Energy Management and Control Strategy of Photovoltaic/Battery Hybrid Distributed Power Generation Systems With an Integrated Three-Port Power Converter

ABSTRACT:

 Photovoltaic (PV)/battery hybrid power units have attracted vast research interests in recent years. For the conventional distributed power generation systems with PV/battery hybrid power units, two independent power converters, including a unidirectional dc–dc converter and a bidirectional converter, are normally required. This paper proposes an energy management and control strategy for the PV/battery hybrid distributed power generation systems with only one integrated three-port power converter. As the integrated bidirectional converter shares power switches with the full-bridge dc–dc converter, the power density and the reliability of the system is enhanced. The corresponding energy management and control strategy are proposed to realize the power balance among three ports in different operating scenarios, which comprehensively takes both the maximumpower point tracking (MPPT) benefit and the battery charging/discharging management into consideration. The simulations are conducted using the Matlab/Simulinksoftware to verify the operation performance of the proposed PV/battery hybrid distributed power generation system with the corresponding control algorithms, where the MPPT control loop, the battery charging/discharging management loop are enabled accordingly in different operating scenarios.

KEYWORDS:

1.      Energy management

2.      Maximum power point tracking

3.      Bidirectional power converter

4.      Photovoltaic/battery hybrid power unit

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Figure 1. The Proposed Pv/Battery Hybrid Distributed Power Generation System.

 EXPECTED SIMULATION RESULTS:

Figure 2. Pv Characteristic Curves With Irradiance = 1 Kw/M2 (Red) And Irradiance = 0.5 Kw/M2 (Blue) (Temperature = 25◦C).

 Figure 3. Steady State Simulation Results Of Operation Scenario 2. (A) Dc Bus Voltage Vbus; (B) Pv Voltage Vpv; (C) Pv Current Ipv; (D) Pv Referenc Voltage Vref; (E) Battery Charging Current Ib.

 

Figure 4. Steady State Simulation Results Of Operation Scenario 4. (A) Dc Bus Voltage Vbus; (B) Pv Voltage Vpv; (C) Pv Current Ipv; (D) Pv Reference Voltage Vref; (E) Battery Charging Current Ib.

Figure 5. Steady State Simulation Results Of Operation Scenario 5. (A) Dc Bus Voltage Vbus; (B) Pv Voltage Vpv; (C) Pv Current Ipv; (D) Battery Charging Current Ib.

Figure 6. Simulation Results With Irradiance Dropping From 1000 W/M2 To 500 W/M2 At T = 2 S. (A) Dc Bus Voltage Vbus; (B) Pv Voltage Vpv; (C) Pv Current Ipv; (D) Pv Reference Voltage Vref; (E) Battery Charging Current Ib.

 

Figure 7. Simulation Results With Load Power Rising From 8 Kw To 10 Kw At T = 2 S. (A) Dc Bus Voltage Vbus; (B) Pv Voltage Vpv; (C) Pv Current Ipv; (D) Pv Reference Voltage Vref; (E) Battery Charging Current Ib.

 

CONCLUSION:

 An integrated three-port power converter as the interface for the PV/battery hybrid distributed power generation system is proposed. Compared with the conventional system topology containing an independent DC-DC unidirectional conversion stage and a bidirectional conversion stage, the proposed sys- tem has advantages in terms of higher power density and reliability. The phase shift angle of the full bridge and the switch duty cycle are adopted as two control variables to obtain the required DC bus voltage and realize the power balance among three ports. Different operating scenarios of the system under various power conditions are discussed in detail and a comprehensive energy management and control strategy is proposed accordingly. The priority controller can enable one of the control loops in different scenarios to optimize the whole system performance, taking both the MPPT benefit and the battery charging/discharging manage- ment requirements into consideration. The simulation results verify the performance of the proposed PV/battery hybrid distributed power generation system and the feasibility of the control algorithm.

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