Apparatus and method for controlling MPPT of photovoltaic system using active power control

An apparatus for controlling maximum power point tracking (MPPT) of a photovoltaic system using active power control, the apparatus comprising:

• a photovoltaic panel;
• a photovoltaic inverter unit which converts direct current (DC) power received from the photovoltaic panel into alternating current (AC) power and outputs the AC power used as commercial power;
• and
• an active power-based inverter control unit which determines a reference value (Pmpp) for output power (Pinv) of a photovoltaic inverter using a curve (Pmpp) connecting maximum power points according to a change in solar irradiance in a P-V curve showing a relationship between photovoltaic output power and a terminal voltage and measures a terminal voltage (Vpv) of the photovoltaic panel to allow the photovoltaic inverter to perform an operation according to MPPT control for tracking a value of the terminal voltage changed according to the solar irradiance,
• wherein the active power-based inverter control unit includes:
• an inverter power control signal output unit which receives a value of a terminal voltage (Vpv) of a parallel capacitor and determines the reference value (Pmpp) for the output power (Pinv) of the photovoltaic inverter from the received value to output an inverter power control signal (P*inv);
• a power controller which receives the inverter power control signal (P*inv) from the inverter power control signal output unit to output a grid current control signal (I*grid);
• a phase locked loop (PLL) which receives a grid voltage (Vgrid) to output a phase angle (θ) for synchronizing the grid voltage;
• a current controller which receives a grid current (igrid), the phase angle (θ) of the PLL, and the grid current control signal (I*grid) to output an output control signal (m) for controlling a pulse width modulation (PWM);
• and
• a PWM control signal generator which receives the output control signal (m) of the current controller to output a PWM control signal for controlling an output of the photovoltaic inverter.