Adaptive Reference Trajectory for Power Quality Enhancement in Three-Phase Four-Wire Standalone Power Supply Systems with Nonlinear and Unbalanced Loads

International audienc

A New DeadBeat-Based Direct Power Control of Shunt Active Power Filter with Digital Implementation Delay Compensation

Active Power Filter (APF) can significantly compensate the current harmonics produced by nonlinear loads. To do this feature, harmonic detection reference current generation play vital role. Direct Power Controller (DPC) has great harmony with instantaneous power compensation (PQ) algorithm as well as the ability to eliminate internal current loops. In addition, DeadBeat Controller (DBC) has high compatibility for digital implementation, superior control performance and fast dynamic response. However, DBC suffers from time delay linked to control action calculation and digital implementation. In this paper, a new deadbeat-based DPC method is proposed firstly to generate reference current and control of APF. Secondly, a simple and robust compensation method is proposed to eliminate aforementioned deadbeat delay thanks to the online/offline predictions. Several simulations are conducted in MATLAB/SIMULINK verified by experimental tests obtained from a DSP-based active power filter to illustrate the effectiveness and superior performance of the proposed control method. By employing the proposed control method, the Total Harmonic Distortion (THD) of grid current is decreased from 22% to 3% under steady state condition. While the dynamic response with proposed delay compensation validates significant transient response improvement.publishedVersionPeer reviewe

Uncertainty and disturbance estimator design to shape and reduce the output impedance of inverter

Power inverters are becoming more and more common in the modern grid. Due to their switching nature, a passive filter is installed at the inverter output. This generates high output impedance which limits the inverter ability to maintain high power quality at the inverter output. This thesis deals with an impedance shaping approach to the design of power inverter control. The Uncertainty and Disturbance Estimator (UDE) is proposed as a candidate for direct formation of the inverter output impedance. The selection of UDE is motivated by the desire for the disturbance rejection control and the tracking controller to be decoupled. It is demonstrated in the thesis that due to this fact the UDE filter design directly influences the inverter output impedance and the reference model determines the inverter internal electromotive force. It was recently shown in the literature and further emphasized in this thesis that the classic low pass frequency design of the UDE cannot estimate periodical disturbances under the constraint of finite control bandwidth. Since for a power inverter both the reference signal and the disturbance signal are of periodical nature, the classic UDE lowpass filter design does not give optimal results. A new design approach is therefore needed. The thesis develops four novel designs of the UDE filter to significantly reduce the inverter output impedance and maintain low Total Harmonic Distortion (THD) of the inverter output voltage. The first design is the based on a frequency selective filter. This filter design shows superiority in both observing and rejecting periodical disturbances over the classic low pass filter design. The second design uses a multi-band stop design to reject periodical disturbances with some uncertainty in the frequency. The third solution uses a classic low pass filter design combined with a time delay to match zero phase estimation of the disturbance at the relevant spectrum. Furthermore, this solution is combined with a resonant tracking controller to reduce the tracking steady-state error in the output voltage. The fourth solution utilizes a low-pass filter combined with multiple delays to increase the frequency robustness. This method shows superior performance over the multi-band-stop and the time delayed filter in steady-state. All the proposed methods are validated through extensive simulation and experimental results

Power Conditioning for Plug-In Hybrid Electric Vehicles

Plugin Hybrid Electric Vehicles (PHEVs) propel from the electric energy stored in the batteries and gasoline stored in the fuel tank. PHEVs and Electric Vehicles (EVs) connect to external sources to charge the batteries. Moreover, PHEVs can supply stand-alone loads and inject power to the grid. Such functionalities have been defined as Vehicle to House (V2H) and Vehicle to Grid (V2G) and promoted by national and international policies such as the Energy Independency and Security Act (EISA) of 2007, enacted by the United States Congress. Exchanging energy between the vehicle and external sources is performed by the vehicular power conditioner (VPC). This dissertation proposes a design procedure for VPCs. The research mainly focuses on the VPC’s power converter design. A conceptual design approach is proposed to select the proper power converter topologies according to the determined power conditioning needs. The related standards and previous works are reviewed to determine the design guidelines. A set of specifications are introduced for a three port onboard VPC. This VPC is a reference for designs, simulations and experiments. The reference VPC is implemented with a modular three-stage isolated topology that utilizes voltage source ac-dc converters as the power conditioning stages. The multiport extension of this topology extends the vehicular power conditioning concept into a novel vehicular integrated power system. All the vehicle’s electric sources and loads can exchange energy in the described multiport integrated power system. Novel design methods are proposed for the power converter, filters, magnetic circuit and control of the VPC. The practical challenges of the VPC development are analyzed. The major contributions of this dissertation include a pioneer grounding scheme for VPC considering the vehicular standards, a novel modeling approach for the Snubberless Dual Active Bridge (DAB) commutation, an innovative integrated ac inductor, and a new experimental modeling method for multiwinding transformers. The contributions are supported by analyses, simulations, and practical experiments

Study and evaluation of distributed power electronic converters in photovoltaic generation applications

This research project has proposed a new modulation technique called “Local Carrier Pulse Width Modulation” (LC-PWM) for MMCs with different cell voltages, taking into account the measured cell voltages to generate switching sequences with more accurate timing. It also adapts the modulator sampling period to improve the transitions from level to level, an important issue to reduce noise at the internal circulating currents. As a result, the new modulation LC-PWM technique reduces the output distortion in a wider range of voltage situations. Furthermore, it effectively eliminates unnecessary AC components of circulating currents, resulting in lower power losses and higher MMC efficiency.Departamento de Tecnología ElectrónicaDoctorado en Ingeniería Industria