Optimization-Based Suppression Method of Oscillations in Photovoltaic Grid-Connected Systems with Controllable Nonlinear Loads
Abstract
:1. Introduction
2. Impedance Modeling of the PV Grid-Connected System with Controllable Nonlinear Loads
3. Stability Analysis and Key Influencing Factor Analysis of the System
4. A Parameter-Optimization Method Balancing System Stability and Response Performance
4.1. Stability Domain Analysis of Parameters
4.2. Key Parameter Optimization Based on Particle Swarm Optimization Algorithm
5. Simulation Verification
5.1. Verification of Stability Analysis
5.2. Verification of Stability Domain Analysis of Parameter
5.3. Verification of the Optimization Method
6. Conclusions
- (1)
- Based on the established impedance model of the PV grid-connected system with controllable nonlinear loads, the influence of different parameters on the system impedance characteristics is analyzed using impedance relative sensitivity. This analysis reveals that the key parameters influencing system stability are the proportional coefficient kp4 of the DC current loop within the controllable nonlinear loads and the proportional coefficient kp2 of the current inner loop in the photovoltaic grid-connected inverter. By tuning these two parameters, the system impedance can be reshaped, thereby enhancing the overall stability of the system.
- (2)
- Considering the interactions between the two key parameters, the stability domain of the key parameters is analyzed. A parameter optimization method balancing system stability and response performance is then proposed, which aims to improve stability of the system while minimizing the impact on response performance. The validity of the proposed parameter-optimization algorithm is verified through comparative experiments conducted before and after the system adopts the optimized parameters. Additionally, simulation-based comparative experiments are carried out under varying conditions, specifically changes in the equivalent inductance of the power grid and alterations in load conditions. The experimental results conclusively demonstrate the robustness of the optimized parameters in suppressing system oscillations.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Parameters | Values | Parameters | Values |
---|---|---|---|
Udc/V | 700 | L2/mH | 0.2 |
Effective value of grid’s line voltage/V | 380 | Cf/uF | 6.8 |
Output active power P of PV/kW | 10 | Rd/Ω | 1.8 |
Output reactive power Q of PV/kVar | 0 | Proportional coefficient kp1 of PLL | 1.72 |
f1/Hz | 50 | Integral coefficient ki1 of PLL | 150 |
Switching frequency fsw/kHz | 35 | Proportional coefficient kp2 of current loop | 10 |
L1/mH | 1.5 | Integral coefficient ki2 of current loop | 700 |
Parameters | Values | Parameters | Values |
---|---|---|---|
R4/Ω | 1 | time constant Tim of the Gim(s) | 1.2 × 10−3 |
L4/mH | 50 | Proportional coefficient kp3 of PLL | 7.64 × 10−3 |
C4/uF | 1000 | Integral coefficient ki3 of PLL | 1.44 |
Vdc0/V | 500 | Proportional coefficient kp4 of DC current loop | 1.1 |
gain kim of the Gim(s) | 0.01 | Integral coefficient ki4 of DC current loop | 30 |
Region | Name | Value |
---|---|---|
unstable domain | A | (0.98, 6.6) |
stable domain | B | (0.79, 4.7) |
Parameter | Value | Parameter | Value |
---|---|---|---|
Spatial dimension | 2 | Population size | 100 |
Inertial weight | 0.8 | Individual learning factor | 0.9 |
Social learning factor | 0.9 | Maximum number of iterations | 50 |
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Zhu, T.; Huang, G.; Ye, X.; Wang, Y.; Ouyang, X.; Zhang, W.; Cheng, Y.; Wang, Y. Optimization-Based Suppression Method of Oscillations in Photovoltaic Grid-Connected Systems with Controllable Nonlinear Loads. Energies 2024, 17, 4120. https://doi.org/10.3390/en17164120
Zhu T, Huang G, Ye X, Wang Y, Ouyang X, Zhang W, Cheng Y, Wang Y. Optimization-Based Suppression Method of Oscillations in Photovoltaic Grid-Connected Systems with Controllable Nonlinear Loads. Energies. 2024; 17(16):4120. https://doi.org/10.3390/en17164120
Chicago/Turabian StyleZhu, Tong, Gechao Huang, Xi Ye, Yanfeng Wang, Xuetong Ouyang, Weilin Zhang, Yangfan Cheng, and Yuhong Wang. 2024. "Optimization-Based Suppression Method of Oscillations in Photovoltaic Grid-Connected Systems with Controllable Nonlinear Loads" Energies 17, no. 16: 4120. https://doi.org/10.3390/en17164120