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The paper presents the design of an output feedback based centralized, damping controller using partial right eigenstructure assignment technique. The algorithm exploits the extra degrees of freedom provided by multi-input-multi-output (MIMO) systems in partially assigning a few, selected eigenvectors in addition to corresponding eigenvalues. Singular value decomposition (SVD) is used for determining...
This paper studies how to sample load more realistically and efficiently for security constraint unit commitment (SCUC) problems in order to achieve a high degree of robustness of the unit commitment (UC) solution. For example, given the UC solution, 95% of load profiles can be supplied. Principal component analysis (PCA) is introduced to find a clear feature of the historical load in two-dimensional...
Interconnection of DFIG-based wind farms with LCC-HVDC is challenging for very weak AC systems. This work focuses on establishing a modeling and control design framework to analyze frequency dynamics in such systems. To that end, an averaged model of the DFIG-based wind farm connected to LCC-HVDC system has been developed where grid frequency control is used to regulate the HVDC rectifier firing angle...
A technique for extracting the dominant spatiotemporal patterns of variability from high-dimensional simulation (measurement) trajectories is presented. The proposed framework integrates concepts from nonlinear dimensionality reduction methods with nonlinear Laplacian spectral analysis, to extract physically meaningful information about the temporal evolution of low-frequency electromechanical modes...
Prior research has shown that spectral decomposition of the reduced power flow Jacobian (RPFJ) can yield participation factors that describe the extent to which particular buses contribute to particular spectral components of a power system. Research has also shown that both variance and autocorrelation of time series voltage data tend to increase as a power system with stochastically fluctuating...
The low frequency AC (LFAC) transmission, in which a power system is operated at a low frequency, i.e., below 50/60 Hz, is superior to the conventional 60 Hz system in terms of power transfer capability. In addition, due to low operating frequency, the line reactance is reduced and thus voltage drops along the line are decreased. The low frequency transmission thus offers a higher voltage profile...
The current power systems are facing an important transition due to the integration of non-synchronous generation through back-to-back Full Rated Converters' (FRC). Coherency behaviour under the presence of large inclusion of renewables requires special attention in order to understand the swing oscillations when the inertia is decreasing due to the decoupling. This paper presents the application...
A robust stability assessment approach is presented to efficiently estimate eigenvalues in microgrids in the presence of bounded uncertainties. Through this method, all possible locations of eigenvalues can be directly obtained, which makes repeatedly eigenvalue calculation unnecessary when dealing with uncertainties. More importantly, a quasi-diagonalization technique is established to reduce the...
In this paper, a technique for designing fixed parameter decentralized power system stabilizers (PSSs) for interconnected power systems is proposed. In the proposed method, local information available at each machine in the multimachine environment, is used to tune parameters of PSS. Conventional design techniques such as P-Vr frequency response approaches, and the method of residues are based on...
To suppress both the low-frequency oscillation and subsynchronous oscillation, the coordinated optimization strategy of the multi-channel PSS and TCSC Damping Controller is researched in this paper. Considering the oscillation modes to be suppressed as the objective modes, and the maximization of the damping ratio of the objective modes as the optimization objects, an optimization model is established...
This paper investigates techniques for frequency and voltage partitioning of power network based on the graph-theory. These methods divide the power system into distinguished regions to avoid the spread of disturbances and to minimize the interaction between these regions for frequency and voltage control of power system. In case of required active and reactive power for improving the performance...
Modal analysis is the well-established method for investigating small-signal stability. Dominant states of a particular oscillatory or monotonous mode can be identified by linearizing the system's differential equations. Since generator oscillation is predominantly influenced by the speed deviation and the rotor angle, whereas other state variables play a minor role, an approach to reduce a generator's...
Harmonic resonance, which is a main concern in power quality, may cause damage of equipments in power system, and consequently affect stable operation of power grid. In addition, with the continued growth of distributed generators and controllable FACTS devices,for example SVCs, in power grid, harmonic resonance becomes more complicated as frequent changes of their equivalent harmonic impedance parameters...
The uncontrolled intermittent availability of renewable energy sources makes integration of such devices into today's grid a challenge. Thus, it is imperative that dynamic simulation tools used to analyze power system performance are able to support systems with high amounts of photovoltaic (PV) generation. Additionally, simulation durations expanding beyond minutes into hours must be supported. This...
A state feedback control strategy for Doubly Fed Induction Generator (DFIGs) is investigated. Both the rotor side converter and grid side converter control of DFIG has been designed using the proposed state feedback control technique. A comparison between the traditional PI based vector control (VC) of DFIG with the proposed form of control has also been presented. It has been shown that this methodology...
An optimal controller for damping of sub synchronous resonance (SSR) due to a series compensated line connected to a DFIG-based wind farm is presented in this paper. The design procedure includes system modeling, analysis of sub synchronous phenomena, linearization of system about an operating point and controller design. The proposed controller is designed based on LQR method and the eigenvalue analysis...
In this paper, a bio inspired hybrid algorithm namely bacterial foraging differential evolution (BFDE) is proposed for design of robust power system stabilizer (PSS) over wide range of operating and system conditions. The benefits of two optimization techniques are integrated in this hybrid algorithm. A multi objective optimization problem with eigenvalue based objective functions is solved for optimal...
This paper introduces a new frequency dependent cable model (FDCM) for the simulation and analysis of electromagnetic transients. The model belongs to the traveling wave class. The key feature of the proposed model is the correct representation of modal propagation function contributions in phase domain. The challenge is in fitting modal contributions that are non-smooth due to their eigenvectors...
Dynamic stability issues of power converter interfaced devices integrating into the power grid have drawn increased attention. This paper studies DC-link voltage control stability for a weak-ac-grid connected wind farm, in which doubly-fed induction generator (DFIG) based wind turbines (WTs) operate in parallel. First, a reduced analytical model is proposed of separated dynamics for different time...
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