• Title/Summary/Keyword: Load Losses

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Path-dependency of Transmission Loss Allocation using Transaction Strategy (거래전략에 따른 송전손실배분의 경로의존성에 관한 연구)

  • Min, Kyung-Il;Ha, Sang-Hyeon;Lee, Su-Won;Moon, Young-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.6
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    • pp.924-931
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    • 2008
  • This paper presents a buswise transmission loss allocation algorithm utilizing the transaction strategy. We prove that whatever calculated by any transaction strategy, the total of the allocated transmission losses of each bus, including no-load loss allocation, almost equals the total loss of AC power flow algorithm and the loss is perfectly slackbus-independent. In this paper, the allocated transmission losses of each bus is calculated by the method of integrating loss sensitivities using by the load level parameter ${\lambda}$. The performance of the proposed algorithm is evaluated by the case studies carried out on the WSCC 9-bus and IEEE 14-bus systems.

Aging Test of 20kVA Amorphous Core Transformer by Loading Back Method (부하반환법에 의한 20KVA 비정질 변압기의 경년열화 연구)

  • 민복기;송재성;정영호;임정재
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.2
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    • pp.278-285
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    • 1994
  • Aging test was done by loading back method for 20kVA amorphous core transformers manufactured by Hyosung Industries Co. and korea Electric Power Corporation. Iron losses, copper losses and insulation oil temperatures of the transfromers was measured for all the testing period. Expected life of amorphous core transformers on the basis of the degradation of the insulators was 46 years at 100% load, and 2.4 years at 130% load. Average temperature rising of transformer oil of amorphous core transformers was higher than that of silicon steel core transformers. Hence lowering the oil temperature by optimized design is needed for improving the expected life of the amorphous transformers.

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A Study of Smart Uninterruptible Power Supply Capable High Efficiency Drive (고효율 운전이 가능한 지능형 무정전 전원장치에 관한 연구)

  • Eom, Tae-Wook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.5
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    • pp.61-66
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    • 2013
  • In this paper, a control scheme with the capability of high efficiency, which is realized by predicting the conditions of a load power and an input power, is proposed for the uninterruptible power supply (UPS). Generally, on-line UPS system supplies a constant voltage and a constant frequency (CVCF). However, the efficiency of the On-line UPS system can be reduced due to the switching losses of semiconductor devices during the power conversion. The these losses are improved by the proposed smart UPS with the high efficiency drive system, which is realized by analysing and predicting the conditions of a load power and an input power.

Highly Efficient Control of the Doubly Fed Induction Motor

  • Drid, Said;Makouf, Abdesslam;Nait-Said, Mohamed-Said;Tadjine, Mohamed
    • Journal of Electrical Engineering and Technology
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    • v.2 no.4
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    • pp.478-484
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    • 2007
  • This paper deals with the high efficient vector control for the reduction of copper losses of the doubly fed motor. Firstly, the feedback linearization control based on Lyapunov approach is employed to design the underlying controller achieving the double fluxes orientation. The fluxes# controllers are designed independently of the speed. The speed controller is designed using the Lyapunov method especially employed to the unknown load torques. The global asymptotic stability of the overall system is theoretically proven. Secondly, a new Torque Copper Losses Factor is proposed to deal with the problem of the machine copper losses. Its main function is to optimize the torque in keeping the machine saturation at an acceptable level. This leads to a reduction in machine currents and therefore their accompanied copper losses guaranteeing improved machine efficiency. The simulation and experimental results in comparative presentation confirm largely the effectiveness of the proposed DFIM control with a very interesting energy saving contribution.

A Multi-level Optimal Power Flow Algorithm for Constrained Power Economic Dispatch Control (제약조건을 고려한 경제급전 제어를 위한 다단계 최적조류계산 알고리즘)

  • Song, Gyeong-Bin
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.50 no.9
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    • pp.424-430
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    • 2001
  • A multi-level optimal power flow(OPF) algorithm has been evolved from a simple two stage optimal Power flow algorithm for constrained power economic dispatch control. In the proposed algorithm, we consider various constraints such as ower balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the two stage optimization method to an average gain of 2.99 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

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A Fast Optimization Algorithm for Optimal Real Power Flow (고속의 유효전력 최적조류계산 알고리즘)

  • Song, Kyung-Bin;Kim, Hong-Rae
    • Proceedings of the KIEE Conference
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    • 1998.07c
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    • pp.926-928
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    • 1998
  • A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

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Direct Load Control Algorithm Based Locational and Electric Load Characteristics (지역적 특성과 부하특성을 고려한 직접부하제어 알고리즘)

  • Shin, Ho-Sung;Song, Kyung-Bin;Moon, Jong-Fil;Kim, Jae-Chul;Nam, Bong-Woo
    • Proceedings of the KIEE Conference
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    • 2006.07a
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    • pp.264-265
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    • 2006
  • This paper presents direct load control algorithm based locational and electric load characteristics. Direct load control is defined that demand-side management program activities that can interrupt consumer load at the time of annual peak load by direct control of the utility system operator by interruption power supply to individual appliances or equipment on consumer premises. Korean power system is divided into 14-areas considering branches operating in KEPCO, and electric loads are classified into 19 load groups considering interruption costs in this paper. The purpose of proposed method is to decrease social losses by controlling electric loads mainly whose interruption costs are low. It is expected that the proposed algorithm can be used as the countermeasure for the emergency state of the electric power dispatch in a operation point of view.

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Regional Analysis of Load Loss in Power Distribution Lines Based on Smartgrid Big Data (스마트그리드 빅데이터 기반 지역별 배전선로 부하손실 분석)

  • Jae-Hun, Cho;Hae-Sung, Lee;Han-Min, Lim;Byung-Sung, Lee;Chae-Joo, Moon
    • The Journal of the Korea institute of electronic communication sciences
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    • v.17 no.6
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    • pp.1013-1024
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    • 2022
  • In addition to the assessment measure of electric quality levels, load loss are also a factor in hindering the financial profits of electrical sales companies. Therefore, accurate analysis of load losses generated from distributed power networks is very important. The accurate calculation of load losses in the distribution line has been carried out for a long time in many research institutes as well as power utilities around the world. But it is increasingly difficult to calculate the exact amount of loss due to the increase in the congestion of distribution power network due to the linkage of distributed energy resources(DER). In this paper, we develop smart grid big data infrastructure in order to accurately analyze the load loss of the distribution power network due to the connection of DERs. Through the preprocess of data selected from the smart grid big data, we develop a load loss analysis model that eliminated 'veracity' which is one of the characteristics of smart grid big data. Our analysis results can be used for facility investment plans or network operation plans to maintain stable supply reliability and power quality.

A Parallel Hybrid Soft Switching Converter with Low Circulating Current Losses and a Low Current Ripple

  • Lin, Bor-Ren;Chen, Jia-Sheng
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1429-1437
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    • 2015
  • A new parallel hybrid soft switching converter with low circulating current losses during the freewheeling state and a low output current ripple is presented in this paper. Two circuit modules are connected in parallel using the interleaved pulse-width modulation scheme to provide more power to the output load and to reduce the output current ripple. Each circuit module includes a three-level converter and a half-bridge converter sharing the same lagging-leg switches. A resonant capacitor is adopted on the primary side of the three-level converter to reduce the circulating current to zero in the freewheeling state. Thus, the high circulating current loss in conventional three-level converters is alleviated. A half-bridge converter is adopted to extend the ZVS range. Therefore, the lagging-leg switches can be turned on under zero voltage switching from light load to full load conditions. The secondary windings of the two converters are connected in series so that the rectified voltage is positive instead of zero during the freewheeling interval. Hence, the output inductance of the three-level converter can be reduced. The circuit configuration, operation principles and circuit characteristics are presented in detail. Experiments based on a 1920W prototype are provided to verify the effectiveness of the proposed converter.

Minimization of Losses in Permanent Magnet Synchronous Motors Using Neural Network

  • Eskander, Mona N.
    • Journal of Power Electronics
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    • v.2 no.3
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    • pp.220-229
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    • 2002
  • In this paper, maximum efficiency operation of two types of permanent magnet synchronous motor drives, namely; surface type permanent magnet synchronous machine (SPMSM) and interior type permanent magnet synchronous motor(IPMSM), are investigated. The efficiency of both drives is maximized by minimizing copper and iron losses. Loss minimization is implemented using flux weakening. A neural network controller (NNC) is designed for each drive, to achieve loss minimization at difffrent speeds and load torque values. Data for training the NNC are obtained through off-line simulations of SPMSM and IPMSM at difffrent operating conditions. Accuracy and fast response of each NNC is proved by applying sudden changes in speed and load and tracking the UC output. The drives'efHciency obtained by flux weakening is compared with the efficiency obtained when setting the d-axis current component to zero, while varying the angle of advance "$\vartheta$" of the PWM inverter supplying the PMSM drive. Equal efficiencies are obtained at diffErent values of $\vartheta$, derived to be function of speed and load torque. A NN is also designed, and trained to vary $\vartheta$ following the derived control law. The accuracy and fast response of the NN controller is also proved.so proved.