A multidisciplinary approach to grapevine zoning using GIS technology: An example of thermal data elaboration

Research NoteIn this study we suggest a multidisciplinary approach to zoning based on G.I.S. technology. An example of thermal data elaboration (air temperature) combined with the information derived from the heat requirements of 22 varieties is presented, based on an experiment conducted in an area of the province of Benevento (Campania region, southern Italy). The method combines thermal informations with the Amerine-Winkler bioclimatic index, to obtain a subdivision of the considered territory into five areas, according their thermal suitability. Through the model it was possible to create a map of the optimum thermal suitability of the considered varieties in the various zones of the studied territory.

MC-PWM Harmonic Losses Determination in IPMSM drive fed by Cascaded H-Bridges Multilevel Inverter

The use of Multilevel Inverters (MIs) in PMSM drives is a possible solution for motor harmonic power losses reduction. In this regard, their experimental determination is a challenging task. This paper addresses an experimental analysis of harmonic losses introduced in an IPMSM drive fed by a Cascaded H-Bridges Multilevel Inverter (CHBMI) controlled with different MultiCarrier PWM strategies (MC-PWM). For this purpose, a frequency domain power analysis approach has been adopted to separate the active power value generated at the fundamental harmonic frequency and the power losses at the higher harmonics. In this analysis, several working conditions, defined in the frequency-torque plane, have been considered and the detected IPMSM total power losses, fundamental power losses and harmonic power losses have been discussed

A Novel Multi-Objective Finite Control Set Model Predictive Control for IPMSM drive fed by a Five-Level Cascaded H-Bridge Inverter

In this work, a novel multi-objective voltage-vector-based finite control set model predictive control for a permanent magnet synchronous machine drive fed by a three-phase five-level cascaded H-bridge multilevel inverter is proposed. This algorithm aims to overcome the main issues relative to model predictive control implementation detected in the scientific literature for electric drives fed by cascaded H-bridge multilevel inverters. In detail, the goals are the minimization of computational cost by reducing the number of required predictions, the minimization of the switching devices state transitions, i.e. the switching losses minimization, and the common mode voltage reduction. These goals are fulfilled through an offline optimization process, thus, no additional terms and weighting factors to be tuned are required for the cost function. Experimental validations are presented to prove the effectiveness of the proposed approach. In detail, an accurate electric drive performance comparison, both in steady state and dynamic working conditions, is carried out when the proposed voltage-vector-based model predictive control and the cell-by-cell-based model predictive control are adopted. As comparison tools, current and voltage total harmonic distortion, apparent switching frequency, common mode voltage amplitude, and torque ripple are adopted

Optimized Finite Control Set Model Predictive Control for a Three-Phase Five-Level Cascaded H-Bridge Multilevel Inverter fed Interior Permanent Magnet Synchronous Machine With On-Line Candidate Switching State Selection

Model predictive control is a novel control strategy that is attracting the scientific community due to the several advantages it offers, such as the ability to consider system nonlinearities, the possibility to synthesize a control for a MIMO system instead of multiple SISO, and so on. Control feasibility, due to the very high computational cost required to solve the optimal control problem, is a challenge. By considering electric drives fed by multilevel inverters, the control design is more challenging due to the increased number of available output voltage vectors. In this work, a simple algorithm for the voltage candidate reduction is presented: it allows for reducing the control computational cost, minimizing the switching losses, and minimizing dv/dt on phase voltage waveforms

Comparison between Voltage Oriented Control and Synchronous Power Control for Grid-Connected Inverter Applications

With the rising of renewable power generation, there are new challenges to be addressed in order to maintain the electrical system operation stability. So, in literature, new grid-connected inverter control techniques have been studied. This paper focuses on a comparison between a grid-following control technique, called Voltage Oriented Control and a grid-forming control technique, called Synchronous Power Control, to underline the advantages offered by the latter. Through a simulation analysis in Matlab/Simulink environment, the benefits and drawbacks of these control approaches have been analyzed and discussed

Phasor Measurement Units Optimal Placement and Performance Limits for Fault Localization

In this paper, the performance limits of faults localization are investigated using synchrophasor data. The focus is on a non-trivial operating regime where the number of Phasor Measurement Unit (PMU) sensors available is insufficient to have full observability of the grid state. Proposed analysis uses the Kullback Leibler (KL) divergence between the distributions corresponding to different fault location hypotheses associated with the observation model. This analysis shows that the most likely locations are concentrated in clusters of buses more tightly connected to the actual fault site akin to graph communities. Consequently, a PMU placement strategy is derived that achieves a near-optimal resolution for localizing faults for a given number of sensors. The problem is also analyzed from the perspective of sampling a graph signal, and how the placement of the PMUs i.e. the spatial sampling pattern and the topological characteristic of the grid affect the ability to successfully localize faults. To highlight the superior performance of presented fault localization and placement algorithms, the proposed strategy is applied to a modified IEEE 34, IEEE-123 bus test cases and to data from a real distribution grid. Additionally, the detection of cyber-physical attacks is also examined where PMU data and relevant Supervisory Control and Data Acquisition (SCADA) network traffic information are compared to determine if a network breach has affected the integrity of the system information and/or operations

Dead-time impact on the harmonic distortion and conversion efficiency in a three-phase five-level Cascaded H-Bridge inverter: mathematical formulation and experimental analysis

To avoid leg short-circuit in inverters, dead time must be introduced on leg gate signals. Dead time affects the inverter output voltage fundamental harmonic amplitude, voltage harmonic distortion and inverter efficiency by introducing additional voltage drops. In this regard, dead time effects have been widely investigated for traditional two-level three-phase voltage source inverters in the literature but not extensively for multilevel topology structures. This paper provides a detailed analysis of dead time impact on the harmonic distortion and efficiency of Cascaded H-Bridges Multilevel Inverters (CHBMIs). For this purpose, a general mathematical formulation to determine voltage drop due to dead time effects, also taking into account the adopted Multicarrier PWM strategy, has been provided and experimentally validated for a five-level three-phase CHBMI structure. As a comparison tool between expected and ideal inverter output voltage, the percentage voltage error e% is introduced. In most of the cases, e% is lower than 5%, and it starts increasing for very low amplitude modulation index or for specific working points where nonlinearities occur. Furthermore, several experimental investigations have been carried out to evaluate the CHBMI performance in terms of harmonic distortion and efficiency by changing, the values of dead time, modulation index and switching frequency for ten different multi-carried PWM strategies. Experimental results confirm the strong dependency between the dead time impact on the converter performance and the adopted Multi Carrier-PWM (MC-PWM) strategy: as a way of example, converter efficiency can be reduced from 80% to 60% when dead time is increased from 0.5 μs to 1.5 μs and Phase Shifted-PWM (PS-PWM) is adopted