Operation and assessment of dc power distribution system suitable to new energy environment

太阳能光伏等分散发电系统已经安装在一些商业设施和个人家庭上。几乎所有的分散发电系统都产生直流电。另一方面，虽然大多数电力负载从电力系统获得交流功率，但负载将交流功率转换为直流功率。在此背景下，本课题提出了适用于新能源环境的直流供电系统，并对直流供电系统和交流供电系统的实验电路进行了功率效率测试。实验结果表明，直流供电系统比交流供电系统的效率高20%，在直流供电系统的建设中，供电电压是一个重要的因素，需要综合考虑各种现象来确定。目前的研究集中在恒功率负载下接收端电压的不稳定性。首先，建立了恒功率负荷的数值计算模型。使用该模型可以显示接收端电压的发散过程。在此基础上，讨论了适用于直流系统的供电电压，并证明了这一现象会使负载端的可接受功率受到限制。根据电路理论成功地解释了这一现象，从而将可接收功率表示为几个电路参数的函数，例如配电线路的电阻。

Dispersed generation systems such as solar photo voltaics have been installed on some of commercial facilities and individual homes. Almost all of the dispersed generation systems generate dc electric power. On the other hand, whereas most of electrical loads receive ac power from the electrical systems, the loads transform the ac power into the dc power. With this background, the present project proposes dc power supply system as the system suitable to new energy environment.A power-efficiency was measured for experimental circuits of DC and AC power supply system. The experimental results showed that DC power system had higher power efficiency by 20 % than AC power system.In construction of dc power supply system, supply voltage is one of important factors and should be determined in consideration of various phenomena. The present research focused on an instability of the voltage at a receiving terminal for a constant-power load. Firstly, the numerical-calculation model for representing the constant-power load was developed. Use of this model permitted to show the diverging process of voltage at the receiving end. On the basis of this phenomenon, the supply voltage suitable to the dc system was discussed.Above phenomenon also proved to cause the receivable power at the load terminal to be limited. This phenomenon was successfully interpreted on the basis of the circuit theory and thus the receivable power was expressed as a function of several circuit parameters such as the resistance of a distribution line.