Current phase lag issue and the compensation scheme for OCC PFC converter

Author(s):  
Peng Mao ◽  
Shaojun Xie ◽  
Aiguo Xu ◽  
Zegang Xu
2020 ◽  
Vol 2 (4) ◽  
pp. 305-317
Author(s):  
Peiliang Sun ◽  
Kang Li ◽  
Chen Xing

Abstract This paper presents a partial compensation scheme for V/v transformer cophase traction power supply in high-speed railway systems. The scheme compensates variable traction load current, and controls the current phase at the secondary side of the V/v transformer for power factor correction and negative sequence current reduction. To achieve this, the grid side current phase angles are optimized while satisfying the grid code on the power factor and voltage unbalance limits. The optimized phase angles are then used to design control references under varying load conditions. The compensation control action is updated regularly based on real-time measurements of the traction load, and the required currents are controlled by a 25-level single-phase back-to-back MMC power conditioner to achieve the compensation target. Static and dynamic load compensation performances are verified based on the simulation studies.


2015 ◽  
Vol 18 (1) ◽  
pp. 57-69 ◽  
Author(s):  
Hossein Askarizadeh ◽  
Hossein Ahmadikia

1989 ◽  
Vol 17 (3) ◽  
pp. 184-200 ◽  
Author(s):  
R. Hanada ◽  
T. Nagumo ◽  
T. Mashita

Abstract Automobile handling can be greatly improved by reducing the phase lag of tire cornering force behind imposed distortion. We have shown experimentally that this lag is related to in-plane stiffness of the belt and to radial, lateral, and circumferential stiffnesses of the sidewall. While the cornering stiffness is related to the belt rigidity, either can be changed without affecting the sidewall stiffnesses. The cornering stiffness, for example, is sensitive to design factors such as tread compound and tread pattern. The radial, lateral, and circumferential sidewall stiffnesses, however, are mutually perpendicular at a given point in a tire, so they cannot be changed independently of each other. In order to reduce the phase lag of the cornering force, the lateral and circumferential stiffnesses must be increased with a minimum increase in radial stiffness. This can be done by either lowering the radial location of the maximum section width of the inflated tire or by proper changes in material and/or design elements of the sidewall.


2020 ◽  
Vol 16 (5) ◽  
pp. 929-949
Author(s):  
A.M. Chernysheva

Subject. After the collapse of the USSR, smaller countries chose different paths in their economic policy during the globalization and the multipolar world. The EU, USA and Russia made a palpable contribution to the economic policy of smaller countries. Some countries of the former USSR failed to find their course, while the others immediately followed their development strategy and stuck to it persistently. Objectives. I examine the economics of the monodirectional strategy of smaller countries of the former USSR. I also evaluate how the countries found their position among different leading countries as points of attraction. The study is based on the assumption that the single direction of the national development and adherence to the same point of attraction will ensure the sustainable development. However, the economic development level depends on the health of a certain economy as a point of attraction. Methods. The study is based on the systems approach, comparative and statistical methods for analyzing macroeconomic data series. Results. I investigated the dynamics of key macroeconomic data in the Republic of Belarus, Latvia and Estonia, such as GDP per capita in current values, unemployment rate and Purchasing Power Index. Given the current phase of globalization and multipolar world, it is crucial for smaller countries to choose a development strategy to follow persistently and achieve proper macroeconomic indicators that depend on the economic stability of counties they treat as their benchmarks. Conclusions and Relevance. I should mention the successful economic policy of Estonia and Latvia, which followed the same course as the other EU countries, as opposed to the Republic of Belarus tending to the policy of the Russian Federation. Nevertheless, the monodirectional development strategy also helps smaller countries ensure their economic stability.


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