Research On The Real-Time Simulation Technology Of Grid-Connected Converter

With the development of new energy technologies and distributed generation, more and more converters connected to grid, which change the structure of the traditional grid and bring a range of issues. Meanwhile, some unusual circumstances to the grid also have a tremendous impact on converter. Due to limitation of experiment condition, most of the studies on interaction of the grid and converter remain in the software simulation stage, not only inefficient, but also the results having the deviation from the actual. This paper presents a real-time simulation platform based on dSPACE and RTDS. Depend on this platform, studies on the mutual influence between converter and distribution network after distributed generation connected to distribution network through real-time simulation methods are researched. The main work as follows:1. The characteristics and advantages of real-time and hardware-in-the-loop simulation are discussed, configuration and usage of hardware for the real-time simulation platform is introduced in detail, and the general principles of modeling real-time simulation based on dSPACE and RTDS is proposed. On the basis of analysis of PV, lithium battery, converter and distribution network principle, the real-time simulation platform is designed and established, the detailed method of real-time simulation modeling is given, furthermore, dynamic real-time operation among energy sources, converters, loads and distribution network is realized.2. Mathematical model of the converter under unbalanced voltage conditions established, and multi-objective control strategy based on the positive and negative sequence component separation is presented; Combined with the standard of LVRT(low voltage ride through)for distributed generation, a LVRT control strategy based on reactive power occurrence patterns is given. According verification in the platform, the results are confirmed with the theoretical analysis, and the system can achieve the expected control objectives, which proves the effectiveness of real-time simulation platform for interactive research of converter and grid.3. In order to solve problems of distributed generation in the future, research on influence of harmonics, voltage and line loss when distributed generation connected into distribution network through real-time simulation platform. A control strategy is proposed to improve the distribution network power quality using energy storage system, meanwhile, the examples show that the control strategy can effectively restrain power fluctuation and stabilize voltage of PCC (point of common coupling).