Modeling and Control of Multi-Terminal Direct Current with Voltage Margin Control Strategy

Implementation of DC voltage controllers on enhancing the stability of multi-terminal DC grids

“…The voltage margin technique was first proposed for the VSC-HVDC network in [27]. This technique is a modification of the master-slave technique in which DC voltage and power control modes are combined, at each time, only one slack bus [12,18]. As shown in Figure 5(a), the P-V characteristics of a PTP-HVDC system, the first converter in orange, and the second converter in blue.…”

“…For the master-slave technique, as a natural extension of the control of PTP VSC-HVDC, only one converter as known (slack bus or master) within the MTDC network could regulate the DC voltage while the rest converters would control the active power transfer and once the master converter fails due to a fault, the MTDC network will be unstable in consequence of having no converter to control DC voltage [10,11]. For the voltage margin technique, the VSCs converters can be changed control mode between DC voltage and active power, only one slack bus at each time [12]. For the voltage droop technique, more than one converter participates in DC voltage regulation of the MTDC network simultaneously [13][14][15].…”

“…These two techniques are implemented in the proposed model, a ±400 kV meshed multi-terminal MTDC network based on VSC technology with four terminals [16,17]. The voltage margin technique is automatically implemented to improve communication between the converters [12,18]. The droop technique or decentralized technique developed in this article is a technique that allows the power sharing between different converters without communications [19].…”