Intelligent droop control for frequency and voltage regulation in Islanded microgrids
Zaeem, Hassan Mehmood (131291)
Intelligent droop control for frequency and voltage regulation in Islanded microgrids - Islamabad Department of Electrical Engineering ( Air University Main Campus) 2016. - xiv; 64 p. C.D.
Renewable Energy Sources (RES) are considered as the replacement of conventional energy sources. These RES can use wind energy, solar light, bio waste and can also be in the form of small hydro power units. RES have very poor power quality and contains voltage fluctuations and variable frequency. These factors make RES a stability risk for the main utility grid. As a solution, currently inverters with different design techniques are being used as an interface between RES and main utility grid. A new technique” estimated droop control” is proposed for inverter design. The conventional droop control technique which was already used in inverter design, has difficulty in synchronizing parallel connected inverters with different droop gains and line impedances. The proposed ”estimated droop control” does not use any predefined droop values for inverters and all inverters are responsible for the estimation of their own droop values with respect to their output power. Therefore, inverters are not bound to use same and static droop values which are considered as a vital communication link. The proposed design methodology has made inverters independent from this only virtual link of communication due to which the reliability of a system has increased. The proposed design technique has given very good results in a simulation run. When the Simulink model was run in parallel connected inverter with different line impedances, it was a success as both inverters started operating with same droop values as they were sharing an equal load. The most important test was with different line impedances because in conventional droop control it is difficult for inverters to keep their synchronism with different line impedances and an unequal load sharing make inverters to deviate from their nominal values and to generate different tracking signals for each set. This problem has been successfully solved with estimated droop control as in this method each inverter set its droop gains according to its output power, which helps an inverter to operate at nominal values with different droop gains and line impedance.
Intelligent droop control for frequency and voltage regulation in Islanded microgrids - Islamabad Department of Electrical Engineering ( Air University Main Campus) 2016. - xiv; 64 p. C.D.
Renewable Energy Sources (RES) are considered as the replacement of conventional energy sources. These RES can use wind energy, solar light, bio waste and can also be in the form of small hydro power units. RES have very poor power quality and contains voltage fluctuations and variable frequency. These factors make RES a stability risk for the main utility grid. As a solution, currently inverters with different design techniques are being used as an interface between RES and main utility grid. A new technique” estimated droop control” is proposed for inverter design. The conventional droop control technique which was already used in inverter design, has difficulty in synchronizing parallel connected inverters with different droop gains and line impedances. The proposed ”estimated droop control” does not use any predefined droop values for inverters and all inverters are responsible for the estimation of their own droop values with respect to their output power. Therefore, inverters are not bound to use same and static droop values which are considered as a vital communication link. The proposed design methodology has made inverters independent from this only virtual link of communication due to which the reliability of a system has increased. The proposed design technique has given very good results in a simulation run. When the Simulink model was run in parallel connected inverter with different line impedances, it was a success as both inverters started operating with same droop values as they were sharing an equal load. The most important test was with different line impedances because in conventional droop control it is difficult for inverters to keep their synchronism with different line impedances and an unequal load sharing make inverters to deviate from their nominal values and to generate different tracking signals for each set. This problem has been successfully solved with estimated droop control as in this method each inverter set its droop gains according to its output power, which helps an inverter to operate at nominal values with different droop gains and line impedance.