Danling Cheng

Smart Model Based Coordinated Control Based on Feeder Losses, Energy Consumption, and Voltage Violations

Abstract There can be significant benefits to utilities for implementing automated and controllable devices. However, due to both the cost of smart devices and the cost of implementing the required monitoring, communication, and control, it is often not cost effective to update all devices on the system at once. This article presents an economic evaluation of a model-based distribution control scheme that is independent of circuit topology and integrates legacy and modern control equipment. Distributed engineering workstation simulation results show cost saving to both the customers and utility due to reduction of demand and losses. These cost savings provide the basis for assessing which feeders should be upgraded with smart devices.

Photovoltaic (PV) Impact Assessment for Very High Penetration Levels

This paper describes a granular approach for investigating the impacts of very high photovoltaic (PV) generation penetration. Studies on two real-world distribution feeders connected to PV plants are presented. The studies include both steady-state and time-series power flow analyses, which include the effects of solar variability. The goal of the study is to predict the effects of increasing levels of PV generation as it reaches very high penetration levels. The loss and return of generation with and without regulation is simulated to capture short-term problems such as voltage fluctuations. Impact results from the analyses are described along with potential mitigations.

Real-Time Power Electric System Modeling, Assessment and Reliability Prediction

Given a large and complex plant to operate, a real-time understanding of the networks and their situational reliability is important to operational decision support. This paper introduces using a unified model to help operators to minimize real-time problems, and also provide a mimic-real time play-back mechanism for system planners on how to upgrade the grid. Real-time simulation architecture is described to identify and predict where problems may occur, how serious they may be, and what is the possible root cause. Multi-views of visualization are plotted for the system area in order to obtain good situational awareness of the scenario.

Economic Evaluation of Distribution System Smart Grid Investments

Abstract This article investigates the economic benefits of smart grid automation investments. A system consisting of 7 substations and 14 feeders is used in the evaluation. Here benefits that can be quantified in terms of dollar savings are considered, termed “hard dollar” benefits. Smart grid investment evaluations to be considered include investments in improved efficiency, more cost effective use of existing system capacity with automated switches, and coordinated control of capacitor banks and voltage regulators. These smart grid evaluations are sequentially ordered, resulting in a series of incremental hard dollar benefits. Hard dollar benefits come from improved efficiency, delaying large capital equipment investments, shortened storm restoration times, and reduced customer energy use. Analyses used in the evaluation involve hourly power flow analysis over multiple years and Monte Carlo simulations of switching operations during storms using a reconfiguration for a restoration algorithm. The economic analysis uses the time-varying value of the locational marginal price. Algorithms used include reconfiguration for restoration involving either manual or automated switches and coordinated control involving two modes of control. Field validations of phase balancing and capacitor design results are presented. The evaluation shows that investments in automation can improve performance while simultaneously lowering costs.

Harmonic Impact Study for Distributed Energy Resources Integrated Into Power Distribution Networks

Smart realization involves a steady increase in inverter-based components like Distributed Energy Resources (DER), energy storage systems, and plug-in electric vehicles. The harmonics related to DER inverters and the spread of power electronic devices raises concerns for utilities and customers. Harmonics can create component failures, thermal losses and control system malfunctions. In this paper the authors analyze the impact of multi-source harmonics from DERs inside distribution networks. The harmonics impacts are evaluated by harmonic measurement indices. Harmonic emission in a real distribution circuit is simulated with the help of power flow analysis. The results are presented with visualization techniques to give a better picture of harmonic propagation vs. different levels of harmonic source magnitude and angle. Due to effect of harmonic on network efficiency, a sensitivity analysis considering power factors is conducted.Copyright

Model Centric Approach for Monte Carlo Assessment of Storm Restoration and Smart Grid Automation

A model centric approach for Monte Carlo simulation for evaluating the economic and reliability benefits of automated switches for storm restoration is presented. A very detailed circuit model with over 20,000 individual customers modeled is used in the simulation. The simulation uses non-constant equipment failure rates based upon actual utility measurements. As part of the Monte Carlo storm simulation, a reconfiguration for restoration algorithm is employed in determining the response to each outage. The reconfiguration for restoration algorithm can work with either manual or automated switches, or both. System reliability with and without automated switching devices is investigated. Cost benefits as well as reliability benefits are considered.

Model-centric Distribution Automation: Capacity, Reliability, and Efficiency

Abstract A series of analyses along with field validations that evaluate efficiency, reliability, and capacity improvements of model-centric distribution automation are presented. With model-centric distribution automation, the same model is used from design to real-time control calculations. A 14-feeder system with 7 substations is considered. The analyses involve hourly time-varying loads and annual load growth factors. Phase balancing and capacitor redesign modifications are used to better prepare the system for distribution automation, where the designs are performed considering time-varying loads. Coordinated control of load tap changing transformers, line regulators, and switched capacitor banks is considered. In evaluating distribution automation versus traditional system design and operation, quasi-steady-state power flow analysis is used. In evaluating distribution automation performance for substation transformer failures, reconfiguration for restoration analysis is performed. In evaluating distribution automation for storm conditions, Monte Carlo simulations coupled with reconfiguration for restoration calculations are used. The evaluations demonstrate that model-centric distribution automation has positive effects on system efficiency, capacity, and reliability.

PV impact assessment for very high penetration levels

This paper describes a granular approach for investigating the impacts of very high PV generation penetration. Studies on two real-world distribution feeders connected to PV plants are presented. The studies include both steady-state and time series power flow analyses, which include the effects of solar variability. The goal of the study is to predict the effects of increasing levels of PV generation as it reaches very high penetration levels. Impact results from the analyses are described along with potential mitigations.

Automation Effects on Reliability and Operation Costs in Storm Restoration

Abstract—Storm response and restoration can be very expensive for electric utilities. The deployment of automated switches can benefit the utility by decreasing storm restoration hours. The automated switches also improve system reliably by decreasing customer interruption duration. In this article, a Monte Carlo simulation is used to mimic storm equipment failure events, followed by reconfiguration for restoration and power flow evaluations. The customer outage status and duration are examined. Changes in reliability for the system with and without automated switching devices are investigated. Economic benefits of utilizing smart grid automated devices are considered.