CN111146784B - Continuous commutation failure suppression method and system based on dynamic current deviation control - Google Patents
Continuous commutation failure suppression method and system based on dynamic current deviation control 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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
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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
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
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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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
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- 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
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Abstract
The invention discloses a method and a system for inhibiting continuous commutation failure of dynamic current deviation control, wherein the method comprises the following steps: acquiring the amplitude of each phase of three-phase voltage of an inversion side current conversion bus in real time; calculating to obtain a voltage drop value of the current conversion bus according to a preset rule and the amplitude value of each phase of the three-phase voltage; determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template; adjusting the arc extinguishing angle in real time according to a preset rule according to the current deviation control curve; the method and the system change the relevance according to the fact that the arc-quenching angle increment can change along with the change of the slope of the current deviation control ramp function, realize the real-time adjustment of the arc-quenching angle through the dynamic current deviation control, effectively reduce the occurrence probability of continuous commutation failure of the direct current system, and improve the running characteristic of the direct current system; the method and the system are easy to realize, do not need to be provided with additional auxiliary equipment, do not need to modify converters and other supplementary input, and have strong engineering practical value.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a continuous commutation failure suppression method and a continuous commutation failure suppression system based on dynamic current deviation control.
Background
The suppression measures for continuous commutation failure of LCC-HVDC systems are roughly classified into 3 types: additional auxiliary equipment is equipped, the topology of the current converter is improved, and a direct current control strategy is optimized.
In the aspect of providing additional auxiliary equipment, the data suggests that the direct current limiter is adopted to limit the rise of direct current so as to reduce the probability of phase commutation failure, but the traditional direct current limiter has limited inhibition capability on continuous phase commutation failure due to the constraint of the economic operation of a direct current system; the superconducting and power electronic dc current limiters have limited their application in practical engineering due to their high cost. There are also documents that the voltage of the receiving-end converter busbar is stabilized from the receiving-end reactive compensation optimization angle so as to achieve the purpose of inhibiting continuous phase conversion failure, but the coupling characteristic between the action mechanism of the reactive compensation equipment and the HVDC system needs to be further researched.
In the aspect of reforming the topology of the converter, the capacitor phase-change converter and the controllable series capacitor phase-change converter utilize the series capacitor to provide auxiliary phase-change voltage to avoid phase-change failure, but the defects of harmonic pollution, high insulation requirement on a converter valve and the like exist, so the capacitor phase-change converter and the controllable series capacitor phase-change converter are not widely applied to practical engineering. In some methods, a certain number of controllable sub-modules are connected in series between an LCC original valve arm or a converter transformer and a converter valve to form a novel converter, so that the aim of auxiliary phase conversion is fulfilled. However, the novel converter topologies have the problems of difficulty in sub-module commutation matching, complexity increase of an LCC-HVDC control system and the like, and the engineering implementation difficulty is high.
In terms of the strategy for optimizing the direct current control to inhibit the continuous commutation failure, the method can be roughly divided into the following steps: reducing the direct current instruction value, and triggering or changing the arc-quenching angle setting value in advance. Reducing the dc current command value optimizes the VDCOL output current command value to suppress the occurrence of continuous commutation failure, but prevents adverse effects on the transient stability of the ac system when the dc system is recovering slowly. In the aspect of triggering in advance or changing the setting value of the arc extinguishing angle, documents combine commutation failure prediction control to realize the early triggering to obtain larger commutation margin, although the risk of commutation failure can be reduced to a certain extent, the early triggering can increase the reactive power consumption and is not beneficial to the recovery of alternating voltage.
Disclosure of Invention
In order to solve the above problems existing in the implementation of the continuous commutation failure measures in the background art, the invention provides a continuous commutation failure suppression method and system based on dynamic current deviation control, wherein the method and system change the correlation according to the change of the arc extinguishing angle increment along with the slope of the current deviation control ramp-up function, and realize the real-time regulation of the arc extinguishing angle through the dynamic current deviation control, thereby effectively reducing the occurrence probability of the continuous commutation failure of the direct current system and improving the running characteristic of the direct current system; the continuous commutation failure suppression method for dynamic current deviation control comprises the following steps:
acquiring the amplitude of each phase of three-phase voltage of an inversion side converter bus in real time;
calculating to obtain a voltage drop value of the current conversion bus according to a preset rule and the amplitude value of each phase of the three-phase voltage;
determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template;
and adjusting the arc extinguishing angle in real time according to a preset rule according to the current deviation control curve.
Further, the real-time collection of each phase amplitude of the three-phase voltage of the inverter side converter bus includes:
and detecting and calculating each phase of the three-phase voltage of the inversion side conversion bus by a second-order generalized integrator detection method.
Further, the preset rule for obtaining the voltage drop value of the commutation bus through calculation includes:
comparing each phase amplitude of the three-phase voltage of the inversion side conversion bus to obtain a minimum amplitude;
and subtracting the minimum amplitude value from 1 to obtain a voltage drop value of the commutation bus.
Further, after the voltage drop value of the commutation bus is obtained through calculation, the method further includes:
comparing the voltage drop value with a preset amplitude limiting interval, and judging whether the voltage drop value is in the preset amplitude limiting interval or not;
if the current time is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
Further, determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template includes:
substituting the voltage drop value into a preset current deviation control function template to obtain a current deviation control curve; the preset current deviation control function template is as follows:
wherein, delta I d The current deviation value between the actually measured direct current and the direct current instruction value is obtained; delta U m Is the voltage sag value; delta gamma max The maximum constant value of the arc extinguishing angle when the alternating current system normally operates; delta I H And the current deviation value constant corresponding to the maximum constant of the arc extinguishing angle when the alternating current system normally operates.
Further, calculating according to a preset rule to obtain the amplitude of the zero sequence component of the voltage of the converter bus;
judging whether the amplitude of the zero-sequence component of the converter bus voltage exceeds a preset threshold value through a preset hysteresis comparator;
and if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value.
Further, the step of calculating and obtaining the amplitude of the zero sequence component of the voltage of the converter bus according to a preset rule comprises:
obtaining a zero-sequence component of the voltage of the inversion side inversion bus according to the mean value of the three-phase voltage of the inversion side inversion bus;
and detecting and calculating by a second-order generalized integrator detection method to obtain the amplitude of the zero-sequence component of the converter bus voltage.
Further, the preset threshold is calculated by the following formula:
U 0mz ＝K r *U 01max
wherein, U 0mz To preset a threshold value, K r For a reliability factor, K r Not less than 1; the U is 01max The maximum value of the zero sequence voltage amplitude of the corresponding commutation bus is the maximum value when the single-phase earth fault just can not cause the commutation failure.
Further, the preset constant value is subjected to simulation preferential determination in a preset voltage drop value amplitude limiting interval by adopting an exhaustion method; the simulation is constrained by the effect of continuous commutation failure caused by restraining single-phase faults and the recovery of direct-current power after the faults are removed.
The continuous commutation failure suppression system for dynamic current deviation control comprises:
the acquisition detection unit is used for acquiring the amplitude of each phase of the three-phase voltage of the inversion side converter bus in real time;
the control calculation unit is used for calculating and obtaining a voltage drop value of the current conversion bus according to a preset rule and the amplitude value of each phase of the three-phase voltage;
the control calculation unit is used for determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template;
and the adjusting unit is used for adjusting the arc extinguishing angle in real time according to the current deviation control curve and a preset rule.
Furthermore, the acquisition detection unit is used for detecting and calculating each phase of the three-phase voltage of the inversion side current conversion bus through a second-order generalized integrator detection method.
Further, the control calculation unit is configured to compare each phase amplitude of the three-phase voltage of the inverter-side converter bus to obtain a minimum amplitude; and subtracting the minimum amplitude value from 1 to obtain a voltage drop value of the commutation bus.
Further, the control calculation unit is configured to compare the voltage sag value with a preset amplitude limiting interval, and determine whether the voltage sag value is within the preset amplitude limiting interval;
if the amplitude is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
Further, the control calculation unit is used for substituting the voltage drop value into a preset current deviation control function template to obtain a current deviation control curve; the preset current deviation control function template is as follows:
wherein, delta I d The current deviation value between the actually measured direct current and the direct current instruction value is obtained; delta U m Is the voltage sag value; delta gamma max The maximum constant value of the arc extinguishing angle when the alternating current system normally operates; delta I H And the current deviation value constant corresponds to the maximum constant of the arc extinguishing angle when the alternating current system normally operates.
Further, the system further comprises a hysteresis comparison unit;
the acquisition detection unit is used for calculating and obtaining the amplitude of the zero-sequence component of the voltage of the converter bus according to a preset rule;
the hysteresis comparison unit is used for judging whether the amplitude of the zero-sequence component of the converter bus voltage exceeds a preset threshold value through a preset hysteresis comparator;
and if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value.
Further, the acquisition detection unit is used for obtaining a zero-sequence component of the voltage of the commutation bus through an average value of three-phase voltages of the commutation bus on the inversion side;
the acquisition detection unit is used for detecting and calculating the amplitude of the zero-sequence component of the voltage of the current conversion bus through a second-order generalized integrator detection method.
The invention has the beneficial effects that: the technical scheme of the invention provides a continuous commutation failure suppression method and a system based on dynamic current deviation control, wherein the method and the system change the relevance according to the change of the arc-extinguishing angle increment along with the change of the slope of a current deviation control ramp function, and realize the real-time regulation of the arc-extinguishing angle through the dynamic current deviation control, thereby effectively reducing the occurrence probability of continuous commutation failure of a direct current system and improving the running characteristic of the direct current system; the method and the system are easy to realize, do not need to be provided with additional auxiliary equipment, do not need to modify converters and other supplementary input, and have strong engineering practical value.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of a continuous commutation failure suppression method based on dynamic current deviation control according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a second-order generalized integrator detection method for detecting AC voltage amplitude according to an embodiment of the present invention;
FIG. 3 is a graph comparing the response of the single fault grounding inductor of 1H according to the present invention and the conventional method;
FIG. 4 is a graph comparing the response of the single-phase fault ground inductor of 0.45H according to the present invention with the conventional method;
FIG. 5 is a graph comparing the response of the three fault grounding inductances of 0.45H according to the embodiment of the present invention and the conventional method;
fig. 6 is a block diagram of a continuous commutation failure suppression system based on dynamic current deviation control according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same unit/element is denoted by the same reference numeral.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a continuous commutation failure suppression method based on dynamic current deviation control according to an embodiment of the present invention, and as shown in fig. 1, the method includes:
in the embodiment, the three-phase voltage of the inversion side commutation bus is acquired in real time, and the continuous commutation failure suppression method under the current condition is obtained through real-time calculation and analysis, so that the timeliness and the effectiveness of the control method are ensured;
the acquisition method comprises the steps of detecting each phase of three-phase voltage of the inversion side conversion bus through a second-order generalized integrator detection method;
FIG. 2 is a schematic diagram of the second order generalized integrator detection method for each phase to detect the AC voltage amplitude; in FIG. 2 u is the input voltage; omega 0 The voltage angular frequency under the power frequency; a. b are the sine and cosine components of the voltage u, respectively. The transfer functions for u to a and b are obtained as follows.
At power frequency, the amplitude and phase of a are the same as those of the input voltage u, the amplitude and phase of b are equal to those of u, and the phase lags by 90 degrees. Therefore, the amplitude of the AC voltage U m This equation can be used to obtain:
specifically, comparing each phase amplitude of the three-phase voltage of the inversion side conversion bus to obtain a minimum amplitude; and subtracting the minimum amplitude from 1 to obtain the voltage drop value of the commutation bus.
Further, in order to avoid the extreme situation of the voltage drop value to deteriorate the system operation, an amplitude limiting interval for the voltage drop value is set, the voltage drop value is compared with a preset amplitude limiting interval, and whether the voltage drop value is within the preset amplitude limiting interval is judged;
if the amplitude is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
In this embodiment, the slice interval is set to 0 to 0.2;
further, in order to improve the suppression capability of phase change failure during single-phase earth fault, when the amplitude of the zero-sequence component of the voltage of the detected current conversion bus exceeds a certain threshold value, the voltage drop value is set to be a constant value; specifically, the method comprises the following steps:
step 111, calculating and obtaining the amplitude of the zero sequence component of the voltage of the converter bus according to a preset rule;
in this embodiment, the zero-sequence component of the voltage of the inversion side inversion bus is obtained by the average value of the three-phase voltage of the inversion side inversion bus;
and detecting and calculating by a second-order generalized integrator detection method to obtain the amplitude of the zero-sequence component of the voltage of the converter bus.
Step 121, judging whether the amplitude of the zero sequence component of the commutation bus voltage exceeds a preset threshold value through a preset hysteresis comparator;
specifically, the preset threshold is calculated by the following formula:
U 0mz ＝K r *U 01max
wherein, U 0mz To preset a threshold value, K r For a reliability factor, K r Not less than 1; the U is 01max The maximum value of the zero sequence voltage amplitude of the corresponding commutation bus is the maximum value when the single-phase earth fault just can not cause the commutation failure.
In this embodiment, the reliability factor K r Taking 1.1;
and step 122, if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value.
Performing simulation preferential determination on the preset constant value in a preset voltage drop value amplitude limiting interval by adopting an exhaustion method; the simulation is constrained by the effect of continuous commutation failure caused by restraining single-phase faults and the recovery of direct-current power after the faults are removed.
In this embodiment, after simulation in the clipping interval (0, 0.2), the constant value is 0.14;
determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template, wherein the determining comprises the following steps:
substituting the voltage drop value into a preset current deviation control function template to obtain a current deviation control curve; the preset current deviation control function template is as follows:
wherein, delta I d The current deviation value between the actually measured direct current and the direct current instruction value is obtained; delta U m Is the voltage sag value; delta gamma max The maximum constant value of the arc extinguishing angle when the alternating current system normally operates; delta I H And the current deviation value constant corresponding to the maximum constant of the arc extinguishing angle when the alternating current system normally operates.
When the AC system is operating normally, Δ U m =0, the current deviation control characteristic is a classical control characteristic at this time; when AC system is in fault, delta U m Not equal to 0, the output upper limit value of the current deviation control ramp function is controlled by delta gamma max rad to (Δ γ) max + Δ Um) rad; when the fault disappears, the AC voltage rises back, Δ U m Gradually becomes zero, and the current deviation control characteristic is restored to the classical control characteristic.
In this embodiment, Δ I is used in normal system operation H Taking 0.1p.u; delta gamma max Take 0.2793rad.
And 140, adjusting the arc extinguishing angle in real time according to the current deviation control curve and a preset rule.
The method has a good effect of inhibiting the continuous commutation failure, and is characterized in that the effectiveness of the method for inhibiting the continuous commutation failure is verified by using a CIGRE model in PSCAD/EMTDC, wherein the direct-current power of a system in a model is 1000MW, the rated voltage is 500kV, and the rated current is 2kA. Since inductive ground faults are the most common fault patterns in real systems and also the most likely cause commutation failure under the same conditions. Therefore, in the simulation process, faults with different severity degrees can be simulated by setting grounding inductors with different sizes, and the smaller inductance value represents the more serious fault.
The following 2 methods are compared to inhibit the continuous commutation failure:
the method comprises the following steps: and adopting a CIGRE standard model control strategy.
The method 2 comprises the following steps: on the basis of the method 1, the method is added.
Comparative example 1: and a single-phase earth fault is set at the inversion side conversion bus, the earth inductance is 1H, the starting time of the fault is 3s, and the time lasts for 0.5s. Under this condition, the relevant electrical quantity variation characteristics of the systems employing methods 1 and 2 are shown in fig. 3.
Grounding inductor L f =1H means that the failure is minor, and in this case, although the dynamic current deviation control is started at this time, Δ I is caused by the minor failure d And is small, so the arc-extinguishing angle increment is equivalent to that when the method 1 is adopted. As can be seen from fig. 3, no commutation failure occurs in method 1 and method 2, and the fault recovery capability of the system is equivalent in 2 methods, which indicates that the dynamic current deviation control method provided by the present invention does not have adverse effects on the operating characteristics of the system.
Comparative example 2: and a single-phase earth fault is set at the inversion side conversion bus, the earth inductance is 0.45H, the starting time of the fault is 3s, and the time lasts for 0.5s. Under this condition, the relevant electrical quantity variation characteristics of the systems employing methods 1 and 2 are shown in fig. 4.
As can be seen from fig. 4, the grounding inductor L in case 2 f =0.45H, which corresponds to a relatively serious ac fault in the project. Even if Δ γ is continuously input 3 times when method 1 is employedThe maximum value is 16 degrees, the arc extinguishing angle can not be prevented from continuously falling to 0 for 3 times, continuous commutation failure is caused, and the direct current power fluctuate greatly until the fault disappears and then the stability is recovered.
When the method 2 is adopted, after a fault occurs, under the action of the dynamic current deviation control method, the extinction angle setting value increment delta gamma is continuously maintained at a larger value, the extinction angle falls to 0 only once, the continuous commutation failure is effectively inhibited, the direct current and the direct current power can be quickly stabilized, the dynamic current deviation control output delta gamma is reduced along with the disappearance of the fault, and the system is gradually recovered to normal steady-state operation.
Comparative example 3: and a three-phase grounding fault is arranged at the inversion side conversion bus, the grounding inductance is 0.45H, the starting time of the fault is 3s, and the time lasts for 0.5s. As shown in fig. 5, the dynamic current deviation control method provided in this embodiment can also better suppress the occurrence of the consecutive commutation failure under the fault condition.
In conclusion, the method provided by the embodiment has a good inhibition effect on the continuous commutation failure.
Fig. 6 is a block diagram of a continuous commutation failure suppression system based on dynamic current deviation control according to an embodiment of the present invention. As shown in fig. 6, the system includes:
the acquisition and detection unit 610 is used for acquiring the amplitude of each phase of the three-phase voltage of the inversion side commutation bus in real time;
further, the acquisition and detection unit 610 is configured to detect and calculate each phase of the three-phase voltage of the inverter-side converter bus by a second-order generalized integrator detection method.
The control calculation unit 620 is used for calculating and obtaining a voltage drop value of the current conversion bus according to a preset rule and the amplitude of each phase of the three-phase voltage;
the control calculation unit 620 is configured to determine a current deviation control curve according to the voltage drop value and a preset current deviation control function template;
further, the control calculation unit 620 is configured to compare each phase amplitude of the three-phase voltage of the inverter-side converter bus to obtain a minimum amplitude; and subtracting the minimum amplitude value from 1 to obtain a voltage drop value of the commutation bus.
Further, the control calculating unit 620 is configured to compare the voltage drop value with a preset amplitude limiting interval, and determine whether the voltage drop value is within the preset amplitude limiting interval;
if the amplitude is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
Further, the control calculation unit 620 is configured to bring the voltage drop value into a preset current deviation control function template to obtain a current deviation control curve; the preset current deviation control function template is as follows:
wherein, delta I d The current deviation value between the actually measured direct current and the direct current instruction value is obtained; delta U m Is the voltage sag value; delta gamma max The maximum constant value of the arc extinguishing angle when the alternating current system normally operates; delta I H And the current deviation value constant corresponds to the maximum constant of the arc extinguishing angle when the alternating current system normally operates.
And the adjusting unit 630, wherein the adjusting unit 630 is used for adjusting the arc-quenching angle in real time according to the current deviation control curve and a preset rule.
Further, the system also comprises a hysteresis comparison unit;
the acquisition detection unit 610 is used for calculating and obtaining the amplitude of the zero sequence component of the voltage of the converter bus according to a preset rule;
the hysteresis comparison unit is used for judging whether the amplitude of the zero-sequence component of the converter bus voltage exceeds a preset threshold value through a preset hysteresis comparator;
and if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value.
Further, the collecting and detecting unit 610 is configured to obtain a zero-sequence component of the voltage of the inversion side inversion bus according to an average value of three-phase voltages of the inversion side inversion bus;
the acquisition detection unit 610 is configured to perform detection by a second-order generalized integrator detection method and calculate to obtain an amplitude of the zero-sequence component of the converter bus voltage.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the disclosure may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Reference to step numbers in this specification is only for distinguishing between steps and is not intended to limit the temporal or logical relationship between steps, which includes all possible scenarios unless the context clearly dictates otherwise.
Moreover, those of skill in the art will appreciate that while some embodiments described herein include some features included in other embodiments, not others, combinations of features of different embodiments are meant to be within the scope of the disclosure and form different embodiments. For example, any of the embodiments claimed in the claims can be used in any combination.
Various component embodiments of the disclosure may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. The present disclosure may also be embodied as device or system programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present disclosure may be stored on a computer-readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the disclosure, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The disclosure may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several systems, several of these systems may be embodied by one and the same item of hardware.
The foregoing is directed to embodiments of the present disclosure, and it is noted that numerous improvements, modifications, and variations may be made by those skilled in the art without departing from the spirit of the disclosure, and that such improvements, modifications, and variations are considered to be within the scope of the present disclosure.
Claims (10)
1. A continuous commutation failure suppression method for dynamic current deviation control, the method comprising:
acquiring the amplitude of each phase of three-phase voltage of an inversion side converter bus in real time;
calculating to obtain a voltage drop value of the current conversion bus according to a preset rule and the amplitude value of each phase of the three-phase voltage;
calculating according to a preset rule to obtain the amplitude of the zero sequence component of the voltage of the converter bus;
judging whether the amplitude of the zero sequence component of the converter bus voltage exceeds a preset threshold value through a preset hysteresis comparator, wherein the preset threshold value is obtained by the following calculation:
U 0mz ＝K r *U 01max
in the formula of U 0mz To preset a threshold value, K r For a reliability factor, K r Not less than 1; the U is 01max The maximum value of the zero-sequence voltage amplitude of the corresponding current conversion bus is the maximum value when the single-phase earth fault can not cause the occurrence of the phase conversion failure;
if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value, wherein the preset constant value is subjected to simulation preferential determination in a preset voltage drop value amplitude limiting interval by adopting an exhaustion method; the simulation is constrained by inhibiting the effect of continuous commutation failure caused by single-phase fault and the recovery of direct current power after fault removal;
determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template, wherein the current deviation control curve comprises the following steps:
substituting the voltage drop value into a preset current deviation control function template to obtain a current deviation control curve; the preset current deviation control function template is as follows:
wherein, delta I d The current deviation value between the actually measured direct current and the direct current instruction value is obtained; delta U m Is the voltage sag value; delta gamma max Is the maximum constant of the arc extinguishing angle when the alternating current system normally operates; delta I H A current deviation value constant corresponding to the maximum constant of the arc extinguishing angle when the alternating current system normally operates;
and adjusting the arc extinguishing angle in real time according to a preset rule according to the current deviation control curve.
2. The method according to claim 1, wherein the real-time acquisition of the amplitude of each phase of the three-phase voltage of the inversion side commutation bus comprises:
and detecting and calculating each phase of the three-phase voltage of the inversion side current conversion bus by a second-order generalized integrator detection method.
3. The method according to claim 1, wherein the calculating the preset rule for obtaining the voltage sag value of the commutation bus comprises:
comparing each phase amplitude of the three-phase voltage of the inversion side conversion bus to obtain a minimum amplitude;
and subtracting the minimum amplitude value from 1 to obtain a voltage drop value of the commutation bus.
4. The method of claim 1, wherein after calculating the voltage sag value of the commutation bus, the method further comprises:
comparing the voltage drop value with a preset amplitude limiting interval, and judging whether the voltage drop value is in the preset amplitude limiting interval or not;
if the amplitude is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
5. The method according to claim 1, wherein the step of calculating and obtaining the amplitude of the zero sequence component of the voltage of the commutation bus according to a preset rule comprises the following steps:
obtaining a zero-sequence component of the voltage of the commutation bus through the average value of the three-phase voltage of the commutation bus at the inversion side;
and detecting and calculating by a second-order generalized integrator detection method to obtain the amplitude of the zero-sequence component of the converter bus voltage.
6. A dynamic current deviation controlled successive commutation failure suppression system, the system comprising:
the acquisition and detection unit is used for acquiring the amplitude of each phase of the three-phase voltage of the inversion side commutation bus in real time and calculating according to a preset rule to obtain the amplitude of the zero-sequence component of the commutation bus voltage;
the control calculation unit is used for calculating and obtaining a voltage drop value of the current conversion bus according to a preset rule and the amplitude value of each phase of the three-phase voltage;
the hysteresis comparison unit is used for judging whether the amplitude of the zero sequence component of the commutation bus voltage exceeds a preset threshold value through a preset hysteresis comparator, and the preset threshold value is obtained through the following calculation:
U 0mz ＝K r *U 01max
in the formula of U 0mz To preset a threshold value, K r For a reliability factor, K r Not less than 1; the U is 01max The maximum value of the zero sequence voltage amplitude of the corresponding current conversion bus is just the maximum value when the single-phase earth fault can not cause the occurrence of the phase conversion failure;
if the voltage drop value exceeds the preset threshold value, setting the voltage drop value as a preset constant value, wherein the preset constant value is subjected to simulation preferential determination in a preset voltage drop value amplitude limiting interval by adopting an exhaustion method; the simulation is constrained by inhibiting the effect of continuous commutation failure caused by single-phase fault and the recovery of direct current power after fault removal;
the control calculation unit is used for determining a current deviation control curve according to the voltage drop value and a preset current deviation control function template; the preset current deviation control function template is as follows:
wherein, delta I d For actually measuring DC current and DC current command valueA current deviation value therebetween; delta U m Is the voltage sag value; delta gamma max The maximum constant value of the arc extinguishing angle when the alternating current system normally operates; delta I H A current deviation value constant corresponding to the maximum constant of the arc extinguishing angle when the alternating current system normally operates;
and the adjusting unit is used for adjusting the arc extinguishing angle in real time according to the current deviation control curve and a preset rule.
7. The system of claim 6, wherein:
the acquisition detection unit is used for detecting and calculating each phase of the three-phase voltage of the inversion side current conversion bus through a second-order generalized integrator detection method.
8. The system of claim 6, wherein:
the control calculation unit is used for comparing each phase amplitude of the three-phase voltage of the inversion side conversion bus to obtain a minimum amplitude; and subtracting the minimum amplitude value from 1 to obtain a voltage drop value of the commutation bus.
9. The system of claim 6, wherein:
the control calculation unit is used for comparing the voltage drop value with a preset amplitude limiting interval and judging whether the voltage drop value is in the preset amplitude limiting interval or not;
if the amplitude is within the amplitude limiting interval, continuing to execute the subsequent steps;
and if the current amplitude is not in the amplitude limiting interval, carrying out extreme condition early warning according to a preset rule.
10. The system of claim 6, wherein:
the acquisition detection unit is used for acquiring a zero-sequence component of the voltage of the inversion bus according to the mean value of the three-phase voltage of the inversion side inversion bus;
the acquisition detection unit is used for detecting and calculating the amplitude of the zero-sequence component of the voltage of the current conversion bus through a second-order generalized integrator detection method.
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| CN113098045B (en) * | 2021-04-02 | 2022-08-30 | 合肥工业大学 | Optimization control method suitable for UHVDC commutation failure fault recovery |
| CN113517712B (en) * | 2021-05-17 | 2022-10-25 | 国网甘肃省电力公司电力科学研究院 | Direct current system commutation method for improving success rate based on self-adaptive threshold of prediction link |
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