CN117439160A - Power decoupling control and reactive power rapid adjustment method for self-synchronous power supply of weak current network - Google Patents
Power decoupling control and reactive power rapid adjustment method for self-synchronous power supply of weak current network Download PDFInfo
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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
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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
- H02J3/381—Dispersed generators
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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
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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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
- H02J3/38—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
- H02J3/48—Controlling the sharing of the in-phase component
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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
- H02J3/50—Controlling the sharing of the out-of-phase component
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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
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- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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Abstract
The invention relates to a decoupling control and reactive power rapid adjustment method for a self-synchronizing power supply of a weak power grid. Based on a self-synchronous power supply system small signal model of a grid-connected running state and an island running state, determining static and transient stability requirements of the self-synchronous power supply system small signal model, and considering power decoupling method requirements of transmission capacity, and providing a virtual impedance range determining method for realizing power decoupling control; further considering the influence on the unbalance of the system and the harmonic current in the virtual impedance application process, performing a virtual impedance-based filter design to realize a complete virtual impedance control module design; the method is characterized in that by determining a proper virtual impedance range, the power decoupling problem is solved, and the voltage distortion problem caused by harmonic load is relieved; in addition, the reactive power rapid adjustment method based on the transient impedance control strategy of the self-adaptive virtual impedance is invented and applied, so that the power control performance during transient and power grid faults is improved.
Description
Technical Field
The invention relates to the field of self-synchronous power supply converter control, in particular to a method for decoupling control and reactive power rapid adjustment of self-synchronous power supply power of a weak current network.
Background
With the development of self-synchronizing power supplies, a micro-grid concept consisting of multiple self-synchronizing power supply clusters is proposed. Compared with the traditional power distribution system, the micro-grid can operate in a grid-connected mode and an island mode, and in order to facilitate operation conversion in the grid-connected mode and the island mode, the voltage-controlled converter is widely studied, and higher reliability and higher power quality are provided.
The self-synchronous power supply control based on communication has the problems of low reliability, high investment and the like. Parallel self-synchronizing supply voltage control, represented by frequency and voltage amplitude droop control, based on measuring local signals is the mainstay of current engineering applications. Among this class of control, active (P) and reactive (Q) power droop control is one of the most popular methods. However, when a large number of distributed units are directly connected to a point of common coupling with resistive feed lines, the following problems arise:
1) The system P-Q coupling and steady state reactive power errors are severe due to the presence of differential feeder impedance.
2) If no additional coupled inductor is introduced between the self-synchronizing power supply unit and the grid-tie point, the stability and transient performance of the self-synchronizing power supply system will be affected.
To solve the power coupling problem described above, virtual active and reactive power architecture methods, as well as virtual voltage and frequency architecture methods, are introduced into the converter control system. However, these methods have difficulty in improving the accuracy of power allocation. Another approach to improve transient performance and suppress power coupling is to add a virtual inductance to the converter. The power control and sharing performance of the self-synchronizing power supply unit may be improved if the virtual impedance is properly designed and implemented. However, if improperly designed, the virtual impedance approach may introduce current distortion, thereby adversely affecting system stability and dynamics.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, provides a self-synchronous power supply power decoupling control and reactive power rapid adjustment method under a weak current network based on self-adaptive virtual impedance, and aims to realize the functions of power decoupling, reactive power rapid adjustment and the like of a controller by performing virtual impedance design under the constraint of power decoupling and stability conditions on the premise of not changing a circuit structure so as to ensure the auxiliary performance of the virtual impedance to the self-synchronous power supply system.
In order to achieve the above purpose, the invention provides a method for controlling the power decoupling of a self-synchronizing power supply of a weak current network, which is characterized by adopting a self-adaptive virtual impedance design, and comprises the following specific steps:
step 1, a power grid small signal model based on a complex matrix is established, a self-synchronous power supply power sag control and grid-connected off-grid operation scene is comprehensively considered, a system small signal model applied to a grid-connected operation state and an island operation state of a converter is respectively established by taking a voltage phase angle and an amplitude of a self-synchronous power supply unit as variables, the developed complex matrix has a similar structure in the grid-connected mode and the island mode, and the matrix is easier to update when the number of power generation units changes.
And 2, according to the power grid small signal model obtained in the step 1, providing a virtual impedance range determining method for realizing power decoupling control based on the static and transient stability requirements of the grid-connected running state and the island running state of the converter and the power decoupling method requirement based on the transmission capacity of the power generation unit. The method specifically comprises the following steps:
in a system operation area, the maximum power output capacity of the self-synchronous power supply unit is larger than the system power requirement; the P-Q decoupling constraint condition should be satisfied; based on the two types of constraint conditions, the virtual impedance design range meeting the system operation requirement can be initially determined.
On the basis, the virtual impedance design needs to further consider the static stability constraint and the transient stability constraint of the system.
Static stability constraint requires: the pole real part is negative and less than a certain negative value standard to meet the system stability margin standard.
Transient stability constraint requires: the absolute value of the imaginary part of the pole is positive, and the ratio of the absolute value to the absolute value of the real part is greater than a certain positive standard to meet the system damping standard.
To ensure proper operation in grid-tie and island modes, all virtual impedance design constraints described above should be satisfied. Meanwhile, to ensure a smooth transition between grid-connected and island operation, the same virtual impedance design is used in both modes.
Step 3, based on the virtual impedance range obtained in the step 1 and the step 2, further considering the influence on the unbalance and harmonic current of the system in the virtual impedance application process, and performing virtual impedance-based filter design to realize complete virtual impedance control module design; the method comprises the following steps:
the invention provides a virtual impedance harmonic wave and unbalance suppression method adopting a multi-loop voltage control scheme. In a micro-grid with remarkable harmonic load, a plurality of harmonic resonance controllers are used corresponding to harmonic frequencies, each harmonic resonance controller adopts a parallel computing mode, and the performance of the converter is improved through the virtual impedance design of each frequency.
On the other hand, the invention provides a self-synchronous power supply reactive power rapid adjustment method under a weak power network based on self-adaptive virtual impedance for further improving the transient performance of a self-synchronous power supply system. The method comprises the following specific steps:
in order to compensate transient impedance voltage drop caused by active power flow, an impedance voltage drop feedforward control strategy is designed, so that the amplitude of the output voltage of the converter is regulated by a proportional-integral controller of a reactive power loop and an active power feedforward controller.
In order to improve the transient performance during the change of the reactive power reference value, an adaptive transient impedance control is designed. During the reactive power step up, due to the influence of the low pass filter, the instantaneous change of reactive power is not monitored, and the output of the reactive power proportional integral controller still introduces reactive power overshoot, resulting in bad transients. The proposed method rapidly increases the output reactive power by comparing the measured reactive power with a reference value to produce an adaptively reduced virtual inductance deviation amount. Furthermore, the method is only effective during transients. When the transient is completed, the virtual impedance is restored to the original value.
In order to improve the grid-connected point voltage disturbance ride-through capability, a disturbance monitoring method based on current monitoring is designed, a current peak is limited by using larger self-adaptive virtual impedance, and the grid-connected point voltage disturbance ride-through capability of the converter is improved. The grid-connected point voltage disturbance is reflected as the inrush current of the output power, and due to the existence of low-pass filtering, the grid-connected electric voltage disturbance is detected by the output power to be too slow to protect the self-synchronous power supply unit, the strategy of adopting the output current amplitude is quicker and more efficient, and the enabling and disabling conditions of the crossing function are determined based on the comparison of the current amplitude and a preset value. And the power grid voltage disturbance ride-through scheme has the highest priority in the adaptive virtual impedance control.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
1. the invention provides a self-synchronous power supply power decoupling control method under a weak current network based on self-adaptive virtual impedance, which provides a scheme for comprehensively determining a required impedance range by comprehensively considering static stability, transient stability and decoupling performance of active and reactive power flows of a self-synchronous power supply.
2. The self-synchronous power supply power decoupling control method under the weak current network based on the self-adaptive virtual impedance provided by the invention has the advantages that the virtual impedance is combined with the proportional resonance controller to optimize the harmonic and unbalanced response characteristics, and compared with the physical impedance, the virtual impedance can also alleviate the voltage distortion problem caused by the harmonic load;
3. the invention provides a reactive power rapid regulation method of a self-adaptive virtual impedance self-synchronous power supply under a weak current network, which introduces the concept of self-adaptive impedance to self-adaptively inhibit the influence of transient impedance voltage drop on the output power flow of a converter when a power reference value changes in a large range or the voltage of the power network is greatly disturbed; power control performance during transients and grid faults is improved.
Drawings
Fig. 1 is a control block diagram of a self-synchronous power supply power decoupling control method under a weak current network based on self-adaptive virtual impedance according to an embodiment of the present invention;
fig. 2 is a control block diagram of a reactive power transient state adjusting method in a self-synchronous power supply reactive fast adjusting method under a weak current network with self-adaptive virtual impedance, which is provided by the embodiment of the invention;
fig. 3 is a control block diagram of a grid-connected point voltage disturbance traversing method in a self-synchronous power supply reactive power rapid adjusting method under a weak power network with self-adaptive virtual impedance provided by the embodiment of the invention;
FIG. 4 is a diagram showing the effect of power decoupling characteristics according to an embodiment of the present invention;
FIG. 5 is a graph showing the effect of the power quick response characteristic according to the embodiment of the present invention;
FIG. 6 is a flowchart of a specific example of a control system provided by an embodiment of the present invention;
fig. 7 is a composition diagram of a specific example of a computer device according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and the specific examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. Referring to fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6 and fig. 7, fig. 1 is a control block diagram of a self-synchronous power supply power decoupling control method under a weak current network based on adaptive virtual impedance according to an embodiment of the present invention; fig. 2 is a control block diagram of a reactive power transient state adjusting method in a self-synchronous power supply reactive fast adjusting method under a weak current network with self-adaptive virtual impedance, which is provided by the embodiment of the invention; fig. 3 is a control block diagram of a grid-connected point voltage disturbance traversing method in a self-synchronous power supply reactive power rapid adjusting method under a weak power network with self-adaptive virtual impedance provided by the embodiment of the invention; FIG. 4 is a diagram showing the effect of power decoupling characteristics according to an embodiment of the present invention; FIG. 5 is a graph showing the effect of the power quick response characteristic according to the embodiment of the present invention; FIG. 6 is a flowchart of a specific example of a control system provided by an embodiment of the present invention; fig. 7 is a composition diagram of a specific example of a computer device according to an embodiment of the present invention.
Example 1
The control block diagram of the self-synchronous power supply power decoupling control method under the weak current network based on the self-adaptive virtual impedance shown in fig. 1 comprises a main circuit and a control module, wherein the main circuit comprises a direct current unit and a direct current/alternating current conversion circuit. The self-synchronous power supply power decoupling control module under the weak current network based on the self-adaptive virtual impedance mainly comprises a virtual impedance module and a multi-ring voltage controller. The invention provides a self-synchronous power supply power decoupling control method under a weak current network based on self-adaptive virtual impedance, which is shown in figure 1 and comprises the following basic steps:
firstly, establishing a power grid small signal model based on a complex matrix according to a system running state, comprehensively considering power sag control, and respectively establishing the system small signal model applied to a grid-connected running state and an island running state of the converter. The method comprises the following specific steps:
first, voltage, current, phase information may be obtained based on grid monitoring equipment.
Then, the existing island detection method can realize judgment of grid-connected operation states and island operation states of the converter.
On the basis, a system small signal model applied to the grid-connected running state and the island running state of the converter is built respectively, and the system small signal model is as follows:
consider self-synchronizing power supply power flow:
wherein V is DG And V PCC Is the magnitude of the voltage vector of the self-synchronous power supply unit and the grid-connected point, theta is the phase angle difference between the two vectors, Y andis the magnitude and phase angle of the feed line conductance.
Under the grid-connected operation scene, the self-synchronous power supply droop control equation:
wherein ω and V DG Controlling the frequency and the voltage of the sagging of the converter respectively, wherein P and Q are the measured output power of the converter, and P ref And Q ref Is the reference power of the converter, V DG0 Represents the nominal value of the voltage amplitude, K P And K I The proportional coefficient and the integral coefficient of the proportional-integral controller are respectively, and s represents a differential operator.
Under island operation scene, from synchronous power supply sagging control equation:
wherein: d (D) p And D q Droop gain, P, representing active and reactive power controllers lated And Q lated Is the rated power of the converter.
In summary, the small signal model with the following formula can be respectively established in the grid-connected state and the island state:
(A(s)-B(s)·C(s))·X＝0 (4)
wherein, X= [ delta theta, delta V DG ] T ，Δθ,ΔV DG The voltage phase angle and the amplitude of the self-synchronizing power supply unit respectively.
The complex matrix developed has a similar structure in grid-connected and island modes, and is easier to update when the number of power generation units changes.
Secondly, according to the power grid small signal model obtained in the first step, a virtual impedance range determining method for realizing power decoupling control is provided based on the static and transient stability requirements of the grid-connected running state and the island running state of the converter and the power decoupling method requirement based on the transmission capacity of the power generation unit; the method specifically comprises the following steps:
the virtual impedance design needs to meet the constraint condition of the P-Q decoupling characteristic of the system:
wherein K is Decouple Is the P-Q decoupling coefficient. High enough K Decouple It will be ensured that both active and reactive power can be controlled with minimal coupling. In a low voltage microgrid, if no additional inductance is added to the self-synchronizing power supply output, the P-Q decoupling coefficient based on the inverter will be significantly lower than that of the synchronous generator. To meet the P-Q decoupling constraints, additional virtual impedances need to be designed to maintain a high K Decouple Coefficients.
Virtual impedance design further considers system static and transient stability constraints:
in the grid-connected operation state, the root track analysis based on the small signal model in the step 1 shows that: when the reactance is small, a pole exists on the right half plane, and the system is unstable. When the reactance increases, the pole moves to the left half plane and the system becomes steady state, but further increases in reactance will attract the pole to the real axis, over-damping the system. Thus, to maintain proper stability and transient performance, two types of constraints are satisfied:
1) The pole real part is negative and less than a certain negative value standard to meet the system stability margin standard.
2) The absolute value of the imaginary part of the pole is positive, and the ratio of the absolute value to the absolute value of the real part is greater than a certain positive standard to meet the system damping standard.
On the other hand, in the system operating region, the maximum power output capacity of the self-synchronizing power supply unit should be greater than the system power demand. By combining the above constraints, the final virtual impedance design range can be determined
The criteria in island operation are similar but in island mode more stringent stability constraint criteria can be used because island mode generally has better stability than grid-connected mode because the latter employs a proportional-integral controlled reactive control loop.
To ensure proper operation in grid-tie and island modes, all virtual impedance design constraints described above should be satisfied. Meanwhile, to ensure a smooth transition between grid-connected and island operation, the same virtual impedance design is used in both modes.
Thirdly, based on the virtual impedance range obtained in the second step, further considering the influence on the unbalance of the system and the harmonic current in the virtual impedance application process, and performing virtual impedance-based filter design to realize complete virtual impedance control module design; the method comprises the following steps:
after determining the desired range of virtual impedance, a generalized virtual impedance format is proposed that includes a virtual resistor and a virtual inductor, at which time the virtual voltage drop of the virtual impedance occurs, since the feeder resistance in the low voltage microgrid may exceed the desired total resistance range:
V V (s)＝(V V,α (s)+jV V,β (s))＝(R V +jω 0 L V )(I α (s)+jI β (s)) (6)
wherein:R V and L V Is designed virtual resistance and inductance, V V,α (s) and V V,β (s)，I α (s) and I β (s) is the voltage drop and current introduced by the virtual impedance in the stationary αβ coordinate system. In low voltage microgrids, the feeder resistance is likely to be higher than the required range. Thus, a negative R is required V To obtain better transient performance.
Furthermore, while the fundamental frequency characteristic is an important point of virtual impedance, its effect on imbalance and harmonic currents must also be discussed. The invention provides a virtual impedance harmonic wave and unbalance suppression method adopting a multi-loop voltage control scheme. The specific adoption ratio resonance controller:
wherein: k (k) p Is a proportional gain, k I_i For the i-th harmonic resonance gain omega c Is the cut-off frequency, ω, of the resonant controller 0 Is the fundamental frequency. In a micro-grid with significant harmonic loading, using multiple harmonic resonance controllers for the corresponding harmonic frequencies can significantly improve converter performance.
Example 2
The invention provides a self-synchronous power supply reactive power rapid adjustment method under a weak current network based on self-adaptive virtual impedance, which is shown in fig. 2 and 3, and basically comprises the following steps:
in order to compensate transient impedance voltage drop caused by active power flow, an impedance voltage drop feedforward control strategy is designed, so that the amplitude of the output voltage of the converter is regulated by a proportional-integral controller of a reactive power loop and an active power feedforward controller.
Under the traditional control strategy: the self-synchronizing power supply voltage amplitude and power relationship class is expressed as:
V DG ＝V PCC +(R total /V PCC )P DG +(X total /V PCC )Q DG (8)
wherein R is total And L is equal to total Respectively, including a virtual part andtotal resistance and total inductance, V, of the actual part pcc Is the voltage of the grid-connected point. In order to compensate for the impedance drop introduced by the transient active power flow (note that the steady state voltage drop is compensated by the reactive power PI controller), a method of implementing transient impedance drop feedforward control over reactive power regulation is employed:
wherein,for grid-connected point rated voltage, the output voltage amplitude of the converter is jointly regulated by a proportional-integral controller and an active power feedforward controller of the reactive power loop through the mode.
In order to improve the transient performance during the change of the reactive power reference value, an adaptive transient impedance control is designed. During the reactive power step up, due to the influence of the low pass filter, the instantaneous change of reactive power is not monitored, and the output of the reactive power proportional integral controller still introduces reactive power overshoot, resulting in bad transients. The proposed method adaptively reduces the differential virtual inductance by comparing the measured reactive power with a reference value to rapidly increase DG output reactive power. Furthermore, the method is only effective during transients. When the transient is completed, the virtual impedance is restored to the original value, as shown in fig. 2.
Furthermore, when a transient impedance is employed, the self-synchronizing power supply impedance should still be within the desired impedance range obtained in the foregoing method. Still according to the required resistance-inductance ratio K R P-Q coupling is minimized. Therefore, the virtual resistance should also be adjusted accordingly. Adaptive transient virtual resistance ΔR V And DeltaL V Still satisfy:
K R (R V +ΔR V +R feeder )＝ω 0 (L V +ΔL V +L feeder ) (10)
wherein R is feeder And L is equal to feeder Respectively a tie line resistance and an inductance.
In order to improve the grid-connected point voltage disturbance ride through capability, a larger self-adaptive virtual impedance is used for limiting a current peak, so that the grid-connected point voltage disturbance ride through capability of the converter is improved. The grid-connected point voltage disturbance is reflected as the inrush current of the output power, and due to the existence of low-pass filtering, the grid-connected electric voltage disturbance is detected by the output power to be too slow to protect the self-synchronous power supply unit, the strategy of adopting the amplitude of the output current is faster and is smiling, and the enabling and disabling conditions of the crossing function are determined based on the comparison of the amplitude of the current and a preset value, as shown in fig. 3. And the power grid voltage disturbance ride-through scheme has the highest priority in the adaptive virtual impedance control.
In summary, based on the method provided by the invention, virtual impedance can be comprehensively designed while considering static and transient stability of the self-synchronous power supply and decoupling performance of active and reactive power flows; the harmonic wave and unbalanced response characteristic of the self-synchronous power supply are optimized by combining the proportional resonance controller, so that the voltage distortion problem caused by harmonic wave load is solved; and the transient power control performance of the self-synchronous power supply is realized through the self-adaptive virtual impedance design when the power voltage is greatly disturbed.
Fig. 4 is a diagram showing the effect of simulated power decoupling characteristics of a self-synchronous power supply power decoupling control method under a weak current network based on self-adaptive virtual impedance; fig. 5 shows a simulated power decoupling characteristic effect diagram of the self-synchronous power supply reactive power rapid adjustment method based on the self-adaptive virtual impedance-based weak current network.
Example 3
The embodiment of the invention provides a system for decoupling control and reactive power rapid adjustment of a self-synchronous power supply of a weak power grid, which is shown in fig. 6 and comprises the following steps:
the small signal model calculation module 1 is used for establishing a small signal model of the self-synchronous power supply system based on a complex matrix. The method specifically comprises the following steps: extracting system running state sampling information from secondary equipment monitoring and carrying out information processing; calculating a self-synchronous power supply system small signal model of the grid-connected state or the off-grid state corresponding to the island detection judgment result based on the sampling data and the self-synchronous power supply control system parameters by judging that the island detection system based on the sampling information is in the grid-connected state or the off-grid state; this module performs the method described in the first step in embodiment 1, and will not be described here.
The virtual impedance range calculating module 2 is configured to calculate a virtual impedance range for implementing power decoupling control, and specifically includes: based on the sampling information, calculating a virtual impedance range meeting an active-reactive power decoupling constraint condition, a virtual impedance range meeting a static stability constraint condition and a virtual impedance range meeting a transient stability constraint condition; based on the constraint range, summarizing the calculation result of the constraint virtual impedance range, and comprehensively determining the virtual impedance range for realizing power decoupling control by combining the self-synchronous power supply capacity with the virtual impedance constraint; this module performs the method described in the second step in embodiment 1, and will not be described here.
The virtual impedance optimization design module 3 is configured to perform negative sequence and harmonic frequency band virtual impedance design, and specifically includes: the virtual impedance harmonic wave and unbalance suppression method adopting the multi-loop voltage control scheme uses a plurality of harmonic resonance controllers corresponding to harmonic wave and negative sequence frequency, each harmonic resonance controller adopts a parallel calculation mode, and the performance of the converter is improved through the virtual impedance design of each frequency; this module performs the method described in the third step in embodiment 1, and will not be described here.
The reactive power rapid adjustment module 4 is configured to implement rapid adjustment of output reactive power of the self-synchronous power supply, and specifically includes: an impedance voltage drop feedforward control link is adopted, the amplitude of the output voltage of the converter is regulated, and the self-synchronous power supply is quickly regulated to output reactive power and limit current peaks by combining the self-adaptive transient impedance; this module performs the method described in embodiment 2, and is not described here.
Example 4
An embodiment of the present invention provides a computer device, as shown in fig. 7, including: at least one processor 401, such as a CPU (Central Processing Unit ), at least one communication interface 403, a memory 404, at least one communication bus 402. Wherein communication bus 402 is used to enable connected communications between these components. The communication interface 403 may include a Display screen (Display) and a Keyboard (Keyboard), and the optional communication interface 403 may further include a standard wired interface and a wireless interface. The memory 404 may be a high-speed RAM memory (Ramdom Access Memory, volatile random access memory) or a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory 404 may also optionally be at least one storage device located remotely from the aforementioned processor 401. The processor 401 may execute the self-synchronous power supply power decoupling control method under the weak network of embodiment 1 and the self-synchronous power supply reactive fast adjustment method under the weak network of embodiment 2. A set of program codes is stored in the memory 404, and the processor 401 calls the program codes stored in the memory 404 for executing the self-synchronous power supply power decoupling control method under the weak electric network of embodiment 1 and the self-synchronous power supply reactive fast adjustment method under the weak electric network of embodiment 2.
The communication bus 402 may be a peripheral component interconnect standard (peripheral component interconnect, PCI) bus or an extended industry standard architecture (extended industry standard architecture, EISA) bus, among others. Communication bus 402 may be divided into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one line is shown in fig. 7, but not only one bus or one type of bus.
Wherein the memory 404 may include volatile memory (English) such as random-access memory (RAM); the memory may also include a nonvolatile memory (english: non-volatile memory), such as a flash memory (english: flash memory), a hard disk (english: hard disk drive, abbreviated as HDD) or a solid-state drive (english: SSD); memory 404 may also include a combination of the above types of memory.
The processor 401 may be a central processor (English: central processing unit, abbreviated: CPU), a network processor (English: network processor, abbreviated: NP) or a combination of CPU and NP.
Wherein the processor 401 may further comprise a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof (English: programmable logic device). The PLD may be a complex programmable logic device (English: complex programmable logic device, abbreviated: CPLD), a field programmable gate array (English: field-programmable gate array, abbreviated: FPGA), a general-purpose array logic (English: generic array logic, abbreviated: GAL), or any combination thereof.
Optionally, the memory 404 is also used for storing program instructions. The processor 401 may invoke program instructions to implement the self-synchronous power supply power decoupling control method under the weak power network of embodiment 2 and the self-synchronous power supply reactive fast adjustment method under the weak power network of embodiment 1 as executed in the present application.
The embodiment of the invention also provides a computer readable storage medium, and the computer readable storage medium is stored with computer executable instructions, and the computer executable instructions can execute the self-synchronous power supply power decoupling control method under the weak power grid of the embodiment 1 and the self-synchronous power supply reactive power rapid adjustment method under the weak power grid of the embodiment 2. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a Flash Memory (Flash Memory), a Hard Disk (HDD), or a Solid-State Drive (SSD); the storage medium may also comprise a combination of memories of the kind described above.
The invention is not limited to the embodiments described above. The above description of specific embodiments is intended to describe and illustrate the technical aspects of the present invention, and is intended to be illustrative only and not limiting. Numerous specific modifications can be made by those skilled in the art without departing from the spirit of the invention and scope of the claims, which are within the scope of the invention.
Claims (14)
1. A method for decoupling control and reactive power rapid adjustment of a self-synchronizing power supply of a weak current network is characterized by adopting a self-adaptive virtual impedance design and comprising the following steps:
step 1, establishing a self-synchronous power supply system small signal model based on a complex matrix, comprehensively considering self-synchronous power supply power sag control and grid-connected off-grid operation scenes, and respectively establishing a system small signal model applied to a self-synchronous power supply grid-connected operation state and an island operation state;
step 2, determining a virtual impedance range determination method for realizing power decoupling control based on static and transient stability requirements of a grid-connected running state and an island running state of the converter according to the self-synchronous power supply system small signal model obtained in the step 1 by cooperatively considering the power decoupling method requirements of self-synchronous power supply capacity;
step 3, based on the self-synchronous power system small signal model obtained in the step 1 and the virtual impedance range determining method obtained in the step 2, adding virtual impedance designs corresponding to disturbance response under harmonic and negative sequence frequency bands for inhibiting harmonic and negative sequence distortion;
and step 4, providing a reactive power rapid adjustment method of a self-adaptive transient impedance control strategy based on the virtual impedance control design in the steps 1-3.
2. The method for decoupling control and reactive fast adjustment of the self-synchronizing power supply of the weak electric network according to claim 1, characterized by comprising the following specific steps: feedforward control of impedance voltage drop, adaptive impedance for reactive power control, and adaptive impedance for grid-tied point voltage disturbance ride-through.
3. The method for decoupling control and reactive fast adjustment of self-synchronizing power supply power of a weak grid according to claim 1, wherein the virtual impedance range is calculated comprehensively based on stability, transient response and power flow performance of the self-synchronizing power supply unit.
4. The method for decoupling control and reactive fast adjustment of self-synchronizing power supply power of weak current network according to claim 1, wherein step 1 establishes a complex matrix-based self-synchronizing power supply system small signal model, and comprises the following specific processes:
determining sagging relation between reactive power and voltage and sagging relation between active power and frequency according to steady-state tide;
under a grid-connected scene, determining the relation between the output frequency and the output voltage of the converter and the output active power and reactive power of the converter, and establishing a small interference model when a grid-connected system is disturbed;
and in an island scene, determining the relation between the output frequency and the output voltage of the converter and the output active power and the output reactive power of the converter, and establishing a small interference model when the island system is disturbed.
5. The method for power decoupling control and reactive fast adjustment of a weak grid self-synchronizing power supply according to claim 1, wherein step 2 provides a virtual impedance range determining method for implementing the power decoupling control, and the specific process is as follows:
determining a first type of impedance boundary in consideration of self-synchronizing power supply power capacity constraints;
determining a second type impedance boundary by considering the active and reactive decoupling capacity constraint of the controller;
combining the two types of impedance boundaries, and determining an impedance range under double condition constraint;
and combining the static stability and transient stability requirements of each of the grid-connected operation mode and the island operation mode, and finally determining the virtual impedance design range.
6. The method for decoupling control and reactive fast adjustment of self-synchronizing power supply power of weak electric network according to claim 1, wherein step 3 provides an optimal design of a virtual impedance control module, comprising:
designing generalized virtual impedance of which the virtual resistance and inductance value range comprises a negative number value range;
virtual impedance corresponding to harmonic and negative sequence frequency bands is designed in response to harmonic and negative sequence distortion.
7. The method for decoupling control and reactive power fast adjustment of a weak grid self-synchronizing power supply according to claim 1, wherein step 4 provides a reactive power fast adjustment method of a self-adaptive transient impedance control strategy, comprising:
an impedance voltage drop feedforward control strategy is designed, so that the amplitude of the output voltage of the converter is regulated by a proportional integral controller of a reactive power loop and an active power feedforward controller;
an adaptive transient impedance control is designed, and when the reactive power step increases, the measured reactive power is compared with a reference value to generate an adaptively reduced virtual inductance deviation value, so that the output reactive power of the self-synchronous power supply is rapidly increased;
a disturbance monitoring method based on current monitoring is designed, and adaptive virtual impedance is used for limiting current peaks.
8. The utility model provides a weak current net is from synchronous power supply power decoupling control and reactive fast adjustment system which characterized in that includes:
the small signal model calculation module is used for establishing a small signal model of the self-synchronous power supply system based on the complex matrix; the virtual impedance range calculation module is used for calculating a virtual impedance range for realizing power decoupling control; the virtual impedance optimization design module is used for carrying out negative sequence and harmonic frequency band virtual impedance design; and the reactive power rapid adjustment module is used for realizing rapid adjustment of the output reactive power of the self-synchronous power supply.
9. The system for decoupling control and reactive fast adjustment of self-synchronizing power supply power of weak electric network according to claim 8, wherein the small signal model calculation module is specifically configured to: extracting system running state sampling information from secondary equipment monitoring and carrying out information processing; and calculating a self-synchronous power supply system small signal model of the grid-connected state or the off-grid state corresponding to the island detection judgment result based on the sampling data and the self-synchronous power supply control system parameters by judging that the island detection system based on the sampling information is in the grid-connected state or the off-grid state.
10. The system for decoupling control and reactive fast adjustment of self-synchronizing power supply power of weak network according to claim 8, wherein the virtual impedance range calculation module is specifically configured to: based on the sampling information, calculating a virtual impedance range meeting an active-reactive power decoupling constraint condition, a virtual impedance range meeting a static stability constraint condition and a virtual impedance range meeting a transient stability constraint condition; based on the constraint range calculation result, virtual impedance constraints are combined with self-synchronous power supply capacity, and a virtual impedance range for realizing power decoupling control is comprehensively determined.
11. The system for decoupling control and reactive fast adjustment of self-synchronizing power supply power of weak current network according to claim 8, wherein the virtual impedance optimization design module is specifically configured to: the virtual impedance harmonic wave and unbalance suppression method of the multi-loop voltage control scheme is adopted, a plurality of harmonic resonance controllers are used for corresponding to harmonic wave and negative sequence frequencies, each harmonic resonance controller adopts a parallel calculation mode, and the performance of the converter is improved through the virtual impedance design of each frequency.
12. The system for decoupling control and reactive power fast adjustment of a weak network self-synchronizing power supply according to claim 8, wherein the reactive power fast adjustment module is specifically configured to: adopting impedance voltage drop feedforward control to adjust the amplitude of the output voltage of the converter; and the self-adaptive transient impedance is adopted to quickly adjust the output reactive power of the self-synchronous power supply and limit the current peak.
13. A computer device, comprising: at least one processor, and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the weak grid self-synchronized power supply power decoupling control and reactive fast regulation method of any one of claims 1-7.
14. A computer readable storage medium storing computer instructions for causing the computer to perform the weak grid self-synchronized power supply power decoupling control and reactive fast regulation method of any one of claims 1-7.
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