Method for calculating continuation power flow of electric power system

• US 9,653,920 B2
• Filed: 02/06/2014
• Issued: 05/16/2017
• Est. Priority Date: 02/06/2013
• Status: Active Grant

• Current Assignee: Tsinghua University
• Original Assignee: Tsinghua University
• Inventors: Ju, Yuntao, Wu, Wenchuan, Zhang, Boming, Sun, Hongbin, Guo, Qinglai
• Primary Examiner(s): Onat, Umut
• Application Number:
  US14/174,114
• Publication Number:
  US 20140222227A1
• Time in Patent Office: 1,195 Days
• Field of Search: None
• CPC Class Codes: H02J 3/06 Controlling transfer of power between connected networks; Controlling sharing of load between connected networks

Abstract

A method for obtaining a continuous power flow of an electric power system is provided. The method uses the bus having the fastest voltage drop as the local parameterization bus, defines a slope of a line determined by the voltage of the geometric parameterization bus and the load growth factor as the parameterization variable, and adds a one-dimensional geometric parameterization constraint equation near turning points to obtain a nonsingular extended power flow equation, such that the continuation power flow can cross the turning points and a continuous P-V curve can be drawn reliably.

Claims

1. A computer-implemented method for calculating a continuation power flow of an electric power system, comprising:

establishing by a computer a first power flow equation for each of a plurality of PQ buses to obtain a plurality of first power flow equations, and establishing by the computer a second power flow equation for each of a plurality of PV buses to obtain a plurality of second power flow equations, wherein a PV bus is a bus having an known injected active power and a known voltage magnitude, a PQ bus is a bus having a known injected active power and a known injected reactive power;

establishing by the computer a group of power flow equations according to the plurality of first power flow equations, the plurality of second power flow equations, a voltage magnitude of a balance bus and a voltage phase of the balance bus;

choosing by the computer a bus having a fastest voltage drop as a parameterization bus, and defining a parameterization variable according to a voltage magnitude of the parameterization bus and a load growth factor;

defining by the computer an equality constraint equation according to the parameterization variable, and generating by the computer a collection of extended power flow equations according to the equality constraint equation and the group of power flow equations;

solving by the computer the collection of extended power flow equations by a plurality of iterations to obtain a plurality of load summations; and

generating by the computer a Power-Voltage (P-V) curve according to the plurality of load summations,

wherein the first power flow equation is;

2. The method according to claim 1, wherein the group of flow power equations is simplified to be:

f(x,λ

)=0,

where, x is the voltage magnitude and the voltage phase of buses in the electric power system.

3. The method according to claim 2, wherein the parameterization variable is defined as

4. The method according to claim 3, wherein the parameterization variable t_β

^k meets a following relation;

t_β

^k=t_β

<sup>k−

1</sup>+Δ

t_β

,

where, t_β

<sup>k−

1</sup> is the parameterization variable in the (k−

1)^th iteration, t_β

^k is the parameterization variable in the k^th iteration, and

5. The method according to claim 4, wherein the collection of extended power flow equations are defined as:

6. The method according to claim 5, wherein the collection of extended power flow equations are solved by a Newton method and an iteration equation is used during solving the collection of extended power flow equations.

7. The method according to claim 6, wherein the iteration is stopped when the load growth factor λ

is less than or equal to 0.