In this paper, a new One-Cycle-Control (OCC) method is designed for a modular multilevel converter (MMC) based on the principle of the equivalent resistance constant. The proposed controller has a simple structure and a small amount of calculation by cancelling the current inner loop proportional integral (PI) controller and the inverse transform in the traditional direct-quadrature (DQ) control. Compared to the traditional OCC controller, the new one separates the control method from the modulation strategy, making it possible to use not only carrier-based pulse-width modulation (PWM), but also nearest level modulation PWM to generate drive signals. Besides, the independent control of the active and the reactive power is implemented by injecting a reference current with the same phase of the supply voltage or a reference current which lags the supply voltage by π/2 into the controller, so the converter can operate in four quadrants and it can work in either a grid-connect or off-grid environment. The feasibility and the performance of the proposed OCC method have been validated by both the simulation under the MATLAB/SIMULINK (R2012a) environment and experimental results.
Abstract-In order to confirm the theoretical knowledge it is important to perform experiments while learning the digital circuit design, which enhances the learning process. The digital design laboratories are often in short supply and introduces a number of limitations. The limitations includes smaller number of instruments and instrument stability, particularly in poor and developing countries. This paper reports the development of a mobile virtual laboratory application (VL-APP) digital design that help students to perform virtual experiments anywhere and anytime. It mainly utilizes simulation of experiments and provides a model and script for users to design experiments independently. The development utilizes Unity3D and 3ds-max for the software platform, and Android for the test installation environment. The test results demonstrates potential of the developed application.
This paper proposes an adaptive iterative learning control (AILC) method for uncertain nonlinear system with continuous nonlinearly input to solve different target tracking problem. The method uses the radial basis function neural network (RBFNN) to approximate every uncertain term in systems. A time-varying boundary layer, a typical convergent series are introduced to deal with initial state error and unknown bounds of errors, respectively. The conclusion is that the tracking error can converge to a very small area with the number of iterations increasing. All closed-loop signals are bounded on finite-time interval
0
,
T
. Finally, the simulation result of mass-spring mechanical system shows the correctness of the theory and validity of the method.
Membrane separation process, which greatly meets the demand of reducing the environmental pollution in the modern industry, has become one of the most important strategies in the durative low carbon economy development.. This paper has studied the transformation structure mechanism of of Al2O3-SiO2-ZrO2 composite membrane produced by the sol-gel method on a porous α-Al2O3 support and the effects of SiO2 and ZrO2 in γ-Al2O3 membrane. Porous Al2O3-SiO2-ZrO2 composite membrane of the average pore size 2~4µm was obtained first time through controlling various factors, The structure crystal type and surface state are characterized by means of optical microscope, XRD, SEM, and IR. The results show that the membrane calcined at 1000°C obtain a composition of γ-Al2O3, t-ZrO2 and amorphous SiO2. The phase transformation has not appeared when heated at 1200°C. As the thermostability of the modified membrane being improved, the phase transformation temperature in the sintering process could be delayed. Therefore, the membranes properties are greatly improved.
Entrepreneurial orientation (EO) has become a core concept in the entrepreneurship research area, which represents a firm's tendency to commit to innovation, act proactively and take some kind of risks. This paper makes a brief introduction of the concept, dimensions as well as the dimensionality of EO, and reviews literature concerning about the relationship between EO and firm performance, including the direct effect and the moderating effect of third variable. Some simple comments about previous studies and suggestions for future research are also presented.
This paper first analyzes the influencing factors of the economy of new energy power generation under the situation of grid parity, then studies the economic analysis method based on the internal rate of return, and establishes the calculation model of the economic analysis of new energy power generation. Finally, taking the economic calculation of wind power field and photovoltaic power station in 2020 as an example. This paper studies the IRR of new energy power generation projects in different regions under parity conditions. On this basis, the paper analyzes the key issues of new energy development scale, development layout, operation consumption, market competition and so on under the situation of grid parity, and studies and judges the development trend of new energy in China in the future.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.