# Grid-Friendly Active Demand Strategy on Air Conditioning Class Load
## 5 Active Management Energy Coordination Control Algorithm and System Simulation  
Figure 8 is a group load operation active demand management and coordination control flow chart. The management scheme developed is focused on active energy management on the demand side. Based on historical data and real-time monitoring parameters, various converters among energy storage, grid, and load are reasonably controlled to realize load-friendly power supply. In the algorithm, considering the grid malfunction and the \(SOC\) of the energy storage and the peak load of the grid, the energy storage dispatch is used rationally to effectively avoid the peak power consumption. Figure 7: Reactive compensation during LVRT. The technical points are as follows:  
1. Historical data of grid load operation are employed to predict grid load change. Based on weather forecast temperature and humidity, the local air conditioning load operation data are predicted. 2. According to the monitored \(SOC\) data, the chargeable and dischargeable power of the energy storage system are predicted. 3. Combining grid load forecasting and local load forecasting data, day-ahead power scheduling is used to achieve storage energy management. 4. With real-time monitoring of the operating status of the air conditioner and the grid load, considering events of the grid load peak period and grid malfunction or LVRT, the flexible entry of energy storage system supply on the air conditioning operation is set up. 5. Once the grid is operating normally and experiencing a non-peak load period, the local air conditioning loads are supplied by the power grid. At the same time, if detected \(SOC\) is lower than 0.8, charging behavior is triggered to ensure that the function of the energy storage system can play normally. Figure 8: Active demand management of group load operation coordination control flow chart. When the _SOC_ is lower than 0.2, considering elapsed a long time of the temperature and humidity change, air conditioning loads can be stopped temporarily to pass the load peak period. Then, it is restarted to realize the staggering power supply. 7. The storage energy supplement is carried out timely during off-peak periods to ensure providing reactive power compensation ability to the grid in the event of LVRT or grid malfunction. 8. During the power grid supplying local air conditioning load, judged by monitoring the current distortion rate in the feeder line of the load circuit, the adaptive APF is put into use to eliminate higher proportion harmonics. The simulation system corresponding to the coordinated control algorithm is shown in Figure 9. Table 3 shows the main simulation parameters. In the system, dynamic monitoring of grid parameters is done, and current and voltage are detected and analyzed. The simulation system used for active demand-side management research is composed of a power grid, PF, APF, AC/DC/AC converter, DC/AC converter, and load. The filters are connected in parallel with the front end of the frequency converter, to actively prevent the grid from being damaged and influence the harmonics caused by the load operation. The energy storage system is connected to the DC bus line of the AC/DC/AC converter through the DC/DC converter. According to the grid monitor status, AC/DC/AC converter working mode is controlled. Once LVRT or grid malfunction happens, the energy of the storage system can flow to the grid and the load side at the same time through the coordination control. Among them, the DC/AC supplies load, the bi-directional AC/DC works as an inverter, providing reactive power compensation to the grid.