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.
Application of unified voltage analysis for high‐ and low‐voltage distribution systems by power flow calculation using indication method between nodes
It has been noted that the voltage of connection points rises according to the reverse power flow when grid‐connected photovoltaic systems are concentrated in distribution systems in residential areas. When this happens, the photovoltaic system may control the power generation output to maintain a suitable voltage for the connection point. Designing a demand area power system aiming at free access to a distributed power supply for energy‐effective practical use requires a precise understanding of this problem. When analyzing photovoltaic systems mainly connected to low‐voltage systems, we looked for a method of analysis in which the high‐voltage systems and the low‐voltage single‐phase three‐wire systems are unified. This report concerns use of the indication method between nodes using power flow calculation, for the purpose of developing a technique of analyzing unified high‐voltage systems and low‐voltage single‐phase three‐wire systems. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(3): 49–62, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10255
Mathematical Modeling of Scour and Deposition
Electronic computers are opening up the field of sedimentation engineering by permitting the analysis of problems which heretofore have required too much time and effort. Movable stream bed profiles are being calculated in addition to water surface profiles. The initial gradation of sediment material in the stream bed may be prescribed to facilitate the calculation of an armor layer. This gradation is continually changed by the computer program in response to sediment particles being deposited on the stream bed and material on the stream bed being removed to satisfy transport capacity. Hydraulic sorting of sediment by grain size is accomodated. The stream bed does not have to be represented by a single grain size. Retardance of motion because of armor layer is calculated.