Research On Optimal Scheduling Method Of AC/DC Hybrid System With Power Electronic Transformer

In recent years,distributed renewable energy has gained more and more applications in the power grid.However,due to the limited interconnection and flexibility of traditional power grids,the intermittent distributed power generation will have a significant impact on the system.The system has insufficient capacity to absorb renewable energy.The Power Electronic Transformer(PET)can flexibly adjust the power to control the power of different ports.Based on this,this paper studies the optimal scheduling method of AC/DC hybrid system with PET.The specific work is as follows:1)A pre-optimized scheduling method for AC/DC hybrid systems with PET is proposed.Firstly,the working principle of PET is given,and the PET equivalent model for optimization scheduling is established.The optimal scheduling model of AC/DC hybrid system with PET is proposed.Through the power regulation function of PET,the power transmission between the AC system and the DC system is controlled,the operating cost of the system is reduced,and the economic operation of the AC/DC hybrid system is realized.2)A pre-optimized scheduling method for AC/DC hybrid systems considering PET loss and controllable load response capability is proposed.By introducing the net input power of PET,a loss-containing scheduling model for PET is established.With the optimization target of minimizing the operating cost of the system and considering the controllable load response capability,an optimal scheduling model for AC/DC hybrid system considering PET loss is established.The effect of PET power conversion efficiency on the optimal scheduling of AC/DC hybrid systems was studied.3)Considering the development trend of microgrid in the future,a two-layer optimal dispatching method for AC/DC hybrid microgrid with PET is proposed.The different ports of PET are set as different stakeholders.A two-layer optimal dispatching model of AC/DC hybrid microgrid with different stakeholders is established.The upper layer pays attention to the purchase cost of PET and the lower layer pays attention to the operation cost of AC/DC microgrid.Karush-Kuhn-Tucker method is introduced to transform the two-layer model into a single-layer model for solution and analysis.