CN102075135A - Method for realizing stabilizer using internal potential frequency of generator as input signal - Google Patents

Abstract

The invention belongs to the field of power systems, and particularly relates to a method for realizing a stabilizer using the internal potential frequency of a generator as an input signal. The realizing method comprises the steps of: computing the internal potential of the generator, and determining the internal potential frequency of the generator, wherein the internal potential of the generator is determined according to a terminal voltage value and a terminal current value of the generator to compute the internal potential frequency, which serves as the input signal of the stabilizer, of the generator, and after being subject to high-frequency filtering, the signal is blocked and integrated, and finally superposed to a voltage reference point of an excitation regulator of the generator, so the function of the power system stabilizer is conducted. The method makes measurement convenient and accurate and solves the problem of difficult measuring of a shaft speed signal of the generator. The power system stabilizer (PSS) only needs a stator voltage signal and a stator current signal of the generator without needing an additional active power converter and a rotation speed converter, solves the problem of idle reverse regulation and thus is initial domestically.

Description

With the implementation method of generator built-in potential frequency as the stabilizer of input signal

Technical field

The invention belongs to field of power, be specifically related to a kind of with the implementation method of generator built-in potential frequency as the stabilizer of input signal.

Background technology

Studies show that of on national network engineering behind national network, a frequency can occur and be the negative damping oscillation mode about 0.15Hz, has a strong impact on safe, stable, the economical operation of electrical network.Adopting single electrical power is the input signal power system stabilizer, PSS (PSS) of (or simple electrical power adds tach signal), adopt to satisfy provide the parameter of positive damping to the low-frequency oscillation in the 0.1-2.0Hz frequency range after, tend to make " the anti-accent " phenomenon to become serious.So-called " the anti-accent " is meant when unit increases the original machine power input, the reactive power of generator has bigger, unallowable minimizing, and when unit reduced the original machine power input, the reactive power of generator had bigger, unallowable increase.This is that at this moment electrical power just equals accelerating power because adopting electrical power is that the supposition mechanical output is constant as the principle of the power system stabilizer, PSS of input signal, and when mechanical output was adjusted, at this moment electric power replaced accelerating power will cause anti-accent phenomenon.The dual input signal accelerating power PSS that is made up of generator shaft speed and active power solves the favourable measure of generator reactive " the anti-accent ", but measuring of tach signal acquires a certain degree of difficulty, need to install speed changer, simultaneously for avoiding the shafting torsional oscillation problem, also need adopt torsion frequency blocking-up filter, increase the probability that fault takes place.

Summary of the invention

In order to overcome the defective of prior art, the invention provides a kind of with the implementation method of generator built-in potential frequency as the stabilizer of input signal, this method has solved the problem that generator shaft speed is difficult for measuring, do not need the active power converter and the speed changer that add, not only can effectively play the effect that suppresses vibration, can also effectively solve the problem of anti-accent.

According to the mechanics law of rotating object, can write out following relational expression to the rotor of synchronous machine

$M\frac{\mathrm{d\ω}}{\mathrm{dt}}=T_m-T_e$

In the formula:

M---the moment of inertia of machine group rotor

T _m---prime motor torque

T _e---the electromagnetic torque of generator

ω---generator shaft speed

Represent that with perunit value when velocity variations was little, available horsepower replaced torque, then relational expression becomes

$M\frac{\mathrm{d\ω}}{\mathrm{dt}}=P_m-P_e---\left(a\right)$

In the formula

P _m---the mechanical output of generator

P _e---the electrical power of generator

Have after the transposition

$P_m=\frac{M}{{\mathrm{\ω}}_0}\frac{\mathrm{d\ω}}{\mathrm{dt}}+P_e$

Write as the deviation form, d/dt replaces with s,

${\mathrm{\ΔP}}_m=\mathrm{Ms}\frac{\mathrm{\Δ\ω}}{{\mathrm{\ω}}_0}+{\mathrm{\ΔP}}_e---\left(b\right)$

Because of containing various noises among the Δ ω, filter function G (s) elimination is taken advantage of at the following formula two ends:

${\mathrm{\ΔP}}_{m}G\left(s\right)=(\mathrm{Ms}\frac{\mathrm{\Δ\ω}}{{\mathrm{\ω}}_0}+{\mathrm{\ΔP}}_e)G\left(s\right)$

Therefore accelerating power is:

$\mathrm{\Δ}{P}_a=(M\frac{\mathrm{s\Δ\ω}}{{\mathrm{\ω}}_0}+{\mathrm{\ΔP}}_e)G\left(s\right)-{\mathrm{\ΔP}}_e---\left(c\right)$

In the formula: Δ P _a---the accelerating power deviation of generator;

With accelerating power Δ P _aWhen being used as the input of PSS for signal, PSS transfers less than anti-, and still measuring of (c) formula medium speed signal acquires a certain degree of difficulty, and needs to install extra speed changer usually, for avoiding the shafting torsional oscillation problem, needs to adopt torsion frequency blocking-up filter.Based on identical this condition of the variation of generator shaft speed with the variation of generator built-in potential frequency, the generator shaft rate signal no longer measures from the generator axle head among the present invention, but the frequency of utilizing generator voltage and current value to calculate the generator built-in potential realizes the function of stabilizer as input signal.

For this reason, the invention provides a kind of with the implementation method of generator built-in potential frequency as the stabilizer of input signal, comprise the calculating of generator built-in potential and determining of generator built-in potential frequency, its improvements are: terminal voltage value and current value according to generator are determined the generator built-in potential, and then ask for the input signal of generator built-in potential frequency as stabilizer, this signal is through behind the High frequency filter, pass through again every straight and integral element, on the automatic excitation adjustor of generator voltage reference points that finally is added to, thus the function of realization power system stabilizer, PSS.

Wherein, described generator built-in potential obtains by following method: with generator voltage value and the current value substitution following formula (1) that records

E _Q(t)＝U _t+I _tR _a+jI _t(X _d-X _q) (1)

Wherein:

U _t: t generator voltage constantly;

I _t: t dynamo current constantly;

E _Q(t): t generator built-in potential constantly;

X _d, X _q: be respectively generator d-axis, quadrature axis reactance;

R _a: generator unit stator resistance;

Wherein, described generator built-in potential frequency obtains by following method:

If only contain fundametal compoment in the built-in potential signal, that is:

A in the formula,

Amplitude and the initial phase angle of representing fundamental voltage respectively, t represents constantly; If use f ₀The expression rated frequency, Δ f represents frequency difference, f represents actual frequency, has following relation between the three:

f＝f ₀+Δf (3)

Because actual frequency the unknown, so the supposition system frequency is rated value f earlier ₀, to time window [0, T ₀] use fourier algorithm to obtain vectorial real part ζ _R0With imaginary part ζ _I0:

By calculating, can obtain actual frequency f to a plurality of time windows:

$f=f_0\sqrt{\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|{\mathrm{\ζ}}_{I\left(i\right)}^2-{\mathrm{\ζ}}_{I(i-1)}^2|}{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|{\mathrm{\ζ}}_{R(i-1)}^2-{\mathrm{\ζ}}_{r\left(i\right)}^2|}}---\left(6\right)$

This frequency f is exactly a generator built-in potential frequency, can be with its input signal as power system stabilizer, PSS.

Wherein, described High frequency filter adopts filter to realize by following method: described filter is the biquadratic power filter of two series connection, and the transfer function of this filter by following formula (7) filters the high fdrequency component in the generator built-in potential frequency,

$\frac{s^2+2{\mathrm{\δ}}_1{\mathrm{\ω}}_{1}s+{\mathrm{\ω}}_1^2}{s^2+2{\mathrm{\δ}}_3{\mathrm{\ω}}_{1}s+{\mathrm{\ω}}_1^2}\·\frac{s^2+2{\mathrm{\δ}}_2{\mathrm{\ω}}_{2}s+{\mathrm{\ω}}_2^2}{s^2+2{\mathrm{\δ}}_4{\mathrm{\ω}}_{2}s+{\mathrm{\ω}}_2^2}---\left(7\right)$

Wherein s is an integral operator, s ²Quadratic power for integral operator; ω ₁, ω ₂, δ ₁, δ ₂, δ ₃, δ ₄Be the configuration parameter of biquadratic power filter,

Be configuration parameter ω ₁, ω ₂Quadratic term.

Will be through the generator built-in potential frequency behind the High frequency filter by an integral element

With four every straight link

On the automatic excitation adjustor of generator voltage reference points that finally is added to,, make the total damping torque of generator for just, thereby realized the effect of power system stabilizer, PSS so just for generator provides extra damping torque; Wherein, K _Qs, T _QsBe integral element configuration parameter, T _Q, T _Q1, T _Q2, T _Q3, T ' _Q, T ' _Q1, T ' _Q2, T ' _Q3Be four eight configuration parameters every straight link, s is an integral operator.

Beneficial effect of the present invention is:

The generator built-in potential frequency that the present invention adopts generator voltage value and current value to calculate replaces the axle speed of generator, input as the PSS1A model, the built-in potential frequency that calculates is identical with the generator shaft frequency, therefore can be used as the input of power system stabilizer, PSS signal.Just can be by measuring generator voltage U and stator current I in the hope of generator built-in potential E _QThereby, be used as the input of PSS1A model by the frequency of asking the generator built-in potential, so just solve tach signal and be difficult for the problem measured, effectively suppress vibration, and solve idle anti-accent problem.The method is convenient to measure and accurately, solved the problem that the generator shaft rate signal is difficult for measuring.This PSS only needs generator unit stator voltage, current signal, does not need the active power converter and the speed changer that add, can also effectively solve idle anti-accent problem simultaneously, belongs to initiative at home.

Description of drawings

Fig. 1 is the transfer function block diagram of PSS of the present invention;

Embodiment

Be further described in detail below in conjunction with the implementation method of accompanying drawing the power system stabilizer, PSS based on generator built-in potential frequency of the present invention.

At first measure generator voltage and electric current, and then calculate generator built-in potential E _QFor built-in potential signal E _Q(t), establish and only contain fundametal compoment in the signal, if use f ₀The expression rated frequency, Δ f represents frequency difference, actual frequency is f.Because actual frequency the unknown can only suppose that in advance system frequency is rated value f ₀, to time window [0, T ₀] use fourier algorithm to obtain vectorial real part and imaginary part:

If order:

$k=\frac{2A}{\mathrm{\π}{T}_0\mathrm{\Δf}(2f_0+\mathrm{\Δf})}\sin \left(\mathrm{\π\Δ}{\mathrm{fT}}_0\right)$

Then:

${\left(\frac{{\mathrm{\ζ}}_{R0}}{f_0}\right)}^2+{\left(\frac{{\mathrm{\ζ}}_{I0}}{f_0+\mathrm{\Δf}}\right)}^2=k^2$

For next time window

Following formula is still set up, that is:

${\left(\frac{{\mathrm{\ζ}}_{R1}}{f_0}\right)}^2+{\left(\frac{{\mathrm{\ζ}}_{I1}}{f_0+\mathrm{\Δf}}\right)}^2=k^2$

Therefore can calculate actual frequency f:

$f=f_0\sqrt{\frac{U_{I1}^2-U_{I0}^2}{U_{R0}^2-U_{R1}^2}}$

More accurate for what calculate, can calculate actual frequency f by a plurality of time windows:

$f=f_0\sqrt{\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|U_{I\left(i\right)}^2-U_{I(i-1)}^2|}{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|U_{R(i-1)}^2-U_{R\left(i\right)}^2|}}$

The frequency f that calculates is exactly a generator built-in potential actual frequency, can be with the input of this actual frequency f as the PSS1A model, but need carry out High frequency filter earlier.High frequency filter is realized by following method: described filter is the biquadratic power filter of two series connection, and the transfer function of this filter by following formula filters the high fdrequency component in the generator built-in potential frequency,

Will be through the generator built-in potential frequency behind the High frequency filter by an integral element

With four every straight link

On the automatic excitation adjustor of generator voltage reference points that finally is added to, so just provide extra damping torque for generator, make the total damping torque of generator for just, thereby realized the effect of power system stabilizer, PSS, so just the power oscillation of generator can be effectively suppressed, and the idle anti-accent problem of generator can be solved.

Though the part-structure of this stabilizer is identical with the PSS1A model, but because the present invention has adopted generator built-in potential frequency as input signal, so not only can effectively suppress vibration, can also effectively suppress idle anti-accent, compare with traditional PSS2A stabilizer, not only input signal reduces, and structure is also more simple and reliable simultaneously.

Should be noted that at last: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the field are to be understood that: still can make amendment or be equal to replacement the specific embodiment of the present invention, and do not break away from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (5)

1. one kind with the implementation method of generator built-in potential frequency as the stabilizer of input signal, comprise the calculating of generator built-in potential and determining of generator built-in potential frequency, it is characterized in that: terminal voltage value and current value according to generator are determined the generator built-in potential, and then ask for the input signal of generator built-in potential frequency as stabilizer, this signal is through behind the High frequency filter, pass through again every straight and integral element, on the automatic excitation adjustor of generator voltage reference points that finally is added to, thus the function of realization power system stabilizer, PSS.

2. the implementation method of power system stabilizer, PSS according to claim 1 is characterized in that, described generator built-in potential obtains by following method:

With generator voltage value and the current value substitution following formula (1) that records

E _Q(t)＝U _t+I _tR _a+jI _t(X _d-X _q) (1)

Wherein:

U _t: t generator voltage constantly;

I _t: t dynamo current constantly;

E _Q(t): t generator built-in potential constantly;

X _d, X _q: be respectively generator d-axis, quadrature axis reactance;

R _a: generator unit stator resistance;

3. the implementation method of power system stabilizer, PSS according to claim 1 is characterized in that, described generator built-in potential frequency obtains by following method:

If only contain fundametal compoment in the built-in potential signal, that is:

A in the formula,

Amplitude and the initial phase angle of representing fundamental voltage respectively, t represents constantly; If use f ₀The expression rated frequency, Δ f represents frequency difference, f represents actual frequency, has following relation between the three:

f＝f ₀+Δf (3)

Because actual frequency the unknown, so the supposition system frequency is rated value f earlier ₀, to time window [0, T ₀] use fourier algorithm to obtain vectorial real part ζ _R0With imaginary part ζ _I0:

By calculating, can obtain actual frequency f to a plurality of time windows:

$f=f_0\sqrt{\frac{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|{\mathrm{\ζ}}_{I\left(i\right)}^2-{\mathrm{\ζ}}_{I(i-1)}^2|}{\underset{i=1}{\overset{M}{\mathrm{\Σ}}}|{\mathrm{\ζ}}_{R(i-1)}^2-{\mathrm{\ζ}}_{R\left(i\right)}^2|}}---\left(6\right)$

This frequency f is exactly a generator built-in potential frequency, can be with its input signal as power system stabilizer, PSS.

4. the implementation method of power system stabilizer, PSS according to claim 1 is characterized in that, described High frequency filter adopts filter to realize by following method:

Described filter is the biquadratic power filter of two series connection, and the transfer function of this filter by following formula (7) filters the high fdrequency component in the generator built-in potential frequency,

$\frac{s^2+2{\mathrm{\δ}}_1{\mathrm{\ω}}_{1}s+{\mathrm{\ω}}_1^2}{s^2+2{\mathrm{\δ}}_3{\mathrm{\ω}}_{1}s+{\mathrm{\ω}}_1^2}\·\frac{s^2+2{\mathrm{\δ}}_2{\mathrm{\ω}}_{2}s+{\mathrm{\ω}}_2^2}{s^2+2{\mathrm{\δ}}_4{\mathrm{\ω}}_{2}s+{\mathrm{\ω}}_2^2}---\left(7\right)$

Wherein s is an integral operator, s ²Quadratic power for integral operator; ω ₁, ω ₂, δ ₁, δ ₂, δ ₃, δ ₄Be the configuration parameter of biquadratic power filter, Be configuration parameter ω ₁, ω ₂Quadratic term.

5. the implementation method of power system stabilizer, PSS according to claim 1 is characterized in that,

Will be through the generator built-in potential frequency behind the High frequency filter by an integral element

With four every straight link

On the automatic excitation adjustor of generator voltage reference points that finally is added to,, make the total damping torque of generator for just, thereby realized the effect of power system stabilizer, PSS so just for generator provides extra damping torque; Wherein, K _Qs, T _QsBe integral element configuration parameter, T _Q, T _Q1, T _Q2, T _Q3, T ' _Q, T ' _Q1, T ' _Q2, T ' _Q3Be four eight configuration parameters every straight link, s is an integral operator.