Power-flow study

About: Power-flow study is a research topic. Over the lifetime, 8091 publications have been published within this topic receiving 155053 citations. The topic is also known as: load-flow study.

Method and system for real-time prediction of power usage for a change to another performance state

Abstract: A method and system for real-time prediction of power usage for a change to another performance state provides input data for power management decision-making processes or for display to system operators. The unit(s) for which power usage is predicted may be a single processor in a uni-processor system or may extend up to the level of facilities within a complex of processing facilities. The method and system gather real-time data on the power consumption of the unit(s) and create a model, such as a regression model, of power versus performance. A resulting power usage change required by a prospective nominal performance state change is shown as display data, or is transmitted to a power budgeting controller to inform the controller as to potential changes that can enhance system operation, such as managing tradeoffs of power allocated to various sub-units of a processing system.

Real time distribution analysis for electric utilities

Abstract: Electric utilities are finding it increasingly necessary to better monitor, analyze and control their distribution systems. Planning and operation of the grid is increasing in complexity on one hand but subject to ever more binding constraints on the other. Real-time analysis is being seen as necessary to achieve acceptable operational efficiencies and quality of service. Real-time analysis is the combination of computerized circuit analysis with measured real-time inputs (voltage and current into the grid) and outputs (customer consumption) to determine the actual and likely near-term voltages and power flows throughout the transmission and distribution grid. With appropriate analytical tools, display options, and control systems, real-time analysis will allow utilities to actively manage the grid to achieve better operating efficiencies and to anticipate and avoid service interruptions and other operating problems. Most of the tools required for real-time analysis are already available. Computer load flow analysis has been used by transmission and distribution utilities for decades to simulate and analyze voltage, current, and real and reactive power flow for system planning and operations. SCADA has reached almost universal usage by transmission and distribution utilities of all sizes and makes it possible to monitor and control generators, transmission lines, substations, distribution lines, and in-line equipment and devices. Smart meters have, in the last decade, become an important and widely used tool not only for reading residential and commercial meters, but also for collecting data about the distribution system. Challenges to real time analysis and active grid management include achieving full deployment of SCADA and smart meters, obtaining the necessary bandwidth and speed of data communications, integrating data from disparate brands and vintage of hardware and software, refining the computational methods, learning to utilize the results for grid planning and operation, and transforming the design of the distribution grid over time to maximize controllability. In this paper we will: (1) Discuss why real-time analysis is needed and useful; (2) Define what real-time analysis is; (3) Describe how real time analysis might be made to work for rural transmission and distribution utilities; and (4) Outline a pilot project being planned at Owen Electric Cooperative in Kentucky.

Design and Implementation of a Two-Stage Grid-Connected High Efficiency Power Load Emulator

Abstract: The need to reduce the time consumption in developing and implementing power converters, and to improve the effectiveness of the test equipment, continues to grow. This trend is further accelerated through the development of electricity-based technology, such as the electric or hybrid vehicle. As the price of energy continues to increase, regenerative test equipment used for validating power converters are gaining importance and attention. This paper focuses on the development of a two-stage regenerative power load emulator. This type of intelligent load requires a connection to the network interface, which, for some applications, should be bidirectional and must possess a galvanic isolation. The development of such grid-connected unit that processes ac-dc conversion is treated in this paper. A 5 kW prototype is used as a base to model, simulate, design, implement, and test such a system. The stability of the interconnection between the two conversion stages is established and tested in real-time applications. The prototype was tested at 180, 220, and 260 V RMS. The measured efficiency is higher than 90%, and the power factor is 0.99 over a wide range of operation.

A Two-Stage Approach for Network Constrained Unit Commitment Problem With Demand Response

Abstract: This paper proposes a two-stage formulation for the day-ahead energy scheduling problem with demand response (DR). The first stage solves a network-constrained unit commitment problem with DR, to determine the hourly net demand changes (i.e., difference between final and initial demand values) happening at each DR bus 1 along with the unit commitment schedule and ac load flow solution. Here, the objective is to maximize the social welfare which is expressed as the total utility of the demand side minus the total generation cost. The second stage solves an incentive or penalty minimization problem to determine the demand shifting and demand curtailment across the 24-h period at each DR bus, offering DR, based on the hourly net demand changes obtained during the first stage. The proposed formulation shows how demand shift and demand curtailment happening at different DR buses can be traced back to the hourly net demand changes occurring at the system level. The results, presented for a six-bus system and IEEE 118 bus system, show the benefits of including DR into the network-constrained unit commitment problem according to the proposed formulation. 1 Any bus which is capable of offering DR will be referred to as DR bus. It should not be mistaken for PQ bus referred in the load flow analysis.