CN105576673B - A kind of forced power oscillation suppressing method and system based on E STATCOM - Google Patents

A kind of forced power oscillation suppressing method and system based on E STATCOM Download PDF

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CN105576673B
CN105576673B CN201610008316.4A CN201610008316A CN105576673B CN 105576673 B CN105576673 B CN 105576673B CN 201610008316 A CN201610008316 A CN 201610008316A CN 105576673 B CN105576673 B CN 105576673B
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oscillation
module
statcom
power
signal
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CN105576673A (en
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蒋平
冯双
吴熙
范子恺
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Southeast University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/10—Flexible AC transmission systems [FACTS]

Abstract

The invention discloses a kind of forced power oscillation suppressing method based on E STATCOM,Also disclose the forced power oscillation suppression system based on E STATCOM,Including signal acquisition module,The input of signal acquisition module connects the left side transmission line of electricity and right side transmission line of electricity being connected with E STATCOM installation buses respectively,The input of the output end connection control signal selecting module of signal acquisition module,The output end of control signal selecting module connects the input of vibration identification module respectively,The input of Reactive Power Control module and the input of active power controller module,The output end of vibration identification module connects the input of Reactive Power Control module and the input of active power controller module respectively,The output end of Reactive Power Control module and the output end of active power controller module are all connected with E STATCOM.The present invention need not be manually operated, has good inhibition to forced power oscillation.

Description

E-STATCOM-based forced power oscillation suppression method and system
Technical Field
The invention relates to the technical field of power system stabilization and control, in particular to a forced power oscillation suppression method and system based on an E-STATCOM.
Background
Under the basic pattern of the interconnection of the west, east and south, china will gradually form a large-scale power grid which is interconnected nationwide, so that the problem of power oscillation of a power system is increasingly prominent. The traditional power oscillation is mainly low-frequency oscillation of a negative damping mechanism caused by insufficient damping of a system, and the suppression measure is to improve the damping of the system. In recent years, some power oscillations cannot be explained by a negative damping mechanism, the oscillations still occur even if a damping device for improving the system is installed, and the oscillations are found to be forced power oscillations and are caused by periodic power disturbance in the system. The forced power oscillation and the low-frequency oscillation of the negative damping mechanism have very similar expression forms, but the suppression method which needs to be adopted is greatly different due to different occurrence mechanisms, and the measure for suppressing the low-frequency oscillation of the negative damping mechanism cannot suppress the forced power oscillation.
The current measures for forced power oscillation in the power grid include raising the voltage, splitting the unit and switching the prime mover to valve position control. These methods require a certain time after the oscillation occurs to allow the control personnel to perform the operation, and force the power oscillation to start oscillating quickly, thereby possibly leading to an expansion of the accident range if the operation is not in time. In addition, because the power disturbance source positioning technology in the actual system is not mature, it is difficult to find the disturbance source accurately and timely for control.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a forced power oscillation suppression method and system based on an E-STATCOM without manual operation.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the following technical scheme:
the invention discloses a forced power oscillation suppression method based on an E-STATCOM, which is characterized by comprising the following steps: the method comprises the following steps:
s1: signal acquisition module acquires voltage U of E-STATCOM installation bus j Frequency f j And the active power signal P of the left power transmission line connected with the E-STATCOM installation bus ij And a reactive power signal Q ij And the active power signal P of the right side transmission line connected with the E-STATCOM installation bus jk And a reactive power signal Q jk ；
S2: inputting the signals acquired by the signal acquisition module in the step S1 into a control signal selection module, and calculating an oscillation energy flow direction index R of the left power transmission line by the control signal selection module 1 And oscillation energy flow direction index R of right side transmission line 2 ；
S3: selecting an oscillation energy flow direction index R i &gt, 0 corresponding to the active power signal and the reactive power signal of the power transmission line as the output signal P of the control signal selection module c And Q c (ii) a Wherein i =1,2;
s4: selecting the output signal P of the module by the control signal c Inputting an oscillation identification module, wherein the oscillation identification module adopts a signal analysis algorithm to calculate the number m of forced power oscillation modes and the oscillation frequency omega corresponding to each oscillation mode n Wherein n =1,2,…,m；
S5: when at t s Oscillation frequency omega corresponding to each oscillation mode obtained in time period n When the standard deviation is smaller than the standard deviation threshold value, the oscillation identification module outputs the number m of the forced power oscillation modes and the oscillation frequency omega corresponding to each oscillation mode n Otherwise, the output of the oscillation identification module is 0;
s6: if the output of the oscillation identification module is 0, no signal is input into the active power control module and the reactive power control module; if the output of the oscillation identification module is not 0, the number of the harmonic oscillator modules of the resonance controllers in the active power control module and the reactive power control module is set to be the number m of the forced power oscillation modes, and the central frequency of each resonance controller is set to be the oscillation frequency omega corresponding to each oscillation mode n ；
S7: selecting the output signal P of the module by the control signal c Inputting an active power control module, and calculating to obtain active power P through a resonance controller and an amplitude limiting unit in the active power control module inj And the reference value is used as the reference value of the active power output by the E-STATCOM; selecting the output signal Q of the module by the control signal c Inputting the reactive power control module, and calculating to obtain the reactive power Q through a resonance controller and an amplitude limiting unit in the reactive power control module inj And is used as a reference value of the reactive power output by the E-STATCOM.
Further, the oscillation energy flow direction index R of the left power transmission line in step S2 1 And oscillation energy flow direction index R of right side transmission line 2 The calculation formula of (c) is:
where t is the length of the time window and Δ represents the amount of change.
Further, t is 3 to 5s.
Further, the signal analysis algorithm adopted by the oscillation identification module in the step S4 is any one of TLS-ESPRIT algorithm, prony algorithm, MUSIC algorithm or FFT algorithm.
Further, the expression of the resonance controller R (S) in step S7 is:
wherein, ω is n For the centre frequency, K, of the nth harmonic sub-module in the harmonic controller R Is the scaling factor and s is the differential operator.
The invention relates to a forced power oscillation suppression system based on an E-STATCOM, which comprises a signal acquisition module, wherein the input end of the signal acquisition module is respectively connected with a left power transmission line and a right power transmission line which are connected with an installation bus of the E-STATCOM, the output end of the signal acquisition module is connected with the input end of a control signal selection module, the output end of the control signal selection module is respectively connected with the input end of an oscillation identification module, the input end of a reactive power control module and the input end of an active power control module, the output end of the oscillation identification module is respectively connected with the input end of a reactive power control module and the input end of an active power control module, and the output end of the reactive power control module and the output end of the active power control module are both connected with the E-STATCOM.
Has the advantages that:
1) Compared with a forced power oscillation suppression method requiring manual operation of system operation control personnel, the method does not need manual operation, and automatically completes oscillation energy flow direction calculation, control signal selection, parameter design of an active power control module and a reactive power control module and control signal processing on line to obtain active power and reactive power signals output by the E-STATCOM, so that forced power oscillation can be suppressed more quickly and effectively;
2) The amplitude of a transfer function from a disturbance signal to the active power and the reactive power of the transmission line at the oscillation frequency is 0, so that the control method can restrain the forced power oscillation amplitude to 0 no matter where the E-STATCOM is installed in the system, and the restraining effect of the E-STATCOM is not influenced by the installation place of the E-STATCOM;
3) Compared with the traditional STATCOM, the output reactive power can be adjusted only through additional damping control, so that the system damping is improved, the oscillation amplitude is reduced, and complete suppression cannot be realized; the invention adopts the STATCOM (E-STATCOM) containing the energy storage unit, can directly inject active power into the system, generates active power with the same size and the opposite direction with the oscillation signal, and can restrain the amplitude of the forced power oscillation to 0, thereby having better restraining effect.
Drawings
FIG. 1 is a block diagram of the system of the present invention;
FIG. 2 is a block diagram of a stand-alone infinity system with an E-STATCOM installed;
FIG. 3 is a simulation result of a system without an E-STATCOM installed;
FIG. 4 shows simulation results of a system with an E-STATCOM installed.
Detailed Description
The technical solution of the present invention will be further described with reference to the following embodiments.
The following description of the present invention will be made by taking a typical stand-alone infinity system as an example. Single machine infinite system with E-STATCOM as shown in FIG. 2, a steam turbine, a governor system and a synchronous generator are connected to a bus i through a transformer, wherein the steam turbine and the governor system are denoted by TR, and the synchronous generator is composed of a voltage source and a transient reactance (X) d ') denotes that the voltage source has an amplitude E g Phase angle of delta g . The E-STATCOM is installed on a bus j and connected to an infinite bus k through a connecting line, and the impedance between the bus i and the bus j is jX L1 The impedance between bus j and bus k is jX L2 . The rated capacity and rated voltage of the synchronous generator are 200MW and 200MW respectively13.8kV, rated frequency 60Hz, and operation at a load factor of 0.7 p.u.. The resonant oscillation frequency of the system is about 6.5102rad/s.
First, a system without E-STATCOM installed was simulated at [10s,40s ]]The frequency of the sinusoidal disturbance added with 0.01pu to the power of the prime motor is the same as the natural oscillation frequency of the system and is 6.5102rad/s. The simulation results obtained are shown in FIG. 3, where the solid line represents the prime mover power P m The dotted line is the power P absorbed by the infinite bus b . As can be seen from fig. 3, since the disturbance frequency is the same as the natural oscillation frequency of the system, the prime mover power disturbance with the amplitude of only 0.01pu induces the active power oscillation absorbed by the infinite bus of 0.14pu, and the disturbance is amplified by 14 times. This indicates the criticality of forced power oscillations.
And then installing the E-STATCOM between the transformer and the transmission line, namely the secondary side of the transformer. The same disturbance is added, and the forced power oscillation suppression method based on the E-STATCOM provided by the invention comprises the following specific steps:
s1: the signal acquisition module 1 acquires the voltage U of an E-STATCOM installation bus j j Frequency f j Active power signal P of transmission line between E-STATCOM installation bus i and bus j ij And a reactive power signal Q ij And the active power signal P of the transmission line between the E-STATCOM installation bus j and the bus k jk And a reactive power signal Q jk Correspondingly, the output signals passing through the signal acquisition module 1 are respectively U jd 、f jd 、P ijd 、Q ijd 、P jkd 、Q jkd ；
S2: inputting the signals acquired by the signal acquisition module 1 in the step S1 into the control signal selection module 2, and calculating the oscillation energy flow direction index R of the left power transmission line by the control signal selection module 2 1 And oscillation energy flow direction index R of right side transmission line 2 The specific calculation formula is as follows:
wherein Δ represents the amount of change; finding R 1 <0、R 2 >0；
S3: due to R 2 &gt, 0, selecting the active power signal P of the transmission line between the E-STATCOM installation bus j and the bus k jkd And a reactive power signal Q jkd As the output signal of the control signal selection module 2;
s4: installing an active power signal P of a transmission line between an E-STATCOM installation bus j and a bus k jkd Inputting the oscillation identification module 3, calculating the number of forced power oscillation modes to be 1 by adopting TLS-ESPRIT algorithm, and obtaining the corresponding oscillation frequency omega 1 ＝6.5102rad/s；
S5: calculating the oscillation frequency omega obtained in 2s 1 Standard deviation of (d), oscillation frequency ω before 14.9s 1 Is greater than the standard deviation threshold value of 2 multiplied by 10 -4 The output of the oscillation identification module 3 is 0; oscillation frequency omega at 14.9s 1 Is less than the standard deviation threshold value of 2 multiplied by 10 -4 The number 1 of the output forced power oscillation modes of the oscillation identification module 3 and the corresponding oscillation frequency ω of the oscillation modes 1 Is 6.5102rad/s;
s6: before 14.9s, if the output signal of the oscillation identification module 3 is 0, no signal is input into the active power control module 5 and the reactive power control module 4; after 14.9s, the output signal of the oscillation identification module 3 is not 0, at this time, the number of the harmonic oscillator modules of the resonance controller in the active power control module 5 and the reactive power control module 4 is set to be 1, and the central frequency of the resonance controller is set to be the numerical value omega of the oscillation frequency corresponding to the oscillation mode 1 ＝6.5102rad/s；
S7: the output signal of the control signal selection module 2, namely the active power signal P of the transmission line between the bus j and the bus k, is acquired jkd Input to the active power control module 5, through the active power control module 5The active power P is obtained by the calculation of the resonance controller and the amplitude limiting unit inj And is used as a reference value of active power output by the E-STATCOM 6; the output signal of the control signal selection module 2, namely the acquired reactive power signal Q of the transmission line between the bus j and the bus k jkd Inputting the reactive power control module 4, and calculating to obtain the reactive power Q through a resonance controller and an amplitude limiting unit in the reactive power control module 4 inj And is used as a reference value of the reactive power output by the E-STATCOM 6.
Wherein the resonant controller R(s) has the expression:
in the formula, omega 1 For the center frequency, omega, of the resonant controller 1 ＝6.5102rad/s，K R Is a proportionality coefficient, K R And 40,s is a differential operator.
The upper limit of the amplitude limiting unit in the active power control module 5 and the reactive power control module 4 is set to be 0.1pu, and the lower limit is set to be-0.1 pu.
E-STATCOM using the suppression method of the present invention was added to the system at [10s,40s ]]In between, a sinusoidal perturbation of 0.01pu is added to the prime mover power, also at a frequency of 6.5102rad/s. The simulation results obtained are shown in FIG. 4, where the solid line represents the prime mover power P m The dotted line is the power P absorbed by the infinite bus b . As can be seen, with the control method proposed herein, the amplitude of the active power absorbed by the infinite bus after about 18s is already small, and finally the oscillation is completely damped. 10s-14.9s-18s is a dynamic process of oscillation frequency identification time and oscillation suppression, and the process can be further reduced by improving a frequency identification algorithm to achieve a better suppression effect.

Claims (5)

1. A forced power oscillation suppression method based on an E-STATCOM is characterized by comprising the following steps: the method comprises the following steps:
s1: the signal acquisition module (1) acquires E-STVoltage U of ATCOM installation bus j Frequency f j And the active power signal P of the left power transmission line connected with the E-STATCOM installation bus ij And a reactive power signal Q ij And the active power signal P of the right side transmission line connected with the E-STATCOM installation bus jk And a reactive power signal Q jk ；
S2: inputting the signals acquired by the signal acquisition module (1) in the step S1 into the control signal selection module (2), and calculating the oscillation energy flow direction index R of the left power transmission line by the control signal selection module (2) 1 And oscillation energy flow direction index R of right side transmission line 2 ；
S3: selecting an oscillation energy flow direction index R i &gt, 0 corresponding to the active power signal and the reactive power signal of the power transmission line as the output signal P of the control signal selection module (2) c And Q c (ii) a Wherein i =1,2;
s4: selecting the output signal P of the module (2) by the control signal c The oscillation identification module (3) is input, the oscillation identification module (3) adopts a signal analysis algorithm to calculate the number m of the forced power oscillation modes and the oscillation frequency omega corresponding to each oscillation mode n Wherein n =1,2, …, m;
s5: when at t s Oscillation frequency omega corresponding to each oscillation mode obtained in time period n When the standard deviation is smaller than the standard deviation threshold value, the oscillation identification module (3) outputs the number m of the forced power oscillation modes and the oscillation frequency omega corresponding to each oscillation mode n Otherwise, the output of the oscillation identification module (3) is 0;
s6: if the output of the oscillation identification module (3) is 0, no signal is input into the active power control module (5) and the reactive power control module (4); if the output of the oscillation identification module (3) is not 0, the number of the harmonic oscillator modules of the resonance controller in the active power control module (5) and the reactive power control module (4) is set to be the number m of the forced power oscillation modes, and the central frequency of each resonance controller is set to be the oscillation frequency omega corresponding to each oscillation mode n ；
S7: selecting the output signal of the module (2) from the control signalP c Inputting an active power control module (5), and calculating active power P through a resonance controller and a limiting unit in the active power control module (5) inj And is used as a reference value of active power output by the E-STATCOM (6); selecting the output signal Q of the module (2) from the control signal c Inputting the reactive power control module (4), and calculating to obtain the reactive power Q through a resonance controller and an amplitude limiting unit in the reactive power control module (4) inj And is used as a reference value of the reactive power output by the E-STATCOM (6).
2. The E-STATCOM-based forced power oscillation suppression method of claim 1, wherein: the oscillation energy flow direction index R of the left power transmission line in the step S2 1 And oscillation energy flow direction index R of right side transmission line 2 The calculation formula of (2) is as follows:
where t is the length of the time window and Δ represents the amount of change.
3. The E-STATCOM-based forced power oscillation suppression method of claim 2, wherein: t is 3-5s.
4. The E-STATCOM-based forced power oscillation suppression method of claim 1, wherein: the signal analysis algorithm adopted by the oscillation identification module (3) in the step S4 is any one of TLS-ESPRIT algorithm, prony algorithm, MUSIC algorithm or FFT algorithm.
5. The E-STATCOM-based forced power oscillation suppression method of claim 1, wherein: the expression of the resonance controller R (S) in step S7 is:
wherein, ω is n For the centre frequency, K, of the nth harmonic sub-module in the harmonic controller R Is the scaling factor and s is the differential operator.
CN201610008316.4A 2016-01-06 2016-01-06 A kind of forced power oscillation suppressing method and system based on E STATCOM Active CN105576673B (en)

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CN107634526B (en) * 2017-11-10 2020-04-17 广东电网有限责任公司电力科学研究院 Method and device for restraining forced oscillation of alternating current-direct current parallel power transmission system
CN108462190B (en) * 2018-01-03 2021-01-19 国网江苏省电力有限公司经济技术研究院 Forced power oscillation suppression method based on UPFC

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