Control of shunt unbalanced power active compensators for reactive and asymmetry elimination in four wire electrical systems using symmetrical components

Selective Shunt Active Power Compensator in Four Wire Electrical Systems Using Symmetrical Components

“…(5) according to the different phenomenona present in the electrical system. Three instantaneous power terms appear due to single-phase linear loads connected to three-phase systems [15][16][17][18]: the effective active fundamental instantaneous power (p e1 (t)), the reactive fundamental instantaneous power (p q1 (t)) and the fundamental unbalance instantaneous power (p U 1 (t)).…”

“…The fundamental unbalance instantaneous power is quantified by the unbalance power (S U 1 ), and following the procedure described in [17], the unbalance power (S U 1 ) can be written as:…”

“…(11), the positive-sequence reactive current and the negativeand zero-sequence components of the fundamental voltage and current are not desirable in the electrical systems [2,[16][17][18]. These terms represent inefficiencies that must be compensated to reach the maximum efficiency in the electrical system.…”

“…In our SSAPC, this extra energy is supplied by the utility as three sinusoidal currents, i z_ref _DC in Eq. (17), in phase with the corresponding positivesequence voltage at the pcc of the SSPAC. These currents represent a constant power flow from the generator to the APC, so this energy ( W eff in Figure 6) is transported through the lines with the best quality conditions (as a positive-sequence active power).…”

“…The second term represents the currents that maintain the voltage of the DC bus Eq. (17). The last summand represents the currents that maintain the DC voltage balance between the top and bottom capacitors of the split DC bus.…”