Bharat Vyakaranam

Modeling of GE Appliances in GridLAB-D: Peak Demand Reduction

The widespread adoption of demand response enabled appliances and thermostats can result in significant reduction to peak electrical demand and provide potential grid stabilization benefits. GE has developed a line of appliances that will have the capability of offering several levels of demand reduction actions based on information from the utility grid, often in the form of price. However due to a number of factors, including the number of demand response enabled appliances available at any given time, the reduction of diversity factor due to the synchronizing control signal, and the percentage of consumers who may override the utility signal, it can be difficult to predict the aggregate response of a large number of residences. The effects of these behaviors can be modeled and simulated in open-source software, GridLAB-D, including evaluation of appliance controls, improvement to current algorithms, and development of aggregate control methodologies. This report is the first in a series of three reports describing the potential of GEs demand response enabled appliances to provide benefits to the utility grid. The first report will describe the modeling methodology used to represent the GE appliances in the GridLAB-D simulation environment and the estimated potential for peak demand reduction at various deployment levels. The second and third reports will explore the potential of aggregated group actions to positively impact grid stability, including frequency and voltage regulation and spinning reserves, and the impacts on distribution feeder voltage regulation, including mitigation of fluctuations caused by high penetration of photovoltaic distributed generation and the effects on volt-var control schemes.

On the Configuration of the US Western Interconnection Voltage Stability Boundary

Stability limits are considered in power system planning and operations to estimate the available stability margins and, if possible, to maximize the use of transmission facilities. These important tasks are influenced by configuration of the voltage stability boundary. This paper first propose a new method to explore static voltage stability conditions in Cartesian coordinates instead of polar coordinates. In this way, the formulated singularity problem can be reduced to solving a set of linear equations with respect to real and imaginary components of nodal voltages. Using the proposed method, several case studies were performed for 17939-bus U.S. Western Interconnection planning model. Significant peculiarities of the boundary configuration were identified, including its non-convexity, discontinuity, branching and internal singularities (“holes”) that were not known before and could not be found by traditional methods.

Towards more transmission asset utilization through real-time path rating

Ratings of transmission paths, typically determined in an offline environment, are static and conservative, leading to underutilization of transmission assets, higher costs of system operation and renewable energy integration, and lower efficiency. With the ever-increasing transmission congestion costs and new challenges from renewable integration, increasing the transfer capability of existing transmission lines is essential. Real-time path rating provides a promising approach to enabling additional power transfer capability and fully utilizing transmission assets. In this paper, the feasibility of real-time path rating is investigated, by introducing several promising computational technologies to achieve such a capability. Various benefits expected from real-time path rating, such as increased transfer capability and reduced total generation cost, are demonstrated through simulations conducted on the Western Electricity Coordinating Council (WECC) system model.

Modeling of protection in dynamic simulation using generic relay models and settings

This paper shows how generic protection relay models available in planning tools can be augmented with settings that are based on NERC standards or best engineering practice. Selected generic relay models in Siemens PSS®E have been used in dynamic simulations in the proposed approach. Undervoltage, overvoltage, underfrequency, and overfrequency relays have been modeled for each generating unit. Distance-relay protection was modeled for transmission system protection. Two types of load-shedding schemes were modeled: underfrequency (frequency-responsive non-firm load shedding) and underfrequency and undervoltage firm load shedding. Several case studies are given to show the impact of protection devices on dynamic simulations. This is useful for simulating cascading outages.

Stochastic Operations and Planning

This document discusses PNNLs efforts to mitigate the changing patterns of electrical system behavior, how it is dispatched, and exchanges of energy.

Modeling of GE Appliances: Final Presentation

This report is the final in a series of three reports funded by U.S. Department of Energy Office of Electricity Delivery and Energy Reliability (DOE-OE) in collaboration with GE Appliances’ through a Cooperative Research and Development Agreement (CRADA) to describe the potential of GE Appliances’ DR-enabled appliances to provide benefits to the utility grid.

WECC Variable Generation Planning Reference Book

This planning reference book is a document reflecting a Western Electricity Coordination Council (WECC) effort to put together multiple sources of information and provide a clear, systemic, comprehensive outline of the problems, both existing and anticipated; their impacts on the system; currently used and proposed solutions by the industry and research community; planning practices; new technologies, equipment, and standards; and expected future trends. This living (periodically updated) document could help WECC and other practicing engineers, especially the younger generation of engineers joining the workforce, to get familiar with a large variety of information related to the integration of variable resources into the WECC system, bypassing in part the need for time-consuming information gathering and learning processes from more experienced engineers or from the literature.

Hybrid cascading outage analysis of extreme events with optimized corrective actions

Power systems are vulnerable to extreme contingencies (like an outage of a major generating substation) that can cause significant generation and load loss and can lead to further cascading outages of other transmission facilities and generators in the system. Some cascading outages are seen within minutes following a major contingency, which may not be captured using only the dynamic simulation of the power system that are usually run for 30 or 40 seconds. The utilities plan for contingencies based on either dynamic or steady-state analysis separately, which may not accurately capture the effect of one process on the other. We addressed this gap in cascading outage analysis by developing the Dynamic Contingency Analysis Tool (DCAT), which can analyze the hybrid dynamic and steady-state behavior of power systems including protection system models in dynamic simulations, and by simulating corrective actions in post-transient steady-state conditions. One of the important implemented steady-state processes is to mimic operator corrective actions to mitigate aggravated states caused by dynamic cascading. This paper formulates an optimization model, called Optimal Power Flow with Corrective Actions (OPFCA), for selecting corrective actions that utility operators can take during major contingencies and thus automate hybrid dynamic/steady-state cascading outage mitigation. The improved DCAT framework with OPFCA is demonstrated on the 3120-bus Polish system.

Power system decomposition for practical implementation of bulk-grid voltage control methods

Power system algorithms such as AC optimal power flow and coordinated volt/var control of the bulk power system are computationally intensive and become difficult to solve in operational time frames. The computational time required to run these algorithms increases exponentially as the size of the power system increases. The solution time for multiple subsystems is less than that for solving the entire system simultaneously, and the local nature of the voltage problem lends itself to such decomposition. This paper describes an algorithm that can be used to perform power system decomposition from the point of view of the voltage control problem. Our approach takes advantage of the dominant localized effect of voltage control and is based on clustering buses according to the electrical distances between them. One of the contributions of the paper is to use multidimensional scaling to compute «-dimensional Euclidean coordinates for each bus based on electrical distance to perform algorithms like K-means clustering. A simple coordinated reactive power control of photovoltaic inverters for voltage regulation is used to demonstrate the effectiveness of the proposed decomposition algorithm and its components. The proposed decomposition method is demonstrated on the IEEE 118-bus system.

Transmission reinforcements in the Central American regional power system

The Central American regional power system (SER) connects the member countries of the regional electricity market (MER): Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama. The SER was a result of a long-term regional effort, and was initially conceived to transfer 300 MW between countries. However, the current transfer limits between countries range from 70 MW to 300 MW. Regional entities, like CRIE (Regional Commission of Electrical Interconnection), EOR (Regional System Operator), and CDMER (Board of Directors of the Regional Market) are working on coordinating the national transmission expansion plans with regional transmission planning efforts. This paper presents a process to recommend transmission reinforcements based on a recent study to achieve 300 MW transfer capacity between any pair of MER member countries. This paper also provides a methodology for technical analysis and coordination among the regional and national entities that is tailored to the characteristics of their transmission systems.