Research On Comprehensive Configuring Of Power Filters In Distribution Network With Multi-harmonic Source

With the rapid development of China's economy, nonlinear loads of distribution network are increaseing at fast speed, and which are represented by arc furnace, inverter, converter, etc; In addition, there are great efforts to develop clean energy, and this clean energy also accesses to distribution networks by inverter and converter. Distribution network becomes a network of multi-harmonic source with the access of these nonlinear devices, and they cause harmonic pollution of distribution network more serious. The traditional local suppression way based on the principle of "those who created pollution are responsible to suppress" can not meet the requirement of harmonic suppression of the multi-harmonic source network, but power filter comprehensive configuration method which is based on the whole network harmonic suppression effect as the goal can effectively solve the problem. With its own advantages, single-tuned filter and shunt active power filter (SAPF) have become the main options of harmonic suppression of distribution network. Power filter comprehensive configuration refers to single-tuned filter and SAPF as the main device, and their installation locations, capacity and parameters are optimally allocated throughout the whole network.Firstly mathematical model and design method of single-tuned filter and SAPF is studied in this paper. The output filter is a key component of SAPF, considering the two indicators of compensation frequency band tracking performance and high-frequency band switching harmonic suppression performance, a parameter computation method of LRC type of output filter is proposed based on the volt-second characteristic. Then SAPF simulation model is designed, and correctness and effectiveness of the established SAPF simulation model and the proposed parameter computation method of LRC type of output filter is validated by simulation.As single tuned filter is equivalent to a current source, and the current source is the same size but opposite direction as the filtered current by the single-tuned filter, the calculation method of the best installation location of single-tuned filter in a step by step planning in distribution network with multi-harmonic source is proposed. The calculation method of the best installation location of SAPF in a step by step planning in distribution network with multi-harmonic source is proposed, which is based on the sensitivity of the sum of squared absolute value of all network node voltage to the installation location of SAPF.According to the advantages of single-tuned filter and SAPF and characteristics of harmonic current of harmonic source, the range of harmonic suppression of single-tuned filter and SAPF is allocated reasonably, and a comprehensive configuration method is proposed in the hierarchical planning process of single-tuned filter and SAPF. This method meets the requirements of harmonic suppression firstly, then this method makes harmonic suppression cost of the whole network minimum and can give full play to the advantages of single-tuned filters and SAPF.Finally, simulation system of multi-harmonic source network is built in the simulation software PSCAD/EMTDC, simulation analysis of the calculation methods of the best installation location of single-tuned filter and SAPF has been done. Aiming at example system, simulation verification of harmonic suppression is achieved by applying the comprehensive configuration method of single-tuned filter and SAPF. Simulation analysis of this method and the traditional local suppression method has been compared at the same time. All simulation results show that the proposed method is correct and effective.