Capacitor voltage balancing in cascaded H‐bridge multilevel inverter and its modelling analysis for grid integrated wind energy conversion system application

Abstract

windmills may operate at variable speeds. 5 Because of variable speed operation and better performance, the doubly fed induction generator (DFIG) has been conventionally used in WECSs. However, permanent magnet synchronous generator (PMSG) has gained broad attention in wind energy applications due to its high efficiency operation, extended speed operating range, self-excitation capability, and leading to a high power factor. For obtaining high efficiency in WECS, it is essential to manage WT such that they can produce maximum power. MPPT algorithm is required for maximal power extraction from the wind energy sources (WES). 1,[6][7][8][9] The output of wind turbine generator (WTG) coupling are inherently unstable dc voltage. The unstable output of WTG contribute to the power quality and stability issues like voltage variations, harmonic generation, and flickers in the grid network. Unwanted harmonics are produced due to the presence of power converters. In addition, due to the varying wind speed, flicker or voltage variation occurs in output power supply. Thus, for the grid integration of WECS, the need of advanced power electronic converters (rectifier, boost converters, and inverters) under transient and steady-state operating condition configuration and their proficient control are necessary to standardize the converter output voltage, even under changing environmental conditions. 3,10 Nowadays, in this type of applications, the multilevel inverters are mostly used in comparison to elementary two-level inverters due to several advantages. [11][12][13][14] Among all standard MLI topologies, "cascaded H-bridge inverter (CHBI)" is primarily used for grid-integrated WECS applications owing to its simpler layout, modular design, reduced number of components as compared with other classical MLI topologies and the use of low voltage rated switches for achieving high or medium power level. [14][15][16][17][18][19] In proposed WECS, WTG coupled systems are connected to two individual H-bridges per phase of CHBMLI through isolated dc link along with respective independent boost converter-based maximum power point tracking (MPPT) system. In addition, by cascading these two H-bridges, the desired five-level output phase voltage is obtained.The major advantage of adopted CHBMLI topology possessing the isolated dc links plays the prominent role to legitimate in connecting two WECS with unequivocal power generation because of deviation of the wind speeds among the windmills at any point of time. In addition, this MLI support to adjoin two medium voltage WECS to feed the total power generated into the high voltage grid without any transformers, but at the same time, the system achieves the better synchronization along with calibrated and controlled power flow. It is an important note to consider that either the CHB topology used as an inverter or a rectifier the mandate of possessing equal dc link voltages is essential to justify identical permissible voltage stress among all switching devices in multilevel topologies at high ...

Finite‐Control‐SetModel Predictive Control for Asymmetrical CascadedH‐BridgeMultilevelGrid‐ConnectedInverter with Flying Capacitor

“…[11]. Meanwhile, some research has been involving in hybrid cascaded multilevel inverter and they have received increasing attention in the last decades because of the capability to synthesize voltage waveforms with reduced harmonic contents without increasing the number of power devices, that is, NPC-CHB multilevel inverter and FCC-CHB multilevel inverter [12][13][14]. These mentioned topologies can minimize the amount of power cells and improve power quality.…”

Photovoltaic‐based grid‐connected transformer‐less three‐phase cascaded diode‐clamped multilevel inverter with reduced leakage current

“…Besides, it needs two additional switches in each H-bridge and passive component, thus increasing the cost. To enhance the power rating in the above-discussed CHBbased MLIs, [29][30][31][32][33][34][35] the input DC-link voltage of each H-bridge is increased. An increase in DC-link voltage increases the stress on the devices.…”

Design of novel universal converter for integration of solar and wind energy for AC and DC load

“…In hybrid generation system, a power electronic converter is necessarily interfaced for power conversion 13 . In a photovoltaic cell, the energy (DC) is converted 14 into AC by using the inverter, 15,16 while for wind energy, the desirable output is generated by cycloconverter or by diode rectifier with an inverter 17,18 . In this proposed manuscript, the multiphase boost converter is used for solar energy extraction from PV cell, a 2n converter with switch reluctance generator is used for wind energy extraction, and a universal converter is proposed to integrate solar and wind energy 19 .…”