Distributed Voltage Regulation Of Intelligent Distribution Network

Due to rapid growth of the global economy in recent years,the consumption of fossil energy has been increasing rapidly,followed by the massive emissions of greenhouse gas and the increasing depletion of non-renewable energy sources.To well faced with the global climate and energy crisis,fossil energy will be gradually replaced by renewable energy such as solar and wind,which has become the consensus of the world.On the one hand,that the large-scale of renewable energy access the power grid will effectively reduce the consumption of non-renewable energy and the emissions of greenhouse gas.On the other hand,the inherent intermittency of renewable energy will cause bad effects for the voltage of distribution network,which will bring new challenges for the distribution network.In traditional distribution networks,voltage regulation is usually implemented by capacitors,On-Line Tap Changer and other equipment.Due to lifetime consideration,the action interval of the above-mentioned traditional voltage regulation equipment is usually measured in hours,making it difficult to follow the rapid voltage fluctuations caused by renewable energy generation fluctuations.On the contrary,the distributed generations connected to the distribution network via power electronic interface are inherently capable of delivering fast reactive power support.Therefore,to improve the voltage profile and reduce the fixed investment in voltage regulation,it is greatly significant to study the voltage regulation of distribution network via fast reactive power support of distributed generations.This paper focuses on the distributed voltage regulation of the distribution networks.Considering that there are usually numerous distributed generations in the distribution network,to accelerate the convergence speed of distributed voltage regulation,at first the distribution network is partitioned into several areas according to the electrical distance between the buses,which is calculated based on the topological characteristics and line parameters.Second,for each area which is seen as a participant of the distributed voltage regulation,the reactive power optimization problem is modeled and the constraints are reasonably linearized.Finally,based on the dual ascending method,the proposed distributed reactive power optimization algorithm is designed.Compared with the existing direct control algorithms in reactive power optimization,not only the indirect control of reactive power output of distributed generation via price of reactive power,but also the additional reactive power output costs of distributed generations in voltage regulation are considered,which is closer to the actual operation of the distribution network and provides a strong motivation for the distributed generations to participate in reactive power optimization.Finally,based on the IEEE 37-bus test feeder,the effectiveness of the proposed distributed reactive power optimization algorithm in improving voltage profile and economic operation of the distribution network is validated by the case studies.