CN113805094B - Method, device, equipment and medium for evaluating short circuit ratio of high-voltage direct-current transmission system - Google Patents
Method, device, equipment and medium for evaluating short circuit ratio of high-voltage direct-current transmission system Download PDFInfo
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Abstract
The invention discloses a method for evaluating the short circuit ratio of a high-voltage direct-current transmission system, which comprises the following steps: when the switching state of the alternating current filter of the converter station is detected to change, the voltage values of the alternating current three-phase buses before and after switching are obtained; calculating the voltage change rate of the alternating current bus before and after switching according to the voltage value of the alternating current three-phase bus; calculating a short-circuit ratio of a converter bus according to rated capacity of an alternating current filter bank of the converter station and rated transmission capacity of a high-voltage direct current transmission system; acquiring the direct current power value transmitted by a high-voltage direct current transmission system and the group number information of the alternating current filter of a converter station in operation in real time; calculating the effective short-circuit ratio of a converter bus; and the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus are evaluated to obtain the system strength of an alternating current system connected with the high-voltage direct current transmission system, so that the problem of parameter drift can be effectively solved, and the accuracy of calculating the short-circuit ratio is improved. The invention also discloses a device, equipment and medium for evaluating the short circuit ratio of the high-voltage direct-current transmission system.
Description
Technical Field
The invention relates to the technical field of high-voltage direct-current transmission systems, in particular to a method, a device, equipment and a medium for evaluating the short-circuit ratio of a high-voltage direct-current transmission system.
Background
The coal resources in China are mainly distributed in the western region and the northern region, the water energy resources are mainly concentrated in the southwest region, the eastern region is deficient in primary energy resources, and the electricity load is relatively concentrated. The imbalance of energy resources and power load distribution determines the necessity of western electric east delivery. The advantages of the high-voltage/extra-high-voltage direct current transmission technology are rapidly developed due to the long transmission distance and large capacity.
The operation of the high-voltage direct-current transmission system requires the alternating-current system to provide the support of the commutation voltage, the safe and stable operation of the system depends on the intensity of the alternating-current system, and the operation of the high-voltage direct-current system connected with the weak alternating-current system has related problems: high dynamic overvoltage, unstable voltage, harmonic resonance and harmonic instability, fault recovery, transient instability and the like, and seriously influence the normal operation of the system. Along with popularization of application scenes of the high-voltage direct-current transmission system, strength indexes for correspondingly judging interaction of the alternating-current and direct-current systems are proposed in the industry: a short-circuit ratio and an effective short-circuit ratio. Therefore, the real-time short-circuit ratio is accurately calculated, and the method has important significance for the operation of a high-voltage direct-current transmission system, wherein the solution of the short-circuit capacity of an alternating-current system is critical. At present, in the research of online calculation of the short circuit ratio and the effective short circuit ratio, the drift problem of the Thevenin equivalent parameters exists, and the real-time short circuit ratio cannot be accurately calculated.
Disclosure of Invention
The method, the device, the equipment and the medium for evaluating the short-circuit ratio of the high-voltage direct-current transmission system can effectively solve the problem of parameter drift in the prior art, and greatly improve the accuracy of calculating the short-circuit ratio.
The embodiment of the invention provides a method for evaluating the short circuit ratio of a high-voltage direct-current transmission system, which comprises the following steps:
when the switching state of the alternating current filter of the converter station is detected to change, acquiring alternating current three-phase bus voltage values in preset time before and after switching of the alternating current filter of the converter station;
calculating the voltage change rate of the alternating current bus before and after switching of the alternating current filter of the convertor station according to the voltage value of the alternating current three-phase bus;
calculating a converter bus short-circuit ratio of a converter station of the high-voltage direct-current power transmission system according to the preset rated capacity of the converter station alternating-current filter bank, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate;
acquiring the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation in real time;
calculating the effective short-circuit ratio of a converter bus of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity;
And evaluating the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system to obtain the system strength of the alternating-current system connected with the high-voltage direct-current power transmission system.
As an improvement of the above solution, the calculating the rate of change of the ac bus voltage before and after switching the ac filter of the converter station according to the ac three-phase bus voltage value specifically includes:
respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station to obtain converted alternating current three-phase bus voltage values;
according to the converted alternating current three-phase bus voltage value, calculating an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching respectively;
and obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage effective value before switching, the alternating current three-phase bus voltage effective value after switching and the preset alternating current bus rated voltage effective value.
As an improvement of the above solution, the calculating the rate of change of the ac bus voltage before and after switching the ac filter of the converter station according to the ac three-phase bus voltage value further includes:
Respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station by adopting a pre-established voltage conversion model to obtain converted alternating current three-phase bus voltage values; the voltage transformation model is determined by the following formula, and the specific formula is as follows:
wherein U is a 、U b 、U c Is the voltage value of an alternating current three-phase bus, e a 、e b E is an intermediate transformation parameter p1 E is the voltage value of the alternating current three-phase bus after the first conversion p2 E is the voltage value of the alternating current three-phase bus after the second transformation q1 、e q2 As a function of the voltage transformation parameters,angular frequency of the alternating current three-phase bus voltage signal;
the effective value of the voltage of the alternating-current three-phase bus is determined according to the following formula, and the specific formula is as follows:
wherein E is p1rms Is the effective value of the voltage of the first alternating current three-phase bus, E p2rms Is the effective value of the voltage of the second alternating current three-phase bus, E rms N is the number of sampling points for the effective value of the voltage of the alternating current three-phase bus;
obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to a formula (7):
ΔU reci ＝100*Min(0.01,Abs(E rms-before -E rms-after ))/U ref (7)
wherein DeltaU reci For the alternating current bus voltage change rate, E rms-before Is the effective value of the voltage of the alternating current three-phase bus before switching, E rms-after U is the effective value of the voltage of the switched alternating current three-phase bus ref Is a preset rated voltage effective value of the alternating current bus.
As an improvement of the above solution, the calculating the short-circuit ratio of the converter bus of the ac power transmission system according to the preset rated capacity of the ac filter bank of the converter station, the rated transmission capacity of the ac power transmission system and the ac bus voltage change rate specifically includes:
obtaining a short-circuit ratio of a converter bus of the high-voltage direct-current power transmission system converter station according to a formula (8):
SCR teory ＝Q acf-ref /(P ref *ΔU reci ) (8)
wherein, SCR t eory For the short-circuit ratio of the converter bus, Q acf-ref For the rated capacity, P, of the converter station AC filter bank ref For the rated delivery capacity ΔU reci And the voltage change rate of the alternating current bus is the voltage change rate of the alternating current bus.
As an improvement of the above solution, the method further includes:
obtaining a direct current power value transmitted by the high-voltage direct current transmission system according to a formula (9):
PU act ＝Max(0.05*P ref ,P act ) (9)
wherein PU act For the DC power value, P act The rated power value of the direct current transmission system is preset;
obtaining the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system converter station according to the formula (10):
wherein ESCR is as follows ACT For the effective short-circuit ratio of the converter bus, Q acf-ref For the rated capacity of the converter station ac filter bank, Δu reci For the alternating current bus voltage change rate, N acf And exchanging the information of the number of groups in operation of the filter for the converter station.
As an improvement of the above solution, the estimating the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system to obtain the system strength of the alternating-current system connected with the high-voltage direct-current power transmission system specifically includes:
when the short-circuit ratio of the converter bus is greater than zero and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset first alternating current system strength judgment standard threshold value, determining that the alternating current system is in a weak system;
when the short-circuit ratio of the converter bus is larger than the strength judgment standard threshold value of the first alternating current system and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset strength judgment standard threshold value of a second alternating current system, determining that the alternating current system is in a medium system;
and when the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus are both larger than the strength judgment standard threshold value of the second alternating current system, determining that the alternating current system is in a strong system.
As an improvement of the above solution, the method further includes:
when the switching state of the alternating current filter of the converter station is not changed, the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus, which are obtained by the last switching of the alternating current filter of the converter station, are obtained and evaluated, and the system strength of the alternating current system connected with the current high-voltage direct current transmission system is obtained.
An embodiment of the present invention provides an evaluation device for a short circuit ratio of a high voltage direct current transmission system, including:
the alternating current three-phase bus voltage value acquisition module is used for acquiring alternating current three-phase bus voltage values in preset time before and after switching of the alternating current filter of the converter station when detecting that the switching state of the alternating current filter of the converter station changes;
the alternating current bus voltage change rate calculation module is used for calculating the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage value;
the converter bus short-circuit ratio calculation module is used for calculating the converter bus short-circuit ratio of the converter station of the high-voltage direct-current power transmission system according to the preset rated capacity of the converter station alternating-current filter bank, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate;
the real-time data acquisition module is used for acquiring the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation in real time;
the converter bus effective short-circuit ratio calculation module is used for calculating the converter bus effective short-circuit ratio of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity;
And the alternating current system strength analysis module is used for evaluating the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct current power transmission system to obtain the system strength of the alternating current system connected with the high-voltage direct current power transmission system.
Compared with the prior art, the method, the device, the equipment and the medium for evaluating the short circuit ratio of the high-voltage direct-current transmission system disclosed by the embodiment of the invention have the following beneficial effects:
when the switching state of the alternating current filter of the converter station is detected to change, an alternating current three-phase bus voltage value in preset time before and after switching of the alternating current filter of the converter station is obtained, the alternating current bus voltage change rate before and after switching of the alternating current filter of the converter station is calculated according to the alternating current three-phase bus voltage value, the converter bus short circuit ratio of the converter station of the high-voltage direct current power transmission system is calculated according to the rated capacity of a preset alternating current filter group of the converter station, the rated transmission capacity of the high-voltage direct current power transmission system and the alternating current bus voltage change rate, the direct current power value transmitted by the high-voltage direct current power transmission system and the group number information of the alternating current filter of the converter station in operation are obtained in real time, according to the direct current power value, the group number information, the alternating current bus voltage change rate and the rated capacity, calculating the effective short-circuit ratio of a converter bus of the high-voltage direct current power transmission system converter station, and evaluating the short-circuit ratio of the converter bus of the high-voltage direct current power transmission system converter station and the effective short-circuit ratio of the converter bus to obtain the system strength of an alternating current system connected with the high-voltage direct current power transmission system, so that the parameter drift problem in the prior art can be effectively solved, the numerical oscillation problem caused by small alternating current voltage fluctuation due to interference of system harmonic waves and switching of an alternating current filter can be solved, the accuracy of calculating the short-circuit ratio is greatly improved, and the method has the characteristics of low cost, high efficiency, large income and large application prospect in the field of the high-voltage direct current power transmission station.
Another embodiment of the present invention provides an apparatus for evaluating a short circuit ratio of a hvdc transmission system, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, where the processor executes the computer program to implement the method for evaluating a short circuit ratio of a hvdc transmission system according to the embodiment of the present invention.
Another embodiment of the present invention provides a storage medium, where the storage medium includes a stored computer program, and when the computer program runs, the device where the storage medium is controlled to execute the method for evaluating the short-circuit ratio of the hvdc transmission system according to the embodiment of the present invention.
Drawings
Fig. 1 is a flow chart of a method for evaluating a short circuit ratio of a hvdc transmission system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an evaluation device for short-circuit ratio of a hvdc transmission system according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. 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.
Referring to fig. 1, a flow chart of a method for evaluating a short circuit ratio of a hvdc transmission system according to an embodiment of the present invention is shown, and the method includes steps S101 to S106.
And S101, when detecting that the switching state of the alternating current filter of the converter station changes, acquiring the voltage value of the alternating current three-phase bus within preset time before and after switching of the alternating current filter of the converter station.
Preferably, before step S101, the method includes: and detecting whether switching of the alternating current filter of the convertor station occurs or not. Optionally, when detecting that the switching state of the alternating current filter of the converter station changes, acquiring real-time information of the switching state of the alternating current filter. The real-time information of the switching state specifically uses the switching-on and switching-off state of the switch of the alternating current filter as a boundary, and the voltage value of the alternating current three-phase bus in delta t time before switching of the alternating current filter and the voltage value of the alternating current three-phase bus in delta t time after switching of the alternating current filter are used.
In an alternative embodiment, when the switching state of the alternating current filter of the converter station is not changed, the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus, which are obtained by the last switching of the alternating current filter of the converter station, are obtained and evaluated, and the system strength of the alternating current system connected with the current high-voltage direct current transmission system is obtained.
S102, calculating the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage value.
In one embodiment, step S102 includes:
respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station to obtain converted alternating current three-phase bus voltage values;
according to the converted alternating current three-phase bus voltage value, calculating an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching respectively;
and obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage effective value before switching, the alternating current three-phase bus voltage effective value after switching and the preset alternating current bus rated voltage effective value.
The rated transmission capacity P of the HVDC transmission system is preset ref Rated voltage effective value U of alternating current bus ref Rated capacity Q of a converter station ac filter bank acf-ref . Further, the converted ac three-phase bus voltage values are respectively low-pass filtered in consideration of the influence of harmonics, so that the effective values of the ac three-phase bus voltages are calculated for the filtered quantities. Further, when the switching state of the alternating current filter of the converter station is detected to change, the effective value of the alternating current three-phase bus voltage in delta t time before switching of the alternating current filter and the effective value of the alternating current three-phase bus voltage in delta t time after switching are respectively calculated, and then the alternating current bus voltage change rate in the switching process is obtained.
In another embodiment, step S102 includes:
respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station by adopting a pre-established voltage conversion model to obtain converted alternating current three-phase bus voltage values; the voltage transformation model is determined by the following formula, and the specific formula is as follows:
wherein U is a 、U b 、U c Is the voltage value of an alternating current three-phase bus, e a 、e b E is an intermediate transformation parameter p1 E is the voltage value of the alternating current three-phase bus after the first conversion p2 E is the voltage value of the alternating current three-phase bus after the second transformation q1 、e q2 As a function of the voltage transformation parameters,angular frequency of the alternating current three-phase bus voltage signal;
the effective value of the voltage of the alternating-current three-phase bus is determined according to the following formula, and the specific formula is as follows:
wherein E is p1rms Is the effective value of the voltage of the first alternating current three-phase bus, E p2rms Is the effective value of the voltage of the second alternating current three-phase bus, E rms And N is the number of sampling points for the effective value of the voltage of the alternating current three-phase bus. In this embodiment, the ac three-phase bus before switching can be calculated based on the above voltage transformation modelLine voltage effective value E rms-before And the effective value E of the voltage of the switched alternating current three-phase bus rms-after . In order to improve the accuracy of the calculated value, an average value of the effective value of the first ac three-phase bus voltage and the effective value of the second ac three-phase bus voltage is taken as the effective value of the ac three-phase bus voltage in the embodiment.
In some embodiments, the rate of change of the ac bus voltage before and after switching of the ac filter of the converter station is obtained according to formula (7):
ΔU reci ＝100*Min(0.01,Abs(E rms-before -E rms-after ))/U ref (7)
wherein DeltaU reci For the alternating current bus voltage change rate, E rms-before Is the effective value of the voltage of the alternating current three-phase bus before switching, E rms-after U is the effective value of the voltage of the switched alternating current three-phase bus ref Is a preset rated voltage effective value of the alternating current bus.
S103, calculating the short-circuit ratio of the converter bus of the converter station of the high-voltage direct-current power transmission system according to the preset rated capacity of the converter station alternating-current filter bank, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate.
In a preferred embodiment, step S103 includes:
obtaining a short-circuit ratio of a converter bus of the high-voltage direct-current power transmission system converter station according to a formula (8):
SCR teory ＝Q acf-ref /(P ref *ΔU reci ) (8)
wherein, SCR teory For the short-circuit ratio of the converter bus, Q acf-ref For the rated capacity, P, of the converter station AC filter bank ref For the rated delivery capacity ΔU reci And the voltage change rate of the alternating current bus is the voltage change rate of the alternating current bus.
S104, acquiring the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation in real time.
Preferably, the dc power value transmitted by the hvdc transmission system is obtained according to the formula (9):
PU act ＝Max(0.05*P ref ,P act ) (9)
Wherein PU act For the DC power value, P act Is a preset rated power value of the direct current transmission system. In addition, the group number information of the current alternating current filter of the converter station in operation is specifically the group number information of the alternating current filter in operation after switching of the current alternating current filter of the converter station.
S105, calculating the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity.
In a preferred embodiment, step S105 includes:
obtaining the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system converter station according to the formula (10):
wherein ESCR is as follows ACT For the effective short-circuit ratio of the converter bus, Q acf-ref For the rated capacity of the converter station ac filter bank, Δu reci For the alternating current bus voltage change rate, N acf Group number information for the current converter station ac filter in operation
S106, evaluating the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system, and obtaining the system strength of an alternating-current system connected with the high-voltage direct-current power transmission system.
In a preferred embodiment, step S106 includes:
When the short-circuit ratio of the converter bus is greater than zero and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset first alternating current system strength judgment standard threshold value, determining that the alternating current system is in a weak system;
when the short-circuit ratio of the converter bus is larger than the strength judgment standard threshold value of the first alternating current system and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset strength judgment standard threshold value of a second alternating current system, determining that the alternating current system is in a medium system;
and when the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus are both larger than the strength judgment standard threshold value of the second alternating current system, determining that the alternating current system is in a strong system.
The ac system intensity determination standard threshold S is preset 1 ,S 2 And judging the system strength of an alternating current system connected with the high-voltage direct current transmission system according to the short circuit ratio of the converter bus and the effective short circuit of the converter bus and a preset system strength judging condition. Exemplary, the system strength determination condition includes that the system strength determination condition is 0<SCR t eory 、ESCR ACT ≤S 1 As a condition for determining that the ac system is in a weak system; the system strength determination condition includes S 1 <SCR teory 、ESCR ACT ≤S 2 As a condition for determining that the ac system is in the medium system; the system strength determination condition includes S 2 <SCR teory 、ESCR ACT As a condition for determining that the ac system is in a strong system.
According to the evaluation method for the short circuit ratio of the high-voltage direct current transmission system, when the switching state of the alternating current filter of the converter station is detected to change, the alternating current three-phase bus voltage value in the preset time before and after switching of the alternating current filter of the converter station is obtained, the effective short circuit ratio of the alternating current bus of the converter station is calculated according to the alternating current three-phase bus voltage value, the rated capacity of the alternating current filter group of the converter station, the rated transmission capacity of the high-voltage direct current transmission system and the alternating current bus voltage change rate, the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation are obtained in real time, the effective short circuit ratio of the alternating current bus of the converter station is calculated according to the direct current power value, the group number information, the alternating current bus voltage change rate and the rated capacity, the effective short circuit ratio of the converter of the high-voltage direct current transmission system is calculated, the current transmission system has high-voltage ratio and the current power value of the converter, the current power system is greatly reduced, the current power transmission system has high-voltage ratio of the current power transmission system is greatly-factor of fluctuation, and the current power transmission system has high-voltage fluctuation ratio, and high-current power factor ratio fluctuation ratio, and high-current oscillation factor ratio is solved, and the problem is high, and has high current and high current-current efficiency and short-current efficiency.
Referring to fig. 2, a schematic structural diagram of an apparatus for evaluating a short-circuit ratio of a hvdc transmission system according to an embodiment of the present invention is provided, including:
the alternating current three-phase bus voltage value acquisition module 201 is used for acquiring alternating current three-phase bus voltage values in preset time before and after switching of the alternating current filter of the converter station when detecting that the switching state of the alternating current filter of the converter station changes;
the ac bus voltage change rate calculating module 202 is configured to calculate an ac bus voltage change rate before and after switching of the ac filter of the converter station according to the ac three-phase bus voltage value;
the converter bus short-circuit ratio calculation module 203 is configured to calculate a converter bus short-circuit ratio of a converter station of the high-voltage direct-current power transmission system according to a preset rated capacity of an alternating-current filter bank of the converter station, a preset rated transmission capacity of the high-voltage direct-current power transmission system, and a preset alternating-current bus voltage change rate;
the real-time data acquisition module 204 is configured to acquire, in real time, a dc power value transmitted by the high-voltage dc power transmission system and group number information of the ac filter of the converter station in operation;
the converter bus effective short-circuit ratio calculation module 205 is configured to calculate a converter bus effective short-circuit ratio of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity;
And the ac system strength analysis module 206 is configured to evaluate a short-circuit ratio of a converter bus and an effective short-circuit ratio of the converter bus of the high-voltage dc power transmission system, so as to obtain a system strength of an ac system connected to the high-voltage dc power transmission system.
Preferably, the ac bus voltage change rate calculation module 202 includes:
the conversion unit is used for respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station to obtain converted alternating current three-phase bus voltage values;
the alternating current three-phase bus voltage effective value calculating unit is used for respectively calculating an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching according to the converted alternating current three-phase bus voltage value;
and the alternating current bus voltage change rate calculation unit is used for obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage effective value before switching, the alternating current three-phase bus voltage effective value after switching and the preset alternating current bus rated voltage effective value.
Preferably, the ac bus voltage change rate calculation module 202 further includes:
The voltage value conversion unit is used for respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station by adopting a pre-established voltage conversion model to obtain converted alternating current three-phase bus voltage values; the voltage transformation model is determined by the following formula, and the specific formula is as follows:
wherein U is a 、U b 、U c Is the voltage value of an alternating current three-phase bus, e a 、e b E is an intermediate transformation parameter p1 E is the voltage value of the alternating current three-phase bus after the first conversion p2 E is the voltage value of the alternating current three-phase bus after the second transformation q1 、e q2 As a function of the voltage transformation parameters,angular frequency of the alternating current three-phase bus voltage signal;
the effective value acquisition unit of the alternating current three-phase bus voltage is used for determining the effective value of the alternating current three-phase bus voltage according to the following formula, and the specific formula is as follows:
wherein E is p1rms Is the effective value of the voltage of the first alternating current three-phase bus, E p2rms Is the effective value of the voltage of the second alternating current three-phase bus, E rms N is the number of sampling points for the effective value of the voltage of the alternating current three-phase bus;
the alternating current bus voltage change rate acquisition unit is used for obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the formula (7):
ΔU reci ＝100*Min(0.01,Abs(E rms-before -E rms-after ))/U ref (7)
wherein DeltaU reci For the alternating current bus voltage change rate, E rms-before Is the effective value of the voltage of the alternating current three-phase bus before switching, E rms-after U is the effective value of the voltage of the switched alternating current three-phase bus ref Is a preset rated voltage effective value of the alternating current bus.
Preferably, the converter bus short-circuit ratio calculation module 203 includes:
the converter bus short-circuit ratio acquisition unit is used for obtaining the converter bus short-circuit ratio of the high-voltage direct-current transmission system converter station according to the formula (8):
SCR teory ＝Q acf-ref /(P ref *ΔU reci ) (8)
wherein, SCR teory For the short-circuit ratio of the converter bus, Q acf-ref For the rated capacity, P, of the converter station AC filter bank ref For the rated delivery capacity ΔU reci And the voltage change rate of the alternating current bus is the voltage change rate of the alternating current bus.
Preferably, the real-time data acquisition module 204 includes:
the current direct current power value acquisition unit is used for acquiring the direct current power value transmitted by the high-voltage direct current power transmission system according to the formula (9):
PU act ＝Max(0.05*P ref ,P act ) (9)
wherein PU act For the DC power value, P act Is a preset rated power value of the direct current transmission system.
Preferably, the converter bus effective short-circuit ratio calculation module 205 includes:
the converter bus effective short-circuit ratio acquisition unit is used for obtaining the converter bus effective short-circuit ratio of the high-voltage direct-current power transmission system converter station according to the formula (10):
wherein ESCR is as follows ACT For the effective short-circuit ratio of the converter bus, Q acf-ref For the rated capacity of the converter station ac filter bank, Δu reci For the alternating current bus voltage change rate, N acf For the exchange ofThe stream station exchanges information of the number of groups the filter is operating on.
Preferably, the ac system strength analysis module 206 includes:
the first system strength judging unit is used for determining that the alternating current system is in a weak system when the short-circuit ratio of the converter bus is larger than zero and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset first alternating current system strength judging standard threshold value;
the second system strength judging unit is used for determining that the alternating current system is in the middle system when the short-circuit ratio of the current conversion bus is larger than the first alternating current system strength judging standard threshold value and the effective short-circuit ratio of the current conversion bus is smaller than or equal to a preset second alternating current system strength judging standard threshold value;
and the third system strength judging unit is used for determining that the alternating current system is in a strong system when the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus are both larger than the second alternating current system strength judging standard threshold value.
Preferably, the device for evaluating the short-circuit ratio of the hvdc transmission system further comprises:
and the non-switching operation module is used for acquiring and evaluating the short-circuit ratio of the current converting bus and the effective short-circuit ratio of the converting bus, which are obtained by switching the alternating current filter of the converter station last time, when the switching state of the alternating current filter of the converter station is not changed, so as to obtain the system strength of the alternating current system connected with the current high-voltage direct current transmission system.
According to the evaluation device of the short-circuit ratio of the high-voltage direct-current power transmission system, when the switching state of the alternating-current filter of the converter station is detected to change, the alternating-current three-phase bus voltage value in the preset time before and after switching of the alternating-current filter of the converter station is obtained, the alternating-current bus voltage change rate before and after switching of the alternating-current filter of the converter station is calculated according to the alternating-current three-phase bus voltage value, the direct-current power value transmitted by the high-voltage direct-current power transmission system and the group number information of the alternating-current filter of the converter station in operation are obtained in real time according to the preset rated capacity of the alternating-current filter group of the converter station, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate, according to the direct current power value, the group number information, the alternating current bus voltage change rate and the rated capacity, calculating the effective short-circuit ratio of a converter bus of the high-voltage direct current power transmission system converter station, and evaluating the short-circuit ratio of the converter bus of the high-voltage direct current power transmission system converter station and the effective short-circuit ratio of the converter bus to obtain the system strength of an alternating current system connected with the high-voltage direct current power transmission system, so that the parameter drift problem in the prior art can be effectively solved, the numerical oscillation problem caused by small alternating current voltage fluctuation due to interference of system harmonic waves and switching of an alternating current filter can be solved, the accuracy of calculating the short-circuit ratio is greatly improved, and the method has the characteristics of low cost, high efficiency, large income and large application prospect in the field of the high-voltage direct current power transmission station.
The device for evaluating the short circuit ratio of the HVDC transmission system in one embodiment of the invention comprises: a processor, a memory and a computer program stored in the memory and executable on the processor, such as a program for evaluating the short circuit ratio of a hvdc transmission system. And the processor executes the computer program to realize the steps in the embodiment of the method for evaluating the short circuit ratio of each high-voltage direct-current transmission system. Alternatively, the processor may implement the functions of the modules/units in the above-described device embodiments when executing the computer program.
The computer program may be divided into one or more modules/units, which are stored in the memory and executed by the processor to accomplish the present invention, for example. The one or more modules/units may be a series of computer program instruction segments capable of performing a specific function for describing the execution of the computer program in an apparatus for evaluating the short circuit ratio of the hvdc transmission system.
The evaluation device of the short circuit ratio of the high-voltage direct-current transmission system can be computing devices such as a desktop computer, a notebook computer, a palm computer and a cloud server. The evaluation device of the short circuit ratio of the high-voltage direct-current transmission system can comprise, but is not limited to, a processor and a memory. It will be appreciated by those skilled in the art that the schematic diagram is merely an example of an evaluation device for a short circuit ratio of a hvdc transmission system, and does not constitute a limitation of the evaluation device for a short circuit ratio of a hvdc transmission system, and may include more or less components than those illustrated, or may combine certain components, or different components, e.g. the evaluation device for a short circuit ratio of a hvdc transmission system may also include an input-output device, a network access device, a bus, etc.
The processor may be a central processing unit (Central Processing Unit, CPU), other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. The general purpose processor may be a microprocessor or the processor may be any conventional processor or the like, which is a control center of the apparatus for evaluating the short circuit ratio of the hvdc transmission system, and connects the respective parts of the entire apparatus for evaluating the short circuit ratio of the hvdc transmission system by using various interfaces and lines.
The memory may be used to store the computer program and/or the module, and the processor may implement various functions of the apparatus for evaluating a short circuit ratio of a hvdc transmission system by running or executing the computer program and/or the module stored in the memory and invoking data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data (such as audio data, phonebook, etc.) created according to the use of the handset, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, smart Media Card (SMC), secure Digital (SD) Card, flash Card (Flash Card), at least one disk storage device, flash memory device, or other volatile solid-state storage device.
Wherein the module/unit integrated by the evaluation device of the short circuit ratio of the hvdc transmission system can be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a separate product. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiment, or may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable medium contains content that can be appropriately scaled according to the requirements of jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is subject to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.
It should be noted that the above-described apparatus embodiments are merely illustrative, and the units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the drawings of the embodiment of the device provided by the invention, the connection relation between the modules represents that the modules have communication connection, and can be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Claims (8)
1. The method for evaluating the short circuit ratio of the high-voltage direct-current transmission system is characterized by comprising the following steps of:
When the switching state of the alternating current filter of the converter station is detected to change, acquiring alternating current three-phase bus voltage values in preset time before and after switching of the alternating current filter of the converter station;
calculating the voltage change rate of the alternating current bus before and after switching of the alternating current filter of the convertor station according to the voltage value of the alternating current three-phase bus;
calculating a converter bus short-circuit ratio of a converter station of the high-voltage direct-current power transmission system according to the preset rated capacity of the converter station alternating-current filter bank, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate;
acquiring the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation in real time;
calculating the effective short-circuit ratio of a converter bus of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity;
evaluating the short-circuit ratio of a converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system to obtain the system strength of an alternating-current system connected with the high-voltage direct-current power transmission system;
the method comprises the steps of calculating the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage value, wherein the method specifically comprises the following steps:
According to the alternating current three-phase bus voltage value, calculating to obtain an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching;
obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to a formula (7):
ΔU reci ＝100*Min(0.01，Abs(E rms-before -E rms-after ))/U ref (7)
wherein DeltaU reci For the alternating current bus voltage change rate, E rms-before Is the effective value of the voltage of the alternating current three-phase bus before switching, E rms-after U is the effective value of the voltage of the switched alternating current three-phase bus ref The method is a preset rated voltage effective value of an alternating current bus;
the short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system converter station is obtained according to the formula (8):
SCR t eory ＝Q acf-ref /(P ref *ΔU reci ) (8)
wherein, SCR t eory For the short-circuit ratio of the converter bus, Q acf-ref For the rated capacity, P, of the converter station AC filter bank ref For the rated delivery capacity ΔU reci The alternating current bus voltage change rate is set;
the method comprises the steps of obtaining a direct current power value transmitted by the high-voltage direct current transmission system according to a formula (9):
PU act ＝Max(0.05*P ref ，P act ) (9)
wherein PU act For the DC power value, P act The rated power value of the direct current transmission system is preset;
the effective short-circuit ratio of the converter bus of the high-voltage direct-current power transmission system converter station is obtained according to the formula (10):
Wherein,ESCR ACT for the effective short-circuit ratio of the converter bus, Q acf-ref For the rated capacity of the converter station ac filter bank, Δu reci For the alternating current bus voltage change rate, N acf And exchanging the information of the number of groups in operation of the filter for the converter station.
2. The method for evaluating the short-circuit ratio of a high-voltage direct-current transmission system according to claim 1, wherein the calculating the alternating-current bus voltage change rate before and after switching of the alternating-current filter of the converter station according to the alternating-current three-phase bus voltage value specifically comprises:
respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station to obtain converted alternating current three-phase bus voltage values;
according to the converted alternating current three-phase bus voltage value, calculating an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching respectively;
and obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage effective value before switching, the alternating current three-phase bus voltage effective value after switching and the preset alternating current bus rated voltage effective value.
3. The method for evaluating the short-circuit ratio of a high-voltage direct-current transmission system according to claim 2, wherein the calculating the alternating-current bus voltage change rate before and after switching of the alternating-current filter of the converter station according to the alternating-current three-phase bus voltage value further comprises:
Respectively converting the alternating current three-phase bus voltage values before and after switching of the alternating current filter of the convertor station by adopting a pre-established voltage conversion model to obtain converted alternating current three-phase bus voltage values; the voltage transformation model is determined by the following formula, and the specific formula is as follows:
wherein U is a 、U b 、U c Is the voltage value of an alternating current three-phase bus, e a 、e b E is an intermediate transformation parameter p1 E is the voltage value of the alternating current three-phase bus after the first conversion p2 E is the voltage value of the alternating current three-phase bus after the second transformation q1 、e q2 As a function of the voltage transformation parameters,angular frequency of the alternating current three-phase bus voltage signal;
the effective value of the voltage of the alternating-current three-phase bus is determined according to the following formula, and the specific formula is as follows:
wherein E is p1rms Is the effective value of the voltage of the first alternating current three-phase bus, E p2rms Is the effective value of the voltage of the second alternating current three-phase bus, E rms And N is the number of sampling points for the effective value of the voltage of the alternating current three-phase bus.
4. The method for evaluating the short-circuit ratio of a hvdc transmission system according to claim 1, wherein the evaluating the short-circuit ratio of a commutated bus and the effective short-circuit ratio of a commutated bus of a commutated station of the hvdc transmission system to obtain the system strength of an ac system to which the hvdc transmission system is connected specifically comprises:
When the short-circuit ratio of the converter bus is greater than zero and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset first alternating current system strength judgment standard threshold value, determining that the alternating current system is in a weak system;
when the short-circuit ratio of the converter bus is larger than the strength judgment standard threshold value of the first alternating current system and the effective short-circuit ratio of the converter bus is smaller than or equal to a preset strength judgment standard threshold value of a second alternating current system, determining that the alternating current system is in a medium system;
and when the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus are both larger than the strength judgment standard threshold value of the second alternating current system, determining that the alternating current system is in a strong system.
5. The method for evaluating the short circuit ratio of a high voltage direct current transmission system according to claim 1, wherein the method further comprises:
when the switching state of the alternating current filter of the converter station is not changed, the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus, which are obtained by the last switching of the alternating current filter of the converter station, are obtained and evaluated, and the system strength of the alternating current system connected with the current high-voltage direct current transmission system is obtained.
6. An evaluation device for short circuit ratio of a high-voltage direct-current transmission system, comprising:
The alternating current three-phase bus voltage value acquisition module is used for acquiring alternating current three-phase bus voltage values in preset time before and after switching of the alternating current filter of the converter station when detecting that the switching state of the alternating current filter of the converter station changes;
the alternating current bus voltage change rate calculation module is used for calculating the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage value;
the converter bus short-circuit ratio calculation module is used for calculating the converter bus short-circuit ratio of the converter station of the high-voltage direct-current power transmission system according to the preset rated capacity of the converter station alternating-current filter bank, the rated transmission capacity of the high-voltage direct-current power transmission system and the alternating-current bus voltage change rate;
the real-time data acquisition module is used for acquiring the direct current power value transmitted by the high-voltage direct current transmission system and the group number information of the alternating current filter of the converter station in operation in real time;
the converter bus effective short-circuit ratio calculation module is used for calculating the converter bus effective short-circuit ratio of the high-voltage direct-current power transmission system converter station according to the direct-current power value, the group number information, the alternating-current bus voltage change rate and the rated capacity;
The alternating current system strength analysis module is used for evaluating the short-circuit ratio of the converter bus and the effective short-circuit ratio of the converter bus of the high-voltage direct current power transmission system converter station to obtain the system strength of an alternating current system connected with the high-voltage direct current power transmission system;
the alternating current bus voltage change rate calculation module is used for calculating the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to the alternating current three-phase bus voltage value, and specifically comprises the following steps:
according to the alternating current three-phase bus voltage value, calculating to obtain an alternating current three-phase bus voltage effective value before switching and an alternating current three-phase bus voltage effective value after switching;
obtaining the alternating current bus voltage change rate before and after switching of the alternating current filter of the convertor station according to a formula (7):
ΔU reci ＝100*Min(0.01，Abs(E rms-before -E rms-after ))/U ref (7)
wherein DeltaU reci For the alternating current bus voltage change rate, E rms-before Is the effective value of the voltage of the alternating current three-phase bus before switching, E rms-after For the switched AC three-phase bus voltageEffective value, U ref The method is a preset rated voltage effective value of an alternating current bus;
the converter bus short-circuit ratio calculation module obtains the converter bus short-circuit ratio of the high-voltage direct-current power transmission system converter station according to the formula (8):
SCR t eory ＝Q acf-ref /(P ref *ΔU reci ) (8)
Wherein, SCR t eory For the short-circuit ratio of the converter bus, Q acf-ref For the rated capacity, P, of the converter station AC filter bank ref For the rated delivery capacity ΔU reci The alternating current bus voltage change rate is set;
the method comprises the steps of obtaining a direct current power value transmitted by the high-voltage direct current transmission system according to a formula (9):
PU act ＝Max(0.05*P ref ，P act ) (9)
wherein PU act For the DC power value, P act The rated power value of the direct current transmission system is preset;
the converter bus effective short-circuit ratio calculation module obtains the converter bus effective short-circuit ratio of the high-voltage direct-current power transmission system converter station according to a formula (10):
wherein ESCR is as follows AcT For the effective short-circuit ratio of the converter bus, Q acf-ref For the rated capacity of the converter station ac filter bank, Δu reci For the alternating current bus voltage change rate, N acf And exchanging the information of the number of groups in operation of the filter for the converter station.
7. An evaluation device of a short circuit ratio of a hvdc transmission system comprising a processor, a memory and a computer program stored in the memory and configured to be executed by the processor, the processor implementing the evaluation method of a hvdc transmission system according to any of claims 1 to 5 when executing the computer program.
8. A computer readable storage medium, characterized in that the computer readable storage medium comprises a stored computer program, wherein the computer program, when run, controls a device in which the computer readable storage medium is located to perform the method of assessing the short circuit ratio of a hvdc transmission system according to any of claims 1 to 5.
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