US 11,901,739 B2
Backup voltage and frequency support method for 100%-renewable energy sending-end grid
Zheren Zhang, Hangzhou (CN); Wentao Liu, Hangzhou (CN); Ying Huang, Hangzhou (CN); Yiyan Dong, Hangzhou (CN); and Zheng Xu, Hangzhou (CN)
Assigned to Zhejiang University, Hangzhou (CN)
Filed by Zhejiang University, Hangzhou (CN)
Filed on Jun. 1, 2023, as Appl. No. 18/327,791.
Application 18/327,791 is a continuation of application No. PCT/CN2023/088704, filed on Apr. 17, 2023.
Prior Publication US 2023/0307921 A1, Sep. 28, 2023
Int. Cl. H02J 3/38 (2006.01); G05B 19/042 (2006.01)
CPC H02J 3/381 (2013.01) [G05B 19/042 (2013.01); G05B 2219/2639 (2013.01); H02J 2300/24 (2020.01); H02J 2300/28 (2020.01)] 6 Claims
OG exemplary drawing
 
1. A backup voltage and frequency support method for a 100%-renewable energy sending-end grid, comprising: (Si) selecting a plurality of support nodes in the 100%-renewable energy sending-end grid; (S2) mounting a backup voltage and frequency support device at each of the plurality of support nodes; and (S3) dynamically adjusting an active power output of a renewable energy station of the 100%-renewable energy sending-end grid according to a frequency of a grid-connection point; wherein in step (Si), all nodes in the 100%-renewable energy sending-end grid are grouped according to voltage level; wherein voltage level includes 35 KV, 110 KV, 220 KV and 500 KV; wherein in step (S2),the backup voltage and frequency support device is an energy-storage modular multilevel converter (MMC); the energy-storage MMC comprises an energy storage device; the energy storage device is centralizedly arranged at a direct-current (DC) side of the energy-storage MMC or decentralizedly arranged in a sub-module of the energy-storage MMC through an interface circuit; and the energy storage device is formed by a plurality of energy storage elements connected in series or parallel, wherein the plurality of energy storage elements are batteries or supercapacitors; and the backup voltage and frequency support device adopts a power-synchronization control strategy; an active power control part of the power-synchronization control strategy is configured to calculate a difference between an active power instruction value and an active power actual value, and output a frequency compensation through a first-order lag element, wherein the active power instruction value is set to zero, and the difference is taken as an input of the first-order lag element; and a reactive power control part of the power-synchronization control strategy is configured to calculate a difference between an AC voltage setting value and an AC voltage actual value, and output a current instruction value through a proportional integral (PI) control, wherein the AC voltage setting value is set to 1.0 per unit (p.u.).