Selective Power Routing in MTDC Grids for Inertial and Primary Frequency Support

Novel MTDC droop scheme with decoupled power control for enhancing frequency stabilities of weak AC systems

“…However, this property might sacrifice much available support from a strong main AC grid that can be utilised for several weak small AC systems. A major challenge is how to simultaneously and autonomously improve the frequency stabilities of several connected weak AC systems via MTDC power modulations [4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…Several feasible control schemes for improving transient frequency stabilities of DC integrated AC systems have been proposed [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], with the core mechanism to provide fast frequency support by altering the active power from converters based on the connected AC system frequency deviation. The available energy sources to do so can be generally divided into three main categories.…”

“…However, the control law is designed based on the particular radial MTDC topology, which cannot be applied to the generalised MTDC networks. A selective power routing scheme based on model predictive control in MTDC grids for inertia and primary frequency support is proposed in [11] to minimise the impact on the AC-side frequencies. An optimised power redistribution scheme that minimises the rotor speed deviations of generators and an equal power alternation redistribution scheme after onshore converter outage are similarly proposed in [12,13], respectively.…”

Frequency regulation of multiple asynchronous grids using adaptive droop in high‐voltage direct current system

“…However, the amount of inertial energy obtained from MMC overloading may not be sufficient to support adjacent AC grids during large disturbances. A few papers in the literature demonstrate the approach of frequency support through asynchronous AC grids connected by HVDC link(s) [6,[13][14][15][16]. A synchronous generator emulation control (SGEC) strategy is proposed in [13] to share the power reserve between two asynchronous AC grids connected by a point-to-point HVDC link.…”

“…To reduce the cost and enhance reliability, a selective power route for supporting PFR using the minimum communication is proposed in [15]. With the assistance of voltage and frequency droop, primary frequency support is provided to the asynchronous AC grids based on the characteristics of the disturbances.…”