2,195 research outputs found
Distributed Primary Frequency Control through Multi-Terminal HVDC Transmission Systems
This paper presents a decentralized controller for sharing primary AC
frequency control reserves through a multi-terminal HVDC grid. By using
Lyapunov arguments, the proposed controller is shown to stabilize the
equilibrium of the closed-loop system consisting of the interconnected AC and
HVDC grids, given any positive controller gains. The static control errors
resulting from the proportional controller are quantified and bounded by
analyzing the equilibrium of the closed-loop system. The proposed controller is
applied to a test grid consisting of three asynchronous AC areas interconnected
by an HVDC grid, and its effectiveness is validated through simulation
Primary frequency control
The frequency value represents the correlation between the balance of the generated and consumed active power in the energy system. Besides the frequency level is an indicator of the quality of the electric energy and shows the work regimes that exist in the energy system at the present moment. Control of the generation and consumption in power supply systemismaintained by System Operator of the Unified Power System
Challenges of Primary Frequency Control and Benefits of Primary Frequency Response Support from Electric Vehicles
As the integration of wind generation displaces conventional plants, system inertia provided by rotating mass declines, causing concerns over system frequency stability. This paper implements an advanced stochastic scheduling model with inertia-dependent fast frequency response requirements to investigate the challenges on the primary frequency control in the future Great Britain electricity system. The results suggest that the required volume and the associated cost of primary frequency response increase significantly along with the increased capacity of wind plants. Alternative measures (e.g. electric vehicles) have been proposed to alleviate these concerns. Therefore, this paper also analyses the benefits of primary frequency response support from electric vehicles in reducing system operation cost, wind curtailment and carbon emissions
Least Squares Estimation-Based Synchronous Generator Parameter Estimation Using PMU Data
In this paper, least square estimation (LSE)-based dynamic generator model
parameter identification is investigated. Electromechanical dynamics related
parameters such as inertia constant and primary frequency control droop for a
synchronous generator are estimated using Phasor Measurement Unit (PMU) data
obtained at the generator terminal bus. The key idea of applying LSE for
dynamic parameter estimation is to have a discrete
\underline{a}uto\underline{r}egression with e\underline{x}ogenous input (ARX)
model. With an ARX model, a linear estimation problem can be formulated and the
parameters of the ARX model can be found. This paper gives the detailed
derivation of converting a generator model with primary frequency control into
an ARX model. The generator parameters will be recovered from the estimated ARX
model parameters afterwards. Two types of conversion methods are presented:
zero-order hold (ZOH) method and Tustin method. Numerical results are presented
to illustrate the proposed LSE application in dynamic system parameter
identification using PMU data.Comment: 5 pages, 6 figures, accepted by IEEE PESGM 201
Contribution of DFIG wind turbines to Primary Frequency Control
In recent years, worldwide power systems are experiencing a steadily growth in wind power penetration. A common concern in the operation of such systems is related to the frequency stability. Modern variable speed wind turbines have a limited capacity in providing ancillary services, such as: fastfrequency response and primary frequency regulation. This thesis aims at developing a new methodology for the analysis of frequency dynamics in largescale power systems with high level of wind energy share. Firstly, a simplified electromechanical model of a doubly fed induction generator (DFIG) based wind turbine has been proposed. In addition, a virtual inertia controller version of the optimized power point tracking method (OPPT) has been adapted for this kind of wind turbines. In this method, the maximum power point tracking curve (MPPT) is shifted to drive variations in the active power injection as a function of the grid frequency deviation, by exploiting the available inertial resources. The proposed methodology integrates the model in a primary frequency control scheme to assess the interaction with the rest of the plants in the power system
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