well as the IEEE 33-bus test system under various operating scenarios. The adverse impact of errors in measurements and system parameters are also investigated on the performance of the developed load modeling method.

Power Distribution Network Dynamic Topology Awareness and Localization Based on Subspace Perturbation Model

Identifying network dynamic topology changes with limited measurement data is a primary challenge for power distribution system analysis. Existing methods require the measurement of the nodal voltage (both amplitudes and phase angles) of a majority of nodes, which means that large-scale installation of advanced monitors is necessary. In this paper, a distribution network dynamic topology awareness method that only requires a synchronized voltage amplitude measurement of a limited number of nodes is proposed. The key idea of the design is to relate network topology changes (including line topology changes, node topology changes and switch actions) to the resultant perturbations in the voltage amplitude covariance matrix. Because perturbations can be identified with incomplete observations, the corresponding topology changes can be identified with limited measurements of voltage amplitude data. With no need for phase-angle measurement, only ordinary root mean square (RMS) based monitors are needed, which can be made available with a relatively minor investment. Simulation tests are performed with the IEEE 123-node system and 8500-node system. Remarkably, 80% of the topology changes can be detected with only 10% of the nodes equipped with monitors, and a 100% correct localization rate can be achieved with 50% of the nodes equipped with monitors.

Voltage Stability of Low-Voltage Distribution Grid with High Penetration of Photovoltaic Power Units

Voltage stability analysis of power distribution systems with high photovoltaic (PV) penetration is a challenging problem due to the stochastic generation of a solar power system. Voltage stability is an important benchmark for defining PV’s penetration level in active distribution networks considering loading capacity. The massive integration of PV power units, the effect of distribution system characteristics, like high ratio of R/X, and the reported collapses in power networks come up in serious studies that investigate their impact and upcoming problems on distribution networks. Therefore, this paper proposes analytical voltage stability and it is implemented on IEEE 34 nodes radial distribution systems with 24.9 kV and 4.16 kV voltage levels. In this regard, in addition to given properties in stability and power loss analysis, a penetration coefficient for PVs is considered. Simulation results prove that the applied method can illustrate the positive and negative effects of PV in distribution networks.

Performance analysis of power distribution systems with weakly grid connected rural homes in India

India is running 11% peak demand as well as short of electrical energy which is the cause of poor grid availability at many sits in India. This motivates the consumer to install their own captive power plant in the building to improve reliability of electricity building. The photovoltaic system cost is rapidly decreasing day by day as well as it is the pollution free source of electricity it is popularity choice of residential consumers. The electronics loads (DC appliances) are increasing in the building. The PV system is also a source of DC power. Therefore, the integration of the DC appliances as well as PV system to the traditional AC distribution system forced to introduce the DC–AC and AC–DC converters at the PV system and appliances. Which decrease the system efficiency, reliability and system capital cost. In this paper, the comparison analysis of the distribution structures (i) Traditional system: AC distribution system with AC compatible appliances (conventional), (ii) Hybrid system: AC distribution system with DC compatible a appliances (high efficient) and (iii) DC system: DC distribution system with DC compatible appliances. The simulation results of this study shows that DC system in the building shows high efficiency and small capital cost as compared to the traditional as well as hybrid system. It is also need small number of AC–DC–sAC conversion stages.

Secondary Low-Voltage Circuit Models—How Good is Good Enough?

Utility power distribution system analysis has traditionally been performed considering only the primary or medium-voltage system. Distributed energy resources are increasingly being located on the secondary, or low voltage, side of the distribution transformer, requiring the low-voltage system to be included in the analysis. However, most distribution system models do not include secondary circuits or they are modeled with limited detail. In the absence of the appropriate model data, secondary circuits models commonly rely on simplifications such as single-phase models, constant power factor, etc. This paper highlights the implications of some of these assumptions and provides guidance in terms of how more accurate secondary models are needed. This paper shows that split-phase secondary circuits can be modeled accurately with single-phase equivalents under perfectly balanced conditions. It also shows that assuming constant power factor or using smart meter measurements with practical 15 min, or larger, time granularity can lead to considerable errors in simulated secondary circuit losses or voltages.

Ensuring Data Integrity of OPF Module and Energy Database by Detecting Changes in Power Flow Patterns in Smart Grids

Recent studies show that smart grid is vulnerable to cyber anomalies. In this paper, an anomaly detection method is proposed to identify the abnormal patterns in the network power flows, which results from the accidental or deliberate changes of the database. The proposed method utilizes a multivariate time series statistical forecasting technique based on vector autoregressive model. To understand the power flow behavior of the system, a multiphase optimal power flow analysis is conducted. The proposed method is validated using IEEE Power Distribution System Analysis Subcommittee recommended 34-node and 123-node test systems. Three different experiments are performed to test the effectiveness of the proposed approach. Vulnerability and computational complexity issues of this paper are also addressed elaborately. Results obtained from this analysis show that the proposed method successfully captures the network anomalies at a high detection rate allowing only a few number of false alarms.

Reliability Analysis of Power Distribution System

Electrical distribution system is a component of electrical power system that is very important because it is closest to the customer. In its operation, the distribution system often suffers that causes the flow of electricity to the customer is interrupted. This situation is not expected by customers or by electric power companies. The more frequent and longer the occurrence of electrical power flow interruption, the lower the system reliability, and vice versa. Reliability of a distribution system can be analyzed based on SAIDI and SAIFI parameters. In this research, reliability analysis of distribution system on Gejayan substation. The analysis result using SAIDI and SAIFI parameters shows that Gejayan substation is reliable enough to national standard, while based on international standard still not reliable.

Dynamic and Transient Analysis of Power Distribution Systems With Fuel Cells—Part I: Fuel-Cell Dynamic Model

The first part of this two-part-paper develops a comprehensive nonlinear dynamic model of a solid-oxide fuel cell (SOFC) that can be used for dynamic and transient stability studies. The model based on electrochemical and thermal equations, accounts for temperature dynamics and output voltage losses. The output voltage response of a stand-alone fuel-cell plant to a step load change, a fuel flow step change, and fast load variations are simulated to illustrate the dynamic behavior of SOFC for fast and slow perturbations. A method for interfacing the proposed fuel-cell models to a power system stability package is developed.

Software Framework Concepts for Power Distribution System Analysis

Software design reuse has been discussed in the past at the component level through Design Patterns. A software framework is an approach to achieve software reusability for an entire domain. This paper presents architectural design concepts of a framework for power distribution system analysis. The commonalities of distribution system analysis, including components, topologies, and algorithms are considered. A layered architecture with strict top-down dependency is proposed to decrease software couplings. Interfaces are used to hide the internal structure of each layer. The Composite and Iterator design patterns are used in the framework design. This paper also presents practical examples of developing customized applications that reuse and extend the framework.