Scalable State-Space Model of Voltage Source Converter for Low-Frequency Stability Analysis

IEEE Trans. Power Electron.

Zhu

Pugliese

et al. 2022

Self Cite

Admittance reshaping is a widely used strategy to address the converters low-frequency stability issues in weak grid, caused by the PLL and its interaction with the dc and ac voltage control. However, the asymmetric control of the d-and q-axis current references and the coupling between the converter ac and dc side restricts the damping capability of Single-Input-Single-Output feedbacks. This phenomena gets even worse in presence of nearby converters. This paper extends the concept of admittance reshaping to Multi-Input-Multi-Output (MIMO) control. A full state-feedback is added to the current reference of the converter to increase the damping of the conventional multi-loop control. A systematic offline algorithm is delegated to design the feedback, and a scalar coefficient is employed to activate/deactivate online the reshaping feedback, making the proposed solution user-friendly. The proposed control is analyzed both in time-and frequencydomain and tested in parallel-operation with other converters, and shows higher damping capability than conventional solutions and good robustness with respect to grid impedance and operating point variations. Experimental tests under ac and dc disturbances are conducted both in lab setup and in Hardware-In-the-Loop.

Section: A Converter Nonlinear Modelingmentioning

confidence: 99%

State Feedback Reshaping Control of Voltage Source Converter

IEEE Trans. Power Electron.

Zhu

Pugliese

et al. 2022

Self Cite

“…The considered converter presents an L-filter L f , motivated by the increasing interest in L-filtered MMCs in converters with inertia emulation [14]- [16]. The lack of the output ac capacitor makes the statespace modeling as well as the double voltage-current loop design challenging [10], [14]. The papers [9], [10] proposed to model the inverter and its current loop G cc (s) = K p + Ki s with the state-space representation of its impedance model to break through this limit.…”

Section: System Description and Modelingmentioning

confidence: 99%

“…The lack of the output ac capacitor makes the statespace modeling as well as the double voltage-current loop design challenging [10], [14]. The papers [9], [10] proposed to model the inverter and its current loop G cc (s) = K p + Ki s with the state-space representation of its impedance model to break through this limit. The model of the current loop is given:…”

Section: System Description and Modelingmentioning

confidence: 99%

See 1 more Smart Citation

Design Oriented Analysis of Control Loops Interaction in Power Synchronization-based Voltage Source Converter

2021 IEEE Energy Conversion Congress and Exposition (ECCE)

Liserre

Liao

et al. 2021

Self Cite

Power synchronization mechanism is coupled with the dc-link, since both synchronization and dc-link dynamics depend on the active power. The active power filter used in the frequency droop is correlated with inertia emulation, which affects the dc-link voltage. Furthermore, the coupling between active and reactive power in the low-voltage grid suggests a possible interaction between dc-link and reactive power control. The strong coupling between all the control loops and the dc-link in power synchronization-based converters represents a challenge both for the stability and for the controller tuning. This paper addresses the tuning of power synchronizationbased converter with consideration of all the control loops interactions. A complete converter state-space model is derived, and a step-by-step tuning procedure based on eigenvalue analysis is proposed. Experimental results are provided to demonstrate the method.

“…III. CONVERTER STATE-SPACE MODELING The converter and its control loops are modeled in the state-space through a set of nonlinear differential and algebraic equations [15]- [17] in the form:…”

Section: System Description and Overmodulationmentioning

confidence: 99%

Analysis of Overmodulation in Power Synchronization-based Voltage Source Converters

2021 IEEE Energy Conversion Congress and Exposition (ECCE)

Pugliese

Liserre

et al. 2021

Self Cite

Low power system inertia in power electronics-dominated grids is a widely discussed problem. Power synchronization allows to emulate inertia by means of the active power low-pass filter, slowing down the grid frequency excursions. Nevertheless, inertia emulation during grid disturbances results in high energy exchange with the dc-link, which brings large dc voltage excursions. When the dc voltage dips below the ac line voltage peak, the modulation index can become too high and make the converter unable to produce the requested ac voltage. The consequent saturation of the voltage can cause current control wind-up, harmonic distortion and loss of controllability. Moreover, when the reference voltage is saturated, the converter does not behave anymore according to the power synchronization control law, making the conventional stability analyses not valid. Despite the relevance of these issues, a systematic analysis about the voltage saturation induced by grid disturbances in power converters is still missing. For that, this paper proposes a mathematical tool based on Bode plots. The target of this tool is to properly chose the converter parameters in order to tolerate grid disturbances without reaching the voltage saturation. Simulations and experiments are provided.