Modified Perturb and Observe-based MPPT control of MHPCS for single-phase power distribution positioned in remote locations

Abstract

This paper introduces a Modified Perturb &Observe (MP&O) method forpersistent voltage and frequency operation of a 3-phase Isolated Induction Generator (IIG) for supplying remotely located domestic loadsand coupled to an ungoverned micro-hydro turbine. With a fixed excitation capacitor bank connected across the stator terminals, the IIG simultaneously supplies power to both ac load (main load) and controlled dc load (dump load). The generated output poweralways remains constant. The generator is operated at maximum output power point corresponding to the capacitor bank connected across the stator terminals of the IIG.The controller diverts power from main load to dump load and vice-versa to maintain the voltage and frequency at constant value. An excitation scheme of three-phase IIG including two capacitors (1C_P–1C_S scheme) has been proposed for single-phase household supply. The electronic circuit is realized using an uncontrolled rectifier-chopper (diode-IGBT) combination connected across the IIG terminals supplying the controlled dc load. The d-q modeling of IIG referred to stationary reference frame is used for simulation in MATLAB 2014a environment. The proposed MPPT controlalgorithm has been experimentally implemented on a 3-phase, 415 V, 2 HP induction machine using dSPACE 1104 platform and the effectiveness of the algorithm has been tested for various transient conditions such as sudden ac load application as well as removal.It has been found that with sudden application and removal of main load, the constant terminal voltage is maintained with proper switching action of the IGBT switch. During load perturbation, momentarily, there is a change in the terminal voltage, but due to the control action, it settles at the reference value within few cycles, which indicates the good time response of the MP&O method. The steady-state response of the entire system shows smooth power transfer between the main load and dump load and thereby,the terminal voltage is maintained at the reference value indicating the effectiveness of the proposed control approach.

Appendices

Appendix 1

The matrices of Eq. (9) are defined as

$$ \left[ v \right] = \left[ {v_{{qs}} v_{{ds}} v_{{qr}} v_{{dr}} } \right]^{T} ,\left[ i \right] = \left[ {i_{{qs}} i_{{ds}} i_{{qr}} i_{{dr}} } \right]^{T} ,\left[ R \right] = diag\left[ {R_{S} R_{S} R_{r} R_{r} } \right] $$

$$ \left[ v \right] = \left[ {v_{qs} v_{ds} v_{qr} v_{dr} } \right]^{T} ,\left[ i \right] = \left[ {i_{qs} i_{ds} i_{qr} i_{dr} } \right]^{T} ,\left[ R \right] = diag\left[ {R_{S} R_{S} R_{r} R_{r} } \right] $$

$$ \left[ L \right] = \left[ {\begin{array}{*{20}c} {L_{{ls}} + L_{m} } & 0 & {L_{m} } & 0 \\ 0 & {L_{{ls}} + L_{m} } & 0 & {L_{m} } \\ {L_{m} } & 0 & {L_{{lr}} + L_{m} } & 0 \\ 0 & {L_{m} } & 0 & {L_{{lr}} + L_{m} } \\ \end{array} } \right] $$

$$ \left[ L \right] = \left[ {\begin{array}{*{20}c} {L_{{ls}} + L_{m} } & 0 & {L_{m} } & 0 \\ 0 & {L_{{ls}} + L_{m} } & 0 & {L_{m} } \\ {L_{m} } & 0 & {L_{{lr}} + L_{m} } & 0 \\ 0 & {L_{m} } & 0 & {L_{{lr}} + L_{m} } \\ \end{array} } \right] $$

$$ \left[ G \right] = \left[ {\begin{array}{*{20}c} 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & { - L_{m} } & 0 & { - L_{lr} - L_{m} } \\ {L_{m} } & 0 & {L_{lr} + L_{m} } & 0 \\ \end{array} } \right] $$

where, L_s = L_ls + L_m and L_r = L_lr + L_m.

Appendix 2

The machine per-phase equivalent circuit parameters are: ${R}_{1}=6.12\Omega , {R}_{2}=2.59\Omega , {X}_{1}=6.23\Omega , {X}_{2}=6.23\Omega .$ The magnetization curve of the machine as obtained by experimentation is given below:

$$ \begin{array}{llll}L_{m} \,= 0.410&{\text{for }}&I_{m} \le 0.792 \\ \qquad= 0.001404I_{m}^{3} {\text{ }} - 0.0018I_{m}^{2}\\ \quad\qquad\, - 0.086082I_{m} {\text{ }} + 0.478980&{\text{for }}&0.792{\text{ }}I_{m} < 4.18 \\ \qquad= 0.18949&{\text{for }}&I_{m} > 4.18{\text{ }} \end{array}$$