| High-power rectifier systems are widely used in high energy-consuming industries,such as chemical industry, metallurgy and railway traction, and transportation. Thenew-type high-power rectifier system mainly features in energy conservation. Theresearches on energy efficiency analysis and online monitoring of this system should beperformed, intending to extend the mentioned energy saving technique. And the keyresearches consist of the established system energy consumption model, high dc currentmeasurement, transmission and anti-interference of huge amounts of data, multi-channelsynchronous data acquisition, parallel and remote calibration, and device developmentand practical application.According to the connection schemes of the traditional and the new-typehigh-power rectifier system and taking harmonic effects into account, the losscalculation models of rectifier transformers, filters and rectifiers in these two sorts ofrectification units are established. And it is indicated by theoretical and simulationresults that the high-power rectifier system of new type has a remarkable performance ofenergy conservation.Based on the relevant relationship of the valve-side ac and dc current, a newmethod of indirect inversion and calculation for high dc current is proposed, which isvalidated by simulations and practical applications. Due to the various harmoniccomponents contained in valve-side current and voltage signals, the high samplingfrequency of voltage and current signals and huge data storage capacity, a Radix-2FFT(fast Fourier transform) based algorithm for data compression is presented. In themeanwhile, with considerations of large amounts of measured points, high-levelanti-interference ability, high-demanding synchronous data acquisition and long-distancecommunication, a kind of energy efficiency analysis and online surveillance systembased on optical fiber Ethernet for high-power rectifier systems is put forward.Compared with the measuring method adopting conventional power quality analyzers, itis evident that the brand-new one has better technical performances.Attempting to ensure the measuring accuracy of energy-efficiency monitoringdevices, their measurement system evaluations of static and dynamic performances areanalyzed. Moreover, various software approaches of the nonlinear self-correction,self-zero-adjustment, self-calibration and self-compensation are proposed to improve thestability and accuracy of the system. To address the issues of data synchronization of multiple measured points, considering the traditional evaluating methods, an improvedway for synchronization performance evaluation based on sine curve fitting convergencealgorithm is described, providing an effective assessment for multi-channel synchronousacquisition performance of the energy efficiency monitoring device.Aiming at the problems of time-consuming process, high cost and unavailableonline operation of the traditional calibration, the error and processing means of thecurrent transformers, the signal conditioning circuits, the A/D converters and thesynchronization acquisition in the monitoring device are analyzed and manifested. Andon the basis of them, a new multi-channel remote parallel calibration technique based onfiber optic Ethernet communication is expressed, and accordingly the software functionsand realization process of the remote calibration unit of the monitoring device are shownin details. In addition, by remote parallel calibration of several channel terminals of theforegoing device, the proposed remote parallel calibration for energy-efficiencysurveillance and the stability and excellent performance of the system are verified.According to the topology structure of a new-type high-power12-pulse rectifiersystem for manganese electrolysis, the corresponding energy efficiency analysis andonline monitoring system based on optical fiber Ethernet is designed in a practicalproject. Consequently, the realization processes of hardware and software of the deviceare stated in details. Furthermore, concentrating on designing of the acquisitionterminals, the fiber optic Ethernet communication, the host system and the front-endprocesser, a set of energy-efficiency analysis software platform for high-power rectifiersystem is developed, which can implement energy efficiency online analysis andevaluation of the three major parts of a rectifying unit.In an attempt to further confirm the validity and feasibility of the proposed newalgorithm and technique and the monitoring system, utilizing the existing laboratoryequipments and conditions, an experimental platform for energy-efficiency monitoringsystem of a new-type12-pulse rectification system is set up. And based on this platform,the indirect inversion algorithm for high dc current, the parallel data samplingperformance of the acquisition terminals, the data compression and remote calibrationtechnique, the energy efficiency online analysis and monitoring of unit components arefunctionally verified. At last, the above system is successfully applied to an engineeringproject of a new high-power12-pulse rectifier system for manganese electrolysis and theefficiency evaluation for the high-power rectifier system and components isimplemented.Nowadays, several sets of the developed energy efficiency monitoring devices for high-power rectification units have been successfully applied in electrolytic manganeserectifying systems, which have been operating in stabilization for nearly two years. Itprovides an important technical approach for power users to exactly assess theequipment efficiency and energy-saving effect, accelerating the proliferation of energyconservation techniques. |
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