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Large-capacity high-voltage inverter satisfies demand of energy saving and emission reduction. This paper presents a new 25MVA/10kV high power motor driving system based on IEGT power modules. The paper introduces the system configuration, and separately describes the design of power modules, the main control system, and motor control algorithm in details. Finally, the experiment results are shown...
Distributed-logic-control is an independent parallel inverter control technique. The strategy to restrain circulating currents based on distributed-logical-control is researched in the paper. The conventional method by power regulation to restrain the circulating current is affected by the parallel impedance and has such disadvantages in the response speed and harmonic component of circulating current...
This paper focused on for the stability of SPWM inverter affected by digital control. The stability of analog control inverter system, discrete system with no-step-delay control and discrete system with one-step-delay control are analyzed respectively so as to determine the relation of the inverter's sampling period vs. controller parameters with critical stability. Then the essential reason was analyzed...
This paper focused on the research on one-step-delay effect of the stability of digital control PWM Inverter. Discrete stability criterion is used to research the stability of discrete system with/without one-step-delay control respectively. The research results are shown that the one-step-delay control degrades the stability system in the high sample frequency while it may increase the stability...
Numerous benefits promote the proliferation of renewable and distributed energy resources in power grids. Some recent research has focused on the concept of microgrids, in which a number of renewable energy sources can be connected together to supply power to customers as a complement to traditional power sources or as main power sources. In a microgrid, multiple distributed energy sources are operated...
This paper presented a design for distributed logic controlled parallel operation UPS systems depending on cycle control. This design proposed a practical parallel operation according to the needs of real industrial application. This protocol ensures correct logic switching and stable information exchanges in toughly interfering application environment. Also this protocol gives the plug and play ability...
Compared with analog control, digital control adopted in PWM inverter possesses the evident advantages but the traditional PID control strategy which is realized in digital method often can't achieve better performance than in analog control. In past references, there is hardly quantitative analysis on the effect of digital process on the performance of PWM inverter. This paper did a creative research...
As the development of distributed generation technology, the renewable energy resources are widely transformed to electricity and transferred to the utility through grid-connected converters. Islanding detection is a mandatory function for the converters. It usually injects perturbations to the converter output to improve the effectiveness of islanding detection. The current research is mainly based...
Based on the instantaneous symmetric components transformation, this paper derived the dynamic equations of three-phase inverters with magnetic couples caused by three-pole reactors and three-pole transformers. The equations are in term by the instantaneous symmetric components, and take into account of the magnetic couples in three-phase inverters, which are simple to be solved and realize decouples...
When multiple three-phase voltage source converters sharing the same DC bus are operated in parallel to supply an AC voltage bus or a load, a zero-sequence path exists. With this path, a zero-sequence circulating current is introduced into the three-phase system, which may be caused by the circuit asymmetry. The zero-sequence circulating currents introduce further asymmetry of electrical variables...
Multiple three-phase voltage source converters may be connected in parallel to supply an AC voltage bus or a load in excess of the rating of an individual power converter. Without a circulating path, a zero-sequence current generally does not exist in a single power converter; however, it typically exists in parallel-connected three-phase power converters. The presence of zero-sequence currents in...
Due to the rapid increase in global energy consumption and the diminishing of fossil fuels, the customer demand for new generation capacities and efficient energy production, delivery and utilization keeps rising. Utilizing distributed generation, renewable energy and energy storage can potentially solve such problems as energy shortage and global warming. A promising structure to interconnect these...
With the primary and a secondary winding ports leading out, a multi-winding transformer with air-gapped core can be regarded as a linear two-port network. Adjust the current relationships between the ports, the input impedance of the primary winding can be a variable reactance; change the short-circuit conditions of other secondary windings, the reactance of primary winding will move in deferent intervals...
In inverters, distortions of output sine voltages caused by factors like dead-times of power switches can be well compensated by instantaneous voltages and/or currents feedback regulators such as PID or repetitive controllers. However, in our experiments, we found that the dead-time differences between inverters would result in significant harmonic circulating currents, and instantaneous regulators...
In inverters, the waveform distortions in output voltage caused by the dead times can be successfully compensated by the instantaneous voltage feedback regulators like PI regulator, and this always makes the dead time effects in parallel inverters be ignored. However, for the filter inductances and output impedances in high power inverters must be very small (for consideration of system cost, internal...
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