|
The following plots shows the inverter’s commanded frequency and the e-board’s estimated frequency. At the beginning the commanded frequency and estimated frequency don’t agree because the inverter is not connected to the microgrid. Once the inverter connects (2 seconds), the estimated and commanded frequency agree with each other. At 3 seconds into the simulation, the inverter’s Preq is reduced to 0.2 pu. This results in a transient in the commanded frequency. Because the main grid is still connected to the grid, there is no drop in the estimated frequency. At 4 seconds into the simulation the main grid disconnects. We see a drop in the frequency that causes the e-board to shed 60W of non-critical load at 4.3 seconds. Upon shedding the load, the frequency stabilizes at about 59.8 Hz. When the inverter Preq is increased to 0.8 pu at 6 seconds, the frequency rises to 60.1 Hz and the e-board reconnects the non-critical load.
This system works as expected.
Figure 22: Response of initial Odyssian bench scale simulation
The simulation of Odyssian’s single-phase testbed was extended to include 3 microsources (200 W) with 4 e-boards (120 W). The simulation models were developed from last month’s microsource models, which modeled the inverter as a controlled voltage source. A block diagram for the simulated single-phase testbed is shown in figure 23. The total amount of microgrid generation is 600 W with a total load of 480 W. This dispatch logic is implemented using “computational agents” attached to the point of common coupling (PCC) and each microsources. This network of agents is used to adjust the microsource requires real power (Preq).
The dispatch algorithms for the Odyssian testbed are simpler than the earlier dispatch agents for mesh microgrids. In the first place, we don’t use event-triggered signaling in these dispatch agents. This will simplify the demonstration’s implementation. Secondly, there is no need for a highly distributed algorithm since all sources and loads in this testbed are directly interconnected. The dispatch logic, therefore, is much simpler. A preliminary form of the logic was developed this month and implemented on the simulation. 
Share with your friends: |
