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An algorithm for the detection and frequency estimation of periodic forced oscillations in power systems is proposed. The method operates by comparing the periodogram of synchrophasor measurements to a detection threshold. This threshold is established by deriving a general expression for the distribution of the periodogram and is related to the algorithm's probabilities of false alarm and detection...
The voltage source converters (VSC) are the key power interfaces between the individual ac grids and dc grids in the hybrid power system. When the ac grid is unbalanced, the grid currents are distorted and the harmonic is induced. Meanwhile, the oscillations in the active and reactive power are also increased,which may damage these interfaces. In order to ensure the safety of the converters and 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...
This paper presents a non-invasive and easy to implement technique using phasor measurement units for accurate estimation of subsynchronous torsional frequencies. This information is relevant for the optimal design of HVDC subsynchronous damping controllers that enhance the effect of HVDC on subsynchronous damping. The method is rigorously justified using mathematical proofs as well as thorough EMT...
Estimation of electromechanical modes of a power system has attracted attention in the past few decades because it can provide vital information about the stability of the system. In this paper, a new state-space model is proposed for online detection of parameters of a ringdown signal using an extended Kalman filter (EKF). The proposed model can estimate both constant and time-varying parameters...
Sustained oscillations observed in power systems can damage equipment, degrade the power quality and increase the risks of cascading blackouts. There are several mechanisms that can give rise to oscillations, each requiring different countermeasure to suppress or eliminate the oscillation. This work develops mathematical framework for analysis of sustained oscillations and identifies statistical signatures...
This paper presents modeling and analysis of electrical oscillations in a wind farm system. The detailed modeling and modal analysis of a wind farm system are presented in this paper. The approach to modeling uses detailed representation of a wind turbine generator and collection system including high voltage direct-current (HVDC) power converter system control, facilitating a comprehensive analysis...
In this paper, we propose a distributed frequency regulation framework for prosumer-based electric energy systems, where a prosumer (producer-consumer) is defined as an intelligent agent which can produce, consume, and/or store electricity. Despite the frequency regulators being distributed, stability can be ensured while avoiding inter-area oscillations using a limited control effort. To achieve...
This paper introduces a screening method to determine the potential risk of interactions between a dynamic device and a generator with torsional oscillations. The proposed method introduces a factor called the radiality factor (RF) which is an indicator of the radialness of the network between the device and the generator. The RF is calculated in the sub-synchronous frequency range and plotted against...
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...
Under distorted grid conditions with high bandwidth, synchronous reference frame (SRF) Phase Lock Loop (PLL) is able to work properly but increased bandwidth introduces harmonics which affect the PLL output and SRF PLL is also not able to produce accurate phase information under distorted grid conditions. This paper suggests a new phase detection technique based on cosine look-up table (cLUT) using...
This paper proposes a new approach to estimate the non-constant nonlinear frequency of a power system electro-mechanical oscillation mode by deriving an approximate, analytic expression about the oscillation amplitude-frequency dependency. The approach uses the Harmonic Balance Method (HBM) together with one of three representative function approximation techniques, i.e. Taylor Expansion (TE), Chebyshev...
This paper presents a novel control of PV solar farm as a STATCOM (PV-STATCOM) coordinated with Power System Stabilizers (PSSs) for damping of electromechanical oscillations in a power system. A two-area power system with a 150 MW PV solar plant connected at the midpoint of the tie line is simulated in PSCAD/EMTDC software. During contingencies, the capacity of the PV inverter remaining after real...
This paper investigates various factors influencing the capability of MMC-VSC-HVDC systems to enhance damping of system oscillations. The investigation is done in the frequency-domain using a detail model of a MMC-VSC-HVDC system. Simulation results demonstrating the controllability of MMC-VSC-HVDC systems on inter-area and local oscillations in interconnected power systems are described. It is revealed...
Phasor Measurement Units (PMU) are playing an increasingly important role in wide-area monitoring and control of power systems. PMUs allow synchronous real-time measurements of voltage, phase angle and frequency from multiple remote locations in the grid, enabled by their ability to align to Global Position System (GPS) clocks. Given that this ability is vulnerable to GPS spoofing attacks, which have...
The tools used for assessment of rotor angle stability should be able to estimate the domain of attraction and the ensuing control laws which would aid in enhancing it. The widely used energy function formulations have limitations in being extended for lossy N-machines owing to the presence of transfer conductances obtained due to the modeling approaches used in transient stability studies. This problem...
The Prony analysis has been considered as a standard method for estimating oscillation modes using ringdown responses in a power grid. Extensive studies have been done to find its optimal performance conditions, but the comparisons between the Prony analysis and other modal analysis approaches from a user perspective are insufficient. This paper compares the performance of two modal analysis methods,...
The dynamics governing power systems are being modified by the continued increase in the installation of wind turbine-generators (WTGs). This paper presents a small-signal analysis on the impact of the power electronic interface of large quantities of wind generation have on the inter-area oscillation of a two-area system. In particular the sensitivity of this inter-area mode with respect to: (i)...
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...
In this paper an intelligent wide-area damping controller is proposed for a wind integrated power grid. The proposed design is based on an energy function based intelligent optimal controller evolved from adaptive critic design using reinforcement learning technique. A Lyapunov function candidate is derived that links the energy function and the transient stability of the integrated system with the...
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