CN107732904B - Active static security domain construction method considering single TCSC equivalent reactance parameter - Google Patents

Abstract

The invention creatively combines the equivalent reactance parameter of the controllable series compensator with the active power of the node to form a method for constructing an active static security domain considering the equivalent reactance parameter of a single TCSC. Aiming at the problem that the TCSC equivalent parameters are not considered in the existing active static security domain construction method, the TCSC is analyzed by converting the effect of the load flow distribution on the TCSC through changing the structure parameters of the power grid into the effect of correcting the node injection power. On the basis, a display expression of the injected power space active static security domain considering the single TCSC equivalent reactance parameter is theoretically deduced; the problem that a series of active static security domains are generated one by traversing TCSC equivalent impedance values in the traditional method can be solved. The method is combined with engineering practice, has higher analysis efficiency, and is suitable for the requirement of online static safety assessment.

Description

Active static security domain construction method considering single TCSC equivalent reactance parameter

Technical Field

The invention relates to a method for constructing an active static security domain considering a single TCSC equivalent reactance parameter.

Background

With the continuous access of the new energy power generation device, the smart grid has the characteristics of random power output, uncertain load level and the like, and the tide distribution is complex and variable. As an important component of the safety domain methodology, the static safety domain is effectively applicable to real-time online safety monitoring and prevention control of the power system under the above-mentioned background.

A static security domain is traditionally a collection of injected power that ensures safe and stable operation of a power system under a given network architecture. For an active static security domain concerned by a power transmission network, the active output constraint of branch power flow constraint and generator nodes is mainly considered in the current research. There is a document based on a direct current power flow model, and a linear relation between node active power injection and branch (phase angle difference) active power flow is utilized to derive an active static security domain, which can approximately represent that hyperplanes on a parameter space with node injected active power enclose a convex hyperplane. However, the existing method takes the influence of the change of the power grid structure parameters into account less.

As a mature FACTS device, a controllable Series compensator (TCSC) is one of effective means for power flow adjustment, and can change its equivalent reactance by control to perform Series Compensation on a power transmission line. Along with the change of the TCSC equivalent reactance parameter, the system node admittance matrix is changed, so that the load flow distribution characteristic of the system is inevitably changed, and the active static security domain of the system is changed.

In order to construct an active static security domain considering TCSC equivalent reactance parameters, the invention analyzes the TCSC by changing the influence of network structure parameters on power flow distribution and converting the influence into the input power through correcting nodes, and creatively deduces a display expression of the active static security domain comprehensively expressed by single TCSC equivalent reactance parameters and node input power.

Disclosure of Invention

A method for constructing an active static security domain considering a single TCSC equivalent reactance parameter is characterized in that:

the TCSC influences the power flow distribution by changing the network structure parameters and is converted into the power injection through the correction node to be analyzed, and the display expression of the active static security domain comprehensively expressed by the single TCSC equivalent reactance parameter and the node power injection is creatively deduced; the problem that the traditional method needs to traverse TCSC equivalent impedance values and generate a series of active static security domains one by one and has low efficiency can be solved.

The method is combined with engineering practice, and can meet the requirement of online static safety assessment under the background of the smart power grid.

The technical scheme of the invention is as follows:

a method for constructing an active static security domain considering a single TCSC equivalent reactance parameter is characterized by comprising the following steps of;

step 1, based on a substitution theorem and a direct current power flow model, a TCSC (controllable series compensator) branch can be equivalently disconnected, and active power flowing through the TCSC is equivalent to net increment of injection power of two end points of the TCSC;

defining two end points of TCSC as l and h respectively, and TCSC equivalent impedance as X_TCSCThen, the active power flowing out from node l and injected into node h through the TCSC branch is:

in the formula, V_l、V_hRespectively taking a per unit value of 1 under the voltage amplitude and the direct current power flow model of the nodes l and h; theta_lhIs the phase angle difference between the nodes l and h;

by the alternative theorem, the TCSC branch l-h is disconnected and is equivalent to:

net incremental active injection on node i:

net increment of active injection on node h:

based on the equivalent processing, the original TCSC branch l-h is disconnected, and the injected active power of the two end points is modified as follows:

in the formula, P_l0、P_h0Initial active injection power of the nodes l and h respectively;

and 2, for the system after the TCSC branch is disconnected, recovering the system grid frame parameters to be constant, and setting the inverse matrix X of the node admittance matrix Y, the imaginary part B and the B as B^-1Are all convenient to obtain; according to the direct current power flow equation, the active static security domain of the branch i-j is obtained as follows:

in the above formula, k_dm＝-B_ij(X_im-X_jm)，k_dh＝-B_ij(X_ih-X_jh)，k_dl＝-B_ij(X_il-X_jl)；P_ijmaxAnd P_ijminThe upper limit value and the lower limit value of the active power of the branch i-j are set; b is_ijIs the susceptance value of branch i-j; x_imIs the ith row of the matrix XElement of m-th column, X_jm、X_ihAnd so on;

step 3, eliminating the intermediate variable theta_lh，Will theta_lhExpressed as the original injected power (P) from each node₁₀、P₂₀、…、P_n0) And X_TCSCThe formula is formed; in particular, the amount of the solvent to be used,

in the formula, a_m＝(X_lm-X_hm)，a_r1＝(X_ll-X_hl)，a_r2＝(X_lh-X_hh) (ii) a Then left and right shifting can be followed:

and 4, obtaining an active static security domain expression comprehensively composed of a single TCSC equivalent reactance and the injected power of each node according to the formula (5) and the formula (3), wherein the active static security domain expression is as follows:

therefore, the invention creatively deduces the display expression of the active static security domain comprehensively expressed by the equivalent reactance parameter of the single TCSC and the node injection power, and is suitable for the requirement of online static security assessment in the background of the smart grid.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and data analysis.

Example (b):

the method provided by the patent is verified under a plurality of calculation models, and is limited by space, and the embodiment is directed to analyzing and verifying the feasibility and effectiveness of the method provided by the patent by taking the improved IEEE39 calculation as an example. The specific situation is as follows:

suppose that a TCSC is connected in series in the branch 2-25 in the IEEE39 calculation example, and the branch 14-4 is used as an object to construct the branch containing X_TCSCThe APSSR of (1).

On the one hand, based on the proposed method, corresponding to equations (3) - (4), the available k is calculated_dm、a_mResults of (5) are shown in Table 1, k_dh、k_dl、a_r1、a_r2The results of (1) are as follows:

TABLE 1 Branch 2-25 equivalent after-disconnect System k_dm、a_mValue of

Then (5) can be modified to:

if X is taken_TCSCEach P is obtained as-0.0015_m0The corresponding hyperplane coefficients are shown in columns 2 and 5 of table 2 below.

TABLE 2X_TCSC-0.0015 hyperplane coefficient comparison

On the other hand, the reactance parameters of the 2-25 branches are set to be 0.0086-0.0015(0.0086 is the original reactance value of the 2-25 branches), then the existing static security domain construction method is adopted for analysis, the branches 14-4 are also taken as objects, and all the obtained P are obtained_m0The corresponding hyperplane coefficients are shown in columns 3 and 6 of table 2 below.

Analysis of table 2 reveals that: the data in column 2 and 3 are completely matched with the data in column 5 and 6, that is, X is taken_TCSCWhen the value is-0.0015, the security domain expression constructed by the method is correct.

For other X_TCSCValues and other different branches contain single TCSC scenes, and test results all accord with the conclusion.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (1)

1. A method for constructing an active static security domain considering a single TCSC equivalent reactance parameter is characterized by comprising the following steps of;

step 1, based on a substitution theorem and a direct current power flow model, a TCSC (controllable Series compensator) branch can be equivalently disconnected, and active power flowing through the TCSC is equivalent to net increment of injection power of two end points of the TCSC;

defining two end points of TCSC as l and h respectively, and TCSC equivalent impedance as X_TCSCThen, the active power flowing out from node l and injected into node h through the TCSC branch is:

in the formula, V_l、V_hRespectively taking a per unit value of 1 under the voltage amplitude and the direct current power flow model of the nodes l and h; theta_lhIs the phase angle difference between the nodes l and h;

by the alternative theorem, the TCSC branch l-h is disconnected and is equivalent to:

net incremental active injection on node i:

net increment of active injection on node h:

based on the equivalent processing, the original TCSC branch l-h is disconnected, and the injected active power of the two end points is modified as follows:

in the formula, P_l0、P_h0Initial active injection power of the nodes l and h respectively;

and 2, for the system after the TCSC branch is disconnected, recovering the system grid frame parameters to be constant, and setting the inverse matrix X of the node admittance matrix Y, the imaginary part B and the B as B^-1Are all convenient to obtain; according to the direct current power flow equation, the active static security domain of the branch i-j is obtained as follows:

in the above formula, k_dm＝-B_ij(X_im-X_jm)，k_dh＝-B_ij(X_ih-X_jh)，k_dl＝-B_ij(X_il-X_jl)；P_ijmaxAnd P_ijminThe upper limit value and the lower limit value of the active power of the branch i-j are set; b is_ijIs the susceptance value of branch i-j; x_imIs the ith row and the mth column element of the matrix X, X_jm、X_ihAnd so on;

step 3, eliminating the intermediate variable theta_lhB, mixing theta_lhExpressed as the original injected power (P) from each node₁₀、P₂₀、…、P_n0) And X_TCSCThe formula is formed; in particular, the amount of the solvent to be used,

in the formula, a_m＝(X_lm-X_hm)，a_r1＝(X_ll-X_hl)，a_r2＝(X_lh-X_hh) (ii) a Then left and right shifting can be followed:

and 4, obtaining an active static security domain expression comprehensively composed of a single TCSC equivalent reactance and the injected power of each node according to the formula (5) and the formula (3), wherein the active static security domain expression is as follows:

Ω₁: