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Model predictive direct power control (MPDPC) has been widely concerned in the control of doubly fed induction generator (DFIG) systems owing to its simple concept and good multivariate control ability. The optimal voltage vector is selected based on the principle of power error minimization. Nevertheless, the conventional MPDPC still presents relatively high power ripples and the switching frequency...
At present, the research on the quality of micro-grid power at home and abroad is still at the initial stage, which focuses on the study of the power quality characteristics of micro-sources. There is little research on the quality control of micro-grid power and the power quality adjustment device for microgrid. In particular, there is no literature on the power quality of the microgrids containing...
Current harmonics are the major concern in modern equipment. In this paper, an adaptive radical basis function neural network (RBFNN) is proposed to deal with dynamic tracking error problems which are the mathematic model uncertain or complex for the three-phase active power filter (APF). APF is necessary to compensate the harmonics exits in the nonlinear load to maintain the supply current stabilization...
An interleaved current-fed capacitor-less DC/AC converter for PV systems is proposed in this paper with the merits low input current ripple, high power density and high reliability. This proposed DC/AC converter is composed of an interleaved current-fed dc/pulsating-dc converter cascaded with a three-phase pulsating-dc/ac inverter through pulsating-dc-link modulation. The pulse width modulation of...
This paper presents a simplified direct modulation prediction approach for modular multilevel converters (MMC). By using the Euler approximation, the grid-side and circulating currents are firstly predicted to obtain the values in the next switching cycle. Then the modulations are directly calculated based on the established mathematical models for the six-arms of MMC. Subsequently, the capacitor...
Space solar array simulators (SSASs) typically use linear power stages to guarantee high dynamic performance. However, commercial SAS modular products widely used in aerospace power supply system testing require multiple modules in parallel, to improve the output power level and efficiency. This paper proposes a simple thermal design for the linear power stage of an SSAS, which combines a linear power...
With the rapid development of bulk power grid under extra-high voltage (EHV) AC/DC hybrid power system and extensive access of distributed energy resources (DER), operation characteristics of power grid have become increasingly complicated. To cope with new severe challenges faced by safe operation of interconnected bulk power grids, an in-depth analysis of bulk power grid security defense system...
In single-phase photovoltaic (PV) systems, power mismatching between input and output terminal leads to power pulsation, seriously affecting maximum power point tracking (MPPT). Paralleling an electrolytic capacitor (e-cap) across PV panel to smooth power pulsation seems to be an unreliable method owing to its short lifetime. Various power decoupling methods used in micro-inverters have been proposed...
In this paper, a virtual synchronous generator with photovoltaic energy storage hybrid system (VSG-PV) is adopted. VSG-PV can not only output the maximum power of photovoltaic, but also can maintain a stable voltage and frequency of the point of common coupling when system worked in the island model comparing to the conventional photovoltaic generation system. The small signal model of the hybrid...
Off-highway dump truck contains amounts of potential energy and kinetic energy. During the braking process, these two parts are consumed in the form of heat on the braking resistance, and the energy consumption will be about 24 percent of total energy consumption of the Truck. Hence, it is necessary to recover the braking energy. This paper, aiming at the characteristics of electric drive system in...
Conventional finite control set model predictive control (FCS-MPC) for multilevel converters can realize multi-objective control and contain the nonlinear characteristics. However, conventional FCS-MPC may lead to high computational complexity and unwanted switching transition, which is not easy to implement. To solve the issues of computational burden and unwanted switching transition, this paper...
A model predictive control method for a bi-directional DC/DC converter with feedback correction is presented. This method can improve the ability of energy storage system to maintain the stability of the DC voltage, and the converter inductor current track the given fast. The bus voltage overshoot is inhibited. The response speed of storage system to the power fluctuation of DC microgrid is enhanced...
Open-end winding induction motor can be powered by double inverters at both ends. Comparing with conventional single-ended inverter induction motor drive, this new configuration produces some advantages, such as high error tolerance capability, high flexibility, and low DC voltage rating, and so on. Under single DC power supply however, the zero-sequence currents may be produced by the common mode...
VIENNA rectifier with simple structure, which is widely used in charging systems for electric vehicle, realizes the operation of unit power factor and low harmonic. However, grid voltage unbalance will aggravate the dc-link voltage ripple and input current THD. A novel control scheme is presented to solve the impacts of three unbalanced grid voltage for VIENNA rectifier in this paper. The enhanced...
The paper proposes a novel voltage event-triggered P-U control strategy for improving related active power sharing accuracy in low-voltage microgrid (MG). Active power sharing inaccuracy is associated with voltages difference of distributed generation units (DGs) that is basically attributed to mismatched lines impedance. So the inaccuracy is inevitable. The proposed voltage control strategy contains...
In this paper, we propose a backstepping based nonlinear control strategy to ensure the transient performances for the Modular Multilevel Converter (MMC), especially under the emergencies like changing load and operating mode. According to the backstepping control technique, the control input is derived from the Lyapunov stability theory and the established mathematical model. Meanwhile, it can be...
Based on the analysis of the existing problems of photovoltaic(PV) systems with energy storage devices, the new modular independent PV power supply combined the PV cell and energy storage module was designed which contains the following five parts: the PV array, Battery module, Boost circuit, Buck circuit and the controller. The maximum power point tracking(MPPT) is located by the strategy of combining...
In this paper, the relationship between real and reactive power sharing in islanded microgrid considering the complex impedance effect is analyzed. It is determined that traditional droop control has drawbacks in achieving accurate power sharing caused by the mismatched feeder line effect. In order to enhance the power sharing accuracy, an adaptive droop control using virtual impedance for islanded...
A novel voltage equalizer called Multilevel Architecture is proposed for series-connected photovoltaic (PV) system to prevent negative influence of mismatch issues. This undesirable mismatch triggers multiple power maxima in PV string P-V characteristics, encumbering maximum power points tracking (MPPT) algorithms. This paper designed a control scheme for isolated-port flyback converter operating...
In railway traction applications, due to the limitation of switching frequency and the attempt to fully utilize the DC-link voltage, the traction inverters usually work in six-step (or quasi-square-wave) mode under heavy load or high frequency condition. Meanwhile, DC-link voltage fluctuation, stemming from a common single-phase grid-side power supply, has a great impact on the drive system. To maintain...
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