Quick load shedding is a common measure for power systems to remain stable after a fault. In this paper
a DC microgrid load shedding decision-making method based on on-line load sensitivity identification is proposed for the DC microgrid with power electronics transformer(PET) as its core. Firstly
the voltage of PET DC terminal
is controlled to realize the on-line load sensitivity identification
and to obtain the real-time sensitivity of load power to the voltage change; then
the load characteristic parameters are applied to the voltage droop control curve of DC microgrid’s voltage regulating units
so as to accurately evaluate the influence of the load removal on the DC voltage and to quickly determine the load removal sequence. At last
a DC microgrid that includes wind/light microsources
energy storage
and various characteristic loads is established on Matlab/Simulink
and the cut-off load is determined according to the proposed voltage evaluation formula considering load sensitivity when the AC main grid side is faulty or the distributed power output is limited and the DC voltage is lower than the droop voltage regulation range. Then the system DC bus voltage and the operating modes of voltage regulating unit can be operated according to the theoretically determined value
which verifies the effectiveness of the proposed method. In addition
this method overcomes the problems of the load time-varying
and has the characteristics of simple principle and convenient calculation.