Time-Domain Nonlinear Stability Analysis of Multi-VSC System as Affected by Distribution Feeder Parameters

The rapid development of renewable energy has promoted the development of power electronic devices. A large number of devices represented by voltage source converter (VSC) have been incorporated into the power grid, which has caused a series of stability problems correspondingly. Thus, this paper starts from the distribution feeder parameters and investigates their influence on the stability of the multi-VSC system. In this paper, an improved Kron reduction method is proposed to reduce the order of multi-VSC system equivalently. This method can eliminate unnecessary nodes in any power network which contributes to simplifying later calculation. Then based on the reduced multi-VSC system, the dynamic equation of VSC is established and extended to multi-VSC system. Third, a new system stability criterion is proposed by using the average method. In order to analyze the influence of distribution feeder parameters on multi-VSC system stability, the generalized short circuit ratio calculation formula of the multi-VSC system is introduced. For the real system, the influence of the distribution feeder parameters on the stability of the system can be obtained by finding out the relationship between the new stability criterion proposed in this paper and the generalized short-circuit ratio. The case study has illustrated the effectiveness of the proposed methods. The conclusion of this paper is helpful to study the influence of complex distribution feeder on multi-VSC system stability and provide the basis for stability analysis of specific real power network.