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By modeling the typical electromechanical transient of grid-tied PWM inverters, this paper firstly proves that PWM inverters and Rotational Synchronous Generators (RSGs) are similar in physical mechanism and equivalent in mathematical model, and the concept of Static Synchronous Generator (SSG) is thereby developed. Furthermore, the rationality and feasibility of migrating the concepts, tools and...
In this paper, a detailed mathematical presentation of Photovoltaic (PV) generation system, as well as its simulation model based on MATLAB / Simulink is established first. Its inverter-based simplified models, i.e. the switching-function equivalent model and average model, are simulated and compared quantitatively from different aspects. Simulation results reveal that the switching-function equivalent...
Three-phase PWM inverters function as energy converters and grid-connected power generators in renewable energy generation systems, and its dynamic and stability characteristics affect the security and reliability of the entire generator sets and even the connected grid. The three-phase PWM inverters based on the VSG (Virtual Synchronous Generator) technology, which is referred to as the Static synchronous...
Impedance is very important for power electronic systems because of the close relationship between impedance and system stability. The power converters are typical nonlinear dynamic systems in frequency domain. With a sinusoidal input voltage perturbation excitation, the input current contains not only the input perturbation frequency, but also multiple other frequency components. Therefore, the input...
In this paper, a thermal model used to determine the cell temperature of a photovoltaic (PV) module is developed. This model takes into account the ambient temperature and wind velocity to predict the performance of a PV module. The validity and utility of the proposed model are assessed by comparing the simulation result with that of the experiment. Finally, it is shown how this model can be effectively...
The characteristic parameters of the micro-grids determine its transient response and the stability. The generation, the grid structure and the electric loads of all the whole micro-grids are always changing randomly due to the random load changes and the integration of large-scale batch energy, indicating that the characteristic parameters of the micro-grids also changes. A novel real-time and on-line...
The characteristic parameters of micro-grid determine its transient response and stability. Due to uncertain load changes as well as large-scale intermittent energy accesses, the micro-grid systems are always subjected to large number of random disturbances which results in micro-grid structure parameters change. To solve this problem, this paper presents a novel model for characteristic parameters...
The conventional mathematic model of PV (Photovoltaic) cells contains logarithmic terms, which is not conducive to derivation calculation in small-signal modeling. The parameters of PV system are coupling due to its double-loop control method, and it's hard to precisely choose controller parameters. To solve these two problems above, this paper is based on PV system connected to an infinite power...
A fast simulation platform dedicated to Micro Grid (MG) applications is proposed in the paper. The proposed simulation platform is essentially an additional library of the general simulation software PSCAD, which includes components and models in MG application. The content of the proposed simulation platform is introduced with 2 example models. A seamless control strategy is proposed to evaluate...
For high power grid connected devices with power quality compensation function, directly paralleled 3-phase 4-wire inverter is the most simple configuration to chose, but the zero sequence current is always a big problem that have to deal. This paper established the phase-leg averaging model of this type system, developed the dynamic model of zero sequence current, then indroduced a simple method...
This paper presents some mathematic models of compensation capacity for the total relative compensation capacity of symmetrical compensation system. Based on minimum compensation capacity mode and fixed compensation port mode, curves for compensation capacity under different compensation conditions are analyzed. The comparisons for different transformer connections based on the minima and maxima of...
This paper presents the analysis, control strategy and realization of a digital frequency controller of a two stage ballast for HID Lamps. First, the small signal phasor model of the LCSCP resonant inverter is established and verified. Based on this model, a double loop digital compensator is designed to control the current and power of the lamp. Then the overall control strategy for the long term...
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