Ron OfirTechnion - Israel Institute of Technology | technion · Faculty of Electrical Engineering
Ron Ofir
Bachelor of Science
About
23
Publications
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94
Citations
Citations since 2017
Publications
Publications (23)
The ribosome flow model (RFM) is a phenomenological model for the flow of particles along a one-dimensional chain of n sites. It has been extensively used to study ribosome flow along the mRNA molecule during translation. When the transition rates along the chain are time-varying and jointly T-periodic the RFM entrains, i.e. every trajectory of the...
A Lurie system is the interconnection of a linear time-invariant system and a nonlinear feedback function. We derive a new sufficient condition for $k$-contraction of a Lurie system. For $k=1$, our sufficient condition reduces to the standard stability condition based on the bounded real lemma and a small gain condition. However, Lurie systems ofte...
We consider a Lurie system obtained via a connection of a linear time-invariant system and a nonlinear feedback function. Such systems often have more than a single equilibrium and are thus not contractive with respect to any norm. We derive a new sufficient condition for $k$-contraction of a Lurie system. For $k=1$, our sufficient condition reduce...
The ribosome flow model (RFM) is a phenomenological model for the flow of particles along a 1D chain of sites. It has been extensively used to study ribosome flow along the mRNA molecule during translation. When the transition rates along the chain are time-varying and jointly T-periodic the RFM entrains, i.e., every trajectory of the RFM converges...
Compound matrices have found applications in many fields of science including systems and control theory. In particular, a sufficient condition for $k$-contraction is that a logarithmic norm (also called matrix measure) of the $k$-additive compound of the Jacobian is uniformly negative. However, this may be difficult to check in practice because th...
The flow of an
$n$
-dimensional
$k$
-contracting system, with
$k\in \lbrace 1,\ldots,n\rbrace$
, contracts
$k$
-dimensional parallelotopes. For
$k=1$
, this reduces to a standard contracting system. One reason for the usefulness of 1-contracting systems is that many interconnections of contracting subsystems yield an overall 1-contracting...
We consider the problem of making a networked system contracting by designing minimal effort local controllers. Our method combines a hierarchical contraction characterization and a matrix-balancing approach to stabilizing a Metzler matrix via minimal diagonal perturbations. We demonstrate our approach by designing local controllers that render con...
We propose an optimal control method for storage systems that are affected by the power grid's ramp constraints. Such problems are becoming increasingly important in recent years due to the integration of renewable energy sources, which often leads to duck curve effects. The main idea of the proposed method is to limit the number of computations in...
We consider the problem of making a networked system contracting by designing “minimal effort” local controllers. Our method combines a hierarchical contraction characterization and a matrix-balancing approach to stabilizing a Metzler matrix via minimal diagonal perturbations. We demonstrate our approach by designing local controllers that render c...
This paper presents necessary and sufficient conditions for a linear three-phase circuit to have a linear and time-invariant
$dq0$
model. More specifically, we show that a circuit with state and input matrices that can be partitioned into three-by-three circulant matrices at the
$abc$
frame of reference, can be transformed into a linear and tim...
The multiplicative and additive compounds of a matrix have important applications in geometry, linear algebra, and dynamical systems described by difference equations and by ordinary differential equations. Here, we introduce a generalization of the multiplicative compound to matrix pencils. We analyze the properties of this new compound and descri...
The COVID-19 pandemic and the preventive measures that followed it have significantly impacted generation and consumption patterns in power systems across the globe, calling for new tools to efficiently evaluate generation and load profiles. In this work, we propose one possible tool, which we name the smoothness index, that evaluates a profile bas...
The flow of contracting systems contracts 1-dimensional parallelotopes, i.e., line segments, at an exponential rate. One reason for the usefulness of contracting systems is that many interconnections of contracting sub-systems yield an overall contracting system. A generalization of contracting systems is $k$-contracting systems, where $k\in\{1,\do...
In the field of power system dynamics, a main challenge is to properly tune the inverters control parameters, where one important parameter is the inverter's output impedance, physical or virtual. In this work, we provide a proof showing that a minimal output impedance must be used in order to keep the system stable. Although this result is well kn...
The flow of contracting systems contracts 1-dimensional polygons (i.e. lines) at an exponential rate. One reason for the usefulness of contracting systems is that many interconnections of contracting sub-systems yield an overall contracting system. A recent generalization of contracting systems is called $k$-contracting systems, where $k\in\{1,\dot...
We consider energy storage systems having nonlinear efficiency functions, which are becoming increasingly important as shown in several recent works, and propose an optimal solution based on Pontryagin's minimum principle. A central challenge in such problems is the hard limits on the state variable, which restrict the use of the minimum principle....
Recently there have been extensive research efforts to identify possible adverse effects of distributed sources and power electronics based devices when integrated into existing power grids, where two main challenges are low rotational inertia and stability. This paper studies the dynamics and stability of two simple systems: an ideal power source...
Recently there have been extensive research efforts to identify possible adverse effects of distributed sources and power electronics based devices when integrated into existing power grids, where two main challenges are low rotational inertia and stability. This paper studies the dynamics and stability of two simple systems: an ideal power source...
Virtual Inertia Emulation (VIE) and traditional Active Power Droop Control (APDC) are among the most common approaches for regulating the active power output of inverter-based generators. Furthermore, it has been shown that, under certain conditions, these two methods can be equivalent. However, neither those studies, nor the analyses of different...
Projects
Project (1)
Currently it is widely accepted that a major barrier toward massive integration of renewable energy sources is the complex dynamic behavior of large-scale power systems. In many cases, the need to preserve system reliability and stability is a bottleneck, which practically prevents the use of such sources, despite their positive environmental impact and low cost. In addition, power systems with high penetration level of renewable energy sources will probably require new control methods and management strategies.
In light of these challenges we explore the fundamental limits of large-scale power systems, from the point of view of the system dynamics. For instance: how much power can be generated by renewable energy sources without critical consequences? Is 100% renewables energy integration a feasible goal in principle? What is the fundamental lower limit on the amount of stored energy in a system? Is it possible to operate a power system without energy storage devices, and if not, what is a lower limit on the energy stored in the system?
See more on our project's web-page:
https://a-lab.ee/projects/dq0-dynamics
