Operating region and control for power converters connected to a variable frequency and amplitude voltage grid supply

2015 ◽  
Author(s):  
Jaime Rohten ◽  
Jose Espinoza ◽  
Jose Silva ◽  
Javier Munoz ◽  
Daniel Sbarbaro ◽  
...  
Keyword(s):  
Power Converters ◽  
Variable Frequency ◽  
Operating Region ◽  
And Control

Design and Control of the Double Side Variable Frequency Based Brushless Doubly-Fed Generator System

2021 ◽  
Author(s):  
Yakun Zhou ◽  
Zhongchao Wei ◽  
Xi Chen ◽  
Xuefan Wang ◽  
Guoqing Hu ◽  
...  
Keyword(s):  
Variable Frequency ◽  
Generator System ◽  
Doubly Fed ◽  
Doubly Fed Generator ◽  
And Control ◽  
Side Variable

Design a PLC-Based Variable-Frequency Governing Pressure-Constant Water-Supply Control System

2014 ◽  
Vol 1044-1045 ◽  
pp. 755-758
Author(s):  
Xin Hui Yang
Keyword(s):  
Control System ◽  
Water Supply ◽  
Pressure Sensors ◽  
Variable Frequency ◽  
Pipe Network ◽  
Monitoring And Control ◽  
Control Software ◽  
Industrial Control ◽  
Time Basis ◽  
And Control

This paper provides a design for a PLC-based, variable-frequency governing, pressure-constant, automatic water-supply control system. This design is based on the current situations at the water supply plants found in small and medium cities in China. In this control system, the pressure signal across the pipe network is acquired by pressure sensors and then transmitted to PID modules in the PLC in order to control switching between pump motors. At the same time, the PLC is connected with a personal computer for industrial control purposes. On this computer, monitoring and control software has been installed in order to monitor and control the pressure-constant water-supply system on a real-time basis.

Research on Surveillance Risk Index System of Unified and Interconnected Electricity Market in China

2014 ◽  
Vol 1070-1072 ◽  
pp. 1516-1523
Author(s):  
Chun Cheng Gao ◽  
Shu Hong Shi
Keyword(s):  
Electricity Market ◽  
Index System ◽  
Risk Index ◽  
First Grade ◽  
Risk Level ◽  
Electricity Trading ◽  
Operating Region ◽  
Market State ◽  
Grid Operation ◽  
And Control

After the establishment of the unified and interconnected electricity market in China, electricity trading range will cover the entire State Grid operating region, and headquarters market and provincial market will become interconnected, unified and coordinated operation. Aiming at the surveillance risk under the unified and interconnected electricity market, a relatively complete surveillance risk index system is proposed. The proposed risk index system includes six first grade indices, i.e., market state, transaction plan, contract and settlement, market coordination, energy efficiency and power grid operation. The risk index system can reasonably and overall reflect the risk level of the electric power transaction under the unified and interconnected electricity market circumstances. It is useful for State Grid to achieve risk management and control of electricity trading surveillance, rectify the irregularities, and maintain a fair and impartial market order.

Physical Modeling and Control of a Multi-Cylinder HCCI Engine

2009 ◽  
Author(s):  
Nikhil Ravi ◽  
Matthew J. Roelle ◽  
Hsien-Hsin Liao ◽  
Adam F. Jungkunz ◽  
Chen-Fang Chang ◽  
...  
Keyword(s):  
Direct Injection ◽  
Work Output ◽  
Compression Ignition ◽  
Piston Engine ◽  
Modeling And Control ◽  
Hcci Engine ◽  
Operating Region ◽  
Control Scheme ◽  
And Control ◽  
Wide Operating

Homogeneous charge compression ignition (HCCI) is one of the most promising piston-engine concepts for the future, providing significantly improved efficiency and emissions characteristics relative to current technologies. This paper presents a framework for controlling a multi-cylinder HCCI engine with exhaust recompression and direct injection of fuel into the cylinder. A physical model is used to describe the HCCI process, with the model states being closely linked to the thermodynamic state of the cylinder constituents. Separability between the effects of the control inputs on the desired outputs provides an opportunity to develop a simple linear control scheme, where the fuel is used to control the work output and the valve timings are used to control the phasing of combustion. Experimental results show good tracking of both the work output and combustion phasing over a wide operating region. In addition, the controller is able to balance out differences between cylinders, and reduce the cycle-to-cycle variability of combustion.

Approach and Effect Analysis of Amplitude Frequency Performance Improvement in Metal Bar Cropping with Variable Frequency Vibration

2012 ◽  
Vol 152-154 ◽  
pp. 770-774
Author(s):  
Li Jun Zhang ◽  
Jie Qiong Xue ◽  
Sheng Dun Zhao ◽  
Yong Rui Zhao
Keyword(s):  
Performance Improvement ◽  
Cross Section ◽  
Narrow Range ◽  
Experimental Results ◽  
Variable Frequency ◽  
Structure Model ◽  
Effect Analysis ◽  
Steel Bar ◽  
Different Types ◽  
And Control

In order to solve the narrow range and control difficulties of the excited frequency in metal bar cropping with variable frequency vibration, the structure of the eccentric block in cropping machine was improved on in the paper and a new structure model of changing the integral eccentric block into one of main eccentric block and some small adjustable eccentric blocks, was also proposed. The key parameters of the cropping machine in the action of two different types of eccentric blocks were analyzed theoretically in detail. At the same time, the corresponding amplitude frequency characteristics of the cropping machine were also obtained. The cropping experimental results of 45 steel bar show that the cross-section quality and the cropping time are improved remarkably in the action of one main eccentric block and four adjustable eccentric blocks, comparing with the cropping results in the action of the whole eccentric block.

Predicting the Quality of One-Dimensional Periodic Micro and Nano Structures Fabricated via Wrinkling

2012 ◽  
Author(s):  
Sourabh K. Saha ◽  
Martin L. Culpepper
Keyword(s):  
Defect Density ◽  
Compressive Strain ◽  
Element Model ◽  
Target Pattern ◽  
One Dimensional ◽  
Nano Structures ◽  
Operating Region ◽  
Dislocation Defects ◽  
And Control

Wrinkling of thin films due to buckling-based surface instabilities is a fast and inexpensive technique for template-free fabrication of periodic micro/nano scale structures. Although one-dimensional (1-D) periodic micro and nano structures have been fabricated via wrinkling in the past, wrinkling is not yet appropriate for a manufacturing environment. This is because it is currently not possible to predict and control the quality of the fabricated patterns. Pattern quality is quantified in terms of the uniformity of the pattern, i.e., defect density within the patterned area. Herein, we (i) identify the process parameters that affect pattern quality, (ii) model the effect of these parameters on wrinkling quality and (iii) quantify the feasible operating region for a target pattern quality. During wrinkling, dislocation defects are observed due to local geometric imperfections such as voids or variations in the material properties. We have developed a finite element model of the wrinkling process that accounts for voids in the material. The wavelength and amplitude predictions of this model were found to be within ∼13% of the experimental observations. Also, it was found that below a threshold void size, the non-uniformity in the pattern due to voids decays with an increase in the applied compressive strain. This provides a practical means to minimize the non-uniformity in 1-D wrinkled patterns by increasing the compression. However, the defect density due to surface cracks increases with an increase in the compressive strains. Our analysis enables one to identify and predict the feasible operating region within which uniform 1-D patterns can be obtained, thereby improving manufacturability via wrinkling.

scholarly journals A Novel Dynamic Absorber with Variable Frequency and Damping

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Tian Wang ◽  
Ruilan Tian ◽  
Xinwei Yang ◽  
Ziwen Zhang ◽  
Xiaolong Zhang
Keyword(s):  
Coupled System ◽  
Smoothing Parameter ◽  
Current Intensity ◽  
Variable Frequency ◽  
Dynamic Vibration Absorber ◽  
Sd Oscillator ◽  
Dynamic Absorber ◽  
Control Principle ◽  
And Control ◽  
Two Degree Of Freedom

Smoothness and discontinuous (SD) oscillator is a nonlinear oscillator with the variable frequency, whose frequency can be varied with the smoothing parameter. However, how to adjust the smoothing parameter has not been solved in the actual device. In this paper, the shape memory alloy (SMA) is introduced into the SD oscillator to form the SMA-SD oscillator to adjust the smoothing parameters. Combining the SMA-SD oscillator with MRF, a nonlinear dynamic vibration absorber (DVA) with variable frequency and damping is designed. The structure and control principle of the designed DVA is studied to achieve the two variable characteristics simultaneously by adjusting the current intensity. Numerical results on a two-degree-of-freedom coupled system show that the proposed DVA can adapt to different working conditions only by adjusting the current intensity.

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