CN201167238Y

CN201167238Y - Power system stabilizer

Info

Publication number: CN201167238Y
Application number: CNU2007203001073U
Authority: CN
Inventors: 毛承雄; 陆继明; 周友斌; 李小平; 熊鸿滔; 王丹; 娄慧波
Original assignee: HUBEI PROV POWER TEST INST; Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology; State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
Priority date: 2007-12-21
Filing date: 2007-12-21
Publication date: 2008-12-17
Anticipated expiration: 2017-12-21

Abstract

The utility model discloses a power system stabilizer. The stabilizer comprises a filter, a repositor, a phase compensator and a surge suppressor which are connected in sequence. The filter is used for filtering an input signal, the repositor is used for eliminating direct-current component of the filtered input signal, the phase compensator is used for executing phase compensation for the input signal after eliminating the direct-current component through a phase compensation transfer function and obtaining a phase compensation input signal, and the surge suppress is used for limiting volt for phase compensation input signal and output a result of the limited volt. The phase compensator of the utility model adopts the phase compensation transfer function with the polynomial numerator and denominator, and the selective freedom of the parameter of function is large and can be better close to a compensating curve of a required target so that the retarding phase of an generator is well compensated in whole low frequency oscillating range.

Description

A kind of power system stabilizer, PSS

Technical field

The utility model belongs to the electrical engineering technical field, be specifically related to a kind of power system stabilizer, PSS (Power System Stabilizer, PSS).

Background technology

At present, known PSS structure partly is made up of phase compensation link, additional excitation multiplication factor, the link that resets, transducer and input signal.Introduce one or two signals, remove the damping torque of generator in the system of increasing electric power by excitation system.PSS commonly used is generally according to undamped natural mechanical mode frequency j ω _nPerhaps the plural frequency σ+j ω of the local oscillation pattern that is obtained by the analysis of system features value designs, so PSS has the good restraining effect to the power oscillation of design frequency and near frequency thereof.

Interconnected along with regional power grid, the strong correlation oscillation mode that generators in power systems participates in may have two or more, and for the safe and stable operation of electric power system, the scope that requires PSS to suppress low-frequency oscillation is 0.1Hz～3Hz.The phase compensation part of conventional PSS is made up of two-stage or three grades of lead-lag links, be difficult to meet the demands, reason is: the limit of three grades of lead-lag link generation leading phases is 150 °～160 ° on the one hand, and a lot of generator lagging phases often surpass 200 ° in the electric power system, can't compensate; Two to three grades lead-lag link has only 4～6 parameters on the other hand, is difficult in the whole low-frequency oscillation scope generator lagging phase is compensated.

Summary of the invention

The purpose of this utility model is to propose a kind of power system stabilizer, PSS, can carry out good compensation to the generator lagging phase in 0.1Hz～3Hz low-frequency oscillation scope.

The power system stabilizer, PSS that the utility model provides, it is characterized in that, comprise the filter, restorer, phase compensator and the surge suppressor that connect successively, filter is used for input signal filtering, restorer is used to eliminate the DC component of filtered input signal, and the input signal after phase compensator is used to adopt the phase compensation transfer function to the elimination DC component carries out phase compensation, obtains the phase compensation output signal, surge suppressor is used for phase compensation output signal limit volt, output limit volt result.

Phase compensator in the utility model adopts the molecule denominator to be polynomial phase compensation transfer function, its parameter selects the degree of freedom big, can better approach required target compensated curve, thereby the generator lagging phase be carried out good compensation in whole low-frequency oscillation scope.

Description of drawings

Fig. 1 is the utility model structural representation;

Fig. 2 is an embodiment fitting result schematic diagram.

Embodiment

Below knot and accompanying drawing and example the utility model is described in further detail.

As shown in Figure 1, the utility model comprises: the filter 1 that is connected successively, restorer 2, phase compensator 3 and surge suppressor 4.

1 pair of input signal of filter carries out filtering, and with the interference in the elimination input signal, and the low-frequency oscillation frequency in the filtering input signal is with external signal.Generally have: generator amature rotational speed omega, generator power Pe and accelerating power Pa as the PSS input signal.Filter is divided into two kinds, and when input signal was rotational speed omega or electrical power P e, filter transfer function was

A wherein ₁, A ₁Be filter parameter, A ₁, A ₁∈ (0,0.5).When input signal was accelerating power Pa, the form of filter was

T wherein ₈, T ₉, M, N are filter parameter, T ₈, T ₉∈ (0.1,0.5), M, N ∈ (1,5), Laplace transform factor s is a complex variable.

Restorer 2 is used for eliminating the direct current shunting of filtered input signal, and the transfer function of restorer is

T _ωBe the link time constant that resets, T _ωSpan is (4,15).

Input signal after 3 pairs of eliminations of phase compensator DC component carries out phase compensation and obtains phase compensation link output signal.

4 pairs of phase compensation links of surge suppressor output signal is limit volt, limit volt scope is determined by actual conditions such as generator, generator geographical position, to limit the phase compensation link output signal after lying prostrate to export again, as the additional excitation control signal that strengthens the electric power system positive damping to the external generator automatic pressure regulating device.Surge suppressor is a decision mechanism, when input signal at (u _Smin, u _Smax) between, output signal is an input signal; When input signal less than u _Smin, output signal is u _SminWhen output signal greater than u _Smax, output signal is u _Smax, u wherein _Smin, u _Smax∈ (0.5,0.5), u _Smin＜u _Smax

The phase compensation transfer function that phase compensator is taked is determined according to following steps:

1) by the phase characteristic of spectrum measurement instrument from in-site measurement or simulation calculation acquisition generator

2) require to calculate PSS compensation of phase characteristic according to predetermined backoff

The PSS input signal does not require the phase characteristic of compensation simultaneously

Also different.When introducing rotor speed ω as input signal, phase characteristic

Phase characteristic when introducing generator power Pe or accelerating power Pa as input signal

Be the predetermined backoff requirement,

Because the filtering link and the link that resets have bigger influence in ultralow frequency range to phase compensation, need consider the phase characteristic of these links when carrying out match, to phase characteristic

Do corresponding the correction: when introducing rotor speed ω as input signal, phase characteristic

Introducing-Pe or accelerating power Pa phase characteristic during as input signal

Be the predetermined backoff requirement,

Be the filtering and the link modifying factor that resets,

3) with the compensation of phase characteristic

As aim curve, be that original function carries out curve fitting with formula (1), obtain a phase compensation curve f (x) who approaches aim curve most, promptly the difference of phase compensation curve and aim curve is minimum under certain tolerance meaning.Module commonly used has

For the fitting effect of strengthening some frequency range adds weighting function in module, form as:

Wherein, a, b are the curve fit scope, a, and b ∈ (0,50), a＜b, ω (x) is a weighting function.

\frac{b_{0} s^{n} + b_{1} s^{n - 1} + \cdot \cdot \cdot + b_{n}}{s^{n} + a_{1} s^{n - 1} + \cdot \cdot \cdot + a_{n}} - - - (1)

The molecule of formula (1) is the multinomial that is equal to or less than the n rank, and denominator is n rank multinomials, wherein multinomial coefficient b ₀, b ₁..., b _n, a ₁, a ₂..., a _nWith natural number n be fitting parameter, s is the Laplace transform factor, is complex variable.With formula (1) is original function, carries out match according to the generator phase-frequency characteristic, and the phase compensation curve that obtains PSS has promptly been determined fitting parameter n, b ₀, b ₁..., b _n, a ₁, a ₂..., a _n, this parameter value has been determined the phase compensation transfer function.This transfer function is owing to molecule, and denominator all adopts polynomial form, and the parameter degree of freedom is big, and the phase compensation curve that match is obtained more is comparable to aim curve, thereby helps improving phase compensation effect.

In the practical application, when employing formula (1) match, positive limit situation may occur,, further propose to carry out match suc as formula (2) or formula (3) for avoiding this situation,

\frac{b_{0} s^{n} + b_{1} s^{n - 1} + \cdot \cdot \cdot + b_{n}}{(1 + s T_{1}) (1 + s T_{2}) \cdot \cdot \cdot (1 + s T_{n})} - - - (2)

In the formula (2): n is a natural number, T _i＞0, i=1 ..., n, n, b ₀, b ₁..., b _n, T ₁, T ₂..., T _nBe fitting parameter.

\frac{b_{0} s^{n} + b_{1} s^{n - 1} + \cdot \cdot \cdot + b_{n}}{(1 + a_{11} s + a_{12} s^{2}) \cdot \cdot \cdot (1 + a_{j 1} s + a_{j 2} s^{2}) (1 + s T_{1}) \cdot \cdot \cdot (1 + s T_{k})} - - - (3)

In the formula (3): 2j+k=n, n, j and k are natural number, T _l＞0, l=1 ..., k, n, b ₀, b ₁..., b _n, a ₁₁..., a _J1, a ₁₂..., a _J2Be fitting parameter, 1+a _U1S+a _U2s ², u=1 ..., j is for having 2 rank multinomials of negative real part conjugation compound radical.

The difference of formula (2) and formula (3) is: the denominator of formula (2) is that n 1 rank factor multiplies each other, and its limit all be negative real root, and the denominator of formula (3) to be 1 rank and 2 rank factors mix multiplies each other, its limit is for bearing real root and conjugation compound radical (bearing real part).The degree of freedom of formula (3) is bigger than formula (2), but the more realistic custom of formula (2).If the limit of formula (1) all is stable, then formula (1) always can be changed the form of an accepted way of doing sth (2) or formula (3).Formula (2), formula (3) and formula (1) all are easy to after the discretization real-time implementation on computers.

Core of the present utility model is the structure of phase compensator, i.e. determining of phase compensation transfer function illustrates this process below in conjunction with Fig. 3, and abscissa is a rotating speed among the figure, with formula (2) for carrying out match.

(1) obtains the lagging phase of actual set, as curve d among Fig. 3;

(2) after being handled, curve 4 is compensated phase characteristic, shown in curve a among Fig. 3;

(3), adopt module according to the compensation of phase characteristic

Carrying out match with the utility model formula (2), to obtain PSS phase compensation curve be phase compensation link parameter value, shown in curve b among Fig. 3; Match obtains phase compensation link transfer function as the formula (4)

\frac{2.99 * 10^{- 5} s^{4} + 1.176 * 10^{- 3} s^{3} + 1.395 * 10^{- 2} s^{2} + 0.2829 s + 0.9387}{1.6 * 10^{- 7} s^{4} + 3.2 * 10^{- 5} s^{3} + 2.4 * 10^{- 3} s^{2} + 0.08 s + 1} - - - (4)

Calculate compensating error according to curve a and curve b, shown in curve c among Fig. 3, curve c is positioned near the phase value " 0 ", and visible the utility model can be good at approaching aim curve in the low-frequency oscillation scope, thereby the generator lagging phase is carried out good compensation.

Claims

1, a kind of power system stabilizer, PSS, it is characterized in that, comprise the filter (1), restorer (2), phase compensator (3) and the surge suppressor (4) that connect successively, filter (1) is used for input signal filtering, restorer (2) is used to eliminate the DC component of filtered input signal, input signal after phase compensator (3) is used to adopt the phase compensation transfer function to the elimination DC component carries out phase compensation, obtain the phase compensation output signal, surge suppressor (4) is used for phase compensation output signal limit volt, output limit volt result.