• Title/Summary/Keyword: Lead-lag control

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Power System Oscillations Damping by Robust Decentralized DFIG Wind Turbines

  • Surinkaew, Tossaporn;Ngamroo, Issarachai
    • Journal of Electrical Engineering and Technology
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    • v.10 no.2
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    • pp.487-495
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    • 2015
  • This paper proposes a new robust decentralized power oscillation dampers (POD) design of doubly-fed induction generator (DFIG) wind turbine for damping of low frequency electromechanical oscillations in an interconnected power system. The POD structure is based on the practical $2^{nd}$-order lead/lag compensator with single input. Without exact mathematical model, the inverse output multiplicative perturbation is applied to represent system uncertainties such as system parameters variation, various loading conditions etc. The parameters optimization of decentralized PODs is carried out so that the stabilizing performance and robust stability margin against system uncertainties are guaranteed. The improved firefly algorithm is applied to tune the optimal POD parameters automatically. Simulation study in two-area four-machine interconnected system shows that the proposed robust POD is much superior to the conventional POD in terms of stabilizing effect and robustness.

Disk Vibration and Eccentricity Compensation of Near Field Recoding Systems Based on the Internal Model Principle (IMP를 이용한 근접장 기록 장치의 디스크 진동 및 편심 보상)

  • Jeong, Jun;Kim, Joong-Gon;Park, No-Cheol;Yang, Hyun-Seok;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.837-842
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    • 2007
  • Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

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Implementation of (RSF + RPP) PWM Inverter for reducing Harmonics

  • Ha, Sang-Mok;Han, Woo-Yong;Lee, Chang-Goo;Kim, Seong-Joong
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.65.4-65
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    • 2002
  • In this paper, RSF+RPP(Random Switching Frequency Ran-domized Pulse Position) PWM for three-phase voltage-controlled inverter is proposed. The LLPWM(Lead-Lag PWM) technique is that three switching pulses are located randomly back and forth in each switching interval But with the restriction of random distribution, the harmonic spectrum cannot be dispersedly and continuously distributed. To tackle this problem , First, the switching frequency is varied randomly. Next, the duty ratio is calculated under the first circumstance. Finally, the switching pulses are located randomly in the switching interval. To verify the validity of the proposed technique, Simulation Study is tried Using Matlab/Si...

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Development of A Pneumatic Actuation System with Damping Pist (감쇄피스톤을 이용한 공압구동장치 설계)

  • 문의준
    • 제어로봇시스템학회:학술대회논문집
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    • 1987.10b
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    • pp.370-375
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    • 1987
  • Damping piston with an orifice in the piston head is utilized to improve the damping characteristics of a pneumatic push-push type rotary actuator. Through linearized analysis, the optimum size of orifice, which gives maximum damping effect at the frequency where damping is desired. most, is predicted. The frequency response test of teal system were carried out to see the effects of damping piston and to obtain true optimum size of orifice by trying orifices of various size near the predicted value. During the tests, both air and helium were tried as working fluid, and a lag-lead compensation circuit was incorporated to improve system dynamics. The finally chosen orifice size is a little bigger than that predicted from analysis, however it gives high damping effects for the finally designed pneumatic system enough to have wide frequency response bandwidth.

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Nonlinear PSS by Lie Group Theory based $H{\infty}$ Switching Control (Lie Group Theory에 기준한 $H_{\infty}$ 스위칭 제어 비선형 전력계통안정화장치(NPSS))

  • Lee, Sang-Seung;Li, Shan-Ying;Park, Jong-Keun;Moon, Sung-Il;Yoon, Yong-Tae
    • Proceedings of the KIEE Conference
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    • 2004.11b
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    • pp.179-182
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    • 2004
  • 본 논문에서는 Lie Group theory에 기준한 $H_{\infty}$ 스위칭 제어기에 의한 비선형 전력계통안정화장치 (NPSS)를 설계하고 이를 1기 무한 모선에 적용하여 제안된 제어기의 제어효과 및 영향분석을 실시하였다. 이 분석에 사용된 기존의 PSS type은 Lead-lag 형태의 선형화 제어기이며, 제안된 제어기는 전력계통에 매우 강한 비선형을 반영하여 제어가 가능한 Lie Group theory에 기준한 비선형 제어기로 되어있다. 제안된 Lie Group theory에 기준한 비선형 전력계통안정화장치 (NPSS)의 효과분석은 MATLAB을 이용하여 1기 4차 비선형 전력계통의 모델에 적용하여 시뮬레이션하였다.

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Disk Vibration and Eccentricity Compensation of Near Field Recording Systems Based on the Internal Model Principle (IMP를 이용한 근접장 기록 장치의 디스크 진동 및 편심 보상)

  • Jeong, Jun;Kim, Joong-Gon;Park, No-Cheol;Yang, Hyun-Seok;Park, Young-Pil
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.6 s.123
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    • pp.539-546
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    • 2007
  • Information storage devices using disks have a disk vibration at the frequency which is equivalent to the disk rotational speed. They also have a track vibration due to the disk eccentricity at the same frequency. In near field recording systems, the former affects the air-gap servo and the latter affects the tracking servo. In this paper, we introduce a novel control algorithm based on the internal model principle to both servos. A controller block designed by the principle is connected to the base lead-lag type compensator in parallel in order to cancel the repeatable run-out due to the disk vibration or eccentricity. Simulation and practical application of the algorithm on a near field recording system show good servo performance.

Dominant Synoptic Patterns Controlling PM10 Spatial Variabilities over the Korean Peninsula

  • Park, Hyo-Jin;Wie, Jieun;Moon, Byung-Kwon
    • Journal of the Korean earth science society
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    • v.40 no.5
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    • pp.476-486
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    • 2019
  • This study examines the controlling role of synoptic disturbances on $PM_{10}$ spring variability in the Korean Peninsula by using empirical orthogonal function (EOF) and back trajectory analyses. Three leading EOF modes are identified, and a lead-lag analysis suggests that $PM_{10}$ variabilities be closely related to the synoptic weather systems. The first EOF shows the spatially homogeneous distribution of $PM_{10}$, which is influenced by travelling anticyclonic disturbance with negative precipitation and descending motion. The second and third modes exhibit the dipole structures of $PM_{10}$, being associated with propagating cyclones. Furthermore, the back-trajectory analysis suggests that the transport of pollutants by anomalous winds associated with synoptic disturbances also contribute to the altered $PM_{10}$ concentration. Hence, a substantial synoptic control should be considered in order to fully understand the $PM_{10}$ spatiotemporal variability.

Evaluation and Comparison of the Low-Frequency Oscillation Damping Methods for the Droop-Controlled Inverters in Distributed Generation Systems

  • Tao, Yong;Deng, Yan;Li, Guangdi;Chen, Guipeng;He, Xiangning
    • Journal of Power Electronics
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    • v.16 no.2
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    • pp.731-747
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    • 2016
  • The droop-based control strategy is widely applied in the interfacing inverters for distributed generation. This can be a problem since low-frequency stability issues may be encountered in droop-based microgrid. The objective of this paper is to classify, evaluate and compare various low-frequency damping methods. First, low-frequency stability problems are analyzed and an equivalent model of a droop-controlled inverter is investigated to classify the damping methods into the source-type damping strategies and the impedance-type damping strategies. Moreover, the lead-lag compensation network insertion control is proposed as a beneficial part of the source-type damping strategies. Then, the advantages and disadvantages of the different types of damping methods are theoretically evaluated and experimentally tested. Furthermore, the damping methods are comprehensively compared to illustrate the application field of each method. Finally, the synthesis of different damping methods to enhance the low-frequency stability is discussed and experimental validation is presented.

H_{\infty} Control Synthesis for Power System Design using LMI Optimization Method (LMI 최적화기법을 적용한 $H_{\infty}$제어 시스템의 전력계통 안정화장치(PSS) 설계)

  • Jeong, Dae-Won;Ju, Un-Pyo;Kim, Geon-Jung
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.4
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    • pp.165-174
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    • 2000
  • This paper presents the application of H$\infty$ control synthesis using LMI optimization method to power system stabilizer(PSS) design. Since power system is usually operated under circumstance of unmeasurable uncertainties and external disturbances, the improvement of small signal stability becomes one of the most important issue for securing system stability and preventing low frequency oscillation phenomena. The LMI optimized H$\infty$ PSS provides robust performance and guarantees the internal stability under these operating conditions. The global optimal H$\infty$ norm is found using LMI convex optimization method which is more systematic than standard two Riccati solution method. The design results are simulated for a case study. We verified that the LMI method shows the best performance characteristic smong standard Riccati method and conventional lead/lag method.

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Design of Robust Power System Stabilizers Using Disturbance Rejection Method (외란 소거법을 이용한 강인한 전력 계통 안정화 장치 설계)

  • Kim, Do-Woo;Yun, Gi-Gab;Kim, Hong-Pil;Yang, Hai-Won
    • Proceedings of the KIEE Conference
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    • 1998.07c
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    • pp.1195-1199
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    • 1998
  • In this paper a design method of robust power system stabilizers is proposed by means of robust linear quadratic regulator design technique under power system's operating condition change, which is caused by inner structure uncertainties and disturbances into a power system. It is assumed that the uncertainties present in the system are modeled as one equivalent signal. In this connections an optimal LQR control input for disturbance rejection, the output feedback gain for eliminating the disturbance are calculated. In this case. PSS input signal is obtained on the basis of weighted ${\Delta}P_e$ and $\Delta\omega$. In order to stabilize the overall control of system. Pole placement algorithm is applied in addition. making the poles of the closed loop system to move into a stable region in the complex plane. Some simulations have been conducted to verify the feasibility of the proposed control method on a machine to infinite bus power system. From the simulation results validation of the proposed method could be achieved by comparisons with the conventional PSS with phase lag-lead compensation.

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