| Feeder automation(FA) system can effectively locate fault location, automatic isolate fault and fastly restore the power of non-fault section automatically, improves the reliability of the distribution network. With the development of distribution automation, feeder automation, as the basic function of distribution automation system, will be more and more widely employed in distribution network. So it has important theoretical and practical significance to analyze the influence of feeder automation on the reliability of distribution system and to carry out the reliability evaluation model of distribution network with feeder automation.At present, there are mainly two types feeder automation system: FTU(Feeder Terminal Unit, FTU) feeder automation and recloser feeder automation system. Recloser feeder automation and FTU feeder automation system both can isolate faults and quickly restore power automatically, so, they all can improve the reliability of distribution network. But the two types FA system have completely different operation logic and failure mode, lead to the reliability of distribution network that installed the two types FA system has a huge difference. This paper respectively from the perspective of the running mechanism of the recloser and FTU feeder automation system, and based on network partition to deduce all kinds of time to restore power gradually, then the reliability indices expectation and reliability index probability distributions are obtained. The main research contents are as follows:(1) This paper establishes the reliability model of FTU and sectionalizer based on the feeder automation system's view, which reduces the complexity of the analysis of the influence of the probability characteristic of feeder automation system on the reliability of distribution network. According to the terminal whether can support feeder automation system to finish positioning fault and isolating fault automaticly, simplifing the failure mode of remote-controlled terminal and telesignalling terminal, then establishing the FTU feeder automation system probabilistic model; inductiving recloser feeder automation system practical control process, according to control flow path the sectionalizer's reliability model is established.(2) The load points are divided into 4 classes and multiple subclasses, the same type of load point has the same calculation method of power supply time. As the feeder automation system can isolate fault and restore the power of non-fault section automatically, the load points have more ways to restore the power supply, the operators also have more means to restore the power supply. In this paper, the new classification method of load type not only can deal with the diversity of the load points supply time, but also when the operator uses a different restoration strategy of power supply, the model of this paper is still suitable(3) The distribution network reliability evaluation model that considering the FTU feeder automation is established, and the reliability evaluation model that considering recloser feeder automation system is established, Based on FTU terminals probability model, the switch control logic of FTU feeder automation and distribution network partition perspective, the formula of all kinds of load point recovery power supply time is deduced, and then the analytic formula of reliability indices of expected value is obtained; the characteristic of the recloser feeder automation system restored power supply is that system need multiple sectionalizers cooperate with each other, therefore, according to the 7 steps in the process of restoration of power supply, the expected time calculation formula of each load point of all classes is deduced step-by-step in this paper. then obtaining the function of reliability indices of the expected value. Finally, the model is further modified, so that the model can be applied to the reliability analysis of distribution network with other FTU or recloser type automation system.(4) Based on the calculation formula of the reliability indices expectation, the probability distribution of distribution network's reliability indices are deduced. In the practical application, it is very difficult to obtain the probability distribution of the reliability indices directly, so the nonparametric kernel density estimation technique is used to approximate the probability distribution of reliability indices in this paper.(5) Finally, this paper points out neglecting the influence of feeder automation will seriously underestimate the distribution network's reliability, and the characteristics of feeder automation system also have important influence on the reliability of distribution network, which is also a nonnegligible factor in the reliability assessment. |
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