PI passivity-based control of modular multilevel converters for multi-terminal HVDC systems

Abstract

In this work, a decentralized PI passivity-based controller (PI-PBC) is applied to the Modular Multilevel Converters (MMCs) to ensure global asymptotic stability of a multiterminal MT-HVDC system. Since continuous MMC state-space models naturally have time-periodic steady-state solutions, a first step towards the derivation of the controller is the formulation of an equivalent model characterized by constant steady-state solutions, obtained via a multi-frequency orthogonal coordinates transformation. For the design of the controller, the overall system is represented in an appropriate port-Hamiltonian formulation, which allows the derivation of the stabilizing control law using passivity-based arguments. The results are validated on a threeterminal simulation benchmark.

PI Passivity-Based Control and Performance Analysis of MMC Multiterminal HVDC Systems

“…Based on such a representation, in Section IV the results of [10], [11] are directly applied both for the case of an individual MMC and of an MT-HVDC with meshed topology. The stability properties and performance guarantees of the resulting controllers are validated and thoroughly analyzed with the support of detailed time-domain simulations on a single and meshed four-terminal configuration in Section V. Thus, this work extends our initial result presented in [17], which was limited to the radial case, and lacked detailed time- Fig. 1.…”

Particle Swarm Optimization Tuning of Modular Multilevel Converters in a Time-Invariant Framework

“…A possible approach for a plug and play stability guaranteed control design with simple PI controllers for the MMC was implemented in [5], [6], based on the passivity theory [7]- [10], and therefore extending to the MMC case the works of [11], [12] originally applied to 2L-VSCs. Nonetheless, even if global asymptotic stability was guaranteed, the controller in [5], [6] had sub-optimal tuning, and therefore below par performance. Thus, we are interested here in improving the tuning and consequently the performance of the nonlinear control applied to the MMC in [5], [6].…”

“…Nonetheless, even if global asymptotic stability was guaranteed, the controller in [5], [6] had sub-optimal tuning, and therefore below par performance. Thus, we are interested here in improving the tuning and consequently the performance of the nonlinear control applied to the MMC in [5], [6].…”

“…Towards this end, in this paper we investigate the potential of applying the Particle Swarm Optimization (PSO) algorithm [13], originally proposed in [14], to tune the MMC control parameters of the nonlinear control structure presented in [5], [6]. The PSO algorithm has been chosen due to its capability of handling system nonlinearities, its simple implementation and relatively low computational cost, compared to other methods [15], as well as its success in the power system community [16].…”

A new control strategy forMMCunder grid voltage unbalance condition

“…1 A mathematical model is established based on the topology of MMC in Dekka et al 2 and Debnath and Chinthaval. 3 Cui et al, 4 Bergna-Diaz et al, 5 and Li et al 6 are control strategies for the external MMC, and Ji et al, 7 Yang et al, 8 Geddada et al 9 are the control methods of the internal circulating current under grid voltage balance. These methods achieve good results when the grid voltage is balance, but when the grid voltage is unbalanced, both the external control method and the internal circulating current control methods will lose their effect and are no longer suitable.…”