123 research outputs found
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
A modular design of incremental Lyapunov functions for microgrid control with power sharing
In this paper we contribute a theoretical framework that sheds a new light on the problem of microgrid analysis and control. The starting point is an energy function comprising the kinetic energy associated with the elements that emulate the rotating machinery and terms taking into account the reactive power stored in the lines and dissipated on shunt elements. We then shape this energy function with the addition of an adjustable voltage-dependent term, and construct incremental storage functions satisfying suitable dissipation inequalities. Our choice of the voltage-dependent term depends on the voltage dynamics/controller under investigation. Several microgrids dynamics that have similarities or coincide with dynamics already considered in the literature are captured in our incremental energy analysis framework. The twist with respect to existing results is that our incremental storage functions allow for an analysis of the coupled microgrid obviating the need for simplifying linearization techniques and for the restrictive decoupling assumption in which the frequency dynamics is fully separated from the voltage one
Gather-and-broadcast frequency control in power systems
We propose a novel frequency control approach in between centralized and
distributed architectures, that is a continuous-time feedback control version
of the dual decomposition optimization method. Specifically, a convex
combination of the frequency measurements is centrally aggregated, followed by
an integral control and a broadcast signal, which is then optimally allocated
at local generation units. We show that our gather-and-broadcast control
architecture comprises many previously proposed strategies as special cases. We
prove local asymptotic stability of the closed-loop equilibria of the
considered power system model, which is a nonlinear differential-algebraic
system that includes traditional generators, frequency-responsive devices, as
well as passive loads, where the sources are already equipped with primary
droop control. Our feedback control is designed such that the closed-loop
equilibria of the power system solve the optimal economic dispatch problem
- …