CN107508307B - Active disturbance rejection direct current additional damping control method for suppressing subsynchronous oscillation - Google Patents
Active disturbance rejection direct current additional damping control method for suppressing subsynchronous oscillation Download PDFInfo
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Abstract
The invention discloses an active disturbance rejection direct current additional damping control method for inhibiting subsynchronous oscillation, which aims at the problem that the subsynchronous oscillation of a thermal power plant can be aggravated by large-scale wind power access of a power grid at a transmitting end, firstly utilizes TLS-ESPRIT algorithm to identify and obtain a low-order transfer function of a system in each subsynchronous oscillation mode, then, combining the ITAE index and the maximum and minimum value principle to obtain a controlled system control target, optimizing and determining the parameters of a multi-channel Active Disturbance Rejection Controller (ADRC) by using an improved genetic algorithm, and finally building a test system model containing wind power on a PSCAD/EMTDC, wherein simulation verification shows that the designed subsynchronous additional damping controller is applied to various operation modes and fault conditions of a transmission end power grid, the method can effectively inhibit the subsynchronous oscillation of the steam turbine generator unit, has high robustness, has a good control effect on the low-order ADRC, and is suitable for the practical application of engineering.
Description
Technical Field
The invention belongs to the field of high-voltage direct-current transmission, and particularly relates to an improved active disturbance rejection direct-current additional damping control method for subsynchronous oscillation of a wind-fire bundling delivery system.
Background
With the annual increase of the development scale of new energy, a large amount of new energy represented by wind power is connected into a traditional power system mainly based on thermal power, which brings new challenges to the research of subsynchronous oscillation (SSO). High Voltage Direct Current (HVDC) may cause subsynchronous torsional vibration of a steam turbine generator unit, cause fatigue accumulation and even breakage of a large shaft of the unit, and seriously threaten the stable operation of an electric power system (Lixing source, high voltage direct current transmission system [ M ] Beijing: scientific publishing agency, 2010: 177-183.). After wind power is switched in, sub-synchronous interaction among wind power, thermal power and HVDC becomes more complex.
In 2014, the Khatina to Zhengzhou kilovolt high-voltage direct-current transmission project is built and put into operation, and plays an important role in bundling wind, fire and electricity and delivering the bundled electricity to the outside in Xinjiang. However, with the large-scale access of the wind power base, serious subsynchronous oscillation of a turbo generator set shaft system at the transmitting end of the Hami power grid is detected for many times in actual operation, and torsional oscillation protection starting is caused. Therefore, the subsynchronous oscillation suppression of the reinforced wind fire bundling and conveying system is imperative.
For the subsynchronous oscillation caused by the sending of the thermal Power generating unit through HVDC, an additional direct current damping controller is mostly adopted to suppress (BJORKLIND H, JOHANSON K E, LISS G. damping of subsynchronous oscillations in systems regulating and HVDC links [ J ]. IEEETransactions on Power2007, 22 (1): 314-. The prior art designs additional sub-synchronous damping controllers (SSDC) with new methods in modern control engineering, such as genetic algorithms, particle swarm algorithms, fuzzy immunization methods, etc.
Although the various control methods have good suppression effect on subsynchronous oscillation, the requirements on the scale of a system model and the accuracy of parameters are high, the control performance of the control methods has certain limitations, and the condition of wind power access is not considered. Active Disturbance Rejection Control (ADRC) absorbs the results of modern control theory, develops and enriches the thought essence of PID control of eliminating errors based on errors, and has been widely applied to electric power systems in China. Therefore, the method has important significance for the research of the method for designing the low-order robust damping controller.
Disclosure of Invention
Aiming at the problem that large-scale wind power access of a power transmission end grid can aggravate sub-synchronous oscillation of a thermal power plant, the method comprises the steps of firstly identifying and obtaining a low-order transfer function of the system in each sub-synchronous oscillation mode by utilizing a TLS-ESPRIT (total least square method for harmonic frequency estimation) algorithm, then obtaining a controlled system control target by combining an ITAE index (a performance index obtained by multiplying time of the performance index by an absolute value of error integral) and a maximum minimum value principle, optimizing and determining a multi-channel Active Disturbance Rejection Controller (ADRC) parameter by using an improved genetic algorithm, and finally building a wind power-contained test system model on PSCAD/EMTDC.
The method can effectively inhibit the subsynchronous oscillation of the steam turbine generator unit under various operation modes and fault conditions of the power grid at the sending end, has stronger robustness, has better control effect on the low-order ADRC, and is suitable for practical engineering application.
In order to solve the technical problems, the invention adopts the technical scheme that:
an active disturbance rejection direct current additional damping control method for suppressing subsynchronous oscillation comprises the following steps:
step 1: screening out a power plant which is most likely to generate subsynchronous oscillation near a sending end direct current converter station by using a unit action coefficient method, applying 0.02p.u. step disturbance to a constant current position at an HVDC rectification side, taking a rotor angular speed difference of the power plant unit when small disturbance exists as output, and identifying oscillation characteristics of a test system under the condition that a wind power field is accessed or not by using a TLS-ESPRIT algorithm;
step 2: decomposing different oscillation modes into different channels by using a 6-order Butterworth band-pass filter, identifying system models of all oscillation modes by using a TLS-ESPRIT algorithm again, reducing orders by using a balanced truncation method, and reserving leading poles corresponding to all the oscillation modes to obtain system low-order transfer functions corresponding to all the oscillation modes;
and step 3: taking the system low-order transfer functions corresponding to all the oscillation modes obtained in the step (2) as controlled objects of active disturbance rejection control, and designing a multi-channel 2-order active disturbance rejection controller by adopting the active disturbance rejection control of an improved genetic algorithm;
the improved genetic algorithm adopted in the active disturbance rejection control of the improved genetic algorithm is as follows:
1) generating an initial population
Randomly generating initial population, using floating point coding mode for individual, using chromosome length as parameter to be solved [ β01,β02,β03,β1,β2]The number of (2);
2) determining fitness function
Setting a reasonable fitness function is an important link for the overall optimization of the genetic algorithm; selecting an error functional evaluation index in a control system: the time-multiplied absolute error integral criterion is used as a control target of active disturbance rejection control, the inherent saturation characteristic of a controlled object is considered, a control quantity limiting factor is introduced in a weighting mode, and a multi-target evaluation index comprehensively considering control energy limitation and an error functional is set, and the following formula is shown:
wherein e (t) is the control error, t is the integration time, umax、uminThe maximum value and the minimum value of the control quantity are respectively, η is a weight coefficient, η is more than 0;
defining a final fitness function of the genetic algorithm as follows:
in the formula, a matrix C is an operation condition matrix of the system; r1For all possible sets of controller parameters, R2As a set of all possible operating conditions;
3) genetic manipulation
a) Selecting: calculating the fitness value of each individual in the population, and sorting out the elite parent generation according to the quality sequence;
b) crossing and mutation: the self-adaptive adjustment is carried out by selecting the cross probability and the mutation probability according to the following formula:
wherein P is the cross probability PcOr the probability of variation Pm，fmaxIs the maximum fitness value of the population, favgIs the average fitness value of each generation of population, and f is the fitness value of the individual to be crossed or mutated; k is a radical of1,k2Taking the value in the interval (0, 1); respectively taking different k according to requirements1,k2Value to calculate Pc、PmFurther adaptively adjusting PcAnd Pm。
Further, after different oscillation modes are decomposed into different channels by using a 6 th-order butterworth bandpass filter in step 2, positive damping can be provided for a certain oscillation mode, and negative damping can not be provided for other oscillation modes or a new oscillation mode is excited.
Compared with the prior art, the invention has the beneficial effects that:
1) the problem of subsynchronous oscillation of new energy accessed to the vicinity of a traditional thermal power plant is considered, a test system which is based on actual engineering and contains large-scale wind power integration and is sent out through LCC-HVDC is established, a transfer function of the system in each subsynchronous oscillation mode is obtained through TLS-ESPRIT algorithm identification, and the complexity of establishing a mathematical model of the large system is reduced.
2) The advantage that the total disturbance inside and outside the system can be estimated and compensated in real time under the condition that the precise mathematical model of the controlled object is not available in the active disturbance rejection control is utilized, and meanwhile, the active disturbance rejection additional damping controller based on the improved genetic algorithm is designed by combining the ITAE index of the controlled limited system and the maximum and minimum value principle.
3) The ADRC designed aiming at subsynchronous oscillation can quickly and effectively damp the system oscillation under various operation modes and faults of an upward direct current test system, and has stronger robustness.
Drawings
Fig. 1 is a schematic diagram of an active disturbance rejection controller.
Fig. 2 is a flow chart of active disturbance rejection controller design based on an improved genetic algorithm.
Fig. 3 is a structural schematic diagram of a multi-channel active disturbance rejection direct current additional damping controller.
Fig. 4 is a diagram of a test system island operation topology.
Fig. 5 shows the rotor angular velocity difference (SSO1 mode rotor angular velocity difference) of the mode 1 fox unit in the example.
Fig. 6 shows the rotor angular velocity difference (SSO2 mode rotor angular velocity difference) of the mode 1 fox unit in the example.
FIG. 7 is the shafting torque (T) of the mode 2 Foxi machine set in the embodimentA-B)。
FIG. 8 is the shafting torque (T) of the mode 2 Foxi machine set in the embodimentB-G)。
Fig. 9 is a rotor angular velocity difference (fuxi unit rotor angular velocity difference) of the sub-synchronous oscillation frequency band of each power plant unit in the mode 3 in the embodiment.
FIG. 10 is the rotor angular velocity difference (Luzhou set rotor angular velocity difference) of the subsynchronous oscillation frequency band of each power plant set in the mode 3 in the embodiment.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
1. Basic principle and structure of active disturbance rejection controller
The active disturbance rejection control can effectively solve the control problems of large-scale, variable-structure and uncertain systems, does not depend on an accurate mathematical model of a controlled object, can automatically estimate and compensate internal and external disturbance of the controlled object, and has strong adaptability and robustness.
Compared with the defects that an Error extraction method is unreasonable, an Error differential signal is not easy to extract, integral Feedback may deteriorate the dynamic characteristic of a system, weighting and strategies are not optimal and the like in PID control, active disturbance rejection control reasonably improves an Extended State Observer (ESO) and a Nonlinear Error Feedback (NLSEF) by using a Nonlinear differential Tracker (TD), an ESO and the NLSEF, so that a better control effect is achieved.
a) The fastest discrete tracking differentiator is designed to arrange a proper transition process, relieve the contradiction between 'rapidity' and 'overshoot', and reasonably extract an error differential signal.
In the formula, v0To a setting value, v1、v2Representing the scheduled transition and its differential signal; h is an integration step length; r is0Is a velocity factor, h0For the filter factor, fhan is a korean function, the detailed calculation of which is described in the literature (hangin. active disturbance rejection control technique — control technique of estimating compensation uncertainty factor [ M]Beijing: national defense industry press, 2013: 255-261.).
b) The estimated system state and total disturbance are tracked with the system output y and input u using the extended state observer.
In the formula, z in ESO3Estimated is the "real-time contribution" of the unknown part of the "total disturbance"; b0β as compensation factor, the main regulating parameter when controlling time-lag system01,β02,β03Is a set of adjustable parameters.
c) Nonlinear error feedback is used for replacing linear feedback, a controlled object is converted into an integral series system by using a dynamic compensation linearization means, and a final control quantity is formed.
In the formula, the fal functions are the same as those in the formula (2) and are power functions, and detailed calculation thereof is described in the literature (Han Jingqing. auto disturbance rejection control technology-control technology for estimating and compensating uncertainty factor [ M [)]Beijing, national defense industry Press, 2013, 255-1,β2As well as a set of adjustable parameters.
The active disturbance rejection controller is composed of the three core parts, and the specific structure is shown in fig. 1.
2. Active disturbance rejection parameter setting based on improved genetic algorithm
The auto-disturbance-rejection controller has more parameters to be set, and the design is based on the literature (Hanjingqing auto-disturbance-rejection control technology-control technology for estimating and compensating uncertain factors [ M)]Beijing: national defense industry press, 2013: 255 plus 261.)0＝10，h＝h0＝0.01，b 05 and the extended state observer parameter β01,β02,β03And nonlinear feedback parameters β1,β2The invention provides an improved Genetic Algorithm (GA), and solves parameters during active disturbance rejection optimal control based on the improved genetic algorithm [ β ] to solve parameters during active disturbance rejection optimal control01,β02,β03,β1,β2]The value of (c). The specific tuning process of the improved genetic algorithm is as follows (Guo-Yi-Feng, Xuzhao-Dong, Zhao-Qing, etc.. the optimization analysis of the weight matrix in the LQR algorithm based on the genetic algorithm [ J]Vibration and shock, 2010, 29 (11): 217-220.):
a) generating an initial population
Randomly generating initial population, using floating point coding mode for individual, using chromosome length as parameter to be solved [ β01,β02,β03,β1,β2]The number of (2).
b) Determining fitness function
Setting a reasonable fitness function is an important link for overall GA optimization. Selecting an error functional evaluation index in a control system: and (3) taking a time-multiplied-absolute-error integration criterion (ITAE) as a control target of active disturbance rejection control, simultaneously considering possible inherent saturation characteristics of a controlled object, weighting and introducing a controlled quantity limiting factor, and setting a multi-target evaluation index comprehensively considering control energy limitation and an error functional, wherein the index is shown as a formula (4).
Wherein e (t) is the control error, t is the integration time, umax、uminThe maximum value and the minimum value of the control quantity are respectively, η is a weight coefficient, η is more than 0;
the key to the ADRC design is to determine the controller parameter matrix β ═ β01,β02,β03,β1,β2]So as to ensure that the controller can obtain ideal control effect under all possible operation conditions of the system. This problem can be classified as a mathematical maximum-minimum problem, so defining the final fitness function of the genetic algorithm as:
where the matrix C is the operating condition matrix of the system, R1For all possible sets of controller parameters, R2Is the set of all possible operating conditions.
c) Genetic manipulation
a. Selecting: and calculating the fitness value of each individual in the population, and sorting the elite parents according to the quality sequence.
b. Crossing and mutation: the cross operator and the mutation operator can keep the diversity of the population, so that the algorithm has active random search capability. In order to avoid GA falling into local optimum, a self-adaptive crossing and variation mode is adopted.
In the conventional genetic algorithm, the cross probability PcUsually, the value is large, and the mutation probability PmAnd otherwise, the optimization is kept unchanged in the whole optimization process. In fact, as the evolution algebra increases, the individuals tend to be consistent and continue to use the overlarge cross probability PcTo produce new individuals with very low efficiency; at the same time, the smaller mutation probability PmThe population can not be effectively dragged to be over-plane, and the population is easy to fall into local optimal predicament. Therefore, the crossover and mutation probabilities are selected for the genetic manipulation and are adaptively adjusted according to the formula (6).
In the formula (f)maxIs the maximum fitness value of the population, favgIs the mean fitness value of each generation population, f isFitness values of individuals to be crossed or mutated; k is a radical of1,k2Taking the value in the interval (0,1), and respectively taking different k if required1,k2Value to calculate Pc、PmCan adaptively adjust PcAnd Pm. The invention calculates PcTaking k by time1＝0.7,k2When P is 0.9, P is calculatedmTaking k by time1＝0.005,k2＝0.2。
After the cross probability and the variation probability are adjusted in a self-adaptive manner, P can be realized when the individual fitness value of the population tends to be consistent or locally optimalcAnd PmIncreasing and vice versa. While f is made higher than favgGet smaller PcAnd PmProtecting the individual from entering the next generation preferentially; for f is lower than favgGet larger PcAnd PmThe individual is accelerated to be eliminated. The design steps of the self-defense warfare controller based on the improved genetic algorithm are shown in FIG. 2.
In summary, the method of the present invention comprises the following steps:
step 1: a power plant which is most likely to have subsynchronous oscillation near a sending end direct current converter station is screened out by using a unit action coefficient method (UIF), 0.02p.u. step disturbance is applied to a constant current position on an HVDC rectification side, the rotor angular speed difference of the power plant unit when small disturbance exists or not is taken as output, and oscillation characteristics of a test system are identified by using a TLS-ESPRIT algorithm under the condition that a wind power plant is accessed or not.
Step 2: different oscillation modes are decomposed to different channels by using a 6 th-order Butterworth (Butterworth) band-pass filter, so that mutual influence among the oscillation modes is restrained (when the controller restrains subsynchronous oscillation, positive damping is possibly provided for a certain mode, negative damping is provided for another mode, and even a new oscillation mode is excited), system models of all the oscillation modes are identified by using a TLS-ESPRIT algorithm again respectively, the order is reduced by using a balanced truncation method, a dominant pole corresponding to each oscillation mode is reserved, and system low-order transfer functions corresponding to all the oscillation modes are obtained.
And step 3: and (3) taking the system low-order transfer functions corresponding to all the oscillation modes obtained in the step (2) as a controlled object of the active disturbance rejection control, and designing a multichannel 2-order active disturbance rejection controller by utilizing the proposed active disturbance rejection control based on the improved genetic algorithm. The structure of the active disturbance rejection direct current additional damping controller is shown in figure 3.
The technical scheme of the invention is described and beneficial technical effects are verified by the following embodiments.
The simulation model of the embodiment adopts the upward direct current sending end island operation of the Sichuan power grid. Based on an upward direct current topological structure, a wind power base is connected to a position near a power plant at a transmitting end, and a topological wiring diagram of wind-fire bundling and external transmission through LCC-HVDC shown in fig. 4 is constructed.
When a test system electromagnetic transient model is built, a 500kV line is mainly considered, and a 220kV line and a load are processed with proper equivalence. In the wind power plant, 360 doubly-fed wind generators are equivalently aggregated and then connected into a Yibin transformer substation, and the rated capacity is 500 MW. The aggregation model is obtained by connecting ideal controlled current sources in parallel on a single DFIG detailed model. The number of the sending ends is 5 turbo generator sets with the same model number, and the turbo generator sets are all represented by 4 mass block models, and a rotor shaft system of the turbo generator set mainly comprises 4 shaft sections of a high-middle combined cylinder (HIP), a low-pressure cylinder A (LPA), a low-pressure cylinder B (LPB) and a Generator (GEN).
1. System oscillation characteristic identification
The unit action coefficient method is used for determining that each unit of the Fuxi power plant is most likely to generate subsynchronous oscillation, so that 0.02p.u. step disturbance is applied to a constant current position on a direct current rectification side, the rotor angular speed difference of the Fuxi No. 1 unit is taken as output when small disturbance exists, the TLS-ESPRIT algorithm is used for identifying the oscillation characteristics of the test system under the condition that a wind power field is accessed or not, and the identification result is shown in Table 1.
TABLE 1TLS-ESPRIT Algorithm oscillation pattern identification results
According to the identification result, 2 subsynchronous frequency band oscillation modes exist in the system when a wind power plant exists or not, the frequencies are respectively 13.4Hz and 24.5Hz, but after the wind power plant is connected to the grid, the amplitudes and phase angles of the oscillation modes SSO1 and SSO2 are deviated, the original damping of the system is weakened, the damping of the mode 1 is changed to be negative, the oscillation is easy to disperse, and the stable operation of the system is not facilitated.
2. Active disturbance rejection additional damping controller design
According to the identification result in table 1, different oscillation modes are decomposed into different channels by using a 6-order Butterworth (Butterworth) band-pass filter, the system models of 2 oscillation modes are identified by using TLS-ESPRIT algorithm respectively, then the order is reduced by using a balanced truncation method, the dominant pole corresponding to each oscillation mode is reserved, and the system low-order transfer functions corresponding to the two oscillation modes are obtained, as shown in formulas (7) and (8). The ESO in the active disturbance rejection control can compensate for the system model uncertainty caused by the reduction.
The transfer functions shown in the formula (7) and the formula (8) are respectively used as controlled objects of the active disturbance rejection control, and the steps shown in the figure 2 are used for the proposed active disturbance rejection control based on the improved genetic algorithm, so that the multichannel 2-order active disturbance rejection controller is designed. The structure of the active disturbance rejection direct current additional damping controller is shown in figure 3.
When the genetic algorithm is optimized by the formula (5), the parameter search range R of the controller is taken1Is β03∈(1,50)，[β01,β02,β1,β2]∈ (0,001,1), System operating conditions search Range R2Is taken as PDC∈ (10%, 100%), in combination with the principle of maximum and minimum, an objective function is defined as:
the multi-channel second-order active disturbance rejection controller is designed for the oscillation modes SSO1 and SSO2 to remove β in SSO1031.91, SSO2 medium β03Other than 6.93, the rest parametersThe two oscillation modes are the same and are respectively [ β ]01,β02,β1,β2]＝[0.548,0.461,0.639,0.44]。
3. Accuracy verification
A simulation model shown in figure 4 is built on a PSCAD, and after the improved multi-channel active disturbance rejection damping controller, the traditional active disturbance rejection damping controller and the classic PI controller provided by the invention are added at a constant current position on an upward direct current rectification side, the dynamic characteristics of the system under various operation modes and different disturbance actions are simulated and analyzed so as to verify the suppression action of each controller on SSO. And during simulation, the wind speed is controlled to be constant at 15m/s, and the wind power plant is fully developed. Because the control signal is selected to be the Fuxi No. 1 unit delta omega and is a wide-area measurement signal instead of a local signal, 5ms signal transmission time lag is considered during simulation, and the time lag is approximately replaced by a Pade link.
Three disturbances, namely an upward direct-current bipolar full-power operation three-phase fault (mode 1), a monopolar power reduction to 50% operation three-phase fault (mode 2) and a bipolar power reduction to 15% operation single-phase fault (mode 3), are selected during island. The failure setting mode is as follows:
a) three-phase earth faults occur at 0.5s of the converter bus at the converter side of the converter, and the faults last for 0.05 s;
b) when Luzhou arrives at 99% of the line to the Home dam, a single-phase (A-phase) earth fault occurs at 1s, and the fault lasts for 0.1 s.
The results of the 3-way simulation are shown in fig. 5-10, respectively, and are limited to space, with each fault only given a typical generator oscillation condition. FIGS. 5 and 6 are rotor angular velocity differences of the Foxi power plant in mode 1 at 13.4Hz and 24.5Hz sub-synchronous oscillation modes, respectively; fig. 7 and 8 show the torques T of the low pressure cylinder a to the low pressure cylinder B in the mode 2, respectivelyA-BAnd torque T from low pressure cylinder B to generatorB-G(ii) a Fig. 9 and 10 are the rotor angular speed differences within 5-45Hz of the sub-synchronous frequency band for the fuxi power plant and the luzhou power plant, respectively, in mode 3.
Simulation results of different modes show that the subsynchronous oscillation of a power plant without the SSDC front end is serious, and the fatigue accumulation of a large shaft of a unit is easy to cause. FIG. 5, FIG. 6, FIG. 7 and FIG. 8 show the same kind of fault under different conditions, after adding the improved active disturbance rejection SSDCShafting torsional vibration T no matter severe three-phase earth fault occurs in upward direct current unipolar or bipolar operationA-BCorresponding SSO1 mode, TB-GThe corresponding SSO2 mode subsynchronous oscillation can be well inhibited. The improved active disturbance rejection SSDC can effectively subside oscillation after the fault is cleared for 2.5s, and compared with the traditional ADRC and PI controllers, the improved active disturbance rejection SSDC can damp subsynchronous oscillation of a system in a shorter time, and has a good inhibiting effect on SSO of a Foxi power plant thermal power unit. Fig. 9 and 10 show that when the system operation mode and the applied fault type are changed simultaneously, the inhibition effect of the PI additional controller is obviously poor, continuous amplitude-reduced oscillation with larger amplitude still exists in the rotor angular velocity difference of each power plant thermal power generating unit in the sub-synchronous frequency band after 20s simulation, and the ADRC optimized by the GA can still realize quick and stable inhibition on the sub-synchronous oscillation under the condition, has robustness superior to that of the traditional ADRC and PI controller, and is more beneficial to prolonging the service life of each steam turbine unit.
Therefore, under various working conditions and different faults, the improved active disturbance rejection subsynchronous additional controller optimized through the genetic algorithm can effectively damp shafting torsional vibration among all mass blocks of the thermal power generating unit in a short time, ensures the shafting safety of a steam turbine generator of a sending end system, and has better control performance compared with the traditional ADRC and PI controllers.
Claims (2)
1. An active disturbance rejection direct current additional damping control method for suppressing subsynchronous oscillation is characterized by comprising the following steps:
step 1: screening out a power plant which is most likely to generate subsynchronous oscillation near a sending end direct current converter station by using a unit action coefficient method, applying 0.02p.u. step disturbance to a constant current position at an HVDC rectification side, taking a rotor angular speed difference of the power plant unit when small disturbance exists as output, and identifying oscillation characteristics of a test system under the condition that a wind power field is accessed or not by using a TLS-ESPRIT algorithm;
step 2: decomposing different oscillation modes into different channels by using a 6-order Butterworth band-pass filter, identifying system models of all oscillation modes by using a TLS-ESPRIT algorithm again, reducing orders by using a balanced truncation method, and reserving leading poles corresponding to all the oscillation modes to obtain system low-order transfer functions corresponding to all the oscillation modes;
and step 3: taking the system low-order transfer functions corresponding to all the oscillation modes obtained in the step (2) as controlled objects of active disturbance rejection control, and designing a multi-channel 2-order active disturbance rejection controller by adopting the active disturbance rejection control of an improved genetic algorithm;
the improved genetic algorithm adopted in the active disturbance rejection control of the improved genetic algorithm is as follows:
1) generating an initial population
Randomly generating initial population, using floating point coding mode for individual, using chromosome length as parameter to be solved [ β01,β02,β03,β1,β2]The number of (2);
2) determining fitness function
Setting a reasonable fitness function is an important link for the overall optimization of the genetic algorithm; selecting an error functional evaluation index in a control system: the time-multiplied absolute error integral criterion is used as a control target of active disturbance rejection control, the inherent saturation characteristic of a controlled object is considered, a control quantity limiting factor is introduced in a weighting mode, and a multi-target evaluation index comprehensively considering control energy limitation and an error functional is set, and the following formula is shown:
wherein e (t) is the control error, t is the integration time, umax、uminThe maximum value and the minimum value of the control quantity are respectively, η is a weight coefficient, η is more than 0;
defining a final fitness function of the genetic algorithm as follows:
in the formula, a matrix C is an operation condition matrix of the system; r1For all possible sets of controller parameters, R2As a set of all possible operating conditions;
3) genetic manipulation
a) Selecting: calculating the fitness value of each individual in the population, and sorting out the elite parent generation according to the quality sequence;
b) crossing and mutation: the self-adaptive adjustment is carried out by selecting the cross probability and the mutation probability according to the following formula:
wherein P is the cross probability PcOr the probability of variation Pm，fmaxIs the maximum fitness value of the population, favgIs the average fitness value of each generation of population, and f is the fitness value of the individual to be crossed or mutated; k is a radical of1,k2Taking the value in the interval (0, 1); respectively taking different k according to requirements1,k2Value to calculate Pc、PmFurther adaptively adjusting PcAnd Pm。
2. The ADRC control method for suppressing subsynchronous oscillation of claim 1, wherein the different oscillation modes are decomposed into different channels by using a 6 th-order Butterworth band-pass filter in step 2, so that a certain oscillation mode can be positively damped, while other oscillation modes are not negatively damped or a new oscillation mode is excited.
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| CN114928074B (en) * | 2022-05-12 | 2024-02-02 | 西安交通大学 | Subsynchronous oscillation suppression method and system based on transfer learning and active disturbance rejection control |
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