US 11,870,254 B2
Multi-terminal differential protection setting method for distributed generator T-connected distribution network
Botong Li, Tianjin (CN); Fahui Chen, Tianjin (CN); Bin Li, Tianjin (CN); and Jing Zhang, Tianjin (CN)
Assigned to Tianjin University, Tianjin (CN)
Filed by Tianjin University, Tianjin (CN)
Filed on Apr. 14, 2023, as Appl. No. 18/301,023.
Claims priority of application No. 202310182206.X (CN), filed on Mar. 1, 2023.
Prior Publication US 2023/0253786 A1, Aug. 10, 2023
Int. Cl. H02J 3/00 (2006.01); H02J 3/38 (2006.01)
CPC H02J 3/001 (2020.01) [H02J 3/381 (2013.01); H02J 2203/20 (2020.01); H02J 2300/24 (2020.01)] 6 Claims
OG exemplary drawing
 
1. A multi-terminal differential protection setting method for a distributed generator T-connected distribution network, comprising the following steps:
S1: connecting a distributed generator into a distribution network by means of T-connection, and making the distributed generator equivalent to a positive sequence current source controlled by grid interconnection voltage, wherein an equivalent model for making the distributed generator equivalent to the positive sequence current source controlled by grid interconnection voltage is:

OG Complex Work Unit Math
wherein Upcc(1) is an effective value of grid interconnection positive sequence phase voltage, Upcc(1).N is an effective value of grid interconnection positive sequence phase voltage in the rated running state, IDGm.N is an amplitude of rated current, Pref.N is a rated active reference value, Pref is an active reference value before failure, İDG is output current, ιd(1) and iq(1) are a d-axis component and a q-axis component of the positive sequence component of the output current, and φ is the phase of Upcc(1);
S2: acquiring multi-terminal current according to the positive sequence current source controlled by grid interconnection voltage;
S3: calculating the overall maximum error of superimposed multi-terminal current errors according to the multi-terminal current;
S4: establishing non-convex constraint space according to the overall maximum error of superimposed multi-terminal current errors;
S5: reducing and discretizing the non-convex constraint space;
S6: obtaining the optimization problem of the non-convex constraint space based on the reducing and discretizing results of the non-convex constraint space;
S7: solving the optimization problem of the non-convex constraint space;
S8: analyzing and verifying the solution result of the optimization problem of the non-convex constraint space;
S9: controlling the distributed generator T-connected distribution network based on the solution result of the optimization problem of the non-convex constraint space.