H_∞ loop-shaping controller design for a grid-connected single-phase photovoltaic system

Figures & data

Figure 1. Equivalent circuit diagram of a grid-connected single-phase PV system.

Figure 2. Block diagram of the grid-connected single-phase PV system.

Figure 3. LFT representations of the uncertainty parameters.

Figure 4. Proposed H_∞ loop-shaping control configuration.

Figure 5. Achievement of Criterion 1: (a) Singular value of the closed loop of the grid-connected single-phase PV system and (b) Singular values of S(s) and 1/W ₁(s).

Figure 6. Achievement of Criterion 2: (a) Singular values of W ₂(s) and the worst-case profile of uncertainty and (b) Robust performance of the controller.

Figure 7. Achievement of Criterion 3: Singular values of S(s) and T(s).

Figure 8. Singular values of the original controller K(s) and the reduced order controller K _r (s).

Figure 9. Implementation block diagram of the proposed controller.

Table 1. Grid-connected single-phase PV system parameters.

	Parameter	Value
PV	Rated power	3.5 kW
	Irradiation, s	1000 W/m^2
	Working temperature, T	298 K
	Light generated current from one PV cell, I L	8.15 A
	Short-circuit current from one PV cell, I S	8.47 A
	Diode saturation current from one PV cell, I O	9.56× 10^−11 A
	Number of cells in series, N s	14
	Number of modules in parallel N p	1
	Shunt resistance, R sh	230.58 Ω
	Series resistance, R s	0.267 Ω
	Line resistance, R	30 Ω
	Line inductance, L	2 mH
Inverter	Rated power	3.5 kVA
	Dc-link capacitance, C c	3000 μF
	Rated dc-link voltage v c	400 V
	Switching frequency	3.78 kHz
	Sampling frequency	3.78 kHz
Grid	Filter inductance, L 1, L 2	1.2 mH
	Filter capacitance, C	2 μF
	Voltage	240 V RMS
	Frequency	60 Hz

Figure 10. Response from grid-connected single-phase PV system during standard atmospheric condition: (a) output dc power (in Watt) and (b) grid voltage (in Volt) [dashed line] and grid current (in Ampere) [solid line].

Figure 11. Grid current flow from grid-connected single-phase PV system during changing atmospheric condition: (a) solar irradiation and (b) grid current.

Figure 12. Grid current flow from grid-connected single-phase PV system during fault condition.