Online Estimation Method of DC-Link Capacitors for Reduced DC-Link Capacitance IPMSM Drives

Author(s):  
Nannan Zhao ◽  
Runfeng Gao ◽  
Gaolin Wang ◽  
Dawei Ding ◽  
Guoqiang Zhang ◽  
...  
2020 ◽  
Vol 10 (11) ◽  
pp. 3812
Author(s):  
Xiaohui Wang ◽  
Peng Wang ◽  
Yunbo Wang ◽  
Fang Shi

The potential short-circuit current in active distribution network features time-variance with the increasing distributed generations. This feature makes the online estimation of fault level necessary. In this paper, a novel online estimation method is proposed to be implemented by either phasor measurement unit (PMU) or the measurements from protection relays. The equivalent circuit of the radial distribution network with distributed generators (DGs), e.g., wind turbines and photovoltaic cells, is derived with necessary simplifications. The natural disturbances downstream are used to evaluate the parameters of the equivalent circuit so that the potential fault level can be estimated in advance of the actual fault occurrence. A fuzzy logic identifier is presented to rank the confidence of the measurements incurred by the disturbance and to distinguish the qualified disturbance to launch the estimation. The mechanism based on multi-measurements and confidence indices was applied, to improve the accuracy. A typical distribution network in the United Kingdom (UK) with DGs was taken, as an example, to validate the proposed method under various load fluctuation. The results confirm the effectiveness of the proposed method, which is suitable for online estimation of short-circuit fault level in active distribution networks.


2009 ◽  
Author(s):  
Hiroaki Kitano ◽  
Masahiko Kurishige ◽  
Takanori Matsunaga

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 805 ◽  
Author(s):  
Xiangyu Kong ◽  
Yuying Ma ◽  
Xin Zhao ◽  
Ye Li ◽  
Yongxing Teng

In view of the existing verification methods of electric meters, there are problems such as high maintenance cost, poor accuracy, and difficulty in full coverage, etc. Starting from the perspective of analyzing the large-scale measured data collected by user-side electric meters, an online estimation method for the operating error of electric meters was proposed, which uses the recursive least squares (RLS) and introduces a double-parameter method with dynamic forgetting factors λa and λb to track the meter parameters changes in real time. Firstly, the obtained measured data are preprocessed, and the abnormal data such as null data and light load data are eliminated by an appropriate clustering method, so as to screen out the measured data of the similar operational states of each user. Then equations relating the head electric meter in the substation and each users’ electric meter and line loss based on the law of conservation of electric energy are established. Afterwards, the recursive least squares algorithm with double-parameter is used to estimate the parameters of line loss and the electric meter error. Finally, the effects of double dynamic forgetting factors, double constant forgetting factors and single forgetting factor on the accuracy of estimated error of electric meter are discussed. Through the program-controlled load simulation system, the proposed method is verified with higher accuracy and practicality.


2018 ◽  
Vol 3 (3) ◽  
pp. 1816-1823 ◽  
Author(s):  
Preetham Chalasani ◽  
Long Wang ◽  
Rashid Yasin ◽  
Nabil Simaan ◽  
Russell H. Taylor

Sign in / Sign up

Export Citation Format

Share Document