CURENT hardware Testbed (HTB) uses an analog-digital real-time emulation approach based on PECs, with each PEC representing one individual or composite element, a generator, a line segment, a battery, etc. The PEC analog hardware models the fast electronic dynamics and provides analog interfaces to other elements, while the PEC digital controller models the slower dynamics of the element. There are real power flows between PECs that emulate power system elements.Compared with digital simulators, including real-time digital simulators, the hybrid emulator has many advantages:

1) It handles multi-physics models better, covering shorter time-scale switching events to longer-term power system events.
2) It can incorporate more realistic power hardware, especially in the case of power electronics-based hardware, such as PEC interfaced RES.
3) It is easy to integrate real communication, measurement, control, and protection equipment,
4) Functions such as black start are straightforward in the hybrid emulator but very difficult in real-time digital simulators like RTDS.