Search for: power-system-frequencies
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    Modified power reserve management solution in power system considering frequency constraints

    , Article IEEE Systems Journal ; Volume 14, Issue 1 , 2020 , Pages 1125-1134 Hosseini, S. A ; Toulabi, M ; Ashouri Zadeh, A ; Ranjbar, A. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    In this paper, security constrained reserve management (SCRM) problem is formulated. In this trend, security constrained economic dispatch as well as operating reserve in both normal and {N-1} contingency condition are considered. To address the computational complexity associated with the SCRM problem, the distributed-SCRM (D-SCRM) is proposed. In the suggested method, the power system is decomposed to several subsystems called zone. These zones are interconnected via some tie-lines. By defining two virtual generation units at the middle of each tie-line, all neighbor zones become isolated. This causes the main SCRM problem to be converted to some subproblems. To solve these subproblems,... 

    Different approaches for estimation of dampings and frequencies of electromechanical modes from PMU ambient data

    , Article 2015 IEEE 15th International Conference on Environment and Electrical Engineering, EEEIC 2015 - Conference Proceedings, 10 June 2015 through 13 June 2015 ; June , 2015 , Pages 1748-1753 ; 9781479979936 (ISBN) Farrokhifard, M ; Hatami, M ; Parniani, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Small signal stability of power systems is one of the most crucially important issues, since the electrical demand is increasing at a galloping rate and power systems are expanding day by day. In this regard, estimation of dampings and frequencies of electromechanical modes through the analysis of field measurements has become a heated study topic for electrical power system researchers in recent years. There have been several methods to analyze different types of Phasor Measurement Units (PMUs) signals i.e., transient, ambient, and probing. Among the proposed techniques, those which are capable of analyzing ambient data seems to be more practical, since this type of data can be achieved... 

    Frequency stability improvement in windthermal dominated power grids

    , Article IET Generation, Transmission and Distribution ; Volume 14, Issue 4 , 2020 , Pages 619-627 Ashouri Zadeh, A ; Toulabi, M ; Dobakhshari, A. S ; Ranjbar, A. M ; Sharif University of Technology
    Institution of Engineering and Technology  2020
    With the proliferation of intermittent renewable energy sources, power systems need to withstand an increasing number of disturbances that may affect system frequency. In this paper, we focus on the effects of high penetration level of wind turbine-generators (WTG) on the power system operational planning from the frequency point of view. Specifically, an exact formulation for the minimum frequency calculation is presented to increase accuracy and speed of analyses. Then, the effect of WTG's frequency response on the power system frequency stability is investigated to compute the maximum acceptable generation outage as a function of penetration level. Finally, as an application to power... 

    Estimation of power system frequency using an adaptive notch filter

    , Article IEEE Transactions on Instrumentation and Measurement ; Volume 56, Issue 6 , December , 2007 , Pages 2470-2477 ; 00189456 (ISSN) Mojiri, M ; Karimi Ghartemani, M ; Bakhshai, A ; Sharif University of Technology
    An algorithm based on the concept of adaptive notch filter (ANF) is proposed for estimation of power system frequency. The ANF is a second-order notch filter that is further furnished with a nonlinear differential equation to update the frequency. The method permits direct estimation of frequency and its rate of change for a power system signal. The performance of the algorithm is compared with that of a newly introduced algorithm, which is based on using an enhanced phase-locked loop (PLL) system. Unlike the PLL-based frequency estimator, the proposed algorithm does not employ a voltage-controlled oscillator. This makes its structure much simpler for implementation. The transient response... 

    Frequency Control Improvement of Power Systems with High Penetration of Wind Power Generation

    , Ph.D. Dissertation Sharif University of Technology Ravanji, Mohammad Hassan (Author) ; Parniani, Mostafa (Supervisor)
    Global trends of electrical energy production indicate high penetration of renewable wind energy resources in power grids around the world.Although high penetration of these resources benefits the grid operators and end-users in various aspects, several new challenges should be addressed. These challenges can be focused on in various studies with different time intervals and different technical and economic issues. One of the most important issues relates to the system frequency regulation and control aspects in high wind and photovoltaic (PV) penetrated grids. This is due to the fact that wind turbine generators (WTGs) as well as PV systems do not provide inertial response for the system... 

    Dynamic participation of wind farms in system frequency control

    , Article IEEE PES Innovative Smart Grid Technologies Conference Europe, 14 October 2012 through 17 October 2012 ; October , 2012 ; 9781467325974 (ISBN) Toulabi, M ; Ranjbar, A. M ; Karimi, H ; Shiroie, M ; Sharif University of Technology
    In this paper, the participation of wind farms in load frequency control (LFC) is studied. A previously proposed macromodel for the wind farm is employed to regulate its output power. The wind farm including its proposed control strategy is incorporated into the conventional LFC model. The proposed LFC structure is able to dynamically maintain the system frequency at the nominal value against the power imbalances. To achieve proper transient response, the integral control parameter of the LFC controller is optimized using the genetic algorithm (GA). To verify the effectiveness of the proposed method, several simulation case studies are carried out. The results show that the wind farm can... 

    Frequency monitoring and control during power system restoration based on wide area measurement system

    , Article Mathematical Problems in Engineering ; Volume 2011 , 2011 ; 1024123X (ISSN) Nourizadeh, S ; Yari, V ; Ranjbar, A. M ; Sharif University of Technology
    Frequency control during power system restoration has not been strongly addressed. Operators are often concerned with the offline sizing of load and generation steps, but, nowadays, the introduction of Wide Area Measurement System (WAMS) makes it possible to monitor the stability of power system online. The constraints of WAMS operation result in some changes in power system frequency control. This paper proposes a novel methodology for frequency control and monitoring during the early steps of power system restoration based on WAMS. Detailed load modeling is achieved based on the static load modeling approach. Power generators' modeling is also accomplished utilizing the single machine... 

    Modified virtual inertial controller for prudential participation of DFIG-based wind turbines in power system frequency regulation

    , Article IET Renewable Power Generation ; Volume 13, Issue 1 , 2019 , Pages 155-164 ; 17521416 (ISSN) Ravanji, M. H ; Parniani, M ; Sharif University of Technology
    Institution of Engineering and Technology  2019
    This study proposes a modified virtual inertial control (MVIC) scheme for doubly-fed induction generator (DFIG)based wind turbines (WTs), which both improves the frequency response of these renewable resources and enhances the power system oscillation damping capabilities. It is shown that the proposed control structure enables the WT to participate prudentially in system frequency regulation, which means the amount of WT kinetic energy released to the grid and its participation in system frequency support is alleviated as its stored energy decreases. The proposed control strategy is introduced conceptually, and its performance is verified analytically. Effects of wind speed variations on... 

    Application of bang-bang controller to emulate primary frequency response in DFIGs

    , Article IEEE Systems Journal ; Volume 14, Issue 2 , 2020 , Pages 2615-2623 Toulabi, M ; Ashouri Zadeh, A ; Kazari, H ; Ranjbar, A. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    This article proposes a bang-bang auxiliary frequency control scheme for doubly-fed induction generator (DFIG)-based wind turbines. It results in the DFIGs emulate the primary frequency control of conventional units and, thus, increases the power system frequency stability. Indeed, the suggested hysteresis controller causes to deliver the maximum extractable kinetic energy of DFIGs to the grid and consequently further enhance the power system frequency. This is accomplished using different frequency deviation indices, which determine the size of power mismatch and lead to an appropriate frequency response by the DFIGs. The operational constraints of the DFIGs are taken into account in the... 

    Coordinated control of doubley fed induction generator virtual inertia and power system oscillation damping using fuzzy logic

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 32, Issue 4 , 2019 , Pages 536-547 ; 17281431 (ISSN) Solat, A. R ; Ranjbar, A. M ; Mozafari, B ; Sharif University of Technology
    Materials and Energy Research Center  2019
    Doubly-fed induction generator (DFIG) based wind turbines with traditional maximum power point tracking (MPPT) control provide no inertia response under system frequency events. Recently, the DFIG wind turbines have been equipped with virtual inertia controller (VIC) for supporting power system frequency stability. However, the conventional VICs with fixed gain have negative effects on inter-area oscillations of regional networks. To cope with this drawback, this paper proposes a novel adaptive VIC to improve both the inter-area oscillations and frequency stability. In the proposed scheme, the gain of VIC is dynamically adjusted using fuzzy logic. The effectiveness and control performance of... 

    Delay compensation of demand response and adaptive disturbance rejection applied to power system frequency control

    , Article IEEE Transactions on Power Systems ; Volume 35, Issue 3 , 2020 , Pages 2037-2046 Hosseini, S. A ; Toulabi, M. R ; Salehi Dobakhshari, A ; Ashouri Zadeh, A ; Ranjbar, A. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    In this paper, a modified frequency control model is proposed, where the demand response (DR) control loop is added to the traditional load frequency control (LFC) model to improve the frequency regulation of the power system. One of the main obstacles for using DR in the frequency regulation is communication delay which exists in transferring data from control center to appliances. To overcome this issue, an adaptive delay compensator (ADC) is used in order to compensate the communication delay in the control loop. In this regard, a weighted combination of several vertex compensators, whose weights are updated according to the measured delay, is employed. Generating the phase lead is the...