Research On Power Quality Monitoring Network By Considering Voltage Sag And Difference Of Power Quality Monitors

Nowadays, voltage sag has become the most serious power quality, the optimal allocation of power quality monitors should priority consider the substations, which are greatly affected by voltage sag. Besides, there are various power quality monitors and their performance are obviously diverse and the sensitivity of users’ equipment to voltage sag is also different, which should be considered in the construction of power quality monitoring network. Thus the power quality monitoring network seems to be flexible, active, efficient and interactive. It has important and practical significance to carry out the related research.Firstly, the substation’s basic information, which is easily accessed and quantified from the aspects of outer environment characteristic and inner electric parameters, is adopted to design voltage sag severity evaluation indices. Based on the configuration of power quality monitor in substations, two different evaluation methods are presented to assess voltage sag severity of substations.Secondly, the calculation of voltage sag observation area has ignored the connection of transformer in existing literature, the paper has deeply discussed the influence of transformer’s connection on penetration and monitoring area of voltage sag. Then, the calculation method of voltage sag observation area considering the transformer’s connection is put forward. The IEEE 39-bus system is taken as an example to analyze. The result shows that voltage sag observation area is closely associated with transformer’s connection, which should be considered during the calculation of voltage sag observation matriex.On this basis, the paper improves the optimal model used in traditional method and puts forward a new optimal model for configuration of power quality monitors by considering the voltage sag severity of substation. In the process of building voltage sag observation, this model concerns the transformers’ connection in substations. In the model, certain amount of power quality monitors are configured based on order of sag severity. 220 kV main grid of certain large city in Guangdong power grid is taken as an example and the presented model is verified to have good application value in practice.Then, based on the latest standard DL/T 1227-2013, the power quality monitors are divided into four types, i.e. A, B, C and D. The paper puts forward an optimal method of power quality monitoring network from the aspect of optimizing configuration. In the first stage, the A type of monitors are configured in certain substations to ensure the observation of voltage sag, in second stage, B, C, D type of monitors are configured according to the order of voltage sag severity of substations. The analysis result of example shows that the optimal scheme is feasible and effective.Finally, from the perspective of user, the sensitivity of twelve mainstream low-voltage releasers to voltage sag are tested, and 26,668 groups of test data have been formed. Combined with the test results, revision priciples of power quality monitoring network are put forward. And the network is revised to guarantee the real-time and reliable observation of voltage sag with practical example.This work is supported by the Natural Science Foundation of Guangdong Province(No.2016A030313476).