Photovoltaic Power’s Access Plan In ADN And Influence On Voltage Quality

Distributed photovoltaic power will be accessed to the distribution network extensively and intensely in the future, the spread of active distribution network has become an important trend in development of power grid, to satisfy the requirement of high permeability and reliability. When the new photovoltaic power access to ADN, finding the method to optimize the photovoltaic power and plan out the best scheme so that multiple indicators maintain comprehensive optimum has become an important problem to be solved urgently. With the increasing of photovoltaic permeability, different access capacity and position will bound to influence the quality of grid’s voltage, causing the problem of the deviation and fluctuation of voltage limit. Therefore, after determining the integration scheme, the solution to evaluate its impact on the quality of voltage also becomes critical problem in the distribution network development.Firstly, this paper established the simulated model of photovoltaic grid-connected system based on the platform of matlab/simulink, making the power factor of photovoltaic power being constant value with the aid of PQ control based on phase locked loop and PI regulator. Afterwards, the influence of photovoltaic grid-connected system to feeder voltage is analyzed, the improvement of feeder voltage by different capacity and location of photovoltaic power and limit voltage by corresponding regulating measures are obtained, setting theoretical stage for the follow-up study.To solve the problem of photovoltaic planning in ADN, a method of step-wise screening is proposed in this paper from a standpoint of multiple indicators and multiple selection schemes. Compared with conventional methods, this method considers more indicators and more selection schemes, consider the technical and economic indexes comprehensively, making the planning carry on by step, in which every step only consider a few factors, so that the work can be simplified. Different from the traditional distribution network, ADN has the ability of active control, so that the operating parameters of ADN are adjusted by multiple regulation modes with change of daily illumination and electricity consumption, realizing comprehensive optimum of multiple indicators. This method is applied in the simulation of IEEE 14 nodes system, verifying its effect of optimization of multiple indicators, such as voltage distribution improvement, total harmonic distortion of PCC, voltage stability, power loss and penetration capacity, supplement and perfect the existing methods.To research the influence of photovoltaic power to voltage quality, the influence to voltage deviation and fluctuation by the accession capacity and distribution mode of photovoltaic, and a computing method to solving photovoltaic permeability limit is proposed. The simulated flicker model is established according to the international electrical standard IEC61000-4-15, the relationship of flicker with amplitude and frequency of illumination fluctuation is researched, and the difficulty level of off-limits of voltage fluctuation and flicker. The method is applied in the simulation of IEEE 14 nodes system, the result shows that the proposed method can satisfy the requirements of engineering accuracy, and the desired parameters can be obtained directly from the data of power network, so that it can provide decision-making basis for the reasonable planning of photovoltaic power supply.