Dual-Timescale Control for Power Electronic Zigzag Transformer

Power electronic zigzag transformer is an attractive solution for the flexible interconnection of smart distribution networks.It is constituted by slow-response and low-precision thyristor converters and fast-response and high-accuracy voltage source converters.This paper models its primary circuit and addresses its basic operation mechanism.Then a dual-timescale control scheme is investigated to realize the coordinated regulation of both types of converter.A simulation case is established in PSCAD containing interconnected mid-voltage distribution networks.Simulations with poor-and well-matched control timescales are both carried out.And accordingly,the power flow controllability under these conditions is compared.When the shorter control timescale is no more than tenth of the longer one,the power electronic zigzag transformer will operate with satisfying performances.

马尔可夫预测模型对股票价格波动的预测分析

马尔可夫过程最初由俄罗斯数学家马尔可夫(Markov)于1906年研究而得名,它是一类典型的具有马氏性的随机过程。马氏性是指现在发生的事情与过去曾发生的事件无关。简言之,在已知“现在”的条件下,“将来”与“过去”是独立的。马尔可夫过程理论已发展得较为成熟,在自然科学、工程技术及经济金融管理等领域都有广泛的应用。本文以马尔可夫模型的基本理论为出发点,将马尔可夫模型运用在经济金融领域,使用马尔可夫预测模型和加权马尔可夫预测模型对股票价格的波动情况进行预测分析,并以浦发银行的股票价格数据为例进行实证分析。