CN113241748B - Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid - Google Patents
Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid Download PDFInfo
- Publication number
- CN113241748B CN113241748B CN202110449613.3A CN202110449613A CN113241748B CN 113241748 B CN113241748 B CN 113241748B CN 202110449613 A CN202110449613 A CN 202110449613A CN 113241748 B CN113241748 B CN 113241748B
- Authority
- CN
- China
- Prior art keywords
- control signal
- current
- loop
- signal
- axis current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
-
- 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
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
-
- 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
-
- 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
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention discloses a method and a system for suppressing transient overvoltage of a weak power grid accessed to a power electronic converter, wherein the method comprises the following steps: when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal; and generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting the transient overvoltage of the power grid. The self-adaptive current control instruction is directly added through the influence of the voltage signal, so that the steady-state operation performance of the unit under a weak current network is not influenced, the transient overvoltage of the machine end can be effectively restrained under the AC/DC fault, the friendly grid connection of large-scale new energy is further realized, and stronger support is provided for a high-proportion new energy power system.
Description
Technical Field
The invention relates to the technical field of new energy power generation, in particular to a method and a system for suppressing transient overvoltage of a power electronic converter connected to a weak power grid.
Background
Currently, under the form of increasingly serious global problems such as energy shortage, environmental pollution, climate warming and the like, the large-scale development and utilization of renewable energy sources such as wind, light and the like become important choices of energy strategies of various countries in the world. The characteristic of the reverse distribution of renewable resources and electricity load demands determines that the large-base and long-distance extra-high voltage direct current transmission is one of the dominant forms of new energy development and utilization in China.
With the transformation of the energy structure in China, the structure of the extra-high voltage direct current end matched power supply is deeply changed, the early-stage power supply of the extra-high voltage direct current end is gradually transformed into the wind power generation taking a synchronous generator as a main body to replace the synchronous generator, the high-proportion new energy source causes the further weakness of the power supply net rack, the extra-high voltage direct current phase-change failure, the locking failure and the alternating current failure of the power supply network caused by the system failure can all cause the transient overvoltage of the new energy source machine end, the large-scale new energy source is caused to be off-grid, and the extra-high voltage direct current output capability is severely restricted.
Currently, a dynamic reactive power compensation device (SVC/SVG) is generally adopted to control the transient voltage of a new energy station. Because the dynamic reactive power compensation device has signal sampling inherent delay, the response characteristic of the transient voltage to ms level is seriously lagged, and the transient voltage control function cannot be realized.
Disclosure of Invention
In order to solve the problems that the dynamic reactive power compensation device in the prior art has inherent delay of signal sampling and serious delay of transient voltage response characteristics of ms level, the invention provides a method for inhibiting transient overvoltage of a power electronic converter connected to a weak grid, which comprises the following steps:
when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal;
and generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting the transient overvoltage of the power grid.
Preferably, the voltage outer loop and current inner loop dual control includes:
taking the actual voltage value and the reference voltage value of the direct current capacitor of the power electronic converter as an outer ring control signal and combining the outer ring control signal and the reference voltage value to generate a current ring reference value of the voltage outer ring current inner ring double-ring control;
inputting the three-phase grid-connected voltage and the phase frequency signals to a d-q converter to obtain ud and uq components;
inputting the three-phase output current and the phase frequency signal to a d-q converter to obtain iq and id components;
acquiring a control signal of a d-axis current loop based on the id component, the ud component and a reference value of the current loop;
and acquiring a control signal of a q-axis current loop based on the iq component and the uq component.
Preferably, when the alternating-current weak power grid is in a fault ride-through operation condition, generating the self-adaptive disturbance-free current control signal based on the three-phase grid-connected voltage control acquired in real time and adding the self-adaptive disturbance-free current control signal to the q-axis current loop controlled by the voltage outer loop and the current inner loop in a double loop manner to obtain the q-axis current loop control signal comprises:
when the transient overvoltage is generated, inputting the transient overvoltage into the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component;
comparing the iq component, the reactive current set point and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
the q-axis current loop is overlapped with the uq component after passing through the PI controller to form a q-axis current loop control signal.
Preferably, the current loop reference value that takes the actual voltage value and the reference voltage value of the dc capacitor of the power electronic converter as the outer loop control signal and combines the two loop control that generates the voltage outer loop current inner loop includes:
comparing an actual voltage value of a direct-current capacitor of the power electronic converter with a reference voltage value to obtain a direct-voltage deviation signal;
and processing a reference value for generating a current loop through a PI controller based on the direct voltage deviation signal.
Preferably, the obtaining the control signal of the d-axis current loop based on the id component, the ud component and the reference value of the current loop includes:
comparing the id component with a current loop reference value to generate a d-axis current loop deviation signal;
and the deviation signal is input into a PI controller, and then the generated signal is overlapped with the ud component to generate a d-axis current loop control signal.
Preferably, the generating the final control command based on the q-axis current loop control signal and the d-axis current control, the suppressing the transient overvoltage of the power grid includes:
inputting the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
and inputting the three-phase modulation voltage of the power electronic converter to a PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit the transient overvoltage of the power grid.
Preferably, the generating a final control instruction based on the q-axis current loop control signal and the d-axis current control further includes, before suppressing the transient overvoltage of the power grid: and decoupling and suppressing the q-axis current loop control signal and the d-axis current loop control signal.
Based on the same inventive concept, the invention provides a transient overvoltage suppression system for a power electronic converter connected to a weak power grid, which is characterized by comprising the following components: a signal adding module and a signal modulating module;
the signal adding module is used for generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal when the alternating-current weak power grid is in a fault ride-through operation condition;
the signal modulation module is used for generating a final control instruction based on the q-axis current loop control signal and d-axis current control and inhibiting transient overvoltage of a power grid.
Preferably, the signal adding module includes: a signal adding sub-module, a deviation signal sub-module and a superposition signal sub-module;
the signal adding sub-module is used for inputting the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component when the transient overvoltage is generated;
the deviation signal submodule compares the iq component, the reactive current given value and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
and the superposition signal submodule is used for superposing the q-axis current loop with the uq component after passing through the PI controller to form a q-axis current loop control signal.
Preferably, the signal modulation module includes: a modulation signal sub-module and a control signal sub-module;
the modulation signal submodule inputs the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
and the control signal submodule inputs the three-phase modulation voltage of the power electronic converter to the PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit the transient overvoltage of the power grid.
Compared with the prior art, the invention has the beneficial effects that:
a method for suppressing transient overvoltage of a power electronic converter in a weak power grid comprises the following steps: when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal; and generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting the transient overvoltage of the power grid. The self-adaptive current control instruction is directly added through the influence of the voltage signal, so that the steady-state operation performance of the unit under a weak current network is not influenced, the transient overvoltage of the machine end can be effectively restrained under the AC/DC fault, the friendly grid connection of large-scale new energy is further realized, and stronger support is provided for a high-proportion new energy power system.
Drawings
FIG. 1 is a flow chart of a transient overvoltage suppression method according to the present invention;
FIG. 2 is a schematic diagram of a transient overvoltage suppression control strategy according to the present invention;
FIG. 3 is a schematic diagram of transient overvoltage suppression for commutation failure;
FIG. 4 is a schematic diagram of AC fault transient overvoltage suppression;
FIG. 5 is a schematic diagram of the effect of the lower cutoff frequency on transient overvoltage;
FIG. 6 is a schematic diagram of the effect of upper cutoff frequency on transient overvoltage;
fig. 7 is a schematic diagram of the effect of gain on transient overvoltage.
Detailed Description
For a better understanding of the present invention, reference is made to the following description, drawings and examples.
Example 1:
a method for suppressing transient overvoltage of a power electronic converter connected to a weak power grid is shown in fig. 1, and comprises the following steps:
s1: when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal;
s2: and generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting the transient overvoltage of the power grid.
Wherein S1: when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal, wherein the method specifically comprises the following steps of:
taking the actual voltage value and the reference voltage value of the direct current capacitor of the power electronic converter as an outer ring control signal and combining the outer ring control signal and the reference voltage value to generate a current ring reference value of the voltage outer ring current inner ring double-ring control;
inputting the three-phase grid-connected voltage and the phase frequency signals to a d-q converter to obtain ud and uq components;
inputting the three-phase output current and the phase frequency signal to a d-q converter to obtain iq and id components;
acquiring a control signal of a d-axis current loop based on the id component, the ud component and a reference value of the current loop;
and acquiring a control signal of a q-axis current loop based on the iq component and the uq component. S3: when the normal operation condition is changed into the fault ride-through operation condition, adding a self-adaptive undisturbed current control signal to the double-loop controlled q-axis current loop based on the three-phase grid-connected voltage to obtain a q-axis current loop control signal, which specifically comprises the following steps:
when the transient overvoltage is generated, inputting the transient overvoltage into the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component;
comparing the iq component, the reactive current set point and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
the q-axis current loop is overlapped with the uq component after passing through the PI controller to form a q-axis current loop control signal.
S2: generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting transient overvoltage of a power grid, wherein the method specifically comprises the following steps of:
inputting the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
and inputting the modulation voltage to a PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit the transient overvoltage of the power grid.
The grid-connected reactive current response value of the power electronic converter is as follows:
wherein:
iref q(s) is a grid-connected reactive current response value of the power electronic converter;
t(s) is a transfer function corresponding to a reactive current given value in a current loop of the power electronic converter;
wherein:
wherein:
k p the proportional coefficient of the PI controller is arranged in the current inner loop of the power electronic converter;
k i integrating coefficients for a PI controller in a current loop of the power electronic converter;
L f filtering inductance for the power electronic converter;
iref q 0(s) is a current inner loop reactive current given value of the power electronic converter;
Δiref q(s) is a power electronic converter current inner loop adaptive reactive current control given component;
wherein:
wherein:
k 1 is gain;
u d (s) is the d-axis component of the power electronic converter port voltage;
T(θ PLL ) For the port voltage u a 、u b 、u c To u d 、u q 、u 0 Is a transformation matrix of (a);
θ PLL for the port voltage u a 、u b 、u c Phase locking angle;
omega is the grid voltage angular frequency;
U m for the port voltage u a 、u b 、u c Amplitude value;
G 1 (s) is u d (s) a corresponding open loop transfer function;
wherein:
wherein:
ω c1 ＝2πf c1 ；
ω c2 ＝2πf c2 ；
f c1 is a band-pass filter G 1 A lower cutoff frequency of(s);
f c2 is a band-pass filter G 1 An upper cutoff frequency of(s);
i 0q filtering an initial value q-axis component of the inductor current for the power electronic converter;
y(s；i 0q ) Is i 0q A corresponding response component;
wherein the method comprises the steps of
Aiming at the problem that the photovoltaic grid-connected inverter and the full-power wind turbine generator are connected into a weak power grid to cause transient overvoltage off-grid operation of a machine end under direct current faults such as HVDC phase change failure and blocking and the alternating current fault of a transmitting end, the invention provides a transient overvoltage suppression strategy for self-adaptive reactive current control.
Example 2:
based on the same inventive concept, the invention also provides a transient overvoltage suppression system for the power electronic converter connected to the weak power grid, which comprises the following components: a signal adding module and a signal modulating module;
the signal adding module is used for generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal when the alternating-current weak power grid is in a fault ride-through operation condition;
the signal modulation module is used for generating a final control instruction based on the q-axis current loop control signal and d-axis current control and inhibiting transient overvoltage of a power grid.
Preferably, the signal adding module includes: a signal adding sub-module, a deviation signal sub-module and a superposition signal sub-module;
the signal adding sub-module is used for inputting the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component when the transient overvoltage is generated;
the deviation signal submodule compares the iq component, the reactive current given value and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
and the superposition signal submodule is used for superposing the q-axis current loop with the uq component after passing through the PI controller to form a q-axis current loop control signal.
Preferably, the signal modulation module includes: a modulation signal sub-module and a control signal sub-module;
the modulation signal submodule inputs the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
and the control signal submodule inputs the three-phase modulation voltage of the power electronic converter to the PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit the transient overvoltage of the power grid.
Example 3:
at present, a new energy grid-connected power generation device based on power conversion of a power electronic converter relies on the advantages of strong control technology, weak overvoltage capacity, loss of inertia, flux linkage and the like of a traditional synchronous generator, and when various temporary and steady faults occur in a power grid, effective control on system frequency and voltage cannot be realized, so that large-scale new energy linkage off-grid is extremely easy to be caused, and the large-scale new energy safety grid connection is seriously influenced.
The invention starts from a new energy power generation device and provides a transient overvoltage suppression control method, which can not only not influence the steady-state operation performance of a unit under a weak power grid, but also effectively suppress transient overvoltage at a machine end under an AC/DC fault, thereby realizing friendly grid connection of large-scale new energy and providing stronger support for a high-proportion new energy power system.
As shown in fig. 2: the power electronic converter is connected to an alternating current weak power grid by adopting voltage outer ring and current inner ring double-loop control;
the outer ring control signal is the voltage Vdc of the DC capacitor cdc, and the reference DC signal is obtained
Comparing the obtained Vdc with the collected Vdc to obtain a direct voltage deviation signal, inputting the direct voltage deviation signal into a PI controller of a direct current voltage ring, and outputting the signal as a reference value of a current ring;
three-phase output currents ia, ib and ic are collected, phase frequency signals sin-cos of the three-phase output voltages are extracted, and ia, ib, ic and sin-cos are input to a dq conversion module to obtain id and iq components.
And acquiring three-phase voltages of a power grid, and inputting ua, ub, uc and sin-cos into a dq conversion module to obtain Ud, wherein Uq is the quadrature axis voltage and the direct axis voltage.
And comparing the reference value of the current loop with id to obtain a d-axis current deviation signal, inputting the d-axis current deviation signal into a direct current voltage loop PI controller, and combining the output signal with Ud to obtain the d-axis deviation signal.
The power electronic converter is in a normal steady-state operation condition, a control channel of the power electronic converter is '0', the power electronic converter works according to a dispatching reactive power instruction, the dispatching reactive power instruction value is 0, and the reactive power additional compensation quantity is 0;
when the power electronic converter encounters a fault working condition, the normal steady-state working condition is changed to a fault crossing working condition, the control channel is channel '1', the switching from channel '0' to channel '1' is realized, channel '2' is a low voltage crossing control reactive power instruction required by national standards, channel '3' is a high voltage crossing control reactive power instruction required by national standards, the self-adaptive reactive power extra compensation quantity is a self-adaptive reactive current control component provided by the patent,
the delta iref q(s), the iref q 0(s) and the q-axis current component are input to a direct current loop PI controller after being compounded, and an output signal and the uq component are overlapped to be used as a q-axis deviation signal;
decoupling the d-axis deviation signal and the q-axis deviation signal to obtain a d-axis control signal and a q-axis control signal;
when d-q conversion is carried out on the mathematical model of the inverter, the d-axis control quantity and the q-axis control quantity are coupled, so that the output signals of the two PI controllers on the d-axis current loop and the q-axis current loop are needed to be subjected to feedforward decoupling and then are easy to control respectively. The feedforward decoupling method comprises the following steps of;
d-axis control signal plus iq omega L f The d-axis control signal after decoupling is obtained, and the q-axis control signal is subtracted by iq omega L f Obtaining a decoupled q-axis control signal;
the sin-cos, d-axis control signal and q-axis control signal are input into dq inverse transformation to obtain three-phase modulation signal, and then input into pwm generator to generate switch control signal.
Wherein C in the figure dc The direct current capacitor is a direct current capacitor of the power electronic converter; v (V) dc The direct-current capacitor voltage of the power electronic converter;
vref dc is the given value of the voltage of the direct-current capacitor of the power electronic converter;
S a1 、S a2 the power electronic converter a-phase upper bridge arm IGBT switch tubes and the power electronic converter a-phase lower bridge arm IGBT switch tubes are respectively arranged;
S b1 、S b2 the switching tubes are respectively an upper bridge arm IGBT switching tube and a lower bridge arm IGBT switching tube of a b-phase of the power electronic converter;
S c1 、S c2 the switching tubes are respectively an upper bridge arm IGBT switching tube and a lower bridge arm IGBT switching tube of a c-phase of the power electronic converter;
v a 、v b 、v c the three-phase output voltage of the power electronic converter is obtained;
m va 、m vb 、m vc modulating voltages for three phases of the power electronic converter;
L f 、R f 、C f the power electronic converter AC filter inductor, the filter resistor and the filter capacitor are respectively arranged;
i a 、i b 、i c three-phase output current of the power electronic converter;
u a 、u b 、u c is electric powerThree-phase grid-connected voltage of the electronic converter;
L g the equivalent inductance of the power grid;
omega is the grid voltage angular frequency;
θ PLL for three-phase grid-connected voltage u a 、u b 、u c Phase locking angle;
u d 、u q respectively three-phase grid-connected voltage u a 、u b 、u c Is a dq component of (2);
i d 、i q respectively three-phase grid-connected current i a 、i b 、i c Is a dq component of (2);
I n rated current of the power electronic converter;
k is the depth coefficient of the voltage variation;
iref q 0(s) is a reactive current given value;
H u (s) is a direct current voltage ring transfer function;
wherein:
wherein:
k vp the proportional coefficient of the PI controller is the direct-current voltage ring of the power electronic converter;
k vi integrating coefficients of a PI controller of a direct-current voltage ring of the power electronic converter;
H i (s) is a current loop transfer function;
wherein:
wherein:
k p the proportional coefficient of the current loop PI controller of the power electronic converter is;
k i integrating coefficients for a current loop PI controller of the power electronic converter.
The invention aims at the problem that a photovoltaic grid-connected inverter and a direct-driven wind turbine generator are connected to a weak power grid to cause transient overvoltage off-grid operation of a machine end under direct-current faults such as HVDC phase conversion failure, locking and the like and a power transmission end alternating-current fault, and provides a transient overvoltage suppression control method for self-adaptive reactive current control.
Compared with the original control strategy, the self-adaptive reactive current control of the invention has the advantages that the change of the pole machine voltage and the reactive power is shown in figure 3 when the commutation failure occurs, and the transient overvoltage suppression change condition is shown in figure 4 when the alternating current failure occurs.
(1) Adaptive reactive current control
The power electronic converter has small moment of inertia, short electromagnetic transient process and millisecond transient overvoltage, and the patent provides a transient overvoltage suppression method based on self-adaptive reactive current control.
(2) Principle for selecting upper and lower limit cut-off frequency of filter
Adjusting upper and lower limit cut-off frequency f of band-pass filter of self-adaptive reactive current control unit c1 、f c2 The aim of optimizing the transient reactive characteristic of the power electronic converter is fulfilled, and further the suppression of the transient overvoltage of the power electronic converter is realized. The effect of the lower cut-off frequency on the transient overvoltage is shown in fig. 5, and the effect of the upper cut-off frequency on the transient overvoltage is shown in fig. 6.
(3) Filter gain selection principle
Adjusting gain k of band-pass filter of self-adaptive reactive current control unit 1 The aim of optimizing the transient reactive characteristic of the power electronic converter is fulfilled, and further the suppression of the transient overvoltage of the power electronic converter is realized. Wherein the effect of gain on transient overvoltage is shown in fig. 7.
It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof, but rather as providing for the use of additional embodiments and advantages of all such modifications, equivalents, improvements and similar to the present invention are intended to be included within the scope of the present invention as defined by the appended claims.
Claims (2)
1. The method for suppressing the transient overvoltage of the power electronic converter in the weak power grid is characterized by comprising the following steps of:
when the alternating-current weak power grid is in a fault ride-through operation condition, generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time, and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal;
generating a final control instruction based on the q-axis current loop control signal and d-axis current control, and inhibiting transient overvoltage of a power grid;
the voltage outer loop and current inner loop dual control comprises:
taking the actual voltage value and the reference voltage value of the direct current capacitor of the power electronic converter as an outer ring control signal and combining the outer ring control signal and the reference voltage value to generate a current ring reference value of the voltage outer ring current inner ring double-ring control;
inputting the three-phase grid-connected voltage and the phase frequency signals to a d-q converter to obtain ud and uq components;
inputting the three-phase output current and the phase frequency signal to a d-q converter to obtain iq and id components;
acquiring a control signal of a d-axis current loop based on the id component, the ud component and a reference value of the current loop;
acquiring a control signal of a q-axis current loop based on the iq component and the uq component;
when the alternating-current weak power grid is in a fault ride-through operation condition, generating the self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal comprises the following steps:
when the transient overvoltage is generated, inputting the transient overvoltage into the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component;
comparing the iq component, the reactive current set point and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
the q-axis current loop is overlapped with uq components after passing through the PI controller to form a q-axis current loop control signal;
the current loop reference value which takes the actual voltage value and the reference voltage value of the direct current capacitor of the power electronic converter as the outer loop control signal and combines the two loop control signals to generate the voltage outer loop current inner loop comprises the following steps:
comparing an actual voltage value of a direct-current capacitor of the power electronic converter with a reference voltage value to obtain a direct-voltage deviation signal;
generating a reference value of a current loop through PI controller processing based on the direct voltage deviation signal;
the obtaining the control signal of the d-axis current loop based on the id component, the ud component and the reference value of the current loop comprises the following steps:
comparing the id component with a current loop reference value to generate a d-axis current loop deviation signal;
the deviation signal is input to a PI controller, and then the generated signal is overlapped with the ud component to generate a d-axis current loop control signal;
generating a final control instruction based on the q-axis current loop control signal and d-axis current control, wherein the restraining the transient overvoltage of the power grid comprises the following steps:
inputting the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
the three-phase modulation voltage of the power electronic converter is input to a PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit transient overvoltage of a power grid;
the method for generating the final control instruction based on the q-axis current loop control signal and the d-axis current control further comprises the following steps: and decoupling and suppressing the q-axis current loop control signal and the d-axis current loop control signal.
2. The transient overvoltage suppression system for the power electronic converter connected to the weak power grid is characterized by comprising a signal adding module and a signal modulating module;
the signal adding module is used for generating a self-adaptive disturbance-free current control signal based on three-phase grid-connected voltage control acquired in real time and adding the self-adaptive disturbance-free current control signal to a q-axis current loop controlled by a voltage outer loop and a current inner loop in a double loop manner to obtain a q-axis current loop control signal when the alternating-current weak power grid is in a fault ride-through operation condition;
the signal modulation module is used for generating a final control instruction based on the q-axis current loop control signal and d-axis current control and inhibiting transient overvoltage of a power grid;
the signal adding module includes: a signal adding sub-module, a deviation signal sub-module and a superposition signal sub-module;
the signal adding sub-module is used for inputting the adaptive reactive current control module based on the ud component to generate an adaptive reactive additional compensation quantity as an adaptive reactive current control component when the transient overvoltage is generated;
the deviation signal submodule compares the iq component, the reactive current given value and the adaptive reactive current control component to generate a q-axis current loop deviation signal;
the superposition signal submodule is used for superposing the q-axis current loop with the uq component after passing through the PI controller to form a q-axis current loop control signal;
the signal modulation module includes: a modulation signal sub-module and a control signal sub-module;
the modulation signal submodule inputs the q-axis current loop control signal and the d-axis current loop control signal to a d-q inverter to generate three-phase modulation voltage of the power electronic converter;
and the control signal submodule inputs the three-phase modulation voltage of the power electronic converter to the PWM inverter to generate a switch control signal of the power electronic converter so as to inhibit the transient overvoltage of the power grid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110449613.3A CN113241748B (en) | 2021-04-25 | 2021-04-25 | Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110449613.3A CN113241748B (en) | 2021-04-25 | 2021-04-25 | Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113241748A CN113241748A (en) | 2021-08-10 |
| CN113241748B true CN113241748B (en) | 2023-06-06 |
Family
ID=77129163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110449613.3A Active CN113241748B (en) | 2021-04-25 | 2021-04-25 | Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113241748B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113725859B (en) * | 2021-08-31 | 2024-01-26 | 深圳威迈斯新能源股份有限公司 | Self-adaptive compensation control method and circuit |
| CN113991692A (en) * | 2021-09-13 | 2022-01-28 | 国网冀北电力有限公司电力科学研究院 | Static var generator control method and device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6917124B2 (en) * | 2000-10-27 | 2005-07-12 | Liebert Corporation | Uninterruptible power supply |
| CN104935006A (en) * | 2015-06-15 | 2015-09-23 | 许继集团有限公司 | High voltage ride through control method |
| CN107994588A (en) * | 2017-12-08 | 2018-05-04 | 甘肃省电力公司风电技术中心 | Lift the idle control strategy of wind power plant of wind power integration light current net transient stability |
| CN111509773A (en) * | 2020-04-24 | 2020-08-07 | 浙江运达风电股份有限公司 | Voltage source type wind turbine generator fault ride-through control method suitable for weak power grid |
-
2021
- 2021-04-25 CN CN202110449613.3A patent/CN113241748B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6917124B2 (en) * | 2000-10-27 | 2005-07-12 | Liebert Corporation | Uninterruptible power supply |
| CN104935006A (en) * | 2015-06-15 | 2015-09-23 | 许继集团有限公司 | High voltage ride through control method |
| CN107994588A (en) * | 2017-12-08 | 2018-05-04 | 甘肃省电力公司风电技术中心 | Lift the idle control strategy of wind power plant of wind power integration light current net transient stability |
| CN111509773A (en) * | 2020-04-24 | 2020-08-07 | 浙江运达风电股份有限公司 | Voltage source type wind turbine generator fault ride-through control method suitable for weak power grid |
Non-Patent Citations (1)
| Title |
|---|
| 基于暂态功率特性调整无功电流的高电压穿越控制策略;李曼;王冰;曲立楠;唐桢;晏松;徐强;;电力系统自动化;第44卷(第6期);59-65 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113241748A (en) | 2021-08-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Luo et al. | Fuzzy-PI-based direct-output-voltage control strategy for the STATCOM used in utility distribution systems | |
| Hu et al. | Impedance characteristic analysis and stability improvement method for DFIG system within PLL bandwidth based on different reference frames | |
| CN107196344B (en) | Self-synchronizing virtual synchronous inverter grid-connected controller and method with local load based on SPF-PLL | |
| Geng et al. | A novel low voltage ride through control method for current source grid-connected photovoltaic inverters | |
| CN113241748B (en) | Method and system for suppressing transient overvoltage of power electronic converter accessing weak power grid | |
| CN101951178A (en) | Method used for balancing three phases of direct current side voltages of chain power regulating device | |
| Jia et al. | Transient fault current analysis of IIRESs considering controller saturation | |
| CN104009486A (en) | Current limiting method for asymmetric compensation for SVG of three-phase three-wire system | |
| CN110336318A (en) | A kind of single-phase grid-connected photovoltaic power generation system and control method | |
| Liu et al. | Recent advances of control technologies for brushless doubly-fed generators | |
| Cheng et al. | Coordinated derived current control of DFIG’s RSC and GSC without PLL under unbalanced grid voltage conditions | |
| Guo et al. | Decoupled control of active and reactive power for a grid-connected doubly-fed induction generator | |
| Dong et al. | Mitigation strategy of subsynchronous oscillation based on fractional-order sliding mode control for VSC-MTDC systems with DFIG-based wind farm access | |
| Xiao et al. | Sliding mode SVM-DPC for grid-side converter of D-PMSG under asymmetrical faults | |
| Wang et al. | A novel low voltage ride through control strategy based on virtual synchronous generator | |
| Yu et al. | Internal model startup control for VSC-LCC based hybrid pseudo bipolar HVDC system | |
| Deng et al. | An optimal short-circuit current control method for self-synchronization controlled wind turbines | |
| Al-Dwa et al. | New Modeling and Improved Current Control Strategy to Eliminate the Impact of Synchronization Method and Parks Transformation for Grid-connected Four-leg PWM Inverter | |
| Jing et al. | Network topology and operation control of DC distribution network with AC DC converter | |
| Liu et al. | The Current Sequence Components Extraction for Dual Synchronous Rotation Frame Current Control in Unbalanced Grid Conditions | |
| Orlando et al. | Grid voltage support by means of a small wind turbine system | |
| Wu et al. | Study on an exact equivalent model of DPFC | |
| Li et al. | Parallel impedance-reshaping control strategy for suppressing wide range high-frequency resonance of shunt compensated DFIG system | |
| Jing et al. | Control strategy of current balance based on VSG of DFIG under unbalanced grid voltage conditions | |
| Wang et al. | Mitigation of Subsynchronous Control Interaction in DFIG-Based Wind Farm Using Repetitive-PI |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |