arXiv subjects

Silvia Mastellone

Publications and source records attributed to Silvia Mastellone.

11 recordsLinked to original sources

arXiv2026

A Gray-Box Approach for Decentralized Grid-Equivalent Model Identification

We propose a decentralized, frequency-domain identification algorithm that estimates the grid-equivalent model using local measurements from the perspective of each converter. Since local electric signals in a multi-converter setup are affected by voltage inputs from the grid, estimating a direct equivalent impedance yields biased and inaccurate results. To overcome this, we design a framework that decouples the effect of the equivalent impedance (passive) from that of the equivalent voltage (active). The parameters and equivalent grid voltages are then estimated using a least-squares algorithm and a Kalman filter, respectively, applied across frequency samples, with additional pre-processing techniques to remove the influence of the grid on the locally estimated models. We then demonstrate the accuracy and performance of our algorithm on an interconnected $5-$converter system in grid-forming mode, with minimal voltage excitations and non-nominal operating conditions.

eess.SP↗

arXiv2026

Transferring the driveshaft inertia to the grid via the DC-link in MV drive systems

This paper investigates a control approach that renders the driveshaft inertia completely available on the grid side and enhances the fault ride-through behavior of medium-voltage (MV) drive systems. Two main contributions are presented. First, we show how the rotational inertia of the driveline shaft can be synchronously coupled to the grid through a modification of the speed control reference signal and through an adapted DC-link control strategy. For the latter, we pursue two alternatives: one based on conventional cascaded control and another based on synchronous machine (SM) model matching. Second, we demonstrate that both the standard phase-locked loop (PLL) and the matching control approach can be interpreted, via the ray-circle complementarity, as feedback optimization schemes with distinct steady-state maps. This perspective allows us to revisit matching control, reveal its embedded PLL, highlight its current-limiting and tracking capabilities, and provide an extensive simulation study.

eess.SY↗

arXiv2026

Advanced safety filter based on SOS Control Barrier and Lyapunov Functions

This paper presents a novel safety filter framework that ensures both safety and the preservation of the legacy control action within a nominal region. This modular design allows the safety filter to be integrated into the control hierarchy without compromising the performance of the existing legacy controller during nominal operation. For a control-affine system, this is accomplished by formulating multiple Control Barrier Functions (CBFs) and Control Lyapunov-like Functions (CLFs) conditions, alongside a forward invariance condition for the legacy controller, as sum-of-squares constraints. Additionally, the state-dependent inequality constraints of the resulting Quadratic Program (QP) -- encoding the CBF and CLF conditions -- are designed to remain inactive within the nominal region, ensuring preservation of the legacy control action and performance. Our safety filter design is also the first to include quadratic input constraints, and does not need an explicit specification of the attractor, as it is implicitly defined by the legacy controller. To avoid the chattering effect and guarantee the uniqueness and Lipschitz continuity of solutions, the state-dependent inequality constraints of the Quadratic Program are selected to be regular. Finally, we demonstrate the method in a detailed case study involving the control of a three-phase ac/dc power converter.

eess.SY↗

arXiv2025

Resilient AFE Drive Control using Neural Networks with Tracking Guarantees

Industrial installations across several sectors have seen a dramatic increase in productivity, accuracy and efficiency over the last decade due to expanded utilization of medium voltage, variable speed power electronic converters to drive their processes. Specifically, active front-end (AFE) drives have become popular due to their ability to deliver power while maintaining safe electrical setpoints. However, under abnormal grid conditions such as phase loss, conventional AFE control may fail to enforce safety constraints, potentially leading to drive shutdown and significant financial losses. In this work, we propose using reference-tracking Performance Boosting (rPB) to improve the resilience of standard AFE control to faults. This neural-network control framework provides a principled way to optimize transient performance while preserving the steady-state tracking properties of AFE-based drives. By carefully shaping the input signals to the rPB controller, we ensure that it activates only during grid faults, leaving nominal operation unaffected. Simulation results show that the proposed approach successfully maintains the DC bus voltage and the grid current within safe limits during single-phase loss events.

eess.SY↗

arXiv2025

Reactive power flow optimization in AC drive systems

This paper explores a limit avoidance approach in the case of input (modulation) and output (current) constraints with the aim of enhancing system availability of AC drives. Drawing on the observation that, in a certain range of reactive power, there exists a trade-off between current and modulation magnitude, we exploit this freedom and define a constrained optimization problem. We propose two approaches, one in the form of an activation-function which drives the reactive power set-point towards safety, and an approach which uses online feedback optimization to set the reactive power dynamically. Both methods compromise reactive power tracking accuracy for increased system robustness. Through a high fidelity simulation, we compare the benefits of the two methods, highlighting their effectiveness in industrial applications.

eess.SY↗

arXiv2025

Optimal Current Control Strategy for Reliable Power Electronics Converters: Frequency-Domain Approach

Power electronics converters are key enablers in the global energy transition for power generation, industrial and mobility applications; they convert electrical power in a controlled, reliable and efficient manner. The semiconductor switching devices, at the core of power converters, are the most likely component to fail due to the damage caused by the current-induced temperature cycling. Damage models of semiconductors have been developed and employed to study their reliability, improve their design and to estimate the lifetime of the converter in various power applications. However, those models can offer more if employed in the design of strategies to actively operate the converter. Specifically, properly controlling the current, and hence the temperature cycling, can effectively contribute to reducing the accumulated damage in the semiconductor and increase its reliability and lifetime. In this paper we propose a novel current control approach that integrates reliability requirements into the design framework, based on a frequency-domain model of the semiconductor damage.

eess.SY↗

arXiv2025

Safety Filter for Limiting the Current of Grid-Forming Matrix Modular Multilevel Converters

Grid-forming (GFM) converters face significant challenges in limiting current during transient grid events while preserving their grid-forming behavior. This paper offers an elegant solution to the problem with a priori guarantees, presenting a safety filter approach based on Control Barrier Functions (CBFs) to enforce current constraints with minimal deviation from the nominal voltage reference. The safety filter is implemented as a Quadratic Program, enabling real-time computation of safe voltage adjustments that ensure smooth transitions and maintain the GFM behavior during nominal operation. To provide formal safety certificate, the CBF is synthesized offline using a Sum-of-Squares optimization framework, ensuring that the converter remains within its allowable operating limits under all conditions. Additionally, a Control Lyapunov Function is incorporated to facilitate a smooth return to the nominal operating region following grid events. The proposed method is modular and can be integrated into many of the GFM control architectures, as demonstrated with two different GFM implementations. High-fidelity simulations conducted with an enhanced matrix modular multilevel converter connected to both high-inertia and low-inertia grid scenarios validate the effectiveness of the safety filter, showing that it successfully limits current during faults, preserves GFM behavior, and ensures a seamless recovery to nominal operation.

eess.SY↗

arXiv2024

Fast and Efficient Estimation of Resonant Modes: A Case Study of Mechanical Drivelines

This work presents the development of an online parameter estimation algorithm for the identification of resonating modes in a linear system of arbitrary order. The method employs a short-time Fourier transform of the input and output signals and uses a recursive least square (RLS) algorithm to detect resonant frequencies and damping factors of the resonant modes.

eess.SY↗

arXiv2024

Advanced Safety Filter for Smooth Transient Operation of a Battery Energy Storage System

In this paper, we implement an advanced safety filter to smoothly limit the current of an inverter-based Battery Energy Storage System. The task involves finding suitable Control Barrier Function and Control Lyapunov Function via Sum-of-Squares optimization to certify the system's safety during grid transients. In contrast to the conventional safety filter, the advanced safety filter not only provides a safety certificate but also achieves finite-time convergence to a nominal region. Within this region, the action of the nominal control, i.e. the Enhanced Direct Power Control, remains unaltered by the safety filter. The advanced safety filter is implemented using a Quadratically Constrained Quadratic Program, providing the capability to also encode quadratic input constraints. Finally, we showcase the effectiveness of the implementation through simulations involving a load step at the Point of Common Coupling, and we compare the outcomes with those obtained using a standard vector current controller.

eess.SY↗

arXiv2023

Reliability-aware Control of Power Converters in Mobility Applications

This paper introduces an automatic control method designed to enhance the operation of electric vehicles, besides the speed tracking objectives, by including reliability and lifetime requirements. The research considers an automotive power converter which supplies electric power to a permanent magnet synchronous motor (PMSM). The primary control objective is to mitigate the thermal stress on the power electronic Insulate Gate Bipolar Transistors (IGBTs), while simultaneously ensuring effective speed tracking performance. To achieve these goals, we propose an extended H-inf design framework, which includes reliability models. The method is tested in two distinct scenarios: reliability-aware, and reliability-free cases. Furthermore, the paper conducts a lifetime analysis of the IGBTs, leveraging the Rainflow algorithm and temperature data.

eess.SY↗

arXiv2023

SOS Construction of Compatible Control Lyapunov and Barrier Functions

We propose a novel approach to certify closed-loop stability and safety of a constrained polynomial system based on the combination of Control Lyapunov Functions (CLFs) and Control Barrier Functions (CBFs). For polynomial systems that are affine in the control input, both classes of functions can be constructed via Sum Of Squares (SOS) programming. Using two versions of the Positivstellensatz we derive an SOS formulation seeking a rational controller that - if feasible - results in compatible CLF and multiple CBFs.

math.OC↗