Dynamic frequency coordination control method for asynchronous regional power grids during wet and dry seasons

A dynamic frequency coordination control method for asynchronous regional power grids during wet and dry seasons, comprising the following steps:

• S1, collecting a frequency of a sending-end grid and a frequency of a receiving-end grid;
• S2, when a non-zero frequency difference is detected between the frequency of the sending-end grid and the frequency of the receiving-end grid, activating a frequency synchronous control in a voltage source converter based high voltage direct current (VSC-HVDC) for control;
• S3, when an output power controlled by a system based on the frequency synchronous control in a VSC-HVDC activation strategy is detected to exceed a preset power limit, determining a first frequency difference between a current sending-end grid frequency and a steady-state frequency, and a second frequency difference between a current receiving-end grid frequency and the steady-state frequency respectively to see whether the first frequency difference and the second frequency difference both exceed a dead-band of a line-commutated converter-based high-voltage direct current (LCC-HVDC) frequency limiting control (FLC);
• S4, when the first frequency difference and the second frequency difference both exceed the dead-band of the LCC-HVDC FLC calling an LCC-HVDC FLC activation strategy and a VSC-HVDC adaptive reactive power support control activation strategy for control;
• S5, when the first frequency difference is detected to exceed a preset primary frequency regulation dead-band of a renewable energy, determining a real-time short-circuit ratio at a sending-end renewable energy grid connection point to see whether the real-time short-circuit ratio is greater than a preset threshold;
• S6, when the real-time short-circuit ratio is greater than the preset threshold, activating a grid-following additional frequency control strategy for a grid-connected renewable energy generation;
• when the real-time short-circuit ratio is less than or equal to the preset threshold, activating a grid-forming control strategy for the grid-connected renewable energy generation.