scholarly journals A High-Gain Observer-Based Adaptive Super-Twisting Algorithm for DC-Link Voltage Control of NPC Converters

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1110 ◽  
Author(s):  
Xiaoning Shen ◽  
Jianxing Liu ◽  
Abraham Marquez ◽  
Wensheng Luo ◽  
Jose I. Leon ◽  
...  
Keyword(s):  
Disturbance Rejection ◽  
High Efficiency ◽  
Dynamic Performance ◽  
High Gain ◽  
Voltage Regulation ◽  
Industrial Applications ◽  
High Gain Observer ◽  
Twisting Algorithm ◽  
The Impact ◽  
Fast Dynamic

Acting as an interface between the grid and many energy systems, the active front-end (AFE) has been widely used in a large variety of industrial applications. In this paper, in order to ensure the fast dynamic performance and good disturbance rejection ability of the AFE, a high-gain observer (HGO) plus adaptive super-twisting algorithm (STA) for the three-level neutral-point-clamped (NPC) converter is proposed. Comparing with the conventional PI control strategy, the proposed controller implements the adaptive STA in the voltage regulator to provide a faster transient response. The gains of the adaptive STA keep varying according to the rules being reduced in steady state but increasing in transient conditions. Therefore, the chattering phenomenon is mitigated and the dynamic response is guaranteed. Additionally, to undermine the impact of external disturbances on the dc-link voltage, a high-efficiency HGO is designed in the voltage regulation loop to reject it. Experimental results based on a three-level NPC prototype are given and compared with the conventional PI method to validate the fast dynamic performance and high disturbance rejection ability of the proposed approach.

scholarly journals Impact of communication time delays on combined LFC and AVR of a multi-area hybrid system with IPFC-RFBs coordinated control strategy

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
C H. Naga Sai Kalyan ◽  
G. Sambasiva Rao
Keyword(s):  
Time Delays ◽  
Power Flow ◽  
Frequency Control ◽  
Dynamic Performance ◽  
Coordinated Control ◽  
Voltage Regulation ◽  
Load Frequency Control ◽  
Superior Performance ◽  
Communication Time ◽  
The Impact

AbstractIn this paper, the impact of communication time delays (CTDs) on combined load frequency control (LFC) and automatic voltage regulation (AVR) of a multi-area system with hybrid generation units is addressed. Investigation reveals that CTDs have significant effect on system performance. A classical PID controller is employed as a secondary regulator and its parametric gains are optimized with a differential evolution - artificial electric field algorithm (DE-AEFA). The superior performance of the presented algorithm is established by comparing with various optimization algorithms reported in the literature. The investigation is further extended to integration of redox flow batteries (RFBs) and interline power flow controller (IPFC) with tie-lines. Analysis reveals that IPFC and RFBs coordinated control enhances system dynamic performance. Finally, the robustness of the proposed control methodology is validated by sensitivity analysis during wide variations of system parameters and load.

Experimental Investigation of the Diffuser Vane Clearance Effect in a Centrifugal Compressor Stage With Adjustable Diffuser Geometry: Part I — Compressor Performance Analysis

2014 ◽  
Author(s):  
Stefan Ubben ◽  
Reinhard Niehuis
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Negative Impact ◽  
Pressure Ratio ◽  
Industrial Applications ◽  
Flow Measurements ◽  
Flow Phenomena ◽  
Compressor Performance ◽  
Compressor Map ◽  
The Impact

The combination of variable speed control and adjustable diffuser vanes offers an attractive design option for centrifugal compressors applied in industrial applications where a wide operating range at high efficiency level and a favorable surge line is required. However, the knowledge about the impact on compressor performance of a diffuser vane clearance between vane and diffuser wall which is mandatory since the diffuser geometry adjustment has to take place during operation, is still not satisfying. This two-part paper summarizes results of investigations performed at the Institute of Jet Propulsion and Turbomachinery at RWTH Aachen with an industrial-like centrifugal compressor, featuring a design pressure ratio of 4 and a design speed of 35200 rpm. Particular attention was directed to the influence of the diffuser clearance on the operating behavior of the entire stage, the pressure recovery in the diffuser and on the diffuser flow by a systematic variation of the parameters diffuser clearance height, diffuser vane angle, radial gap between impeller exit and diffuser inlet, and rotor speed. Compressor map measurements provide a summary of the operating behavior related to diffuser geometry and impeller speed, whereas detailed flow measurements with temperature and pressure probes allow a breakdown of the losses between impeller and diffuser and contribute to a better understanding of relevant flow phenomena. The results presented in Part I show that an one-sided diffuser clearance does not necessarily has a negative impact on the operation and loss behavior of the centrifugal compressor, but instead may contribute to an increased pressure ratio and improved efficiency. The flow phenomena responsible for this detected performance behavior are exposed in Part II [28], where the results of detailed measurements with pressure probes at diffuser exit and Particle Image Velocimetry (PIV) measurements conducted inside the diffuser channel, revealing the complex and unsteady flow leaving the impeller and passing the diffuser channel, are discussed. The experimental results are published as an open CFD testcase “Radiver 2” [26], extending the experimental data base of the testcase “Radiver” published in 2003 by Ziegler [31].

scholarly journals CFD-Based Structural Optimization of Rotor Cage for High-Efficiency Rotor Classifier

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1148
Author(s):  
Xinliang Mou ◽  
Fangchao Jia ◽  
Ying Fang ◽  
Chuanwen Chen
Keyword(s):  
Flow Field ◽  
Structural Optimization ◽  
Field Distribution ◽  
Classification Accuracy ◽  
High Efficiency ◽  
Industrial Applications ◽  
Classification Performance ◽  
Discrete Phase Model ◽  
Rotor Cage ◽  
The Impact

Due to the uneven materials dispersion and high dust concentration in industrial applications of turbo air classifiers, a high-efficiency rotor classifier was designed. Numerical simulations by ANSYS-Fluent 19.0, the effects of rotor cage shape, the number of blades, and the blade profile on the inner flow field, as well as classification performance, were investigated. The simulation results indicated a significant improvement in flow field distribution near the classification surface with the conical rotor cage. Furthermore, there was an average reduction of 10.1% in cut size, as well as a 23.6% increase in classification accuracy. When the number of blades was 36, the flow field distribution between the blades was relatively uniform and a smaller cut size was obtained at a higher classification accuracy. A streamline blade with 52° as the inlet installation angle effectively reduced the impact of the airflow on the blade and eliminated the inertia anti-vortex between blades. The cut size reduction was 4.7–6.3%, with a basically unchanged classification accuracy. The material classification experimental results were in agreement with the simulated results. The discrete phase model (DPM) could well-predict the cut sizes and classification accuracy, but it could not present the fishhook effect. The present study provides theoretical guidance for the structural optimization of an air classifier with a rotor cage.

scholarly journals A novel active disturbance rejection controller for an electromagnetic valve actuator

2018 ◽  
Vol 202 ◽  
pp. 02010
Author(s):  
Jiayu Lu ◽  
Siqin Chang
Keyword(s):  
Motion Control ◽  
Trajectory Planning ◽  
Disturbance Rejection ◽  
Dynamic Performance ◽  
Engine Performance ◽  
Valve Lift ◽  
Electromagnetic Valve ◽  
Active Disturbance Rejection ◽  
Variable Valve ◽  
The Impact

In order to achieve fully variable and precise motion control of the electromagnetic valve actuator, enhance the engine performance, a novel active disturbance rejection controller for an electromagnetic valve actuator based on trajectory planning and acceleration feedforward is proposed. A fourth-order trajectory planning is used to achieve fully variable valve motion control, including variable valve lift and timing. It can also reduce the impact and vibration of EMVA system. Active disturbance rejection controller is used to estimate the variant dynamic and external disturbances of the system. The acceleration feedforward is compensated for the system to improve the tracking and steady state accuracy. Comparative simulations results show the proposed controller can improve the dynamic performance and the robustness of the system, and enhance the control precision.

scholarly journals A Study on the V2G Technology Incorporation in a DC Nanogrid and on the Provision of Voltage Regulation to the Power Grid

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2655
Author(s):  
Ioannis Skouros ◽  
Athanasios Karlis
Keyword(s):  
Renewable Energy ◽  
High Efficiency ◽  
Reactive Power ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Voltage Regulation ◽  
Energy Sources ◽  
Distribution Grid ◽  
Energy Storage Devices ◽  
The Impact

Currently, environmental and climate change issues raise a lot of concerns related to conventional vehicles and renewable energy generation methods. Thus, more and more researchers around the world focus on the development and deployment of Renewable Energy Sources (RES). Additionally, due to the technological advancements in power electronics and electrical batteries, Electrical Vehicles (EVs) are becoming more and more popular. In addition, according to the Vehicle-to-Grid (V2G) operation, the EV batteries can provide electrical energy to the power grid. In this way, many ancillary services can be provided. A Direct Current (DC) nanogrid can be composed by combining the aforementioned technologies. Nanogrids present high efficiency and provide a simple interaction with renewable energy sources and energy storage devices. Firstly, the present study describes the design considerations of a DC nanogrid as well as the control strategies that have to be applied in order to make the V2G operation feasible. Furthermore, the provision of voltage regulation toward the power grid is investigated though the bidirectional transfer of active and reactive power between the DC nanogrid and the power grid. Afterwards, the voltage regulation techniques are applied in an Alternating Current (AC) radial distribution grid are investigated. The proposed system is simulated in Matlab/Simulink software and though the simulation scenarios the impact of the voltage regulation provided by the DC nanogrid is investigated.

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