METHOD FOR CALCULATING CONTINUATION POWER FLOW OF ELECTRIC POWER SYSTEM

• US 20140222227A1
• Filed: 02/06/2014
• Published: 08/07/2014
• Est. Priority Date: 02/06/2013
• Status: Active Grant

• Current Assignee: Tsinghua University
• Original Assignee: Tsinghua University
• Inventors: WU, Wenchuan, ZHANG, Boming, SUN, Hongbin, GUO, Qinglai, JU, Yuntao
• Granted Patent: US 9,653,920 B2
• Time in Patent Office: Days
• US Class Current: 700/291
• 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 comprises: establishing first power flow equations for PQ buses, and establishing second power flow equations for PV buses; establishing power flow equations according to the first flow equations, the second power flow equations, and a voltage magnitude and a voltage phase of a balance bus; choosing 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 the load growth factor; defining an equality constraint equation according to the parameterization variable, and generating an extended power flow equation according to the equality constraint equation and the power flow equations; solving the extended power flow equation by a plurality of iterations to obtain a plurality of load summations; generating a P-V curve according to the plurality of load summations.

Claims

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

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

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

choosing 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 the load growth factor;

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

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

generating a P-V curve according to the plurality of load summations.

2. The method according to claim 1, wherein the first power flow equation is:

3. The method according to claim 2, 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.

4. The method according to claim 3, wherein the parametric variable is defined as

5. The method according to claim 4, 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

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

7. The method according to claim 6, wherein the extended power flow equations are solved by a Newton method and a following iteration equation is used during solving the extended power flow equation:

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

is less than or equal to 0.