The Partition Of Distributed Network For Voltage Control With Distributed Generation

With the rapid development of smart grid and the incrementally requirements of environmental quality, distributed generation(DG) which is based on clean energy has got widely used increasingly. The DG units is playing a more and more active role because their permeability is gradually improving in distribution network, in another way, the DGs can participate in voltage regulation of the distribution network via controlling their own power in order to support the stability and reliability of the power grid; in addition, the problem of abandoning solar and wind energy still exists despite the relevant technology about DG is more mature in recent years, so how to control the power supply of DGs to take an active part in voltage regulation and improve the digestive ability of distribution network for DG units is a worth researched topic. It not only has the features of increasing the digestive ability, but also having no effects on the use of natural resource and the active power output after applying local control on distribution system. In accordance with the needed inductive or capacitive reactive power, it could adjust the reactive power output continuously within the capacity limit of reactive power that the DG holds, further achieving the distribution network reactive-voltage control and solving the undervoltage and overvoltage problems.The researched voltage control method of distribution network containing DG units mainly focuses on reactive power optimization both at home and abroad currently, but actually due to its small generating capacity, scattered layout features, the DG units mainly are connected to a lower voltage level distribution network, therefore the voltage control method on distribution network only considering the impact of reactive power is still not perfect. Based on the particularity of distribution network, this paper uses the concept of the integrated voltage sensitivity, taking into account the impact of DG’s active power and reactive power on distribution network voltage simultaneously, according to the comprehensive voltage sensitivity the node which is most in need of reactive power compensation is obtained, when the voltage regulation is not required quickly act or the output change of DGs does not meet the requirements of voltage regulation, the traditional reactive power compensation devices for voltage adjustment can be used.The distribution network can be split into smaller controllable areas termed local controllable zones(LCZs) in order to realize the local control. In this paper, the proposed local control structure can be achieved via voltage increment matrix based on integrated voltage sensitivity, and by using the Hopkins statistic to judgement whether it makes sense conducting clustering analysis for voltage increment matrix, elbow method is used to determine the clustering number, at the same time the k-means algorithm and hierarchical clustering method are adopted to partition the distribution network. According to its region partition result, DG units have larger voltage support for these nodes which are divided into the same LCZ.Using the partition results as a guide, the MATLAB/Simulink simulation model is established based on the constraint of power capability curve and concepts of control domain and operative domain. To eliminate the voltage deviation and solve voltage fluctuation problem, the output of DG can be changed using algorithm based on the gathered real-time information, and the reactive power is the first one to be changed allowing maximum active power production simultaneously, the active power modulation will take place when the reactive power is up to the capacity limit proposed by the capability curves and the voltage level is not within the operative limit. The simulation results show that use the zone partition result as a guide to implement the local control, not only can increase the absorptive capacity of the distribution network for DGs, but also being able to control the node voltage is within the requirement which is in the same LCZ with DG significantly.