Real time simulation of reduced switch multilevel inverter with PWM switching sequence control

<span lang="EN-US">Reduction of switch count in symmetrical and asymmetrical reduced switch multilevel inverter designs has been proposed regularly with operation of conventional carrier-based pulse width modulation technique. In this study, a novel structure of symmetrical Hexa shaped model reduced switch seven level output inverter is proposed without any auxiliary switch and H-bridge. Proposed structure offers a smaller number of switch count and voltage sources which results in the cost and complexity reduction of its implementation. To operate the switching sequence of inverter from carrier based APOD, POD and PD methods, suitable logical expression to be realize which gained more prominence. Active utilization of two voltage sources in each mode of operation results in significant reduction of voltage stress across each switch is achieved. A comparative study of proposed MLI with various reduced switch MLIs has been presented. Initially, simulation model implementation has been carried out with MATLAB/Simulink and observed the performance parameters and THD. Simulation results are carried for the comparison of the results obtained in the real time work performed on OPAL-RT 5700 simulator</span><span lang="EN-US">.</span>

A Sensitivity-Based Three-Phase Weather-Dependent Power Flow Approach for Networks with Local Controllers—PART II: Case Studies

<p><b>Power flow is an integral part of distribution system planning, monitoring, operation, and analysis. This two-part paper proposes a sensitivity-based three-phase weather-dependent power flow approach for accurately simulating distribution networks with local voltage controllers (LVC). This part II, firstly, presents simulation results of the proposed approach in an 8-Bus and 7-Bus network, which are validated using dynamic simulation. Secondly, simulation results for the IEEE 8500-node network are also presented. An extensive comparison is conducted between the proposed sensitivity-based approach and the other existing power flow approaches with respect to result accuracy and convergence speed. Moreover, the influence of weather and magnetic effects on the power flow results and the LVC states is also investigated. Simulation results confirm that the proposed sensitivity-based approach produces more accurate results than the existing approaches since it considers the actual switching sequence of LVCs as well as the weather and magnetic effects on the network. Moreover, the proposed algorithm exhibits accelerated convergence due to the usage of the sensitivity parameters, which makes it an important tool for distribution system analysis. </b></p>

Protocol-Based Control for Cyber-Physical Systems with Environment-Dependent Energy Harvesting Sensors

In this paper, a protocol-based controller is designed for Cyber-Physical Systems (CPSs) with multiple sensors, which are powered by environment-dependent energy harvesting (EDEH) devices, respectively. The Round-Robin (RR) protocol is adopted to coordinate the data transmission of sensors. The protocol-based transmission can be realized only when the energy harvested by EDEH devices is sufficient. The aim of this paper is to design the protocol-based controller to ensure the stochastic finite-time boundedness (FTB) with EDEH and RR protocol. Firstly, modeling the EDEH by a switching sequence with varying sojourn probabilities, assuming a finite battery capacity constraint, and associating protocol-based transmission with a given energy cost, we propose a new recursive model to depict the dynamic of energy levels for each sensor. Then, combining with stochastic analysis and the dynamic of energy levels, the explicit expressions of the controller for each environment with average dwell time (ADT) are obtained. Finally, an example is provided to demonstrate the effectiveness of the designed controllers.

Continuous Control Set Model Predictive Control for an Indirect Matrix Converter

A continuous control set model predictive power control strategy for an indirect matrix converter is proposed in this paper. The load reactive power, the load active power, and the input reactive power are controlled simultaneously. This control strategy can obtain output waveforms with fixed switching frequency. Additionally, an optimal switching sequence is proposed to simplify the commutations of the indirect matrix converter. To suppress the input filter resonance, an active damping method is proposed. Experimental results prove that the proposed method features controllable input reactive power, controllable load active and reactive power, fixed switching frequency output waveforms, zero-current switching operations, and effectively suppresses input filter resonance.

Energy Management of a Multi-Source Power System

This work focuses on energy management for a system operated by multiple energy sources which include batteries, super capacitors, a hydrogen fuel cell, and a photovoltaic cell. The overall objective is to minimize the power consumption from all sources needed to satisfy the system’s power demand by optimizing the switching between the different energy sources. A dynamic mathematical model representing the energy sources is developed taking into account the different constraints on the system, i.e., primarily the state-of-charge of the battery and the super capacitors. In addition to the model, a heuristic approach is developed and compared with the mathematical model. Both approaches were tested on a multi-energy source ground robot as a prototype. The novelty of this work is that the scheduling of an energy system consisting of four different types of sources is compared by performing analysis via dynamic programming, and a heuristic approach. The results generated using both methods are analyzed and compared to a standard mode of operation. The comparison validated that the proposed approaches minimize the average power consumption across all sources. The dynamic modeling approach performs well in terms of optimization and provided a superior switching sequence, while the heuristic approach offers the definite advantages in terms of ease of implementation and simple computation requirements. Additionally, the switching sequence provided by the dynamic approach was able to meet the power demand for all simulations performed and showed that the average power consumption across all sources is minimized.

Implementation of 7-Level and 31-Level Cascaded H-Bridge Multilevel Inverters with Reduced Number of Semiconductor Switches

Multilevel inverters are widely used because of its increased power rating with reduced harmonics and electromagnetic interference. The proposed 7-level cascaded H-Bridge inverter is symmetrical in nature and uses equal sources of DC voltage. Whereas 31-level cascaded H-Bridge inverter is asymmetrical in nature and uses unequal sources of DC voltage. The PD-PWM modulation technique was used here to achieve switching sequence. The proposed idea was validated through simulation and the results provide better efficiency, fewer low order harmonics and lower switching losses. The proposed topology is simulated using MATLAB / SIMULINK.