CN103972911A - Emergency control method for limiting largest oscillation angle of electric power system - Google Patents

Abstract

An emergency control method for limiting the largest oscillation angle of an electric power system is used for actually measuring responses of an electric generator, namely the power angle, the angular velocity and the unbalanced power information, according to a wide area dynamic information system WAMS and calculating required control quantities for limiting the largest oscillation angle of the system within a given range in real time. The emergency control method includes the following steps that first, whether the system is stable or not is distinguished; second, the largest oscillation angle delta<max> of an equivalent single machine infinite bus system is given; third, the target value of the first-order derivative k of the angular velocity of the equivalent single machine infinite bus system to the power angle is calculated; fourth, the control quantity lambda of the equivalent single machine infinite bus system is calculated; fifth, the control quantity delta P<m> required by a multi-machine system is calculated; sixth, generator tripping operation is executed. Through the method, the power angle, the angular velocity and the unbalanced information of the electric generator are actually measured according to the wide area dynamic information system WAMS, and the required control quantities for limiting the largest oscillation angle of the system within the given range can be calculated in real time.

Description

Limit the emergency control method of the maximum angle of oscillation of electric power system

Technical field

The invention belongs to POWER SYSTEM EMERGENCY CONTROL technical field, be specifically related to a kind of emergency control method that limits the maximum angle of oscillation of electric power system.

Background technology

Along with wide area measurement system (WAMS, Wide Area Measurement System) in the installation of electric power system, in dynamic process, the curve movement of unit can directly be measured and needn't rely on numerical computations, and this is undoubtedly for the real-time emergency control of electric power system provides new development opportunity.WAMS can capture the real-time dynamic process of Large Scale Interconnected Systems each point under the same reference time, and Data Update speed reaches ms level, for the instable Real time identification of transient state of electric power system provides possibility, its basic thought is the system trajectory information of utilizing WAMS to provide, mining track information rule and mechanism behind, find out the relation between trace information and the stability of a system, realize Real-time Emergency Control algorithm.

And the difference of controlling target can obtain different control methods.The present invention, by the maximum angle of oscillation of a given system, makes system in given maximum angle of oscillation place's backswing.Controlling target is that to make system by control will be zero at the angular speed at given maximum angle of oscillation place.

Summary of the invention

The problem existing in order to solve above-mentioned prior art, the object of the present invention is to provide a kind of emergency control method that limits the maximum angle of oscillation of electric power system, the method, according to wide area dynamic information system (WAMS) actual measurement generator responds (merit angle, angular speed and uneven moving rate) information, can be calculated in real time the maximum angle of oscillation of system is limited to needed controlled quentity controlled variable in given scope.

In order to realize foregoing invention object, the technical scheme that the present invention takes is:

Limit the emergency control method of the maximum angle of oscillation of electric power system, according to wide area dynamic information system WAMS actual measurement generator responds, be merit angle, angular speed and uneven moving rate information, calculate in real time the maximum angle of oscillation of system is limited to needed controlled quentity controlled variable in given scope; Specifically comprise the steps:

Step 1: according to the merit angle of wide area dynamic information system WAMS actual measurement system, angular speed mechanical input power and electromagnetism power output, and whether judgement system is stable;

Step 2: supposing the system Failure Model is two groups of unstabilitys, the pattern of hiving off of known system is divided into critical machine S and all the other cluster A, and two groups of system equivalents become one machine infinity bus system; In the time that system is unstable, the maximum angle of oscillation δ of given equivalent one machine infinity bus system _max;

Step 3: cut the merit angle of machine moment Tc according to equivalent one machine infinity bus system, angular speed and maximum angle of oscillation δ _max, calculate and make after system recovers the action of stable control measure, the desired value of the first derivative k of equivalent one machine infinity bus system angular speed to merit angle:

$k=\frac{-\mathrm{\&Delta;}{\mathrm{\&omega;}}_c}{{\mathrm{\&delta;}}_{\max }-{\mathrm{\&delta;}}_c}$

In formula:

δ _c---equivalent one machine infinity bus system is cut the merit angle in machine moment;

Δ ω _c---equivalent one machine infinity bus system is cut the angular speed in machine moment;

δ _max---the maximum angle of oscillation of equivalent given one machine infinity bus system;

Step 4: according to the above-mentioned k value of equivalent one machine infinity bus system, calculate the controlled quentity controlled variable λ of equivalent one machine infinity bus system:

$k=\frac{(1-\mathrm{\&lambda;})P_m-P_{\mathrm{ec}}}{(1-\mathrm{\&lambda;})\mathrm{M\&Delta;}{\mathrm{\&omega;}}_c}\&DoubleRightArrow;\mathrm{\&lambda;}=1-\frac{P_{\mathrm{ec}}}{P_m-\mathrm{M\&Delta;}{\mathrm{\&omega;}}_{c}k}$

In formula:

Needed controlled quentity controlled variable when λ---system is recovered to stablize;

The first derivative at the relative merit of the angular speed angle of k---equivalent one machine infinity bus system;

P _ec---the electromagnetic power of equivalent one machine infinity bus system is in the value of cutting machine moment Tc;

The inertia time constant of M---equivalent one machine infinity bus system;

P _m---the mechanical output of equivalent one machine infinity bus system;

Step 5: the controlled quentity controlled variable reduction of the equivalent one machine infinity bus system obtaining, to multimachine system side, is obtained to the needed controlled quentity controlled variable Δ of multimachine system P _m:

${\mathrm{\&Delta;P}}_m=P_{\mathrm{msc}}-(\frac{k{\mathrm{MM}}_T{\mathrm{\&Delta;\&omega;}}_c+(P_{\mathrm{mac}}-P_{\mathrm{eac}})M_s}{M_a}+P_{\mathrm{esc}})$

In formula:

The first derivative at the relative merit of the angular speed angle of k---equivalent one machine infinity bus system;

P _esc---the equivalent electromagnetic power of critical machine is in the value of cutting machine moment Tc;

P _msc---the equivalent mechanical output of critical machine is in the value of cutting machine moment Tc;

P _eac---the equivalent electromagnetic power of all the other group of planes is in the value of cutting machine moment Tc;

P _mac---the equivalent mechanical output of all the other group of planes is in the value of cutting machine moment Tc;

P _esc---the equivalent electromagnetic power of critical machine is in the value of cutting machine moment Tc;

The inertia time constant of M---equivalent one machine infinity bus system;

M _t---the inertia time constant summation of all generators;

M _s---the equivalent inertia time constant of critical machine;

M _a---the equivalent inertia time constant of all the other group of planes;

Step 6: obtain the needed controlled quentity controlled variable Δ of multimachine system P according to step 5 _m, carry out and cut machine operation.

Compared to the prior art, tool has the following advantages in the present invention:

1. the present invention is in the transient analysis process of electric power system, do not need to obtain in advance the network configuration of electric power system and the model and parameter of element, method information needed is obtain or calculate according to real-time measuring data, the complex model of energy adaptive system, the true ruuning situation that can reflect exactly system, reaches real-time matching fault mode;

2. the controlled quentity controlled variable that the present invention obtains, can ensure that the maximum angle of oscillation of system is within given scope, makes power system operation in a comparatively safe stability region.

Brief description of the drawings

Fig. 1 is sample calculation WEPRI36 system wiring figure.

Fig. 2 is at line computation emergency control policy flow chart.

Fig. 3 is the power-angle curve figure of each generator with respect to system inertia center.

Fig. 4 is the system power-angle curve figure after 0.65s control strategy is implemented.

Embodiment

Below in conjunction with drawings and the specific embodiments, the present invention is described in further detail.

As shown in Figure 1, WEPRI36 system, fault is set to close bus 33 side generation three-phase shortcircuit earth faults between bus 31 and bus 33, and 0.19 second tripping circuit has excised G8 generator 30% and has exerted oneself in 0.35s according to Policy Table.Determining system at 0.5s will unstability, starts controlled quentity controlled variable algorithm.Now critical machine (S) is G7, G8 generator, and all the other group of planes (A) are G1, G2, G3, G4, G5, G6 generator.Fig. 3 has provided now generator with respect to the power-angle curve figure at system inertia center.

The inertia time constant of each generator G1-G8 is as shown in table 1.

The inertia time constant of critical machine, all the other group of planes and equivalent one machine infinity bus system is as shown in table 2.

Table 1 (unit: s):

G1	G2	G3	G4	G5	G6	G7	G8
								140.812	29.998	79.503	15.679	39.200	2.620	21.999	32.598

Table 2 (unit: s):

Critical machine	All the other group of planes	Equivalent one machine infinity bus system
			54.5975	307.8125	46.3723

When 0.5s, rotor angle, angular speed, mechanical output, the electromagnetic power of critical machine, all the other group of planes and equivalent one machine infinity bus system are as shown in table 3:

Table 3

When 0.5s, G7, the mechanical output of G8 generator is as shown in table 4:

Table 4

	Mechanical output (perunit value)
		G7	2.30786
G8	2.19466

As shown in Figure 2, according to above-mentioned parameter, the concrete control method of the present invention is as follows:

The first step: giving the maximum angle of oscillation of fixed system is 122 °;

Second step: calculate k=-7.81 by formula (1);

The 3rd step: controlled quentity controlled variable λ=0.2137 of calculating equivalent one machine infinity bus system by formula (2);

The 4th step: the controlled quentity controlled variable reduction of the equivalent one machine infinity bus system calculating is arrived to multimachine side Δ P by formula (3) _m=1.1487, therefore obtain making system to recover stable emergency control and exert oneself for excising G7 generator 50%;

The 5th step: carry out control strategy at 0.65s, as shown in Figure 4, now the maximum angle of oscillation of system is 120.92 ° to the power-angle curve figure after control strategy action, and system operates in desired scope.

Claims (1)

1. limit the emergency control method of the maximum angle of oscillation of electric power system, it is characterized in that: according to wide area dynamic information system WAMS actual measurement generator responds, be merit angle, angular speed and uneven moving rate information, calculate in real time the maximum angle of oscillation of system is limited to needed controlled quentity controlled variable in given scope; Specifically comprise the steps:

Step 1: according to the merit angle of wide area dynamic information system WAMS actual measurement system, angular speed mechanical input power and electromagnetism power output, and whether judgement system is stable;

Step 2: supposing the system Failure Model is two groups of unstabilitys, the pattern of hiving off of known system is divided into critical machine S and all the other cluster A, and two groups of system equivalents become one machine infinity bus system; In the time that system is unstable, the maximum angle of oscillation δ of given equivalent one machine infinity bus system _max;

Step 3: cut the merit angle of machine moment Tc according to equivalent one machine infinity bus system, angular speed and maximum angle of oscillation δ _max, calculate and make after system recovers the action of stable control measure, the desired value of the first derivative k of equivalent one machine infinity bus system angular speed to merit angle:

$k=\frac{-\mathrm{\&Delta;}{\mathrm{\&omega;}}_c}{{\mathrm{\&delta;}}_{\max }-{\mathrm{\&delta;}}_c}$

In formula:

δ _c---equivalent one machine infinity bus system is cut the merit angle in machine moment;

Δ ω _c---equivalent one machine infinity bus system is cut the angular speed in machine moment;

δ _max---the maximum angle of oscillation of equivalent given one machine infinity bus system;

Step 4: according to the above-mentioned k value of equivalent one machine infinity bus system, calculate the controlled quentity controlled variable λ of equivalent one machine infinity bus system:

$k=\frac{(1-\mathrm{\&lambda;})P_m-P_{\mathrm{ec}}}{(1-\mathrm{\&lambda;})\mathrm{M\&Delta;}{\mathrm{\&omega;}}_c}\&DoubleRightArrow;\mathrm{\&lambda;}=1-\frac{P_{\mathrm{ec}}}{P_m-\mathrm{M\&Delta;}{\mathrm{\&omega;}}_{c}k}$

In formula:

Needed controlled quentity controlled variable when λ---system is recovered to stablize;

The first derivative at the relative merit of the angular speed angle of k---equivalent one machine infinity bus system;

P _ec---the electromagnetic power of equivalent one machine infinity bus system is in the value of cutting machine moment Tc;

The inertia time constant of M---equivalent one machine infinity bus system;

P _m---the mechanical output of equivalent one machine infinity bus system;

Step 5: the controlled quentity controlled variable reduction of the equivalent one machine infinity bus system obtaining, to multimachine system side, is obtained to the needed controlled quentity controlled variable Δ of multimachine system P _m:

${\mathrm{\&Delta;P}}_m=P_{\mathrm{msc}}-(\frac{k{\mathrm{MM}}_T{\mathrm{\&Delta;\&omega;}}_c+(P_{\mathrm{mac}}-P_{\mathrm{eac}})M_s}{M_a}+P_{\mathrm{esc}})$

In formula:

The first derivative at the relative merit of the angular speed angle of k---equivalent one machine infinity bus system;

P _esc---the equivalent electromagnetic power of critical machine is in the value of cutting machine moment Tc;

P _msc---the equivalent mechanical output of critical machine is in the value of cutting machine moment Tc;

P _eac---the equivalent electromagnetic power of all the other group of planes is in the value of cutting machine moment Tc;

P _mac---the equivalent mechanical output of all the other group of planes is in the value of cutting machine moment Tc;

P _esc---the equivalent electromagnetic power of critical machine is in the value of cutting machine moment Tc;

The inertia time constant of M---equivalent one machine infinity bus system;

M _t---the inertia time constant summation of all generators;

M _s---the equivalent inertia time constant of critical machine;

M _a---the equivalent inertia time constant of all the other group of planes;

Step 6: obtain the needed controlled quentity controlled variable Δ of multimachine system P according to step 5 _m, carry out and cut machine operation.