**7. Concluding Remarks**

This study designed a CCHP system including photovoltaic power generation equipment and energy storage equipment. According to the characteristics of the two typical configuration schemes of energy storage equipment, the operation scheme based on ESS service was proposed, and a mathematical model considering economy and environmental protection was established. Additionally, the IAO algorithm was proposed by introducing improved strategies. The optimal configurations of the system under different operating schemes were obtained by the IAO algorithm and other compared algorithms. The conclusions are as follows.

(1) The IAO algorithm has better seeking ability than the original algorithm and other compared algorithms. The IAO algorithm has a faster convergence speed and higher convergence accuracy. When other conditions are consistent, using the IAO algorithm to optimize the system can ge<sup>t</sup> better results.

(2) The operating scheme proposed in this study is more feasible. For the system in the same place when operating with three different schemes, scheme 1 shows a greater advantage in terms of economy and environmental protection. Compared with scheme 2 and scheme 3, the daily economic cost of the three places decreased by 20.54%, 17.95%, 25.46% and 37.88%, 33.88%, 43.38%, respectively, and the pollutant gas emissions decreased by 16.8%, 28.57%, 32.93% and 32.45%, 43.37%, 49.39% respectively.

(3) Whether to configure energy storage equipment and how to configure energy storage equipment directly affect the configured capacity of PV in CCHP microgrid, thus affecting the pressure of power grid supporting system. Although the three operation schemes can meet the load demand of the system, their economy is different. Scheme 1 can configure a larger scale of PV to reduce the power supply pressure of power grid by matching the PV with the ESS. Taking Place 1 as an example, the electricity provided by the grid is decreased by 43.29% and 61.09%, respectively, when operating with scheme 1 compared to scheme 2 and scheme 3, which improves the system's economic performance.

We put forward a new scheme for the energy storage configuration of CCHP system, and propose the IAO algorithm to optimize the system. The proposed method reduces the power supply pressure of the grid, improves the profits of operators, and is conducive to promoting the development of clean energy, alleviating the energy crisis. However, this study has some limitations. There is only one renewable energy in the system, namely photovoltaic energy, and more kinds of renewable energy can be taken into account in future research.

**Author Contributions:** Conceptualization, N.N. and Y.-W.L.; methodology, Y.-W.L. and L.-L.L.; software N.N. and H.-Y.Y.; writing—original draft preparation, N.N. and Y.-W.L.; writing—review and editing, N.N. and Y.-W.L. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the key project of the Tianjin Natural Science Foundation (Project No. 19JCZDJC32100) and the Natural Science Foundation of Hebei Province of China (Project No. E2018202282).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not Applicable.

**Acknowledgments:** The authors thank Bimenyimana Samuel for valuable help in the final version of this manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
