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483 results on '"Muljadi, Eduard"'

112. Synchronous Condenser Allocation for Improving System Short Circuit Ratio

Author

Jia, Jundi, Yang, Guangya, Nielsen, Arne Hejde, Weinreich-Jensen, Peter, Muljadi, Eduard, Gevorgian, Vahan, Jia, Jundi, Yang, Guangya, Nielsen, Arne Hejde, Weinreich-Jensen, Peter, Muljadi, Eduard, and Gevorgian, Vahan

Abstract

With converter-based renewable energy sources increasingly integrated into power systems and conventional power plants gradually phased out, future power systems will experience reduced short circuit strength. The deployment of synchronous condensers can serve as a potential solution. This paper presents an optimal synchronous condenser allocation method for improving system short circuit ratio at converter point of common coupling using a modified short circuit analysis approach. The total cost of installing new synchronous condensers is minimized while the system short circuit ratios are maintained above a certain level. The presented method is implemented on the simplified western Danish power system for a future scenario.

Published
2018

123. Power-Smoothing Scheme of a DFIG Using the Adaptive Gain Depending on the Rotor Speed and Frequency Deviation

Author

Lee, Hyewon, Hwang, Min, Muljadi, Eduard, Sørensen, Poul Ejnar, Kang, Yong Cheol, Lee, Hyewon, Hwang, Min, Muljadi, Eduard, Sørensen, Poul Ejnar, and Kang, Yong Cheol

Abstract

In an electric power grid that has a high penetration level of wind, the power fluctuation of a large-scale wind power plant (WPP) caused by varying wind speeds deteriorates the system frequency regulation. This paper proposes a power-smoothing scheme of a doubly-fed induction generator (DFIG) that significantly mitigates the system frequency fluctuation while preventing over-deceleration of the rotor speed. The proposed scheme employs an additional control loop relying on the system frequency deviation that operates in combination with the maximum power point tracking control loop. To improve the power-smoothing capability while preventing over-deceleration of the rotor speed, the gain of the additional loop is modified with the rotor speed and frequency deviation. The gain is set to be high if the rotor speed and/or frequency deviation is large. The simulation results based on the IEEE 14-bus system clearly demonstrate that the proposed scheme significantly lessens the output power fluctuation of a WPP under various scenarios by modifying the gain with the rotor speed and frequency deviation, and thereby it can regulate the frequency deviation within a narrow range.

Published
2017

124. The Influence of Heat Loss on Wind Generators to Implement Condition-Monitoring System Based on the Application of the Polynomial Regression Model

Author

ABDUSAMAD, Khaled Bubaker, GAO, David Wenzhong, and MULJADİ, Eduard

Subjects
Condition-monitoring system,polynomial regression model,heat loss,predicted generator temperature,independent variables
Abstract

This paperpresents an application of acondition-monitoring system (CMS) based on a polynomial regression model (PRM)to study the influence of heat loss on a wind generator’s temperatures.Monitoring the wind generator temperatures is a significant for efficientoperation, and plays a key role in an effective CMS. Many techniques, includingprediction models can be utilized to reliably forecast a wind generator’stemperature during operation and avoid the occurrence of a failure. PRMs arewidely used in situations when therelationship between the response and the independent variables are curve-linear.Thesetechniques can be used to construct a normal behavior model of an electricalgenerator’s temperatures based on recorded data. Many independent variables affect agenerator’s temperature; however, the degree of influence of each independent variable on the response is dissimilar. In manysituations, adding a new independent variableto the model may cause unsatisfactory results; therefore,the selection of the variables should be veryaccurate. A generator’s heatloss can be considered a significant independent variable that greatlyinfluences the wind generator with respect to the other variables. A generator’s heat loss can be estimated in intervals by analyzing theexchange in the heat between the hot and cold fluid throughthe heat exchangers of wind generators. Acase study built on data collected from actual measurements demonstrates theadequacy of the proposed model.

Published
2016

144. Modelling and simulation of ternary pumped storage hydropower for power system studies.

Author

Zerui Dong, Jin Tan, St-Hilaire, Antoine, Muljadi, Eduard, Corbus, David, Nelms, Robert, and Jacobson, Mark

Subjects
WATER power, ELECTRIC power, SOLAR energy, ELECTRIC power distribution grids, SIMULATION methods & models, WIND power, ELECTRIC power production
Abstract

As the deployment of wind and solar energy increases in the USA, energy storage (ES) will play an important role in future electric power grids to help manage the variability from high penetration levels of renewable generation, ES can provide promising power/energy demand to coordinate with renewables generation, as a virtual power plant (VPP). There is an industry need for the capability in power system studies to model ternary pumped storage hydropower (T-PSH), a pumped storage technology that offers increased system benefits. This study presents a comprehensive vendor-neutral dynamic model of T-PSH in GE's commercial software positive sequence load flow. A new governor model is developed with detailed gate valve modelling and a shared-penstock function. Specifically, this model is designed to simulate the seamless transition among three operation modes: generation mode, pumping mode, and hydraulic short-circuit mode. The developed T-PSH model has been tested and validated on a 10-bus test system. A comparison study of T-PSH to conventional pumped storage hydropower has also been conducted on the Western interconnection system. [ABSTRACT FROM AUTHOR]

Published
2019
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145. Guest Editorial: Emerging Technologies for Virtual Power Plant and Microgrid.

Author

Muljadi, Eduard

Subjects
*MICROGRIDS, *POWER plants, *TECHNOLOGICAL innovations, *MIXED integer linear programming, *BATTERY storage plants, *ELECTRIC power systems
Abstract

An introduction is presented which discusses various reports published within the issue including microgrid and virtual power plant for power supply, voltage reactive power control of a power system, and virtual power plant real-time energy management along with a brief profile of guest editors.

Published
2019
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146. Zero Sequence Method for Energy Recovery from a Variable-Speed Wind Turbine Generator

Author

Muljadi, Eduard, Hess, Herbert L., and Thomas, Kim

Subjects
Air-turbines -- Usage, Wind power -- Equipment and supplies, Power electronics -- Research, Electric inverters -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

An innovative power conversion system to convert energy from a variable-frequency wind-powered induction generator to a fixed frequency output. A standard six-switch dc link Current Regulated Pulse Width Modulated (CRPWM) inverter is simultaneously modulated with two current components. A three-phase balanced current component at the induction generator's optimum operating frequency transfers energy from the generator to the converter. A single phase zero sequence current component at a fixed 60 Hz frequency transfers energy from the converter through a zero sequence filter to the load. Unity power factor output is shown both in simulation and experiment, though any arbitrary power factor output may be readily commanded. Maximum power capture for a variable-speed wind turbine is achieved using proven control techniques. This method uses only half of the active power switching devices of conventional conversion methods. Simulation and experimental verification are shown. Index Terms--DC-AC power conversion, induction generators, inverters, power conversion, wind energy, wind power generation.

Published
2001

147. Pitch-Controlled Variable-Speed Wind Turbine Generation

Author

Muljadi, Eduard and Butterfield, C. P.

Subjects
Air-turbines -- Research, Alternative energy sources -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

This paper covers the operation of variable-speed wind turbines with pitch control. The system we considered is controlled to generate maximum energy while minimizing loads. The maximization of energy was only carried out on a static basis and only drive train loads were considered as a constraint. In low to medium wind speeds, the generator and the power converter control the wind turbine to capture maximum energy from the wind. In the high-wind-speed regions, the wind turbine is controlled to maintain the aerodynamic power produced by the wind turbine. Two methods to adjust the aerodynamic power were investigated: pitch control and generator load control, both of which are employed to regulate the operation of the wind turbine. Our analysis and simulation show that the wind turbine can be operated at its optimum energy capture while minimizing the load on the wind turbine for a wide range of wind speeds. Index Terms--Pitch controlled, renewable energy, variable speed, wind turbine generator.

Published
2001

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