JPH048129A - Monitoring system for static stability of power system - Google Patents

Abstract

PURPOSE:To judge the static stability in the case that a supposed accident occurs so as to achieve stabilization measures by making up a state equation, which expresses system condition based on the various data measured on-line, and solving this so as to judge the stability. CONSTITUTION:A measuring instrument 1 detects the output and voltage of a power system 1, the power of load, the tide flow of a line, and the voltage of the bus, the opening/closing condition of a breaker, and others, and transmits them to a calculator 4 through a transmitter 3. In the system condition grasping means of the calculator 4 sees the change of the opening/closing condition of the breaker and grasps the system configuration, and decides the voltage and the phase angle of the voltage by at least square estimating method fitted with plumb and condition estimation and calculation, and defines the condition equation which expresses the condition of the system. If the actual part of the peculiar value of the condition equation is negative, it judges it stable, and if the actual part of the peculiar value is positive, it judges it unstable. It performs stabilization measures, and indicates output on a display.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power system steady state stability monitoring system that is applied to a power system to monitor stability.

(Prior Art) Conventional steady-state stability monitoring is performed by confirming that vibration phenomena occur in generator power or the like during actual system operation. In order to prevent vibrations, the output of the generator is reduced or stopped.

(Problem to be Solved by the Invention) When operating a power system, there are various operating states such as starting and stopping one generator with open line, but before implementing each of these operating states, the steady state stability is determined on the solid line of each state. It is not possible to judge in advance whether the

The present invention was made in view of the above circumstances, and determines the steady state stability of the system configuration in the event of a hypothetical accident during online operation of the system, and in the case of instability, takes stabilization measures or takes control variables. The purpose is to provide a power system steady state stability monitoring system that can calculate and present it to operators.

(I'i bottom margin) [Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention provides a measurement means for grasping the operating status of power system configuration 1 generator output, load, etc. and,
A means of transmitting these data, a calculation means for determining the steady-state stability at the time of a hypothetical accident based on the above data, and calculating a control amount in the case of instability, and presenting the results to the operator. It consists of a display device for

(Function) The measurement means measures the CB, power, voltage, etc. of the power system, and transmits it to the calculation device via the transmission device. The calculation device creates a state equation that represents the system state, and determines stability by solving it. As a result, in the case of instability, a control amount for stabilization is calculated and outputted to the display device.

(Example) Examples of solid lines will be described below with reference to the drawings.

FIG. 1 is a functional block diagram of an embodiment of a power system steady state stability monitoring system according to the present invention.

In Figure 1, 1 is a power system, 2 is a measuring device that measures the state of the power system 1, 3 is a transmission device, and 4 is a determination of steady-state stability and stabilization measures based on the transmitted state information. 5 is a display device that outputs the judgment and calculation results.

FIG. 2 is a flowchart of the processing contents in the computer, and shows the system status grasping means S21. Steady state stability determination means S
22. It consists of means S23° for preparing stabilization measures and display means S24.

Next, the effect will be explained.

In FIG. 1, measuring device 2 is the output at the generator end.

The voltage, the power of the load, the power flow 1 of one circuit, the line voltage, and the open/close states of breakers, disconnectors, etc. are detected and transmitted to the computer via the transmission system.

The system state grasping means shown in FIG. 2 grasps the system configuration by looking at changes in the opening and closing states of circuit breakers. Next, the power system measurement data received from the transmission device 3 usually contains errors due to transducer conversion errors, malfunctions, uneven measurement times, etc., and the system status grasping means S21 From the measured values including these errors, the most probable system state values, ie, node voltages and voltage phase angles, are determined by a weighted least squares estimation method, in short, state estimation calculation. Generally, measured values that include errors can be expressed as follows.

z = h (X) ε ・・・・・・
・(1) Here, Z: Vector of measured values X: True value of state variable, that is, vector of node voltage and its phase angle hf vector In this case, the sum of squares of the residuals of the measured value and its estimated value, J-(
z−h (x))tw (z−h (X)) −=(
2) W: matrix of error weights of each measurement value z-h(x): vector of residual errors of measurement values t: Find the estimated value X of the state variable X that minimizes the vector's transposition.

Next, after understanding the estimated value X and the system configuration, a state equation representing the state of the system can be defined. In simple terms, the phase angle δ of the generator i, the number of revolutions ω, the internal voltage e, the II mechanical torque Tl (, the electric torque Tel, the magnetic field voltage E1d, etc.), the change Δδ from the operating point, etc.
, Δω, Δe, ΔT, ΔTq
Using l II eΔEtd, Δ δ = Δω Δω = (ΔT − ΔT, )/M, )
...(3) A differential equation such as the old e and an algebraic equation that holds between the voltage V of each bus and the current flowing into the f line ■ hold.

Above are the differential equations related to generators that show time changes in the state of the power system, and the mother of the system! It can be expressed by simultaneous equations showing the relationship for I voltage and current. Putting this all together, the state equation % formula % (5)
+ A state vector whose components are state variables, and A is a coefficient matrix.

Next, parameters are changed based on the assumed accident.

For example, if one line is open, power flow calculations are performed with one line open to determine voltage distribution, etc., and the coefficient of A is calculated.

Now, let us define the eigenvalue λ and the eigenvector b in equation (5) as (A-
λ)b=0... Obtained by solving (6).

Tol To2... As shown in FIG. 3, if the real part of the eigenvalue is positive, it indicates an unstable mode that diverges with time. It can be seen that if the real parts of all the eigenvalues are negative, even if vibration occurs due to a minute disturbance, it will be attenuated without divergence, and steady-state stability will be maintained.

Based on this idea, in the steady-state stability determination section S22 of FIG. 2, a matrix A is constructed and its eigenvalues are determined. Generally, when there are many state variables, several of the largest eigenvalues are found, and if all of their real parts are negative, it is determined to be stable.

Next, if any of the eigenvalues has a positive real part, it needs to be stabilized. This process is performed in stabilization measure S23 in FIG.

Next, when adjusting the generator output as a stabilization measure, the adjustment amounts ΔP, ΔP2. ...We will show how to find ΔP.

Now, if m eigenvalues are positive, each including the margin is Δλ
, Δλ2. ...If the shift change is small in the negative direction by ΔλD, the difference between Δλ and ΔPK is (9),
When formula (10) is put together, an approximate formula is established.

Here, p and q are the right eigenvector and left eigenvector for the eigenvalue λ of A.

therefore ・・・・・・(9) It is.

On the other hand, since the total sum of generator output adjustments must be zero, Δp1+Δp2+-+Δpo=o ・-・・・-(
10).

(Left below) ・・・・・・(11) Simple name Z=C-X ・Old...(12
)far.

Generally, since m<n, using equation (11), 2,
2 2(ΔP1) -1-(
ΔP2) +...+(ΔP,) to several tens of ΔP1.
ΔP2, . . . ΔPo is obtained as follows. Note that for generators that are not subject to adjustment or are subject to restrictions, calculations will be made by removing "Clk02k...1 house" from the corresponding column.

The stability judgment results obtained in the above process, the amount of adjustment of the generator output for stabilization measures (ΔP, ΔP 2 ).

. . . ΔPn) is output and displayed to the operator on the display section S24 in FIG.

According to the above embodiment, during online operation, the steady-state stability at the time of a hypothetical accident can be checked and necessary stabilization measures can be prepared, thereby improving the reliability of system operation.

As shown in the above description, the present invention aims at determining steady-state stability in a system state after a hypothetical accident occurs, based on the current system state during online operation. However, if the future system configuration is available in a database, etc., it is possible to use it to make a determination and take countermeasures.

[Effects of the Invention] As explained above, according to the present invention, a state equation representing the system state is created based on various data measured online, and stability is determined by solving this equation to determine that it is unstable. By calculating the control amount to stabilize the system in the event of a system failure and displaying it, it is possible to check the steady-state stability at the time of a hypothetical accident before the system status changes, and also to prepare stabilization measures. Therefore, it is possible to improve the stability and further improve the reliability of the power system.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an embodiment of the power system steady state stability monitoring system according to the present invention, Fig. 2 is a flowchart showing the processing contents of the embodiment, and Fig. 3 shows the relationship between the distribution of eigenvalues and the oscillation mode. FIG. 1... Power system 2... Measuring device 3...
Transmission device 4... Computing device 5... Display device Patent applicant: Tokyo Electric Power Company, Inc. (and one other person) Representative patent attorney: Norio Ishii iml No. 2Ii

Claims (1)

[Claims] In a power system steady state stability monitoring system that inputs system information from the power system to a computer via an information transmission device, and determines and displays the steady state stability of the power system based on this information, Understand the operating state of the power system, create a state equation that represents the system state based on the system configuration in the event of a hypothetical accident, and use the state equation to determine the steady-state stability. An electric power system steady stability monitoring system characterized by displaying stabilization measures when it is determined that