Patent ID: 11923680
Assignee: TSINGHUA UNIVERSITY
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G  Y | IPC G  H

Claim 9:
10. The apparatus of claim 9, wherein S4 comprises:
S41, setting an error limit ε of the power feasible region;
S42, calculating a set of initial vertices and an initial approximate polygon of the power feasible region Φ based on the operation basic data;
in which the set of initial vertices of the power feasible region Φ comprises 4 feasible region vertices and is calculated by solving an optimization problem of:

max αP(m)·P0+αQ(m)·Q0 

s.t.(v,θ,Pg,Qg,P0,Q0)∈Ω  (10)

where, (αP(m), αQ(m)) represents coefficients of an objective function of the optimization problem, values of (αP(m), αQ(m)) are taken as (1,1), (1, −1), (−1, 1), and (−1, −1) in sequence, and the equation (10) is solved through a nonlinear optimization algorithm or calling a nonlinear optimization solver to obtain a corresponding optimal solution of the optimization problem as vm=(P0(m), Q0(m))T, vm is the mth initial vertex; a set V0={v1, v2, v3, v4} is formed by initial vertices, and a set of feasible region vertices is initialized as V=V0; a set of equations for each boundary of a polygon formed by the initial vertices is recorded as FT; an average value of the vertices in V0 is calculated as v0=(P0(0), Q0(0))T=(v1+v2+v3+v4)/4;
S43, initializing a set FN of newly added boundaries to be an empty set: FN←Ø;
S44, searching for boundary vertices of the power feasible region Φ by shifting boundaries in FT outward, in which for the kth boundary in Φ, a boundary equation is denoted by f(k):αP(k)·P0+αQ(k)·Q0=β(k), and vertices at both ends of the boundary are v1(k) and v2(k), and a search model is denoted by:

max αP(k)·P0+αQ(k)·Q0 

s.t.(v,θ,Pg,Qg,P0,Q0)∈Ω  (11)

the search model is solved by the nonlinear optimization algorithm or calling the nonlinear optimization solver to obtain a solution of vertexes as vk=(P0(k), Q0(k))T, and an optimal value of the vertexes is recorded as gkmax;
S45, adding the solution of vertexes to the set v of feasible region vertices;
S46, judging whether it is necessary to increase a boundary to be translated according to the error limit ε and an improvement amount of search in S44;
S461, the improvement amount in step S44 is denoted by:, Δ
      ⁢
      
       g
       k
      
     
     =
     
      
       
        g
        k
        max
       
       -
       
        β
        
         (
         k
         )
        
       
      
      
       
        β
        
         (
         k
         )
        
       
       -
       
        (
        
         
          
           α
           P
           
            (
            k
            )
           
          
          ·
          
           P
           0
           
            (
            0
            )
           
          
         
         +
         
          
           α
           Q
           
            (
            k
            )
           
          
          ·
          
           Q
           0
           
            (
            0
            )
           
          
         
        
        )
       
      
     
    
   
   
    
     (
     12
     )
    
   
  
 

S462, when Δgk>ε, calculating line equations f1(k) and f2(k) of vk with v1(k) and v2(k), adding f1(k) and f2(k) into FN, and returning to step S44, and using the (k+1)th boundary to perform a vertex search;
S463, when Δgk≤ε, returning to step S44, using the (k+1)th boundary to perform a vertex search;
S47, after performing the vertex search on all boundaries in FT, judging whether FT is an empty set;
S471, when FT is not the empty set, updating FT to FN;
S472, when FT is the empty set, ending and determining the polygon according to the vertices in v, and determining the power feasible region according to the determined polygon.