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Research On Voltage Quality Of Distributed Power Supply System

Posted on:2015-02-01Degree:MasterType:Thesis
Country:ChinaCandidate:Q N ChenFull Text:PDF
GTID:2272330422484927Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
In recent years, with the study of distributed generation (DG) technologiesdeepening as well as the requirements of power users on supply reliability andvoltage quality constantly increasing, the voltage quality problems of thedistribution system with DG (distributed power supply system) have becomeincreasingly prominent. As the output of DG has volatility and randomness, andloads switch frequently, and system operation is diverse, which makes thevoltage analysis and control of distributed power supply system more complexand difficult. And the new technologies to improve voltage quality havebecome a new research hotspot of the area in recent years.The voltage of distributed power supply system is low, and the capacity ofwhich is small, whose power transmission characteristics and voltage variationare very different from the traditional large power grid, and the traditionalmethod of voltage analysis and control won’t apply any longer. The currentstudies mostly focus on the control of grid inverter, and the voltage variationmechanism of distributed power supply system is rarely involved, as well as thevoltage quality improvement methods and strategies from the view of systempoint. In this paper, from the view of system perspective, it studies the voltagevariation mechanism of distributed power supply system, analyzes the impactof DGs on the voltage quality, and seeks appropriate improvement measures toensure the demand of users on better electrical energy, which is significant.Firstly, considering the differences of the powered form, operation modeand line parameters of distributed power supply system with the traditionallarge power grids, this paper re-derives the power transfer characteristics ofdistributed power supply system, and the voltage variation mechanism ofdistributed power supply system is also studied. Then as for the defect ofignoring the characteristic differences of distributed generation in previousstudy of the impact of distributed generation on voltage quality, this paperconsiders the characteristic differences of different distributed generation fully,and divides them into proper classifications, and studies the impact of each typeof DG on the voltage quality in different operating modes, at last summarizesthe relevant factors of voltage variation in distributed power supply system.As for the voltage fluctuations caused by the output variation ofdistributed generation, it proposes the methods of using super capacitor energystorage and micro-turbines to smooth the fluctuations of DG to improve the voltage quality respectively, and the models and control strategies of the twomethods are studied in depth. And PSCAD-based simulations of the twoproposed methods are performed respectively, and it analyses the improvementof the two methods for voltage quality when wind speed changes, the largeresistance inductive load switches and the external faults happen, and thesimulation results show that the proposed methods are effective and efficient.In addition, in the phase of planning and design, and transformation andconstruction of distributed power supply system, it studies the adaptability ofdistributed generation and regional loads in order to give full play toadvantages of distributed generation and meet the demands of different regionalloads on voltage quality to improve the voltage quality of distributed powersupply system further, and the numerical examples validate the effectiveness ofthe proposed method.Finally, based on the full consideration of the characteristics of distributedgenerations and loads, it proposes a new method of optimizing the networkingdesign of distributed power supply system to improve voltage quality, and thisidea is still rarely seen in the present studies. The research result of theoreticalderivation and proposed methods and ideas of improving voltage quality in thispaper, can provide importance references for the analysis, control andimprovement of voltage quality in the distributed power supply system.
Keywords/Search Tags:distributed generation (DG), voltage quality, distributed powersupply system, super capacitor energy storage, microturbine, loadcharacteristics
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