| Replacing fossil energy with clean energy is the key initiative of energy structure reform.And photovoltaic power generation technology tends to be mature and has been applied on a large scale.With the introduction of the goal of "carbon peak and carbon neutrality",photovoltaics has ushered in a new round of development opportunities,but the safety,stability,and economic operation of the distribution network has also encountered new challenges.Therefore,it is necessary to carry out research on the voltage control of the distribution network with a high proportion of photovoltaic inverters.This paper conducts related research on the problems of voltage violation,sudden change and fluctuation caused by a high proportion of photovoltaics connected to the grid:1)A multi-mode coordinated voltage control strategy for photovoltaic inverters considering the rate of voltage change is proposed.This strategy incorporates the rate of voltage change into the research category,and implements real-time voltage control through the voltage control capability of the photovoltaic inverter itself.First,divide the inverter into three operating modes.And the relationship between the voltage change rate and the injected reactive power change rate under different modes is established,and then the control effect is improved through the coordination of single inverter multi-mode and multi-inverter multi-mode.The cases show that the proposed strategy can delay the voltage change.When the voltage is violated and the limit is severely exceeded,it can shorten the out-of-control time of the distribution network,and complete the control independently within the time permitting.This provides a solution to the problem of voltage sudden changes in high penetration photovoltaic power distribution networks.2)A two-stage voltage control strategy for the distribution network with photovoltaic inverter multi-mode coordination is proposed,which makes full use of the advantages of inverters that can be adjusted quickly and continuously.This strategy divides photovoltaic inverters into economic prevention,economic control,and high-efficiency control operation modes that can be adapted to the two-stage voltage control requirements of the distribution network.It also considers the influence of adaptive time delay,integrates monitoring information,prediction information and communication information to quickly update the control commands,and improves the control accuracy.The cases show that the proposed strategy can effectively prevent voltage violations and suppress voltage fluctuations in distribution network.Realize accurate and fast voltage control by considering the algorithm of multi-information fusion and adaptive delay delay.3)A voltage control strategy for intra-day cooperation of fast and slow devices in active distribution networks is proposed.Firstly,a mixed integer nonlinear programming model containing predictive variables is established,and a strict action time constraint is introduced to regulate the intra-day coordination relationship of fast and slow devices.Then,the optimization results are obtained quickly and accurately by narrowing the solution range using scenario screening,continuousizing discrete variables with Gaussian penalty functions,and further solving with the fireworks algorithm.The cases show that the proposed strategy can solve the problems of insufficient adjustment flexibility in intra-day for slow devices and low adjustment capacity of fast devices.Compared with the traditional control strategy,the proposed strategy can increase the voltage control range and accelerate the convergence.This paper takes into account the role of multi-mode coordination of photovoltaic inverters to study the voltage control of the distribution network,which is of great significance in ensuring the safe and stable operation of the distribution network.It can provide technical support to further increase the scale of photovoltaics and help achieve the goal of "carbon peak and carbon neutrality". |
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