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Tow-stage configurations used in photovoltaic (PV) architectures (microinverter, string inverter or multistring inverter), are commonly used because of the advantages in front of mismatch conditions. In case of a partial shading scenario (produced by cloudy days and dust accumulation), two-stage architectures reach higher efficiencies compared with the traditional central inverter. It is because,...
This paper proposes a frequency observer based control of a solar energy conversion system (SECS). The proposed control eliminates the DC offset and harmonics current and provides fundamental component of load current. The mathematical analysis of the control is corroborated and discussed in terms of filtering capabilities. Besides, capability of maximum power extraction, it integrates maximum extracted...
The paper proposes a three phase nine level T-type neutral point clamped (9L-T-NPC) inverter for medium voltage induction motor drive. The primary objective of the proposed inverter is to improve the output voltage quality with reduced number of devices and passive components. The generation of nine levels in the output pole voltage is achieved using only ten switches per phase. Although the similar...
The ship shaft power generation system based on a stand-alone brushless doubly-fed induction generator (BDFIG) have demonstrated excellent saving-energy performance. This paper presents a new control scheme of the stand-alone BDFIG for supplying unbalanced loads in the ship shaft power generation system. The positive-and negative-sequence components of the unbalanced power winding (PW) voltage caused...
Performance analysis and output voltage regulation of a cascaded step-up switched-capacitor converter (SCC) under zero voltage switching (ZVS) condition is analyzed in this paper. The ZVS condition (converter operation above its resonant frequency) provides 1) zero-voltage switching, which leads to a relatively higher efficiency compared to zero current switching (ZCS) under the resonant frequency...
Multiport Converter gets growing applications due to its advantages of flexible control mode, high power density, bidirectional power delivery capability etc. In this paper, a DAB based partial isolated DC-AC multiport power converter, which combines photovoltaic panel, battery storage and grid connection is studied. Modulation method, analysis for power transmission and control design are provided...
This study deals with impacts of the shunt conductances associated with HVDC cables and VSC-HVDC stations on optimal operation of Multi-Terminal HVDC (MT-HVDC). In this study, for the first time, shunt conductances are integrated to HVDC Optimal Power-Flow (OPF) program that is executed at the Power Dispatch Center (PDC) of the MT-HVDC grid. With the objective of losses minimization, optimal reference...
Cell voltage equalizers are important for the batteries of electric vehicles and other energy storage systems in order not to be reduced their capacity. The authors have proposed a cell voltage equalizer using an LC series circuit; however, the equalizer requires a lot of bi-directional and multi-stage connected switching elements to equalize the voltage across each battery cell. This paper proposed...
Anew control strategy to achieve high performance from solar photovoltaic system using single stage inverter interfacing grid without maximum power point tracking (MPPT) techniques is investigated in this paper. Sinusoid-tracking algorithm and adaptive filter is proposed to improve the power quality and to regulate constant AC voltage at the point of common coupling (PCC). Proportional integral controllers...
With the increasing penetration of renewable energy generations such as solar and wind power, negative impacts of the large-scale integration of renewable energy on the bulk grid cannot be ignored. Thus, grid integration testing of inverter-coupled renewable energy is essential. For this reason, a high power gird simulator capable of emulating various types of realistic grid conditions is needed for...
In order to correctly implement an energy management strategy for a multi-source system, the output currents of different sources should be regulated to the desired references precisely and rapidly. In this paper, the underlying control of hybrid energy storage system composed by battery and supercapacitor is presented. Three current tracking controllers, PID, sliding mode, and fuzzy logic, are designed...
A novel single-phase five-level active rectifier based on the VIENNA-type rectifier with model predictive current control is presented. The proposed topology operates in unidirectional mode, imposing a sinusoidal grid-side current with unitary power factor. A unidirectional electric vehicle battery charger is the target application in which the proposed rectifier is used; however, it can also be used...
Voltage phase control is a novel field-weakening scheme for PMSM which was reported as more stable in high speed region. This paper provides a current ripple reduce method and a frequency-compensation method. The current ripple reduce method deals with the problem that the voltage phase control has bigger current ripple compared to the tradition method. The frequency-compensation method decreases...
The emulation of synchronous machines is an attractive solution to improve the integration of distributed energy resources in weak grids. In this sense, synchronverters have been widely analysed in the literature, but their digital implementation has been seldom studied. This paper presents the discrete-time implementation of the control algorithms for a battery-supported synchronverter in a weak...
Dead-time effect of dual active bridge (DAB) DC-DC converter is usually out of consideration in traditional optimized strategies, causing the deviation of the theoretical and actual results. In this paper, the current stress model of DAB with dead-time effect is given, and combining the transmission power model, a current-stress-optimized strategy is proposed. Meanwhile, the corresponding control...
DC capacitor voltage imbalance is an inherent problem limited the further development of multi-level Neutral Point Clamped (NPC). In this paper, a new hybrid control method based on Space Vector Pulse Width Modulation (SVPWM) for five-level NPC at high modulation index and high power factor is presented. By choosing appropriate switching pattern in lower modulation index sectors and collocating different...
It is generally preferred for the non-inverting buck-boost converter to operate in buck mode when the input voltage is higher than the output voltage and in boost mode vice versa to improve the efficiency. However, the performance of the converter would be degraded under this operating scheme when the input voltage approaches to the output voltage due to the occurrence of the dead-zone. The four-mode...
As the fluctuation of sub-module capacitance voltage when MMC operates at low frequency, the application of MMC in the field of motor drive has been limited. Therefore, this paper proposes a low frequency control method for the MMC with tuned filter circuit. Based on the theoretical analysis for this tuned filter, the circulating current of 2nd frequency could be suppressed effectively at rated frequency...
Digital-physical hybrid real-time simulation is considered to be an advanced method for future power system simulation. However, the physical interface will inevitably exist DC component, which causes negative effects on practical applications, such as degradation of simulation performance, damage to physical equipment, etc. A novel DC component elimination control strategy for the digital-physical...
Voltage deviations of dc-link capacitors are the main problem of multilevel diode-clamped converters (DCC). In this paper, a novel carrier-based voltage balance method is proposed to balance the dc-link capacitors of five-level DCCs. The proposed method is characterized by injecting proper zero-sequence voltages in the modulation signals of carrier-based modulators. The effects of the injected zero-sequence...
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