Inverter Design Considering Grid Conditions


This project will study transient conditions in the grid impacting on the inverter design. These transient conditions include starting motor and energizing transformer. The systems that have high penetration of inverter-based distributed generation (IDG), typically a voltage source inverter (VSI), will have limited current to provide inrush conditions causing some motors may not be able to be started or transformers may be able to be energized. Therefore, starting motor and energizing transformer behaviors are needed to study. Also, VSIs may require a new design to support the inrush current of motors and transformers during the transient conditions.


The studied system and behavior of transient conditions including transformer energizing and motor starting

Typically, starting motor is required high inrush current for several seconds. MATLAB/Simulink is utilized to simulate the transient conditions. For starting motor, most major motor starting techniques including autotransformer starter, star/delta starter, soft starter, and direct online starter with ZIP loads are implemented. The saturated transformer model is also included in the system to study inrush current during the transient condition. Once combining these transient conditions, the current and time of the overall system will be obtained. Therefore, the VSI’s capacity must be designed for these conditions to be able to continuously operate during the transient conditions.

How WBG Can Help

By studying starting motor and energizing transformer behaviors, the inverter design considering grid conditions can be achieved. During the transient conditions in the system, one challenge is lack of high inrush current because of current limiting of VSIs in the power systems. As VSIs are being installed more in the future grid, it is better if VSIs can operate and support during transient conditions to improve stability and reliability of the future grid.

Personnel Involved

  • Nattapat Praisuwanna