Uncertainty Study Of Multi-Inverter Parallel Models Based On Residual Generators

The development of microgrids has led to an increasingly close relationship between their internal load and for the generation capacity.However,due to the limitations of power devices,increasing the capacity of a single inverter does not essentially improve the performance of the microgrid.In order to achieve this,multi-inverter paralleling technology needs to be investigated in order to achieve efficient utilisation of distributed energy sources and to ensure that they are scalable while meeting optimal output requirements.Multi-inverter parallel technology is a prerequisite for the reliability and high redundancy of microgrid systems,and is essential for the safety and stability of distributed generation systems.In this paper,we propose a compensation control strategy based on the residual generator,focusing on how to improve the control performance of the inverters and enhance the robustness of the inverters against disturbances and uncertainties,so as to ensure the safe and stable operation of the microgrid.Firstly,the inverters in the multi-inverter parallel system are modelled,and the circulating current problems in the parallel inverters are analysed and summarised to construct a state-space model of the multiple inverter system under quasi-stable operating conditions,and to realise the analysis and classification of the uncertainty problems arising from them.Secondly,the proposed architecture is applied to the multi-loop control of parallel inverters by using the theoretical derivation of the left mutual mass decomposition and the Euler parameterisation to obtain the compensating control architecture.For the single inverter system with uncertainty problem,the gradient descent optimization algorithm and parameter identification method are used to optimize the current compensation controller Q1,_i.For the problem that the parallel inverters cannot reasonably distribute the power according to the capacity,the voltage compensation controller Q2,_i is proposed to be designed from the perspective of consistent output voltage,and by adding the current compensation controller Q1,_i and voltage compensation The current compensation controller Q1,_i and the voltage compensation controller Q2,_i are added to each parallel inverter to achieve further decoupling of the mutual influence between multiple inverters.Then,based on the proposed control method framework,a small-signal model is built for each controller,which is then fused with the small-signal model of the parallel inverters and their lines to obtain the overall system consisting of multiple inverters in parallel.On this basis,the characteristic root distribution of the system is given according to the steady state operation of the system to check whether the system has small disturbance stability performance.Finally,the hardware-in-the-loop(HIL)experimental platform is tested on a parallel system of three inverters with a capacity ratio of 1:2.The results of the study show that the proposed control strategy has a good suppression effect in various uncertainty problems for a variety of uncertainty factors,which enables the output power of the parallel inverters to be reasonably distributed in terms of capacity ratio when the uncertainty problem occurs.