Microgrid Power Architecture
Power converters, and microgrids driven by such a power converter, in which the converter is controlled by a proportional controller which operates directly on AC waveforms, preferably without conversion to a DC type signal; preferably with use of voltage compensation to remove inherent error of proportional controller; and preferably with use of individual phase RMS voltages in the voltage compensation, to allow for normal operation under any load condition. Undervoltage of one or two phases is automatically compensated by adjusting the voltage of all phases, to retain balance. Line-starting of a motor load is automatically detected, and frequency droop is driven, apart from the other control relations in the system, to complete the line-starting operation as quickly as possible.
1 . A method of operating an electronic power converter, comprising:
measuring the output of an electronic power converter against a varying reference value which has a sinusoidal dependence on time; and
in accordance with the measuring step, generating a first output command for the converter, using a pure proportional control relation with no integration component; and using an additional control relation to adjust the output command, in dependence on the magnitude of a measured electrical value, to remove offset error and thereby generated an adjusted output command for each phase; and
initiating a current limiting operation, which limits current to a varying value which also has a sinusoidal dependence on time, if the measuring step shows an overcurrent value; and
if one or two phases exhibit fault conditions reducing the adjusted output command of the other phase or phases, to thereby restore the balance of the different phases; and
sending the adjusted output command to the converter as a control input.
2 . The method of claim 1 , wherein the additional control relation is a PI control relation.
3 . The method of claim 1 , wherein the current limiting operation is applied to combined current, and also, separately, to the individual single phases.
4 . The method of claim 1 , wherein the additional control relation is a PID control relation.
5 . The method of claim 1 , wherein the current limiting operation is applied to combined current, and also, if the combined current is within bounds, to the individual single phases.
6 . The method of claim 1 , wherein the current limiting operation is supplemented by an absolute limit, which protects against failure of the current limiting operation.
7 . The method of claim 1 , wherein the measuring step comprises measuring the voltage of at least one phase.
8 . The method of claim 1 , wherein the converter is a power-packet-switching converter.
9 . The method of claim 1 , wherein the magnitude is a root-mean-square value.
10 . The method of claim 1 , wherein the possible fault conditions include overcurrent and undervoltage.
11 . A method of operating an electronic power converter, comprising:
measuring an output of the converter with respect to a varying reference value which has a sinusoidal dependence on time; and
in accordance with the measuring step, generating an output command for the converter, using a pure proportional control relation with no integration component;
and using an additional control relation to adjust the output command, in dependence on the magnitude of a measured electrical value, to remove offset error and thereby generate an adjusted output command; and
sending the adjusted output command to the converter.
12 . The method of claim 11 , wherein the additional control relation is a PI control relation.
13 . The method of claim 11 , wherein the additional control relation is a PID control relation.
14 . The method of claim 11 , wherein the measuring step comprises measuring the voltage of at least one phase.
15 . The method of claim 11 , wherein the converter is a power-packet-switching converter.
16 . The method of claim 11 , wherein the magnitude is a root-mean-square value.
17 . A method of operating an electronic power converter, comprising:
controlling power output in accordance with voltage and/or current feedback;
wherein the power output is controlled, at the lowest level, by a proportional control relation, with no integration component, which provides an output command for the converter;
and wherein an additional control relation, which includes an integral term, adjusts the output command to remove offset error.
18 . The method of claim 17 , wherein the additional control relation is a PI control relation.
19 . The method of claim 17 , wherein the additional control relation is a PID control relation.
20 . The method of claim 17 , wherein the measuring step comprises measuring the voltage of at least one phase.
21 - 61 . (canceled)