## 3 Results and Discussion
### Operational Functionality of Micro-Installations
Possibility of long-term operation of the cogeneration unit in the summer season with no demand for heat energy. Heating installation of a research biogas plant before optimization in the summer season with a significant reduction in the demand for thermal energy from the fermentation tank required a troublesome change of settings to ensure continuous cooling of the cogeneration unit engine. After optimization, the fan cooler system, separation plate heat exchanger and three-way control ball valve built into the cogeneration unit ensure easy switching of the unit between operation in the winter and transitional season (with full heat reception to heat the fermentation tank) and the summer season (significant reduction or no demand for thermal energy by the fermentation tank) and its continuous long-term operation regardless of the season. Possibility of operation of the cogeneration unit with changing parameters of the produced biogas. The simplified high-pressure biogas supply system for the cogeneration unit engine before optimization was very sensitive to changes in the CH4 content in the biogas produced in the fermentation tank, causing disturbances in the operation of the unit, unstable operation or even the inability to work regardless of attempts to change the settings by user. Optimization of the biogas cogeneration unit using an advanced Woodward controller of the easYgen 2500/easYgen 2800 series and a throttle integrated with an electronic actuator and a mixer and regulation of the air-gas mixture composition (also made available for testing by Woodward Poland) allows for the stable operation of the cogeneration unit after a change in CH4 content in the biogas produced in the fermentation tank. An advanced Woodward controller of the easYgen 2500/easYgen 2800 series with a throttle integrated with an electronic actuator and a mixer and regulation of the air-gas mixture composition after additional use of a gas engine operation controller with a built-in Woodward PG+ module (also made available for testing by Woodward Poland) operating in a closed loop ensures autonomous regulation of the air-gas mixture composition and continuity of operation of the cogeneration unit, regardless of fluctuations in the CH\({}_{4}\) content in the biogas produced in the fermentation tank without requiring any adjustments to the settings by the user. The Woodward easYgen 2500/easYgen 2800 series controller system, together with a throttle integrated with an electronic actuator and mixer, regulation of the air-gas mixture composition and a gas engine operation controller with a built-in Woodward PG+ module also ensures safe automatic stopping of the cogeneration unit after the biogas pressure drops below the one set by the user pressure without requiring any intervention by the user. Possibility of remote monitoring of the operation of a biogas cogeneration unit. The advanced Woodward easYgen 2500/easYgen 2800 series controller and gas engine operation controller with a built-in Woodward PG+ module, after the additional use of an RS-485/LAN interface and a bridge, enable remote monitoring and visualization of the cogeneration unit's operating parameters on a selected PC computer (together with software) in the local LAN/WiFi network of an individual farm and/or via a secured Internet connection. Autonomous operation of the cogeneration unit without constant user supervision. Before optimization, the control system of the research biogas plant and its heating installation and biogas supply installation was characterized by the need for constant supervision of the operating biogas plant and the introduction of adjustments to parameter settings, causing significant difficulties for the individual farm as a user. The optimization concerned a biogas cogeneration unit using the following:  
1. Advanced Woodward controller of the easYgen 2500/easYgen 2800 series (with automatic synchronization of the cogeneration unit with the public network);
2.