title: A nonlinear modulation strategy for hybrid AC/DC power systems
abstract: A nonlinear control strategy to improve transient stability of a multi-machine AC power system with several DC links terminated in the presence of large disturbances is presented. The approach proposed in this paper is based on differential geometric theory, and the HVDC systems are taken as a variable admittance connected at the inverter or rectifier AC bus. After deriving the analytical description of the relationship between the variable admittance and active power flows of each generator, the traditional generator dynamic equations can thus be expressed with the variable admittance of HVDC systems as an additional state variable and changed to an affine form, which is suitable for global linearization method being used to determine its control variable. An important feature of the proposed method is that, the modulated DC power is an adaptive and non-linear function of AC system states, and it can be realized by local feedback and less transmitted data from, adjacent generators. The design procedure is tested on a dual-infeed hybrid AC/DC system
keyphrases: nonlinear modulation strategy hybrid AC/DC power systems nonlinear control strategy transient stability multi-machine AC power system DC links differential geometric theory HVDC systems variable admittance inverter rectifier AC bus active power flows generator dynamic equations affine form global linearization method local feedback adjacent generators dual-infeed hybrid AC/DC system