Comparative analysis of power scheduling strategies for multi-terminal BTB-DC electric springs in DC microgrids

• The Multi-Terminal BTB-DC Electric Spring (MT-BTB-DCES) and its APSS and AVSS strategies are proposed to achieve voltage stability for critical loads in DC microgrids. • The MT-BTB-DCES has a simple structure and is cost-effective, as the MT-BTB-DCES eliminates costly Energy storage devices. • Compared to AVSS, the APSS control strategy results in better capacity economy for Electric Springs. • Compared to AVSS, the APSS control strategy leads to better voltage stability for Noncritical load. • Simulation and Experiment both validate the effectiveness of these strategies and demonstrate their respective advantages. Voltage fluctuations in DC microgrids can lead to critical loads (CLs) failing to operate properly. DC electric spring (DCES) is an innovative device capable of effectively maintaining the voltage of CLs. However, existing multi-DCES systems require costly energy storage devices (ESDs). Moreover, most studies on multi-DCES systems ignore the capacity of electric springs (ESs) and the voltage tolerance of non-critical loads (NCLs), factors that are important for cost reduction and system reliability. In response, this paper proposes a multi-terminal back-to-back DC electric spring (MT-BTB-DCES). The proposed MT-BTB-DCES is more economical because it eliminates costly ESDs. This paper also proposes two control strategies: the Average Power Scheduling Strategy (APSS) and the Average Voltage Scheduling Strategy (AVSS). Numerical, simulation, and experimental results reveal that under APSS, NCL-side ESs (NCL-ESs) exhibit better power consistency. APSS reduces the power capacity requirement of NCL-ESs by 37.95% compared to AVSS when using NCL-ESs of similar capacity, thereby further reducing investment. Under AVSS, NCL-ESs exhibit better voltage consistency. Compared to APSS, AVSS reduces the maximum voltage fluctuation of NCLs by 33.89%, making it more suitable for application when the voltage tolerance of NCLs is low or uncertain.