Analysis on frequency characteristics of self-excited oscillation pulsed nozzle

2015 ◽  
pp. 817-820
Keyword(s):  
Frequency Characteristics ◽  
Excited Oscillation ◽  
Pulsed Nozzle

An Application of the Self-Excited Oscillation Method to a Hydraulic Motor Angular Velocity System

2005 ◽  
Author(s):  
Takayoshi Ichiyanagi ◽  
Takao Nishiumi
Keyword(s):  
Angular Velocity ◽  
Servo System ◽  
Frequency Characteristics ◽  
Operating Conditions ◽  
The Self ◽  
Hydraulic Motor ◽  
Simple Method ◽  
Excited Oscillation ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

It has been known that a hydraulic servo system can be generally dealt with a second order delay element for designing an adequate controller. In the previous work, our research group developed a simple method utilizing the self-excited oscillation of a hydraulic servo system to directly estimate the dynamic parameters such as the damping ratio and undamped natural frequency. The advantage of this method is the “on-line” ability that is able to identify these parameters instantaneously with changing the operating conditions. Although this method was found to be very useful, it is available only when the spool valve is close to the neutral position. This paper proposes an online parameter estimation method for the hydraulic motor angular velocity system. In this method, the self-excited oscillation around the displaced position from the neutral spool position is utilized. In order to demonstrate the effectiveness, the experimental work is conducted by giving the various input voltages, system pressures and angular velocities. The resulting frequency characteristics of these identified transfer functions are then compared with those of the measured data by the frequency characteristics method in order to confirm coincidence.

New aspects of power grid facilities personnel workplaces electromagnetic environment

2020 ◽  
Vol 60 (9) ◽  
pp. 569-574
Author(s):  
Nina B. Rubtsova ◽  
Sergey Yu. Perov ◽  
Olga V. Belaya ◽  
Tatiana A. Konshina
Keyword(s):  
Transmission Lines ◽  
Power Transmission ◽  
Power Grid ◽  
Spectral Characteristics ◽  
Ground Level ◽  
Frequency Characteristics ◽  
Frequency Range ◽  
Electromagnetic Environment ◽  
Limit Values ◽  
Special Assessment

Introduction. Electromagnetic safety of power grid facilities staff requires the exclusion of electromagnetic fields (EMF) harmful effects. EMF is evaluated by 50 Hz electric and magnetic fields (EF and MF) values in the framework of working conditions special assessment, and very rarely the analysis of the electromagnetic environment (EME) is carried out in depth. The aim of the study - EME hygienic assessment of power grid EHV facilities personnel workplace with adequate 50 Hz EF and MF levels evaluation as well as the analysis of EF and MF in the frequency range from 5 Hz to 500 Hz amplitude-frequency characteristics. Materials and methods. 50 Hz EF and MF values assessment was carried out on open switchgears (S) of substations and within sanitary breaks of 500 and 750 kV overhead power transmission lines (OTL). Measurements along to OTL trasses was performed using matrix-based method. Measurements and analysis of EF and MF values in 5-500 Hz frequency range amplitude-frequency characteristics were performed in the territory of 500 and 750 kV S. Results. Power frequency 50 Hz measurements results at 500 and 750 kV S ground-level personnel workplaces showed the presence of an excess of permissible limit values by EF intensity and the absence of an excess by MF. The measured EF values within 500 and 750 kV OTL sanitary gaps require limiting the working time of linemen due to the excess of the hygienic norms for full work shift, while the MP levels were almost completely within the standard values for persons not occupationally connected with electrical installations maintenance. MF and EE frequency range from 50 Hz to 500 Hz spectral characteristics analysis showed that 3rd harmonic percentage does not exceed 2.5% for EF and 6% for MF of the main level, the level of the 5th harmonic does not exceed 1% for EF and 3.5% for MF, the level of the 7th harmonic does not exceed 0.2% for EF and 0.8% for MF. These data show despite its low levels the contribution of MF different harmonics in a possible adverse impact on humane than EF corresponding harmonics. Conclusions. There was the confirmation of the previously justified use of the "matrix" scheme for of EF and MF values measurement along OTL routes. The relevance of to EF and MF all frequency components expos ure assessing possible health risk in extremely high voltage S territories and under OTL, based on international recommendations due to the lack of sanitary regulations in the Russian Federation for >50 Hz-30 kHz EF and MF, is shown.

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