Stability Considerations for Virtual Capacitor Control in Constant Power DC Loads

Journal Article · 16 December 2024 · IEEE Transactions on Power Electronics

DOI: https://doi.org/10.1109/tpel.2024.3518478 · OSTI ID:2563389

Anees, Muhammad ^[1]; Tu, Hao  ^[2]; Lukic, Srdjan  ^[1]

---

1. North Carolina State University, Raleigh, NC (United States)
2. Sichuan University, Chengdu (China)

In a DC grid, constant power loads (CPLs) necessitate a large bus capacitor to prevent negative impedance instability. Some of the capacitance can be realized virtually through CPL control to reduce the bus capacitor size. Here, this paper analytically studies system stability with virtual capacitor control. We demonstrate that the effectiveness of virtual capacitor control is highly sensitive to the implementation of the derivative action required to emulate the capacitor. For the first time, we theoretically demonstrate that a virtual capacitor can stabilize the system without any physical bus capacitor, provided that a set of analytically derived conditions are met. However, this stabilization is not achievable in practice due to the influence of non-idealities. In an example system requiring a $14$ mF capacitor to stably support the CPL, we show that stability can be achieved through virtual capacitor control, using only a 2 mF physical capacitor to account for the switching ripple non-idealities. Hardware-in-the-loop tests verify the analysis.

• Research Organization: North Carolina State University, Raleigh, NC (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AR0001580
• OSTI ID: 2563389
• Journal Information: IEEE Transactions on Power Electronics, Journal Name: IEEE Transactions on Power Electronics Journal Issue: 4 Vol. 40; ISSN 0885-8993
• Publisher: IEEECopyright Statement
• Country of Publication: United States
• Language: English