Hierarchical Control of HV-MTDC Systems With Droop-Based Primary and OPF-Based Secondary

Abstract

This paper proposes a hierarchical control architecture designed for an arbitrary high voltage multiterminal dc (MTDC) network. In the proposed architecture, the primary control of the MTDC system is decentralized and implemented using a generalized droop strategy. Design criteria for dimensioning the primary control parameters, including voltage limits, are offered by analyzing the transients appearing in the system. The proposed secondary control is centralized and regulates the operating point (OP) of the network so that optimal power flow (OPF) is achieved. Compared to previous works, this paper further elaborates, both analytically and through simulations, on the coordination between the primary and secondary control layers. This includes how local primary controllers have to be driven by the centralized controller in order to ensure a smooth transition to the optimal OP. IndexTerms-Droop control, hierarchical control, multiterminal dc (MTDC) systems, optimal power flow (OPF).

Interaction of droop control structures and its inherent effect on the power transfer limits in multi-terminal VSC-HVDC

“…This is due to the fact that the oscillatory effects are condensed in a single frequency, instead of being spread on several frequencies as in a real cable. This modeling approach can also be justified by the results of [23], indicating that for an appropriate sizing of the capacitor the impedance Fig. 2.…”

Adjustable Inertial Response From the Converter With Adaptive Droop Control in DC Grids

“…Moreover, step changes and random fluctuations from the intermittent generations can lead to drastic fluctuations of the DC bus voltage and power transmitted to AC grid. The voltage droop control is utilized on the converters in the DC grid to ensure its voltage stability by redistributing power automatically during disturbances [6]- [7]. However, the output power of the converter has to approach a new operating point by following the droop curve during disturbances.…”

Active and reactive power control of hybrid offshore AC and DC grids

“…For a stiff voltage control, the net power in the offshore DC grid can be shared among onshore converters by adjusting the slope of the droop values. Also, the network can be operated even if one or more onshore converters malfunction [14]. The realization of a "SuperGrid" at the North and Baltic Sea may require the benefits of both offshore AC collector system and MTDC network.…”