CN111474414A - Link delay testing method and system of flexible direct current control system - Google Patents
Link delay testing method and system of flexible direct current control system Download PDFInfo
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Abstract
The invention discloses a link delay test method of a flexible direct current control system, which comprises the following steps: the acquisition and measurement unit receives a preset sine alternating current synchronous signal, sends the sine alternating current synchronous signal to the oscilloscope, processes the sine alternating current synchronous signal, and sends the processed alternating current synchronous signal to the control unit; the control unit judges whether the alternating current synchronous signal passes through a positive zero point or not, if so, a positive level modulation signal is output, and the positive level modulation signal is sent to the pulse distribution unit; the driving unit executes the input command, generates a corresponding driving level signal and sends the driving level signal to the oscilloscope; the oscilloscope obtains the time difference corresponding to the time from the positive zero point crossing moment of the sinusoidal alternating current synchronous signal to the rising edge moment of the driving level signal, and the time difference is used as the control link delay of the flexible direct current control system, so that the zero crossing point of the input signal of the direct current control protection system can be obtained, and the measurement error is reduced. The invention also discloses a link delay test system of the flexible direct current control system.
Description
Technical Field
The invention relates to the technical field of direct current transmission, in particular to a link delay testing method and system of a flexible direct current control system.
Background
Compared with the traditional direct-current transmission technology, the flexible direct-current transmission technology based on the voltage source type current converter has the advantages of flexible control, low harmonic content, capability of supplying power to a passive system, no problem of commutation failure and the like, and is widely applied to the fields of long-distance transmission, offshore wind power direct-current transmission, new energy grid connection, asynchronous grid interconnection, island drilling platform power supply and the like. However, with the operation of a plurality of flexible direct current projects, the stability problem brought by the flexible direct current projects is obviously reflected, and the harmonic resonance problem caused by the access of a flexible direct current system to an alternating current power grid is widely concerned.
In the operation process of the voltage source type converter, due to the action of a control system, the equivalent impedance characteristic of the voltage source type converter is possibly deteriorated, a negative damping characteristic is presented in certain frequency bands, and when the impedance of a power grid is not matched with the equivalent impedance of the flexible direct current system, a harmonic resonance phenomenon is easily caused. The control link delay is one of important factors influencing impedance characteristics of the flexible direct-current transmission system, and when the control link delay is too large, not only can the operating characteristics of the flexible direct-current transmission system be influenced, but also the impedance characteristics of the flexible direct-current transmission system can be deteriorated, and the risk of harmonic resonance of the system is increased. Therefore, it is necessary to test the link delay of the flexible direct current control system, help to know the equivalent impedance characteristics of the system, and provide a reference value for the proposal of a harmonic resonance suppression strategy.
The control link delay refers to the time difference from the occurrence of an event to the response of a control system to the change event, and comprises links such as sampling measurement device delay, valve group control system (or polar control system) delay, valve control system delay, communication delay among different systems and the like on a physical layer. In the prior art, no effective criterion is added when the zero crossing point of an input signal of the direct current control protection system is obtained, and the zero crossing point cannot be accurately obtained due to the fact that a controller is a discrete system, so that measurement errors are caused.
Disclosure of Invention
The embodiment of the invention provides a link delay testing method and system for a flexible direct current control system, which can effectively solve the problem that the zero crossing point of an input signal of the direct current control protection system cannot be accurately obtained in the prior art and can effectively reduce the measurement error.
An embodiment of the present invention provides a method for testing a link delay of a flexible dc control system, including:
the acquisition and measurement unit receives a preset sine alternating current synchronous signal, sends the sine alternating current synchronous signal to the oscilloscope, processes the sine alternating current synchronous signal, and sends the processed alternating current synchronous signal to the control unit; the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, and the control unit is a valve bank control unit or a pole control unit;
the control unit judges whether the alternating current synchronous signal passes through a positive zero point or not, if so, a positive level modulation signal is output, and the positive level modulation signal is sent to a pulse distribution unit;
the pulse distribution unit responds to the positive level modulation signal, generates a switching command and sends the switching command to a driving unit;
the driving unit executes the input command, generates a corresponding driving level signal and sends the driving level signal to the oscilloscope;
and the oscilloscope acquires a time difference corresponding to the time from the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point to the moment when the drive level signal rises, and the time difference is used as the control link delay of the flexible direct current control system.
As an improvement of the above scheme, before the acquisition and measurement unit acquires the sinusoidal ac synchronization signal, the method further includes:
the mutual inductor collects a preset sine alternating current synchronous signal and transmits the sine alternating current synchronous signal to the collection measuring unit; the mutual inductor is a voltage mutual inductor or a current mutual inductor.
As an improvement of the above scheme, the acquiring and measuring unit processes the sinusoidal ac synchronization signal and sends the processed ac synchronization signal to the control unit, and the method specifically includes:
the acquisition and measurement unit performs voltage conversion, hardware filtering and digital-to-analog conversion on the sinusoidal alternating current synchronous signal to obtain an alternating current synchronous signal, and sends the alternating current synchronous signal to the control unit.
As an improvement of the above scheme, the control unit determines whether the ac synchronization signal passes through a positive zero point, and if so, outputs a positive level modulation signal and sends the positive level modulation signal to the pulse distribution unit, and the method further includes:
the control unit sets a pre-stored control program to an unlocking position;
judging whether the alternating current synchronous signal passes through a positive zero point or not according to a preset over-positive zero point condition; the positive zero crossing condition comprises that an alternating current synchronous signal acquired by previous interruption is smaller than zero, and an alternating current synchronous signal acquired by current interruption is larger than zero and smaller than a preset threshold;
when the alternating current synchronous signal is judged to pass through a positive zero point, executing the control program, outputting a positive level modulation signal, and sending the positive level modulation signal to a valve control unit;
and when the alternating current synchronous signal is judged to be not over a positive zero point, executing the control program, outputting a negative level modulation signal, and sending the negative level modulation signal to the valve control unit.
As an improvement of the above scheme, the control unit determines whether the ac synchronization signal passes through a positive zero point, and if so, outputs a positive level modulation signal and sends the positive level modulation signal to the pulse distribution unit, and the method further includes:
the control unit and the valve control unit perform synchronous processing;
the valve control unit performs an interrupt upon receiving the positive level modulation signal and transmits the positive level modulation signal to the pulse distribution unit.
As an improvement of the above, the method further comprises:
the pulse distribution unit transmits the input command to a sub-module power control unit;
after receiving the input command, the sub-module power control unit generates a driving level signal through the sub-module power control unit and the driving unit so as to drive a switching tube to work;
and the driving unit sends the driving level signal to the oscilloscope.
As an improvement of the above scheme, the oscilloscope obtains the time when the sinusoidal alternating current synchronous signal passes through the positive zero point by the following steps:
when the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal, calculating the measurement error of the sinusoidal alternating current synchronous signal at the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point according to the formula (1):
wherein, UsetTo preset a voltage threshold, UmIs the voltage amplitude of the sinusoidal voltage signal, T is the period of the sinusoidal voltage signal, Δ T is the measurement error;
and measuring for multiple times according to the measurement error, and acquiring the measured minimum value as the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point.
The invention correspondingly provides a link delay test system of a flexible direct current control system, which comprises an acquisition measuring unit, a control unit, a pulse distribution unit, a driving unit and an oscilloscope, wherein the acquisition measuring unit is used for acquiring a signal of a link delay test signal;
the acquisition and measurement unit comprises a signal acquisition and processing module; the signal acquisition and processing module is used for receiving a preset sinusoidal alternating current synchronous signal, sending the sinusoidal alternating current synchronous signal to the oscilloscope, processing the sinusoidal alternating current synchronous signal and sending the processed alternating current synchronous signal to the control unit; the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, and the control unit is a valve bank control unit or a pole control unit;
the control unit comprises a zero crossing point judging module; the zero point judgment module is used for judging whether the alternating current synchronous signal passes through a positive zero point or not, if so, outputting a positive level modulation signal and sending the positive level modulation signal to a pulse distribution unit;
the pulse distribution unit comprises a throw-in command generation module; the input command generating module is used for responding to the positive level modulation signal, generating an input command and sending the input command to the driving unit;
the driving unit comprises a driving signal generation module; the driving signal generation module is used for executing the input command, generating a corresponding driving level signal and sending the driving level signal to the oscilloscope;
the oscilloscope comprises a link delay acquisition module; and the link delay acquisition module is used for acquiring a time difference corresponding to the time from the moment when the sinusoidal alternating-current synchronous signal passes through a positive zero point to the moment when the driving level signal rises, and the time difference is used as the control link delay of the flexible direct-current control system.
Compared with the prior art, the link delay testing method and the link delay testing system of the flexible direct current control system disclosed by the embodiment of the invention have the advantages that a preset sine alternating current synchronous signal is received by the acquisition and measurement unit, sent to the oscilloscope, processed and sent to the control unit; wherein the sinusoidal AC synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, the control unit is a valve group control unit or a polar control unit, the control unit judges whether the AC synchronous signal crosses a positive zero point, if so, a positive level modulation signal is output and sent to a pulse distribution unit, the pulse distribution unit responds to the positive level modulation signal to generate a put command and send the put command to a drive unit, the drive unit executes the put command and generates a corresponding drive level signal, the drive level signal is sent to the oscilloscope, the oscilloscope obtains a time difference corresponding to a time from a time when the sinusoidal AC synchronous signal crosses the positive zero point to a time when the drive level signal rises to serve as a control link delay of the flexible DC control system, according to the invention, by adding the effective zero crossing point criterion when the input alternating current synchronous signal is acquired, the problem that the zero crossing point of the input signal of the direct current control protection system cannot be accurately acquired in the prior art can be effectively solved, and the measurement error can be effectively reduced.
Drawings
Fig. 1 is a schematic flowchart of a link delay testing method of a flexible dc control system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a link delay test connection of a flexible dc control system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a corresponding forward zero-crossing criterion when a sinusoidal AC voltage signal is used as a sinusoidal AC synchronization signal according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating a comparison between ten cycle sinusoidal voltage signals and a driving level signal according to a first embodiment of the present invention;
FIG. 5 is a schematic diagram of an embodiment of comparing a periodic sinusoidal voltage signal with a driving level signal according to an embodiment of the present invention;
FIG. 6 is an enlarged schematic diagram of an embodiment of the present invention in which a sinusoidal voltage signal is compared with a driving pulse signal;
fig. 7 is a schematic diagram of a delay test connection of a control link of a flexible direct current FPT system according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a link delay test system of a flexible dc control system according to a second embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example one
Referring to fig. 1, a schematic flowchart of a method for testing a link delay of a flexible dc control system according to an embodiment of the present invention is shown, where the method includes steps S101 to S105.
S101, receiving a preset sine alternating current synchronous signal by an acquisition and measurement unit, sending the sine alternating current synchronous signal to an oscilloscope, processing the sine alternating current synchronous signal, and sending the processed alternating current synchronous signal to a control unit; the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, and the control unit is a valve group control unit or a pole control unit.
Preferably, before step S101, the method further includes:
the mutual inductor 26 collects a preset sine alternating current synchronous signal and transmits the sine alternating current synchronous signal to the collection measurement unit 21; the transformer 26 is a voltage transformer or a current transformer.
Referring to fig. 2, which is a schematic diagram of a link delay test connection of the flexible dc control system according to an embodiment of the present invention, a transformer 26 is connected to the acquisition and measurement unit 21. Further, for example, given a preset sinusoidal voltage signal, a voltage transformer collects the sinusoidal voltage signal as an input signal of the collection and measurement unit 21, or a current transformer collects a sinusoidal current signal as an input signal of the collection and measurement unit 21.
Preferably, the acquisition and measurement unit 21 processes the sinusoidal ac synchronization signal, and sends the processed ac synchronization signal to the control unit 22, which specifically includes:
the acquisition and measurement unit 21 performs voltage conversion, hardware filtering, and digital-to-analog conversion on the sinusoidal ac synchronization signal to obtain an ac synchronization signal, and sends the ac synchronization signal to the control unit 22.
It should be noted that the sampling measurement unit 21 may be a device with functions of signal acquisition, voltage conversion, hardware filtering, digital-to-analog conversion, electrical-to-optical conversion, and the like, such as a measurement screen chassis. Referring to fig. 2, an input signal (i.e., a sinusoidal ac synchronization signal) of the sampling measurement unit 21 is obtained through a transformer 26, and an input terminal and a ground terminal of the input signal are respectively connected to the voltage channel 1 and the ground terminal of the oscilloscope 25. The sinusoidal ac synchronization signal may be a sinusoidal voltage signal or a sinusoidal current signal, and if the sampling and measuring devices through which the sinusoidal voltage signal or the sinusoidal current signal passes are not the same device, they need to be measured separately. If the sinusoidal AC synchronous signal is a sinusoidal voltage signal, the time delay measured by the oscilloscope 25 is the time delay of the sinusoidal voltage signal passing through the control link; if the sinusoidal ac synchronization signal is a sinusoidal current signal, the delay measured by the oscilloscope 25 is the delay of the sinusoidal current signal through the control link. In addition, the sampling measurement unit 21 performs voltage conversion, hardware filtering, digital-to-analog conversion, and other link processing on the received sinusoidal ac synchronization signal to obtain an ac synchronization signal in the form of an optical fiber communication frame, and then transmits the ac synchronization signal to the control unit 22 through an optical fiber channel. The alternating current synchronous signal can be a processed sinusoidal alternating current voltage signal and a processed sinusoidal alternating current signal.
S102, the control unit judges whether the alternating current synchronous signal passes through a positive zero point, if so, a positive level modulation signal is output, and the positive level modulation signal is sent to a pulse distribution unit.
In this embodiment, the control unit 22 is a valve group control unit or a pole control unit. The control unit 22 is mainly responsible for the calculation of algorithms such as active, reactive, direct-current voltage and additional control, and includes a data receiving and converting link, a data processing link, a control link, a data output link, and the like. Specifically, after receiving the ac synchronization signal, the control unit 22 obtains a modulation signal through a data receiving and converting link, a data processing link, a control link, and a data output link.
In a preferred embodiment, the control unit 22 specifically includes the following control steps:
the control unit 22 sets a pre-stored control program to an unlocking position;
judging whether the alternating current synchronous signal passes through a positive zero point or not according to a preset over-positive zero point condition; the positive zero crossing condition comprises that an alternating current synchronous signal acquired by previous interruption is smaller than zero, and an alternating current synchronous signal acquired by current interruption is larger than zero and smaller than a preset threshold;
when the alternating current synchronous signal is judged to pass through a positive zero point, executing the control program, outputting a positive level modulation signal, and sending the positive level modulation signal to the valve control unit 27;
when it is determined that the ac synchronization signal does not pass through the positive zero point, the control program is executed to output a negative level modulation signal, and the negative level modulation signal is sent to the valve control unit 27.
Referring to fig. 2, the control unit 22 is connected to the sampling and measuring unit 21 for receiving the ac synchronization signal from the sampling and measuring unit 21. Further, the control unit 22 is connected to the valve control unit 27 for transmitting the generated modulation signal to the valve control unit 27. Specifically, the control unit 22 detects the ac synchronization signal and determines acWhether the synchronization signal crosses the positive zero crossing point. The preset threshold may be a preset voltage threshold or a preset current threshold. Referring to fig. 3, it is a schematic diagram of a forward zero crossing point criterion when a sinusoidal ac voltage signal is used as a sinusoidal ac synchronization signal according to an embodiment of the present invention, and if the criterion satisfies U0<0 and U1>0 and U1<UsetThen, the ac sync signal is considered to cross zero, where U0 is the ac sync voltage signal collected by the previous interrupt (i.e. interrupt 1 voltage in fig. 3), U1 is the ac sync voltage signal collected by the current interrupt (i.e. interrupt 2 voltage in fig. 3), UsetIs a preset voltage threshold. Further, after the zero-crossing point determination is completed, a control program such as power (voltage) outer loop control, current inner loop control, additional control, or the like is executed. Further, the control unit 22 issues a corresponding modulation wave according to the zero-crossing point determination result. Preferably, the modulation wave takes the received alternating current synchronous signal as a reference, and outputs a positive level modulation signal of 1ms (time is optional but is not suitable to be more than 15ms) at the positive zero crossing point of the alternating current synchronous signal, otherwise, outputs a negative level modulation signal.
More specifically, in terms of the zero crossing criterion, assuming that the control interrupt frequency is 10kHz, i.e., the control routine is executed every 100 μ s, when U0 is satisfied<0and U1>At 0, the forward zero crossing capture error may be within 100 μ s. When adding the criterion U1<UsetAnd then, the delay measurement error can be limited within tens of microseconds, and the generated delay measurement error range can be obtained according to the preset voltage threshold. Preferably, the smaller the preset voltage threshold, the smaller the measurement error, but in order to prevent the influence of voltage harmonic distortion, the preset voltage threshold may not be set too small.
Based on the above embodiment, preferably, step S102 further includes:
the control unit 22 and the valve control unit 27 perform synchronous processing;
the valve control unit 27 performs an interrupt upon receiving the positive level modulation signal, and transmits the positive level modulation signal to the pulse distribution unit 23.
It should be noted that the valve control unit 27 is configured to control the voltage balance of the power module and execute the modulation signal sent by the control unit. The control unit 22 and the valve control unit 27 perform synchronous processing, and the valve control unit 27 starts to execute interruption after receiving the modulation signal, analyzes the data, and forwards the modulation signal to the pulse distribution unit 23.
And S103, responding to the positive level modulation signal by the pulse distribution unit, generating a switching command, and sending the switching command to a driving unit.
And S104, the driving unit executes the input command, generates a corresponding driving level signal and sends the driving level signal to the oscilloscope.
Preferably, the test method further comprises:
the pulse distribution unit 23 transmits the input command to the sub-module power control unit 28;
after receiving the input command, the sub-module power control unit 28 generates a driving level signal through the sub-module power control unit 28 and the driving unit 24 to drive the switching tube to operate;
the driving unit 24 transmits the driving level signal to the oscilloscope 25.
Referring to fig. 2, the pulse distribution unit 23 is connected to the sub-module power control unit 28, and is configured to receive the switching-on/off command sent by the modulation signal. In addition, a submodule power control unit 28 is connected to the drive unit 24. Specifically, when the positive level modulation signal is received, the pulse distribution result of the pulse distribution unit 23 is a put-in command; when the negative level modulation signal is received, the pulse allocation result is an exit command. Further, after receiving the input command, the sub-module power control unit 28 generates a corresponding driving level signal through the sub-module power control unit 28 and the driving unit 24 to drive the switching tube to normally operate. Further, referring to fig. 2, the driving unit 24 couples the driving level signal to the voltage channel 2 and the ground terminal of the oscilloscope 25.
And S105, the oscilloscope obtains a time difference corresponding to the time from the moment when the sinusoidal alternating current synchronous signal passes through the positive zero point to the moment when the drive level signal rises, and the time difference is used as the control link delay of the flexible direct current control system.
Preferably, step S105 further includes:
when the sinusoidal alternating current synchronous signal is a voltage sinusoidal signal, calculating the measurement error of the sinusoidal alternating current synchronous signal at the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point according to a formula (1):
wherein, UsetTo preset a voltage threshold, UmThe voltage amplitude of the voltage sinusoidal signal is shown, T is the period of the voltage sinusoidal signal, and delta T is the measurement error;
and measuring for multiple times according to the measurement error, and acquiring the measured minimum value as the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point.
Therefore, the measurement result of the control link delay may vary within the range Td-Td + Δ T, and multiple measurements are performed, and the minimum measurement value is the control link delay Td.
Illustratively, referring to fig. 4, which is a comparison graph of ten cycle sinusoidal voltage signals and driving level signals provided by the first embodiment of the present invention, when the control unit detects a positive zero crossing point of the sinusoidal voltage signal, the driving unit sends out a 1ms positive driving level signal. The criterion of the positive zero crossing point of the alternating current synchronous signal is as follows: the alternating current synchronous voltage signal collected in the previous interruption is less than 0, the alternating current synchronous voltage signal collected in the current interruption is greater than 0, and the alternating current synchronous voltage signal collected in the current interruption is less than a preset voltage threshold value. Since the control execution interrupt period is 100 mus, not all interrupts nearest to the zero crossing point can capture the zero crossing point, therefore, the forward level driving signal is not triggered at the forward zero crossing point of part of the alternating voltage. Fig. 5 is a schematic diagram of an embodiment of comparing a periodic sinusoidal voltage signal with a driving level signal according to an embodiment of the present invention, and fig. 6 is an enlarged schematic diagram of an embodiment of comparing a sinusoidal voltage signal with a driving pulse signal according to an embodiment of the present invention, where a time difference from a positive zero crossing point of the sinusoidal voltage signal to a rising edge of the driving level signal is a link delay of the control system.
On the basis of the above embodiment, the link delay test method of the flexible direct current control system is applied to a flexible direct current FPT system. Referring to fig. 7, which is a schematic diagram of a control link delay test connection of a flexible direct current FPT system according to an embodiment of the present invention, it is generally required to test a control system link delay in a flexible direct current system debugging stage, that is, to test an FPT system (functional test system), where a primary loop is a simulation model and a secondary loop is an actual control protection device. Referring to fig. 7, a primary loop in a flexible direct current FPT system control link delay test system includes an RTDS simulation model 301, and a secondary loop includes a power amplifier 302, a measurement screen chassis 303 (i.e., an acquisition measurement unit), a valve group control device 304, a valve control 305, a pulse distribution screen 306, an interface device 307, a sub-module control board 308, a drive board 309, and an oscilloscope 310. The input terminal of the measurement screen case 303 is connected to a voltage channel 1 of the oscilloscope 310, the ground terminal of the measurement screen case 303 is connected to a ground terminal of the oscilloscope 310, the G pole of the driver board 309 is connected to a voltage channel 2 of the oscilloscope 310, and the E pole of the driver board 309 is connected to the ground terminal of the oscilloscope.
Specifically, a sinusoidal ac synchronization signal (which may be ac voltage or current at a phase network side of the flexible dc valve block, or may be a given ideal sinusoidal voltage or current) is given in the RTDS simulation model 301 and sent out via the GTAO channel (i.e., the voltage-current sampling signal in fig. 7), and the sinusoidal ac synchronization signal is sent to the measurement panel chassis via the power amplifier. In the flexible direct current FPT system, a trigger pulse signal sent by a pulse distribution screen 306 is directly sent to an RTDS simulation model 301 through an interface device to control the on and off of a converter valve of the RTDS simulation model 301, and in an actual system, the trigger pulse obtains on and off signals (namely driving level signals) of a submodule switch tube through a submodule control board 308 and a driving board 309. Therefore, when the delay of the control link is measured, one path of trigger pulse optical fiber is connected to the sub-module control board 308 and the drive board 309 to observe the disconnection of the sub-module, so that the complete process of the whole control link is determined. Further, the oscilloscope 310 obtains a time difference corresponding to a time from a time when the sinusoidal ac synchronization signal passes through a positive zero point to a time when the driving level signal rises according to the sinusoidal ac synchronization signal from the measurement screen chassis 303 and the driving level signal from the driving board 309, and uses the time difference as a control link delay of the flexible direct current FPT system.
The link delay testing method of the flexible direct current control system provided by the embodiment of the invention comprises the steps of receiving a preset sine alternating current synchronous signal through an acquisition and measurement unit, sending the sine alternating current synchronous signal to an oscilloscope, processing the sine alternating current synchronous signal, and sending the processed alternating current synchronous signal to a control unit; wherein the sinusoidal AC synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, the control unit is a valve group control unit or a polar control unit, the control unit judges whether the AC synchronous signal crosses a positive zero point, if so, a positive level modulation signal is output and sent to a pulse distribution unit, the pulse distribution unit responds to the positive level modulation signal to generate a put command and send the put command to a drive unit, the drive unit executes the put command and generates a corresponding drive level signal, the drive level signal is sent to the oscilloscope, the oscilloscope obtains a time difference corresponding to a time from a time when the sinusoidal AC synchronous signal crosses the positive zero point to a time when the drive level signal rises to serve as a control link delay of the flexible DC control system, according to the invention, by adding the effective zero crossing point criterion when the input alternating current synchronous signal is acquired, the problem that the zero crossing point of the input signal of the direct current control protection system cannot be accurately acquired in the prior art can be effectively solved, and the measurement error can be effectively reduced.
Example two
Referring to fig. 8, the link delay testing system of the flexible dc control system according to the second embodiment of the present invention includes an acquisition measuring unit 21, a control unit 22, a pulse distribution unit 23, a driving unit 24, and an oscilloscope 25;
the acquisition and measurement unit 21 comprises a signal acquisition and processing module 211; the signal acquisition and processing module 211 is configured to receive a preset sinusoidal ac synchronization signal, send the sinusoidal ac synchronization signal to an oscilloscope, process the sinusoidal ac synchronization signal, and send the processed ac synchronization signal to the control unit 22; the sinusoidal alternating current synchronous signal is a voltage sinusoidal signal or a current sinusoidal signal, and the control unit 22 is a valve bank control unit or a pole control unit;
the control unit 22 includes a zero-crossing point judgment module 221; the zero point judgment module 221 is configured to judge whether the ac synchronous signal passes through a positive zero point, and if so, output a positive level modulation signal and send the positive level modulation signal to a pulse distribution unit;
the pulse distribution unit 23 includes a throw command generation module 231; the put-in command generating module 231, configured to generate a put-in command in response to the positive level modulation signal, and send the put-in command to the driving unit 24;
the driving unit 24 includes a driving signal generating module 241; the driving signal generating module 241 is configured to execute the commissioning command, generate a corresponding driving level signal, and send the driving level signal to the oscilloscope 25;
the oscilloscope 25 comprises a link delay acquisition module 251; the link delay obtaining module 251 is configured to obtain a time difference corresponding to a time from a time when the sinusoidal ac synchronization signal passes through a positive zero point to a time when the driving level signal rises, and use the time difference as a control link delay of the flexible dc control system.
Preferably, the system further comprises a transformer:
the mutual inductor comprises a sinusoidal alternating current synchronous signal acquisition module; the sinusoidal alternating current synchronous signal acquisition module is used for acquiring corresponding sinusoidal alternating current synchronous signals and transmitting the sinusoidal alternating current synchronous signals to the acquisition and measurement unit; the mutual inductor is a voltage mutual inductor or a current mutual inductor.
Preferably, the signal acquisition processing module 211 includes:
and the signal processing unit is used for performing voltage conversion, hardware filtering and digital-to-analog conversion on the sinusoidal alternating current synchronous signal to obtain an alternating current synchronous signal, and sending the alternating current synchronous signal to the control unit.
Preferably, the zero-crossing point determining module 221 includes:
the unlocking unit is used for setting a pre-stored control program to an unlocking position;
the zero crossing point judging unit is used for judging whether the alternating current synchronous signal passes through a positive zero point according to a preset over-positive zero point condition; the positive zero crossing condition comprises that an alternating current synchronous signal acquired by previous interruption is smaller than zero, and an alternating current synchronous signal acquired by current interruption is larger than zero and smaller than a preset threshold;
the first judgment unit is used for executing the control program when judging that the alternating current synchronous signal passes through a positive zero point, outputting a positive level modulation signal and sending the positive level modulation signal to the valve control unit;
and the second judgment unit is used for executing the control program when judging that the alternating current synchronous signal does not pass through a positive zero point, outputting a negative level modulation signal and sending the negative level modulation signal to the valve control unit.
Preferably, the system further comprises a control unit, the control unit comprising:
the synchronization module is used for performing synchronization processing with the valve control unit;
and the modulation signal transmission module is used for executing interruption after receiving the positive level modulation signal and transmitting the positive level modulation signal to the pulse distribution unit.
Preferably, the pulse allocation unit further includes:
and the input command transmission module is used for transmitting the input command to the sub-module power control unit.
Preferably, the system further includes a sub-module power control unit, and the sub-module power control unit includes:
and the signal generation module is used for generating a driving level signal through the sub-module power control unit and the driving unit after receiving the input command so as to drive the switching tube to work.
Preferably, the driving signal generating module 241 includes:
and the driving level signal transmission unit is used for transmitting the driving level signal to the oscilloscope.
Preferably, the link delay obtaining module 251 includes:
a measurement error calculation unit, configured to calculate, when the sinusoidal ac synchronization signal is a voltage sinusoidal signal, a measurement error at a time when the sinusoidal ac synchronization signal passes through a positive zero point according to formula (1):
wherein, UsetTo preset a voltage threshold, UmThe voltage amplitude of the voltage sinusoidal signal is shown, T is the period of the voltage sinusoidal signal, and delta T is the measurement error;
and the multiple measurement unit is used for performing multiple measurements according to the measurement error, and acquiring a measured minimum value as the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point.
In the link delay test system of the flexible direct current control system provided by the second embodiment of the invention, the acquisition and measurement unit receives a preset sine alternating current synchronous signal, the sine alternating current synchronous signal is sent to the oscilloscope, the sine alternating current synchronous signal is processed, and the processed alternating current synchronous signal is sent to the control unit; wherein the sinusoidal AC synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, the control unit is a valve group control unit or a polar control unit, the control unit judges whether the AC synchronous signal crosses a positive zero point, if so, a positive level modulation signal is output and sent to a pulse distribution unit, the pulse distribution unit responds to the positive level modulation signal to generate a put command and send the put command to a drive unit, the drive unit executes the put command and generates a corresponding drive level signal, the drive level signal is sent to the oscilloscope, the oscilloscope obtains a time difference corresponding to a time from a time when the sinusoidal AC synchronous signal crosses the positive zero point to a time when the drive level signal rises to serve as a control link delay of the flexible DC control system, according to the invention, by adding the effective zero crossing point criterion when the input alternating current synchronous signal is acquired, the problem that the zero crossing point of the input signal of the direct current control protection system cannot be accurately acquired in the prior art can be effectively solved, and the measurement error can be effectively reduced.
It should be noted that the above-described system embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. In addition, in the drawings of the embodiment of the system provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, and may be specifically implemented as one or more communication buses or signal lines. One of ordinary skill in the art can understand and implement it without inventive effort.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (8)
1. A link delay test method of a flexible direct current control system is characterized by comprising the following steps:
the acquisition and measurement unit receives a preset sine alternating current synchronous signal, sends the sine alternating current synchronous signal to the oscilloscope, processes the sine alternating current synchronous signal, and sends the processed alternating current synchronous signal to the control unit; the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, and the control unit is a valve bank control unit or a pole control unit;
the control unit judges whether the alternating current synchronous signal passes through a positive zero point or not, if so, a positive level modulation signal is output, and the positive level modulation signal is sent to a pulse distribution unit;
the pulse distribution unit responds to the positive level modulation signal, generates a switching command and sends the switching command to a driving unit;
the driving unit executes the input command, generates a corresponding driving level signal and sends the driving level signal to the oscilloscope;
and the oscilloscope acquires a time difference corresponding to the time from the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point to the moment when the drive level signal rises, and the time difference is used as the control link delay of the flexible direct current control system.
2. The method for testing the link delay of the flexible dc control system according to claim 1, wherein before the acquiring and measuring unit acquires the sinusoidal ac synchronization signal, the method further comprises:
the mutual inductor collects a preset sine alternating current synchronous signal and transmits the sine alternating current synchronous signal to the collection measuring unit; the mutual inductor is a voltage mutual inductor or a current mutual inductor.
3. The method for testing the link delay of the flexible dc control system according to claim 1, wherein the collecting and measuring unit processes the sinusoidal ac synchronization signal and sends the processed ac synchronization signal to the control unit, specifically comprising:
the acquisition and measurement unit performs voltage conversion, hardware filtering and digital-to-analog conversion on the sinusoidal alternating current synchronous signal to obtain an alternating current synchronous signal, and sends the alternating current synchronous signal to the control unit.
4. The method as claimed in claim 1, wherein the control unit determines whether the ac synchronization signal passes through a positive zero point, and if so, outputs a positive level modulation signal and sends the positive level modulation signal to the pulse distribution unit, further comprising:
the control unit sets a pre-stored control program to an unlocking position;
judging whether the alternating current synchronous signal passes through a positive zero point or not according to a preset over-positive zero point condition; the positive zero crossing condition comprises that an alternating current synchronous signal acquired by previous interruption is smaller than zero, and an alternating current synchronous signal acquired by current interruption is larger than zero and smaller than a preset threshold;
when the alternating current synchronous signal is judged to pass through a positive zero point, executing the control program, outputting a positive level modulation signal, and sending the positive level modulation signal to a valve control unit;
and when the alternating current synchronous signal is judged to be not over a positive zero point, executing the control program, outputting a negative level modulation signal, and sending the negative level modulation signal to the valve control unit.
5. The method as claimed in claim 4, wherein the control unit determines whether the ac synchronization signal passes through a positive zero point, and if so, outputs a positive level modulation signal and sends the positive level modulation signal to the pulse distribution unit, further comprising:
the control unit and the valve control unit perform synchronous processing;
the valve control unit performs an interrupt upon receiving the positive level modulation signal and transmits the positive level modulation signal to the pulse distribution unit.
6. The method for testing the link delay of the flexible direct current control system according to claim 4, wherein the method further comprises:
the pulse distribution unit transmits the input command to a sub-module power control unit;
after receiving the input command, the sub-module power control unit generates a driving level signal through the sub-module power control unit and the driving unit so as to drive a switching tube to work;
and the driving unit sends the driving level signal to the oscilloscope.
7. The method for testing the link delay of the flexible direct current control system according to claim 4, wherein the oscilloscope obtains the time when the sinusoidal alternating current synchronous signal passes through a positive zero point by the following steps:
when the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal, calculating the measurement error of the sinusoidal alternating current synchronous signal at the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point according to the formula (1):
wherein, UsetTo preset a voltage threshold, UmIs the voltage amplitude of the sinusoidal voltage signal, T is the period of the sinusoidal voltage signal, Δ T is the measurement error;
and measuring for multiple times according to the measurement error, and acquiring the measured minimum value as the moment when the sinusoidal alternating current synchronous signal passes through a positive zero point.
8. A link delay test system of a flexible direct current control system is characterized by comprising an acquisition measuring unit, a control unit, a pulse distribution unit, a driving unit and an oscilloscope;
the acquisition and measurement unit comprises a signal acquisition and processing module; the signal acquisition and processing module is used for receiving a preset sinusoidal alternating current synchronous signal, sending the sinusoidal alternating current synchronous signal to the oscilloscope, processing the sinusoidal alternating current synchronous signal and sending the processed alternating current synchronous signal to the control unit; the sinusoidal alternating current synchronous signal is a sinusoidal voltage signal or a sinusoidal current signal, and the control unit is a valve bank control unit or a pole control unit;
the control unit comprises a zero crossing point judging module; the zero point judgment module is used for judging whether the alternating current synchronous signal passes through a positive zero point or not, if so, outputting a positive level modulation signal and sending the positive level modulation signal to a pulse distribution unit;
the pulse distribution unit comprises a throw-in command generation module; the input command generating module is used for responding to the positive level modulation signal, generating an input command and sending the input command to the driving unit;
the driving unit comprises a driving signal generation module; the driving signal generation module is used for executing the input command, generating a corresponding driving level signal and sending the driving level signal to the oscilloscope;
the oscilloscope comprises a link delay acquisition module; and the link delay acquisition module is used for acquiring a time difference corresponding to the time from the moment when the sinusoidal alternating-current synchronous signal passes through a positive zero point to the moment when the driving level signal rises, and the time difference is used as the control link delay of the flexible direct-current control system.
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