CN117439179A - Grid-connected converter grid synchronous control method based on biquad generalized integrator - Google Patents
Grid-connected converter grid synchronous control method based on biquad generalized integrator Download PDFInfo
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- CN117439179A CN117439179A CN202311361682.4A CN202311361682A CN117439179A CN 117439179 A CN117439179 A CN 117439179A CN 202311361682 A CN202311361682 A CN 202311361682A CN 117439179 A CN117439179 A CN 117439179A
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- 230000001360 synchronised effect Effects 0.000 title claims abstract description 22
- 230000003068 static effect Effects 0.000 claims abstract description 12
- 230000009466 transformation Effects 0.000 claims abstract description 7
- 238000012544 monitoring process Methods 0.000 claims abstract description 4
- 238000004364 calculation method Methods 0.000 claims description 6
- 238000010586 diagram Methods 0.000 claims description 4
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Classifications
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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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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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
- H02J3/002—Flicker reduction, e.g. compensation of flicker introduced by non-linear load
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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
- H02J3/01—Arrangements for reducing harmonics or ripples
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- Physics & Mathematics (AREA)
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- Inverter Devices (AREA)
Abstract
A grid-connected converter grid synchronous control method based on a biquad generalized integrator belongs to the technical field of communication, and a built grid-connected converter grid synchronous control system monitors grid line voltage u in real time ab 、u bc U is obtained by Clarke transformation α 、u β Then the SOGQ-QSG and the phase-locked loop FLL are used for realizing frequency tracking and self-adaptive control, positive and negative sequence components of the grid voltage in a static coordinate system extracted according to PNSC are used for realizing phase angle monitoring and synchronization through the phase-locked loop PLL, the system can be free from the influence of grid distortion and harmonic waves by obtaining transient symmetrical components based on a second-order generalized integrator self-adaptive filter, the fundamental frequency and the phase angle of the grid voltage are rapidly and accurately captured, and therefore grid-connected stability of the converter is stabilized, compared with other conventional phase-locked loops, the method can be used for rapidly and accurately detecting the fundamental wave of the grid voltage when the grid harmonic wave and the grid fall fault occurFrequency and phase angle acquisition.
Description
Technical Field
The invention belongs to the technical field of communication, and particularly relates to a grid-connected converter grid synchronous control method based on a biquad generalized integrator.
Background
Due to the distributed power generation system of the power electronic converter and the large-scale grid connection of electric equipment in recent years, the stability of the power grid is also poorer and poorer. When abnormal conditions such as falling and sudden rising, frequency fluctuation, harmonic pollution and the like occur in the power grid, the phase locking method is used for rapidly acquiring information such as the phase and the frequency of the power grid, and the like, so that the continuous and stable operation of the power grid is ensured. The suppression capability of the phase locking method to the power quality problem becomes an evaluation standard for checking the phase locking performance. The conventional practice is to perform phase-locked control in a synchronous rotating coordinate System (SRF). However, when three-phase voltage unbalance is encountered, the method cannot decouple positive and negative sequences and energy of each subharmonic of the power grid, so that the synchronous performance of the power grid is affected. The other method is to use a decoupling double synchronous reference frame phase-locked loop (DDSRF-PLL), the system ensures accurate power grid synchronization under asymmetric faults, however, when the method encounters stronger low-order harmonic interference, the decoupling performance of the method can be seriously influenced, and in the transient process of power grid fault dropping and recovery, the transient oscillation can be caused by voltage phase angle jump. For grid-connected converters, grid frequency is often the most stable variable in the power system, and frequency oscillation is therefore a drawback of this approach.
Disclosure of Invention
In order to solve the above problems, the present invention proposes: grid-connected converter grid synchronous control method based on biquad generalized integrator and three-phase voltage u a 、u b And u c Obtaining the voltage u under the static coordinate system through Clarke transformation α And u β The two second-order generalized integrator-quadrature signal generators SOGI-QSG generate direct-axis and quadrature-axis signals for the alpha, beta components in the input vector, respectively, by the two second-order generalized integrator-quadrature signal generators SOGI-QSG: u's' α 、u' β ，qu' α 、qu' β These signals are used as the input of the positive and negative sequence component calculation module PNSC to realize the extraction of positive and negative sequence components of the grid voltage in the static coordinate system; according to positive and negative sequence components of the grid voltage in the static coordinate system extracted by the PNSC, realizing the grid voltage by using the PLL of the synchronous coordinate systemAnd detecting positive and negative sequence phase angles.
Further, the input signal u to the error signal epsilon is obtained u A baud diagram of the transfer function E(s) from u to the quadrature signal qu'.
Further, when the input frequency ω is lower than the resonant frequency ω', ω<Omega', epsilon u In phase with qu', frequency error signal epsilon f The average value is greater than zero; when ω > ω', ε u Inverse to qu', frequency error signal ε f The average value is less than zero; ω=ω', ε f =0; PLL input frequency error signal epsilon f Equivalent to epsilon u And qu'.
Further, a frequency error signal ε is generated from the α, β components in the input voltage vector α And epsilon β Combined with the error signal calculation method
The two-dimensional FLL gain is obtained by using the quadratic sum of the positive sequence component modulus values, i.eNormalized and sent to an integrator through its nominal frequency omega θ The feedforward quantity is overlapped to obtain final frequency locking output omega ', and omega' is used as the input of the SOGI-QSG, so that a closed loop system is formed to realize frequency tracking.
Further, the built grid-connected converter grid synchronous control system monitors the grid line voltage u in real time ab 、u bc U is obtained by Clarke transformation α 、u β Then, frequency tracking and self-adaptive control are realized through an SOGQ-QSG and a phase-locked loop FLL, and phase angle monitoring and synchronization are realized through a phase-locked loop PLL according to positive and negative sequence components of grid voltage in a static coordinate system extracted by PNSC.
The beneficial effects of the invention are as follows: the invention discloses a method for ensuring a grid frequency locking system to rapidly and accurately acquire information such as grid voltage positive and negative sequence fundamental wave amplitude, phase and frequency when a grid is subjected to abnormal conditions such as grid drop and sudden rise, frequency change and harmonic pollution.
Drawings
FIG. 1 is a diagram of a DSOGI control architecture of the present invention;
FIG. 2 is a schematic diagram of a PLL based on positive and negative sequence synchronous coordinate systems of the present invention;
FIG. 3 is a Bode plot of the invention E(s) and Q(s);
fig. 4 is an experimental waveform of the synchronization system of the present invention.
Detailed Description
In order to make the technical means adopted by the invention and achieve the purpose easy to understand, the invention is further described below with reference to the specific embodiment, and a grid-connected converter grid synchronous control method based on a biquad generalized integrator is provided, as shown in fig. 1, the structure of the biquad generalized integrator can know the three-phase voltage u a 、u b And u c Obtaining voltage u under static coordinate system by Clarke transformation α And u β Two second-order generalized integrator-quadrature signal generators (SOGI-QSG) generate direct and quadrature signals, e.g., u ', for the alpha, beta components, respectively, in the input vector' α 、u' β ，qu' α 、qu' β . These signals are used as inputs to a positive and negative sequence component calculation module (PNSC) to effect extraction of positive and negative sequence components of the grid voltage in the stationary coordinate system.
As shown in fig. 2, according to the positive and negative sequence components of the grid voltage in the static coordinate system extracted by the PNSC, the positive and negative sequence phase angles of the grid voltage can be detected by the PLL of the synchronous coordinate system.
As shown in fig. 3, from the input signal u to the error signal epsilon u As can be seen from the transfer function E(s) of (a) and the transfer function Q(s) Bot plot from u to the quadrature signal qu ', when the input frequency ω is lower than the resonance frequency ω', i.e., ω<Omega', epsilon u In phase with qu', frequency error signal epsilon f The average value is greater than zero; when ω > ω', ε u Inverse to qu', frequency error signal ε f The average value is less than zero; ω=ω', ε f =0. Thereby leading out the PLL input frequency error signal epsilon f Equivalent to epsilon u And qu'.
Frequency error signal epsilon generated by alpha, beta components in the input voltage vector according to figure 1 α And epsilon β Combining with error signal calculation method
Such a two-dimensional FLL gain can be obtained by using the sum of the positive-sequence component modulus values squared, i.e Normalized and sent to an integrator through its nominal frequency omega θ The feedforward quantity is overlapped to obtain the final frequency locking output omega ', and omega' is used as the input of the SOGI-QSG in the figure 1, so that a closed loop system is formed, and frequency tracking is realized.
The grid synchronization control system of the grid-connected converter constructed by the method can monitor the voltage u of the power grid line in real time ab 、u bc U is obtained by Clarke transformation α u β Frequency tracking and adaptive control is then achieved through SOGQ-QSG and FLL. And according to positive and negative sequence components of the grid voltage in the static coordinate system extracted by the PNSC, phase angle monitoring and synchronization are realized through the PLL.
Grid voltage background harmonics and fault dips were simulated using Maltab, fig. 4 is an experimental waveform. The d-axis component, angular frequency and lock of the power grid voltage are sequentially arranged from top to bottomPhase angle and grid line voltage u ab (see FIG. 4). In fig. 4a and c, the grid voltage is injected with 5 and 7 times of background harmonic waves, and at the moment, the grid phase angle and the angular frequency detected by the DSOGI-FLL and the DDSRF-PLL synchronous systems are compared, and as can be seen from fig. 4a and c, the high-frequency oscillation phenomenon of the amplitude of the grid synchronous system of the bi-second-order generalized integrator is smaller. Fig. 4b, d show the grid phase angle and angular frequency in case of a 50% imbalance drop of the grid voltage two phases. Fig. 4b adopts a biquad generalized integrator grid synchronization system, and achieves accurate synchronization time of a grid phase angle and a frequency of 5ms when a grid fails to transient.
When the stability of the power grid is poor, the synchronous performance of the synchronous rotation coordinate system is often seriously affected due to unbalanced three-phase voltage when the phase-locked control is performed in the synchronous rotation coordinate system, and the reason for the phenomenon is that the method cannot decouple the positive and negative voltage sequences and the harmonic components. The system obtains transient symmetrical components based on the second-order generalized integrator self-adaptive filter, and can rapidly and accurately capture the fundamental frequency and phase angle of the power grid voltage under the conditions of higher harmonic content of the power grid and power grid fault drop, and the system is not influenced by power grid distortion and harmonic waves.
Compared with other conventional phase-locked loops, the method can capture the fundamental frequency and phase angle of the power grid voltage faster and more accurately when the power grid has higher power grid harmonic and power grid drop faults. The principle of the method is that transient symmetrical components are obtained through a self-adaptive filter based on a second-order generalized integrator, so that the fundamental wave frequency and the voltage phase angle of the power grid voltage are rapidly captured in the transient process of power grid fault dropping and recovery.
The invention belongs to the field of wind power generation, and provides a corresponding control strategy and an application method based on a biquad generalized integrator power grid synchronization system (DSOGI-FLL) aiming at the situation that power grid harmonic is large and power grid faults fall off, which can quickly capture the fundamental frequency and phase angle of power grid voltage without interference of power grid distortion.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical solution and the concept of the present invention, and should be covered by the scope of the present invention.
Claims (5)
1. A grid-connected converter grid synchronous control method based on a biquad generalized integrator is characterized in that the method comprises the following steps of a 、u b And u c Obtaining the voltage u under the static coordinate system through Clarke transformation α And u β The two second-order generalized integrator-quadrature signal generators SOGI-QSG generate direct-axis and quadrature-axis signals for the alpha, beta components in the input vector, respectively, by the two second-order generalized integrator-quadrature signal generators SOGI-QSG: u's' α 、u' β ，qu' α 、qu' β These signals are used as the input of the positive and negative sequence component calculation module PNSC to realize the extraction of positive and negative sequence components of the grid voltage in the static coordinate system; and according to the positive and negative sequence components of the grid voltage in the static coordinate system extracted by the PNSC, the positive and negative sequence phase angles of the grid voltage are detected through the PLL of the synchronous coordinate system.
2. The grid-connected inverter grid synchronization control method based on the biquad generalized integrator according to claim 1, wherein the input signal u to the error signal epsilon are obtained u A baud diagram of the transfer function E(s) from u to the quadrature signal qu'.
3. The grid-connected inverter grid synchronization control method based on the biquad generalized integrator according to claim 2, wherein when the input frequency ω is lower than the resonance frequency ω', ω is<Omega', epsilon u In phase with qu', frequency error signal epsilon f The average value is greater than zero; when ω > ω', ε u Inverse to qu', frequency error signal ε f The average value is less than zero; ω=ω', ε f =0; PLL input frequency error signal epsilon f Equivalent to epsilon u And qu'.
4. The bi-quad generalized integrator-based grid-tie of claim 3The synchronous control method of current transformer power network is characterized by that it utilizes the frequency error signal epsilon produced by alpha and beta components in input voltage vector α And epsilon β Combined with the error signal calculation method
The two-dimensional FLL gain is obtained by using the quadratic sum of the positive sequence component modulus values, i.eNormalized and sent to an integrator through its nominal frequency omega θ The feedforward quantity is overlapped to obtain final frequency locking output omega ', and omega' is used as the input of the SOGI-QSG, so that a closed loop system is formed to realize frequency tracking.
5. The grid-connected inverter grid synchronization control method based on the biquad generalized integrator according to claim 4, wherein the built grid-connected inverter grid synchronization control system monitors grid line voltage u in real time ab 、u bc U is obtained by Clarke transformation α 、u β Then, frequency tracking and self-adaptive control are realized through SOGQ-QSG and FLL, and phase angle monitoring and synchronization are realized through FLL according to positive and negative sequence components of grid voltage in a static coordinate system extracted by PNSC.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117614020A (en) * | 2024-01-24 | 2024-02-27 | 浙江日风电气股份有限公司 | Method, device and medium for software phase-locked loop |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117614020A (en) * | 2024-01-24 | 2024-02-27 | 浙江日风电气股份有限公司 | Method, device and medium for software phase-locked loop |
| CN117614020B (en) * | 2024-01-24 | 2024-03-29 | 浙江日风电气股份有限公司 | Method, device and medium for software phase-locked loop |
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