CN109510227B - Method and device for determining steady-state voltage of converter station bus after direct-current blocking - Google Patents
Method and device for determining steady-state voltage of converter station bus after direct-current blocking Download PDFInfo
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Abstract
The invention provides a method and a device for determining the bus steady-state voltage of a converter station after direct current blocking, wherein when the direct current blocking occurs, the amount of reactive power exchanged between the converter station and an alternating current system is calculated; judging whether the exchange reactive power of the converter station and the alternating current system meets a predetermined reactive power exchange dead zone interval, and when the exchange reactive power exchange dead zone interval is not met, adjusting the exchange reactive power of the converter station and the alternating current system by putting or cutting an alternating current filter; determining the steady-state voltage of a bus of the converter station based on the reactive power exchanged between the converter station and the alternating current system; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station. The method considers the action condition of the alternating current filter in the converter station, the action condition is consistent with the actual condition, the calculated stable state voltage of the bus of the converter station has small deviation with the actual condition, and the accuracy is high.
Description
Technical Field
The invention relates to the field of power system automation, in particular to a method and a device for determining the steady-state voltage of a bus of a converter station after direct-current blocking.
Background
The centralized production of the extra-high voltage alternating current and direct current transmission project enables the grid pattern and the operation characteristics to be changed greatly. The direct current blocking fault is the most common fault form of a direct current system, the direct current blocking not only generates impact on the active frequency of a power grid at a transmitting end and a receiving end, but also causes large change of the steady-state voltage of a converter station, possibly causes high-voltage network disconnection of a new energy plant station at the direct current transmitting end or large-area power failure of the power grid due to collapse of the voltage at the direct current receiving end, and the possibility of developing cascading faults exists in a single direct current blocking fault. Therefore, the stable voltage change condition of the bus of the converter station after the direct current blocking needs to be accurately analyzed in the dispatching operation, so that dispatching operation personnel can conveniently master the operation risk of the power grid in advance and can make a fault handling plan in advance. The alternating current filter does not act after the direct current system has the direct current fault, so that the reactive power of the system after the direct current fault is completely loaded on the filter of the system and is completely transferred to the alternating current system through the filter, so that the reactive power of the alternating current system is increased, the voltage is greatly increased, and the alternating current system has the risk of voltage ride through, thereby endangering the safe and stable operation of the system. The online analysis software can accurately calculate the fault point and the load flow distribution of the network according to the topological change after the fault, consider the steady-state process and give an analysis result in a short time after the fault, ensure the stable operation of the adjacent power grids and ensure that the related equipment does not misjudge or malfunction. However, when the expected failure of the dc blocking is analyzed, the operation condition of the ac filter is not considered, and the operation condition is not in accordance with the actual condition, so that the obtained steady-state voltage deviation of the converter station bus is large, and the accuracy is low.
Disclosure of Invention
In order to overcome the defects of large deviation of the steady-state voltage of the bus of the converter station and low accuracy in the prior art, the invention provides a method and a device for determining the steady-state voltage of the bus of the converter station after direct current blocking, wherein after the direct current blocking occurs, the reactive power of the bus of the converter station and an alternating current system is calculated; judging whether the exchange reactive power of the converter station and the alternating current system meets a predetermined reactive power exchange dead zone interval, and when the exchange reactive power exchange dead zone interval is not met, adjusting the exchange reactive power of the converter station and the alternating current system by putting or cutting an alternating current filter; determining the steady-state voltage of a bus of the converter station based on the reactive power of the converter station and the alternating current system; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station, the action condition of an alternating current filter in the converter station is considered, the action condition is consistent with the actual condition, the obtained steady-state voltage deviation of the bus of the converter station is small, and the accuracy is high.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
on one hand, the invention provides a method for determining the steady-state voltage of a bus of a converter station after direct-current blocking, which comprises the following steps:
when the direct current blocking occurs, calculating the exchange reactive power of the converter station and the alternating current system;
judging whether the exchange reactive power of the converter station and the alternating current system meets a predetermined reactive power exchange dead zone interval, and when the exchange reactive power exchange dead zone interval is not met, adjusting the exchange reactive power of the converter station and the alternating current system by putting or cutting an alternating current filter;
determining the steady-state voltage of a bus of the converter station based on the reactive power of the converter station and the alternating current system;
the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station.
The reactive power exchange dead zone interval of the converter station comprises the following steps:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value, which is determined according to the following equation:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
And determining the reactive power exchange amount of the converter station and the alternating current system according to the following formula:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
When the reactive power exchange dead zone interval is not satisfied by the converter station and the alternating current system, the reactive power exchange dead zone interval is adjusted by putting or cutting the alternating current filter, and the method comprises the following steps:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
The determining of the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the alternating current system comprises the following steps:
and calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm based on the reactive power exchanged between the converter station and the alternating current system.
After determining the steady-state voltage of a bus of the converter station based on the reactive power exchanged between the converter station and an alternating current system, the method comprises the following steps:
determining a state of the converter station bus based on the converter station bus steady-state voltage;
and giving prompt information based on the state of the bus of the converter station.
The determination of the state of the bus of the converter station comprises the following steps:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating the reference voltage, U, of the bus of the converter stationbus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
The giving of the prompt information based on the state of the bus of the converter station comprises the following steps:
and giving prompt information based on the converter station bus in the upper limit state and the converter station bus in the lower limit state.
After determining the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the alternating current system, the method further comprises the following steps:
determining the maximum voltage rise and the maximum voltage drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchange between the converter station and the alternating current system;
determining a maximum voltage-rise bus based on the maximum voltage rise of the power system, and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and giving prompt information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
Determining the maximum voltage rise and the maximum voltage drop of the power system according to the following formula:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
On the other hand, the invention also provides a device for determining the steady-state voltage of the bus of the converter station after direct-current locking, which comprises the following components:
the calculation module is used for calculating the exchange reactive power between the converter station and the alternating current system after the direct current blocking occurs;
the adjusting module is used for judging whether the reactive power exchange dead zone interval of the converter station and the alternating current system meets the requirement of the predetermined reactive power exchange dead zone interval or not, and adjusting the reactive power exchange of the converter station and the alternating current system by putting or cutting an alternating current filter when the reactive power exchange dead zone interval of the converter station and the alternating current system does not meet the requirement of the reactive power exchange dead zone interval; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station.
And the determining module is used for determining the bus steady-state voltage of the converter station based on the reactive power amount exchanged between the converter station and the alternating current system.
The adjusting module determines a reactive power exchange dead zone interval of the converter station according to the following formula:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value, which is determined according to the following equation:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
The calculation module determines the reactive power exchange amount between the converter station and the alternating current system according to the following formula:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
The adjustment module is specifically configured to:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
The determining module is specifically configured to:
and calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm based on the reactive power exchanged between the converter station and the alternating current system.
The device further comprises:
the state determining module is used for determining the state of the bus of the converter station based on the steady-state voltage of the bus of the converter station;
the first prompting module is used for giving out prompting information based on the state of the bus of the converter station.
The state determination module is specifically configured to:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating the reference voltage, U, of the bus of the converter stationbus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
The first prompt module is specifically configured to:
and giving prompt information based on the converter station bus in the upper limit state and the converter station bus in the lower limit state.
The device further comprises:
the maximum pressure difference determining module is used for determining the maximum pressure rise and the maximum pressure drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchange between the converter station and the alternating current system;
the maximum differential pressure bus determining module is used for determining a maximum voltage-rise bus based on the maximum voltage rise of the power system and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and the second prompting module is used for giving out prompting information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
The maximum pressure difference determination module determines a maximum pressure rise and a maximum pressure drop of the power system according to the following formula:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
according to the method for determining the stable state voltage of the bus of the converter station after the direct current blocking, when the direct current blocking occurs, the exchange reactive power of the converter station and an alternating current system is calculated; judging whether the exchange reactive power of the converter station and the alternating current system meets a predetermined reactive power exchange dead zone interval, and when the exchange reactive power exchange dead zone interval is not met, adjusting the exchange reactive power of the converter station and the alternating current system by putting or cutting an alternating current filter; determining the steady-state voltage of a bus of the converter station based on the reactive power of the converter station and the alternating current system; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station, the action condition of an alternating current filter in the converter station is considered, the action condition is consistent with the actual condition, the obtained steady-state voltage deviation of the bus of the converter station is small, and the accuracy is high;
the device for determining the bus steady-state voltage of the converter station after the direct-current blocking comprises a calculation module, an adjustment module and a determination module, wherein the calculation module is used for calculating the exchange reactive power between the converter station and an alternating-current system after the direct-current blocking occurs; the adjusting module is used for judging whether the reactive power exchange dead zone interval of the converter station and the alternating current system meets the requirement of the predetermined reactive power exchange dead zone interval or not, and adjusting the reactive power exchange of the converter station and the alternating current system by putting or cutting an alternating current filter when the reactive power exchange dead zone interval does not meet the requirement; the determining module is used for determining the bus steady-state voltage of the converter station based on the reactive power amount exchanged between the converter station and the alternating current system; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station, the action condition of an alternating current filter in the converter station is considered, the action condition is consistent with the actual condition, the obtained steady-state voltage deviation of the bus of the converter station is small, and the accuracy is high;
the technical scheme provided by the invention ensures the accuracy of the steady-state voltage of the bus of the converter station, is simple, convenient and fast, has strong practicability, and can ensure the safe and stable operation of a large power grid.
Drawings
Fig. 1 is a flow chart of a method for determining a steady-state voltage of a bus of a converter station after dc blocking according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Example 1
The embodiment 1 of the invention provides a method for determining a steady-state voltage of a bus of a converter station after direct-current blocking, a specific flow chart is shown in fig. 1, and the specific process is as follows:
s101: when the direct current blocking occurs, calculating the exchange reactive power of the converter station and the alternating current system;
s102: judging whether the exchange reactive power between the converter station and the alternating current system meets a predetermined reactive exchange dead zone interval, if so, adjusting the exchange reactive power between the converter station and the alternating current system without adjusting the exchange reactive power between the converter station and the alternating current system, and when the exchange reactive power between the converter station and the alternating current system does not meet the reactive exchange dead zone interval, adjusting the exchange reactive power between the converter station and the alternating current system by putting or cutting an alternating current filter;
s103: and determining the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the alternating current system.
The reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station.
The reactive power exchange dead zone interval of the converter station comprises the following steps:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value;
according to the power value transmitted by the line before and after the direct current expected fault, the reactive power exchange reference value of the converter station is set in a grading way, the voltage grade of the converter station, the configuration condition of an alternating current filter and the characteristics of a regional power grid network frame need to be comprehensively considered for setting, and therefore the reactive power exchange reference value of the converter station is determined according to the following formula:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
The determination of the amount of reactive power exchanged between the converter station and the ac system is as follows:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
In the above S102, when the reactive power exchange reactive power between the converter station and the ac system does not satisfy the reactive power exchange dead zone interval, the reactive power exchange reactive power between the converter station and the ac system is adjusted by putting or cutting the ac filter, which is specifically divided into the following two cases:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
In step S102, when the reactive power exchange amount between the converter station and the ac system does not satisfy the reactive power exchange dead zone interval, the ac filter is put in or cut off to adjust the reactive power exchange amount between the converter station and the ac system, and then the following information is obtained: the number of the alternating current filters before direct current blocking, reactive power absorption of the converter station from an alternating current system, a reactive power exchange dead zone interval, the number of the alternating current filters after direct current blocking, reactive power absorption of the converter station from the alternating current system after a fault and the reactive power exchange dead zone interval after the fault.
In S103, the steady-state voltage of the bus of the converter station is determined based on the reactive power exchanged between the converter station and the ac system, and the specific process is as follows:
and calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm based on the reactive power exchanged between the converter station and the alternating current system.
After determining the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the alternating current system, the following operations are further required:
determining a state of the converter station bus based on the converter station bus steady-state voltage;
and giving prompt information based on the state of the bus of the converter station.
The determination of the state of the bus of the converter station is specifically divided into the following three cases:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating the reference voltage, U, of the bus of the converter stationbus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
The presenting of the prompt information based on the state of the converter station bus is specifically to present the prompt information based on the converter station bus in the upper limit state and the converter station bus in the lower limit state.
After determining the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the ac system in S103, the following operations may be further performed:
determining the maximum voltage rise and the maximum voltage drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchange between the converter station and the alternating current system;
determining a maximum voltage-rise bus based on the maximum voltage rise of the power system, and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and giving prompt information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
The maximum voltage rise and the maximum voltage drop of the power system are determined according to the following formula:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
Example 2
Based on the same inventive concept, embodiment 2 of the present invention further provides a device for determining a steady-state voltage of a bus of a converter station after dc blocking, which includes a calculating module, an adjusting module, and a determining module, and the following describes functions of the modules in detail:
the calculation module is used for calculating the reactive power exchange amount between the converter station and the alternating current system after the direct current blocking occurs;
the adjusting module is used for judging whether the reactive power exchange dead zone interval of the converter station and the alternating current system meets the requirement of the predetermined reactive power exchange dead zone interval or not, and adjusting the reactive power exchange of the converter station and the alternating current system by putting or cutting an alternating current filter when the reactive power exchange dead zone interval does not meet the requirement; the reactive power exchange dead zone interval of the converter station is determined based on the reactive power exchange reference value of the converter station;
the determining module is used for determining the steady-state voltage of the bus of the converter station based on the reactive power amount exchanged between the converter station and the alternating current system.
The adjusting module determines a reactive power exchange dead zone interval of the converter station according to the following formula:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value, which is determined according to the following equation:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
The calculating module determines the reactive power exchange amount between the converter station and the alternating current system according to the following formula:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
The adjusting module is specifically configured to:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
The determining module is specifically configured to:
based on the reactive power exchanged between the converter station and the alternating current system, calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm;
the apparatus provided in embodiment 2 of the present invention further includes:
the state determining module is used for determining the state of the bus of the converter station based on the steady-state voltage of the bus of the converter station;
the first prompting module is used for giving out prompting information based on the state of the bus of the converter station.
The state determining module determines the state of the converter station bus based on the steady-state voltage of the converter station bus, and the specific process is as follows:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating the reference voltage, U, of the bus of the converter stationbus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
The first prompting module gives prompting information specifically based on the converter station bus in the upper limit exceeding state and the converter station bus in the lower limit exceeding state.
The device for determining the stable state voltage of the bus of the converter station after the direct current blocking provided by the embodiment 2 of the invention further comprises:
the maximum pressure difference determining module is used for determining the maximum pressure rise and the maximum pressure drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchange between the converter station and the alternating current system;
the maximum differential pressure bus determining module is used for determining a maximum voltage-rise bus based on the maximum voltage rise of the power system and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and the second prompting module is used for giving out prompting information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
The maximum pressure difference determining module determines the maximum pressure rise and the maximum pressure drop of the power system according to the following formula:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
For convenience of description, each part of the above-described apparatus is separately described as being functionally divided into various modules or units. Of course, the functionality of the various modules or units may be implemented in the same one or more pieces of software or hardware when implementing the present application.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalents to the specific embodiments of the present invention with reference to the above embodiments, and such modifications or equivalents without departing from the spirit and scope of the present invention are within the scope of the claims of the present invention as set forth in the claims.
Claims (18)
1. A method for determining a steady state voltage of a bus of a converter station after direct current blocking is characterized by comprising the following steps:
when the direct current blocking occurs, calculating the exchange reactive power of the converter station and the alternating current system;
judging whether the exchange reactive power of the converter station and the alternating current system meets a predetermined reactive power exchange dead zone interval, and when the exchange reactive power exchange dead zone interval is not met, adjusting the exchange reactive power of the converter station and the alternating current system by putting or cutting an alternating current filter;
determining the steady-state voltage of a bus of the converter station based on the reactive power of the converter station and the alternating current system;
the reactive power exchange dead zone interval of the converter station is determined based on a reactive power exchange reference value of the converter station;
the reactive power exchange dead zone interval of the converter station comprises the following steps:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value, which is determined according to the following equation:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
2. The method for determining the steady-state voltage of the bus of the converter station after the direct current blocking according to claim 1, wherein the determination of the reactive power amount of the converter station and the alternating current system is as follows:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
3. The method for determining the steady-state voltage of the bus of the converter station after the dc blocking according to claim 2, wherein when the reactive power exchange reactive power between the converter station and the ac system does not satisfy the reactive power exchange dead zone interval, the adjusting the reactive power exchange reactive power between the converter station and the ac system by switching in or switching out an ac filter comprises:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
4. The method for determining the steady-state voltage of the bus of the converter station after the direct current blocking according to claim 1, wherein the determining the steady-state voltage of the bus of the converter station based on the reactive power amount of the exchange between the converter station and the alternating current system comprises:
and calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm based on the reactive power exchanged between the converter station and the alternating current system.
5. The method for determining the steady-state voltage of the bus of the converter station after the direct current blocking according to claim 1 or 4, wherein after determining the steady-state voltage of the bus of the converter station based on the reactive amount of the exchange between the converter station and the alternating current system, the method comprises the following steps:
determining a state of the converter station bus based on the converter station bus steady-state voltage;
and giving prompt information based on the state of the bus of the converter station.
6. The method for determining the steady state voltage of the converter station bus after DC blocking according to claim 5, wherein the determining the state of the converter station bus comprises:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating reference electricity of bus bars of converter stationPress Ubus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
7. The method for determining the steady-state voltage of the converter station bus after DC blocking according to claim 6, wherein the giving a prompt message based on the state of the converter station bus comprises:
and giving prompt information based on the converter station bus in the upper limit state and the converter station bus in the lower limit state.
8. The method for determining the steady-state voltage of the bus of the converter station after the dc blocking according to claim 5, wherein after determining the steady-state voltage of the bus of the converter station based on the reactive power exchanged between the converter station and the ac system, the method further comprises:
determining the maximum voltage rise and the maximum voltage drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchange between the converter station and the alternating current system;
determining a maximum voltage-rise bus based on the maximum voltage rise of the power system, and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and giving prompt information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
9. The method for determining the steady-state voltage of the bus of the converter station after DC blocking according to claim 8, wherein the maximum voltage rise and the maximum voltage drop of the power system are determined according to the following formula:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
10. A device for determining the steady-state voltage of a bus of a converter station after direct current blocking is characterized by comprising the following components:
the calculation module is used for calculating the exchange reactive power between the converter station and the alternating current system after the direct current blocking occurs;
the adjusting module is used for judging whether the reactive power exchange dead zone interval of the converter station and the alternating current system meets the requirement of the predetermined reactive power exchange dead zone interval or not, and adjusting the reactive power exchange of the converter station and the alternating current system by putting or cutting an alternating current filter when the reactive power exchange dead zone interval of the converter station and the alternating current system does not meet the requirement of the reactive power exchange dead zone interval; the reactive power exchange dead zone interval of the converter station is determined based on a reactive power exchange reference value of the converter station;
the determining module is used for determining the bus steady-state voltage of the converter station based on the reactive power amount exchanged between the converter station and the alternating current system;
the adjusting module determines a reactive power exchange dead zone interval of the converter station according to the following formula:
[Q0-Qthreshold,Q0+Qthreshold]
in the formula, QthresholdRepresenting a reactive exchange threshold of the converter station; q0Representing a converter station reactive exchange reference value, which is determined according to the following equation:
in the formula, P0Representing the value of the active power transmitted by the converter station, PuplimRepresenting an upper limit value, P, of the active power of the converter stationdownlimAnd k is a conversion coefficient, and represents the lower limit value of the active power of the converter station.
11. The apparatus for determining the steady-state voltage of the bus of the converter station after dc blocking according to claim 10, wherein the calculating module determines the amount of reactive power exchanged between the converter station and the ac system according to the following formula:
in the formula, QtransRepresenting the amount of reactive power, Q, exchanged between the converter station and the AC systemlniRepresenting the reactive exchange capacity, Q, of the ith incoming line connected to the bus of the converter stationlnjAnd the j-th outgoing line reactive switching value connected with the bus of the converter station is shown, n represents the number of incoming lines, and m represents the number of outgoing lines.
12. The device for determining the steady-state voltage of the bus of the converter station after dc blocking according to claim 11, wherein the adjusting module is specifically configured to:
when Q istrans＞Q0+QthresholdWhen the converter station is used, an alternating current filter in the converter station is put into the converter station, and the reactive power of the converter station and an alternating current system is adjusted;
when Q istrans＜Q0-QthresholdAnd when the converter station is in operation, the alternating current filter in the converter station is cut off, and the reactive power exchanged between the converter station and the alternating current system is adjusted.
13. The post-dc-blocking converter station bus steady-state voltage determining device according to claim 10, wherein the determining module is specifically configured to:
and calculating the bus steady-state voltage of the converter station by adopting a steady-state load flow calculation algorithm based on the reactive power exchanged between the converter station and the alternating current system.
14. The post dc blocking converter station bus steady state voltage determining apparatus of claim 10 or 13, further comprising:
the state determining module is used for determining the state of the bus of the converter station based on the steady-state voltage of the bus of the converter station;
the first prompting module is used for giving out prompting information based on the state of the bus of the converter station.
15. The post-dc-blocking converter station bus steady-state voltage determining device according to claim 14, wherein the state determining module is specifically configured to:
when U is turnedbus_after＞(1+σ)UnormalDetermining that the state of a bus of the converter station is an upper limit-crossing state;
when U is turnedbus_after＜(1-σ)UnormalDetermining the state of a bus of the converter station as a lower limit state;
when (1-sigma) Unormal≤Ubus_after≤(1+σ)UnormalDetermining that the state of a bus of the converter station is a normal state;
wherein, UnormalIndicating the reference voltage, U, of the bus of the converter stationbus_afterAnd the voltage of the bus of the converter station after the direct current is locked is represented, and the sigma represents a set out-of-limit percentage coefficient.
16. The device for determining the steady-state voltage of the bus of the converter station after the dc blocking according to claim 15, wherein the first prompting module is specifically configured to:
and giving prompt information based on the converter station bus in the upper limit state and the converter station bus in the lower limit state.
17. The post dc blocking converter station bus steady state voltage determining apparatus of claim 14, further comprising:
the maximum pressure difference determining module is used for determining the maximum pressure rise and the maximum pressure drop of the power system by adopting a steady-state power flow algorithm based on the reactive power exchanged between the converter station and the alternating current system;
the maximum differential pressure bus determining module is used for determining a maximum voltage-rise bus based on the maximum voltage rise of the power system and determining a maximum voltage-drop bus based on the maximum voltage drop of the power system;
and the second prompting module is used for giving out prompting information based on the maximum voltage-rise bus and the maximum voltage-drop bus.
18. The post dc blocking converter station bus steady state voltage determination apparatus of claim 17, wherein said maximum voltage difference determination module determines a maximum voltage rise and a maximum voltage drop of the power system according to the following equation:
ΔUmax＝max(Uafter-Ubefore)
ΔUmin＝min(Uafter-Ubefore)
in the formula, Δ UmaxIndicating the maximum voltage rise, Δ U, of the power system after DC blockingminIndicating the maximum voltage drop, U, of the power system after DC blockingafterIndicating the steady state voltage, U, of any bus in the power system after DC blockingbeforeRepresenting the steady state voltage of any bus in the power system before dc blocking.
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| CN111355254B (en) * | 2019-12-09 | 2022-09-23 | 国网江苏省电力有限公司 | Method and system for determining configuration quantity of filter in direct current converter station |
| CN111162529B (en) * | 2020-01-13 | 2022-12-09 | 国家电网有限公司 | Method and device for calculating alternating current bus voltage operating range of series-parallel power grid |
| CN111614098B (en) * | 2020-04-16 | 2022-09-09 | 国网江苏省电力有限公司经济技术研究院 | Method and system for determining input capacity of alternating current filter of hybrid cascade direct current converter station |
| CN112039102B (en) * | 2020-04-24 | 2022-04-15 | 国家电网有限公司 | Method and device for determining control range of converter bus voltage before direct-current unlocking |
| CN111697608B (en) * | 2020-04-26 | 2022-10-18 | 国家电网有限公司 | Method and system for determining voltage operation range of converter bus |
| CN111835020B (en) * | 2020-08-10 | 2021-04-20 | 中国南方电网有限责任公司超高压输电公司柳州局 | Converter station reactive power optimization method considering main transformer low-voltage side reactive power compensation device |
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