Application of single-phase three-wire transformer model in distribution network with solar home system
As solar home systems are concentrated in distribution network in residential areas, the voltage of connection points rises according to the reverse power flow when the demand of load is less than power generation out-put. When single- phase three-wire power distribution transformer (method) is applied to low-voltage distribution network, power flow calculation becomes the major approach to perform quantitative analysis. We looked for a method of analysis in which the high-voltage systems and the low-voltage single-phase three-wire systems are unified for calculating power flow. The first step is setting up a single-phase three-wire transformer model. This paper presents a new model of single-phase three-wire transformer using the indication method between nodes. Meanwhile this paper also gives the model's nodal transform matrix for calculating power flow. Using this model we can solve the problem of power flow calculation by using conventional power- flow-calculation methods when high-voltage and low-voltage with single-phase three-wire distribution systems are intermingled. The results also can reflect the voltage characteristics of connection points when injecting effective power into node from solar home systems. Using this new model we computed an example and analyzed the result. When solar home systems are connected in single-phase three-wire low-voltage distribution network, changing the power generation out-put, the voltage characteristics of connection points are consistent with theoretical analyses. The example shows that the model is feasible for calculating power flow of low-voltage single-phase three-wire systems with solar home system.
Split-phase switched-capacitor ac–ac converter
This study proposes an ac–ac direct static power converter based on the switched-capacitor (SC) principle, aimed at supplying a split-phase system from an ac single-phase voltage source. The main advantages of the proposed split-phase SC converter are (i) the provision of three output voltages, two being equal to the input voltage and one being twice the input voltage, (ii) balanced output voltages even under unbalanced loads, (iii) the absence of magnetic elements in the power circuit, (iv) the stress voltages in all components being equal to the input voltage, (v) the ability to be bidirectional, (vi) high efficiency and (vii) high power density. These characteristics make the proposed converter suitable for modern applications where a split-phase system needs to be generated from a renewable energy source, distributed generation system, uninterruptible power supply (UPS), battery bank, electric/hybrid vehicle, smart grid or even the electrical grid itself. To verify the performance of the proposed converter, a 1 kW prototype was built and tested with standard voltages, such as 110 V input voltage and 110 V/110 V/220 V output voltages. The efficiency, output voltage regulation, tests with input voltages of 16.6, 60 and 400 Hz and other experimental results are reported herein.
Application of Automatic Tracking Correlation Filtering in Motored Spindle Dynamic Balancing
According to the information characteristics of the dynamic imbalance signal and the definition of correlation function,the principles and algorithm of relevant filter with automatic tracking is given.In labview development system,based on the principles of relevant filter with automatic tracking,the graphics programming of extracting the dynamic imbalance signal is developed.With this programming,the vibration signal including different frequency harmonic signals and noise is processed by simulation and on-site experiment.The results show that: through relevant filter with automatic tracking,the dynamic imbalance signal under different rotating speed can be extracted accurately,and it can meet the requirement of motored spindle dynamic balancing measurement.