171,359 research outputs found
Design and Stability of Load-Side Primary Frequency Control in Power Systems
We present a systematic method to design ubiquitous continuous fast-acting
distributed load control for primary frequency regulation in power networks, by
formulating an optimal load control (OLC) problem where the objective is to
minimize the aggregate cost of tracking an operating point subject to power
balance over the network. We prove that the swing dynamics and the branch power
flows, coupled with frequency-based load control, serve as a distributed
primal-dual algorithm to solve OLC. We establish the global asymptotic
stability of a multimachine network under such type of load-side primary
frequency control. These results imply that the local frequency deviations at
each bus convey exactly the right information about the global power imbalance
for the loads to make individual decisions that turn out to be globally
optimal. Simulations confirm that the proposed algorithm can rebalance power
and resynchronize bus frequencies after a disturbance with significantly
improved transient performance.Comment: 14 pages, 13 figures. To appear in IEEE Transactions on Automatic
Contro
Stability and Frequency Regulation of Inverters with Capacitive Inertia
In this paper, we address the problem of stability and frequency regulation
of a recently proposed inverter. In this type of inverter, the DC-side
capacitor emulates the inertia of a synchronous generator. First, we remodel
the dynamics from the electrical power perspective. Second, using this model,
we show that the system is stable if connected to a constant power load, and
the frequency can be regulated by a suitable choice of the controller. Next,
and as the main focus of this paper, we analyze the stability of a network of
these inverters, and show that frequency regulation can be achieved by using an
appropriate controller design. Finally, a numerical example is provided which
illustrates the effectiveness of the method
Inertia emulation control of VSC-HVDC transmission system
The increasing penetration of power electronics interfaced renewable generation (e.g. offshore wind) has been leading to a reduction in conventional synchronous-machine based generation. Most converter-interfaced energy sources do not contribute to the overall power system inertia; and therefore cannot support the system during system transients and disturbances. It is therefore desirable that voltage-source-converter (VSC) based high voltage direct current (HVDC) interfaces, which play an important role in delivery of renewable power to AC systems, could contribute a virtual inertia and provide AC grid frequency support. In this paper, an inertia emulation control (IEC) system is proposed that allows VSC-HVDC system to perform an inertial response in a similar fashion to synchronous machines (SM), by exercising the electro-static energy stored in DC shunt capacitors of the HVDC system. The proposed IEC scheme has been implemented in simulations and its performance is evaluated using Matlab/Simulink
Inertia emulation control strategy for VSC-HVDC transmission systems
There is concern that the levels of inertia in power systems may decrease in the future, due to increased levels of energy being provided from renewable sources, which typically have little or no inertia. Voltage source converters (VSC) used in high voltage direct current (HVDC) transmission applications are often deliberately controlled in order to de-couple transients to prevent propagation of instability between interconnected systems. However, this can deny much needed support during transients that would otherwise be available from system inertia provided by rotating plant
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