PIDR Sliding Mode Current Control with Online Inductance Estimator for VSC-MVDC System Converter Stations under Unbalanced Grid Voltage Conditions

Abstract

This study aims to present a novel proportional-integral-derivative-resonant law-based sliding mode current control strategy with online inductance estimator (PIDR-SMCC-OIE) for voltage source converter medium voltage direct current (VSC-MVDC) system converter stations under unbalanced grid voltage conditions. A generalized current reference calculation method, by which the ratio of the amplitude of the active power ripple to that of the reactive power ripple can be continuously controlled without current distortion is presented. A dynamic model of the current control errors in the positive sequence synchronous reference frame is developed, and a PIDR law-based sliding mode current controller is designed, where derivatives of the current references are obtained by simple algebraic operations. An OIE adopting the dynamic filtering method and gradient algorithm is proposed to further improve system robustness. In this OIE, the converter pole voltages are obtained by computation utilizing the gate signals of the switching devices and the DC bus voltage, so that no additional voltage sensors are needed. To verify effectiveness of the PIDR-SMCC-OIE strategy, simulation studies on a two-terminal VSC-MVDC system are conducted in PSCAD/EMTDC. The results show it can provide satisfactory performance over a wide range of operating conditions.

An electrothermal current prediction method for overload protection of miniature circuit breakers

“…In addition to current sensors, several current prediction techniques were proposed in [18][19][20][21]. Although they are effective in motor and grid control, they cannot be applied in MCBs due to different structural characteristics and calculation premises.…”

Adaptive Backstepping Control with Online Parameter Estimator for a Plug-and-Play Parallel Converter System in a Power Switcher

“…Moreover, while the stability of the estimation error dynamics of an ESO is easily determined [16,17], the stability of the whole control process has been rarely examined.…”