CN114825419B - Self-adaptive island control system and method for direct-current converter station and electronic equipment - Google Patents
Self-adaptive island control system and method for direct-current converter station and electronic equipment Download PDFInfo
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- CN114825419B CN114825419B CN202110071233.0A CN202110071233A CN114825419B CN 114825419 B CN114825419 B CN 114825419B CN 202110071233 A CN202110071233 A CN 202110071233A CN 114825419 B CN114825419 B CN 114825419B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The application provides a self-adaptive island control system for a flexible direct current converter station, which is connected with a new energy source or a passive system and comprises the following components: the acquisition conversion unit is used for converting the acquired three-phase voltage and three-phase current of the alternating-current side of the flexible direct-current converter station into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system; the self-adaptive island control unit can stabilize the system by automatically switching to the control without inner loop current and without negative resistance caused by time delay such as sampling control, thereby avoiding the problem of medium-high frequency oscillation caused by introducing negative resistance component due to closed loop control and providing a more preferable scheme for large-scale new energy access.
Description
Technical Field
The application relates to the technical field of flexible direct-current transmission of power systems, in particular to a self-adaptive island control system and method for a direct-current converter station and electronic equipment.
Background
In order to solve the problem of global warming caused by the increase of carbon emission, new energy power generation is increasingly being regarded as a green energy source by governments of various countries. Wind power generation, photovoltaic power generation and the like are increasingly paid attention to as green energy sources in various countries, and new energy sources including wind power and photovoltaic power generation are being developed on a large scale in various main countries of the world.
The large-scale photovoltaic and wind power resources are generally far away from the load center, the large-scale offshore wind power resources close to the load center are required to be transmitted through cables, and how to realize high-efficiency and high-quality access of large-scale new energy to the power grid is a difficulty in grid connection of the current new energy. Although offshore wind power is close to a load center, as a cable is adopted, when the distance from a wind farm to the shore exceeds 60km, the difficulty of power loss, sea area occupation, reactive compensation and the like is gradually increased by adopting a traditional alternating current output mode, so that the alternating current access advantage is reduced.
In the flexible control mode, the flexible direct current transmission does not generate reactive power, and small sea area occupation becomes an optional choice for large-scale wind power transmission.
When the flexible direct current transmission is connected with large-scale new energy, the flexible direct current adopts island control, most of patents and researches at present focus on the soft and straight starting and fault crossing of the new energy access, and the main scheme of the existing flexible direct current island control adopts two control strategies of open loop and closed loop: on one hand, the double closed-loop control scheme can effectively inhibit fault current, but middle-high frequency oscillation is brought about by the introduction of inner loop current control, and concretely, for example, patent CN201610938897 discloses a double closed-loop control method and article "overview of oscillation phenomenon analysis and control method of a flexible direct current transmission system" describes middle-high frequency oscillation phenomenon analysis;
on the other hand, if the open-loop control is adopted, an open-loop control mode is proposed in paper 'study on black start control capability of a flexible direct current transmission system' and 'direct voltage control of passive network power supply of an MMC (Modular multilevel converter) flexible direct current transmission system', but the open-loop control mode causes uncontrollable current to trip, so that the open-loop control mode is unfavorable for new energy transmission.
The above information disclosed in the background section is only for enhancement of understanding of the background of the application and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
The application provides a self-adaptive island control system, a self-adaptive island control method and electronic equipment for a direct current converter station, which enable a flexible direct current converter station control system connected with new energy to adaptively select to adopt a self-adaptive island control method with an inner loop current control mode or a self-adaptive island control method without the inner loop current control mode according to the running state of a flexible direct current transmission system, and the self-adaptive island control system can enable the system to be stable by automatically switching to the self-adaptive island control method without the inner loop current control mode, and can avoid the problem of medium-high frequency oscillation caused by the fact that sampling control and other delay are not caused, thereby avoiding the risk of medium-high frequency oscillation and realizing the controllable fault current under the fault state.
According to one aspect of the application, an adaptive island control method for a direct current converter station is provided, which comprises the steps of collecting three-phase voltage and three-phase current of an alternating current side of the flexible direct current converter station, and converting the three-phase voltage and the three-phase current into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system; and generating a self-adaptive island control bridge arm reference wave by selecting a control mode according to the received voltage set reference value, the frequency set reference value, the dq-axis lower voltage signal and current signal, and the three-phase voltage signal and the three-phase current signal of the alternating current side of the flexible direct current converter station.
According to an example embodiment, the selecting a control mode includes selecting an island control mode with inner loop current control or selecting an island control mode without inner loop current control.
According to an embodiment, the island control mode with or without the inner loop current control is selected, including during start-up unlocking and idlingIn the state, when the system power P is satisfied<Pset1 or current peak I peak <Iset1 orWhen the island control mode without inner loop current control is selected to operate; otherwise, automatically switching to island mode with in-band loop current, wherein the P set1 ≤0.1pu，I set1 ≤0.1pu。
According to an example embodiment, the selecting an island control mode with or without inner loop current control, or selecting an island control mode without inner loop current control, further includes automatically switching to an island control mode without inner loop current control when detecting that a network side voltage harmonic content us_h > us_hset or a current harmonic content i_h > iv_hset is in a control mode of an inner loop current control module, wherein us_hset is greater than or equal to 0.01pu, and iv_hset is greater than or equal to 0.01pu.
According to an example embodiment, the selecting the island control mode with or without inner loop current control further includes detecting the net side zero sequence voltage U when the net side zero sequence voltage U is already under the control of the inner loop current control module 0 >U 0 Set or net side current Is>Is_set or bridge arm current I b >I b If_set, then automatically switch to the in-band loop current control module, wherein U 0 _set≥0.05pu，Is_set≥1.15pu，I b _set≥1.15pu。
According to another aspect of the present application there is provided an adaptive island control system for a dc converter station comprising: the acquisition conversion unit is used for converting the acquired three-phase voltage and three-phase current of the alternating-current side of the flexible direct-current converter station into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system; the self-adaptive island control unit is used for generating self-adaptive island control bridge arm reference waves according to the received voltage set reference value, the frequency set reference value, the dq-axis lower voltage signal and current signal, and the three-phase voltage signal and the three-phase current signal of the alternating-current side of the flexible direct-current converter station.
According to an example embodiment, the adaptive island control unit includes an island control module with inner loop current control for generating a dq-axis closed loop voltage reference wave; the island control module is not provided with inner loop current control and is used for generating dq axis open-loop voltage reference waves; the frequency phase control module is used for generating synchronous phase signals for converting an abc/dq coordinate system of the acquisition and conversion unit and converting a dq/abc coordinate system of the reference wave generation module; the self-adaptive island control selection module is used for selecting an island control module with inner loop current control or an island control module without inner loop current control; the reference wave generation module is used for receiving the synchronous phase signal conversion dq/abc coordinate system of the frequency phase control module and generating six bridge arm reference waves.
According to an example embodiment, the island control module with inner loop current control includes an output signal that converts the received voltage set reference value, the dq-axis lower voltage signal, and the dq-axis lower current signal into a dq-axis closed loop voltage reference wave.
According to an example embodiment, the island control module without inner loop current control includes an output signal that converts the voltage set reference value and the dq-axis lower voltage signal into a dq-axis open loop voltage reference wave.
According to an example embodiment, the adaptive island control selection module comprises an output signal converting the three-phase voltage signal and the three-phase current signal of the ac side of the flexible dc converter station, the dq-axis closed-loop voltage reference wave, the dq-axis open-loop voltage reference wave into an adaptive input reference wave voltage.
According to an example embodiment, the voltage outer loop controller and the current loop controller in both the island control module with and the island control module without inner loop current control comprise PI controllers and/or PR controllers.
According to an aspect of the present application, there is provided an electronic apparatus including: one or more processors; a storage means for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the methods as described above.
According to the technical scheme, the acquisition and conversion unit is used for converting the acquired three-phase voltage and three-phase current on the alternating side of the flexible direct current converter station into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system; the self-adaptive island control unit realizes automatic switching to control without inner loop current, and can stabilize the system because of no negative resistance caused by delay such as sampling control, thereby avoiding the problem of medium-high frequency oscillation caused by introducing negative resistance component due to closed loop control and providing a more preferable scheme for large-scale new energy access.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application as claimed.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it will be apparent that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings by those skilled in the art without departing from the scope of the claimed application.
Fig. 1a shows a schematic diagram of a flexible direct current power transmission converter station connection new energy source or passive system composition according to an example embodiment of the application.
Fig. 1b shows a flow chart of an adaptive island control method for connecting a flexible dc converter station to a new energy source according to an exemplary embodiment of the application.
Fig. 2 shows a schematic structural diagram of an adaptive island control system for connecting a flexible dc converter station to a new energy source according to an embodiment of the present application.
Fig. 3 shows a schematic structural diagram of a control unit of an adaptive island control system for connecting a flexible dc converter station to a new energy source according to an embodiment of the present application.
Fig. 4 shows a block diagram of an electronic device of a control apparatus of an adaptive island control system of a flexible direct current converter station connected to a new energy source according to an embodiment of the present application.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted.
The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the disclosure. One skilled in the relevant art will recognize, however, that the disclosed aspects may be practiced without one or more of the specific details, or with other methods, components, materials, apparatus, etc. In such instances, well-known structures, methods, devices, implementation steps, materials, or operations are not shown or described in detail.
Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
The terms first, second and the like in the description and in the claims and in the above-described figures are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.
Fig. 1a shows a schematic diagram of a flexible dc power transmission converter station connected to a new energy source or a passive system, for example, a large wind farm, according to an exemplary embodiment of the present application.
As shown in fig. 1a, a flexible dc power converter station connection offshore wind power new energy system 1000 generally includes an ac booster station 1001, an offshore flexible dc power converter station 2001 (hereinafter referred to as an offshore converter station), and an onshore converter station 3001, according to an embodiment. The electric energy generated by the offshore wind farm is boosted by the ac booster station 1001 and is connected to the offshore converter station 2001. Direct current is output through the offshore converter station 2001 and is connected to the onshore converter station 3001 through the sea cable 4000, thereby enabling transmission of wind farm power from the sea to the onshore ac grid 5000.
With continued reference to fig. 1a, the offshore converter station 2001 typically comprises: ac bus 2100, station transformer 2200, coupling transformer 2300, valve side bus 2400, valve side switch (not shown), converter valve and dc field device 2600, and corresponding measurement or control devices. The converter valve and dc field device 2600 typically includes a converter valve, a bridge arm reactor, a dc field device, and the like.
According to an embodiment, during the transmission of electricity, wind power generated by the offshore wind farm is boosted and then connected to ac bus 2100 of offshore converter station 2001. The ac bus 2100 is connected to the valve side bus 2400 via two sets of parallel connection transformers 2300. The valve-side busbar 2400 is connected to the ac side of the converter valve and the dc field device 2600. The offshore converter station 2001 powers other equipment of the offshore converter station via a high voltage station power transformer 2200. In the whole control process, the offshore converter station generates stable alternating voltage through island control for offshore wind power new energy grid connection.
Fig. 1b shows a flow chart of an adaptive island control method for connecting a flexible dc converter station to a new energy source according to an exemplary embodiment of the application.
Referring to fig. 1b, according to an embodiment, at S101, three-phase voltages and three-phase currents on the ac side of the flexible dc converter station are collected and converted into a dq-axis lower voltage signal and a dq-axis lower current signal via an abc/dq coordinate system.
And S103, generating a self-adaptive island control bridge arm reference wave according to the received voltage set reference value, the frequency set reference value, the dq-axis lower voltage signal and current signal, and the three-phase voltage signal and the three-phase current signal of the alternating current side of the flexible direct current converter station by selecting a control mode.
According to an embodiment, the selection of the control mode comprises selecting an island control mode with or without inner loop current control, and the specific switching process of both modes will be described in detail in connection with fig. 3.
Fig. 2 shows a schematic structural diagram of an adaptive island control system for connecting a flexible dc converter station to a new energy source according to a first exemplary embodiment of the present application.
As shown in fig. 1b and fig. 2, according to an exemplary embodiment, the adaptive island control method for a flexible direct current power transmission converter station provided by the present application includes:
and S101, acquiring three-phase voltage and three-phase current on the alternating current side of the flexible direct current converter station, and converting the three-phase voltage and the three-phase current into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system.
And S103, generating a self-adaptive island control bridge arm reference wave according to the received voltage set reference value, frequency set reference value, dq-axis lower voltage signal and current signal, and three-phase voltage signal and three-phase current signal reflecting the flexible and straight running state by selecting a control mode.
According to an embodiment, the selection of the control mode comprises selecting an island control mode with inner loop current control or selecting an island control mode without inner loop current control. An embodiment of specifically selecting the control mode as described above will be described later with reference to fig. 3. The specific structure of the control system will be described below with reference to fig. 2.
Referring to fig. 2, the adaptive island control system for a flexible direct current power transfer converter station includes an acquisition conversion unit 100 and an adaptive island control unit 200.
The acquisition and conversion unit 100 is configured to convert the acquired three-phase voltage and three-phase current on the ac side of the flexible dc converter station into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system.
The adaptive island control unit 200 is configured to generate an adaptive island control bridge arm reference wave according to the received voltage setting reference value, the dq-axis lower voltage signal and the current signal, and the three-phase voltage signal and the three-phase current signal reflecting the flexible-straight running state.
According to an embodiment, the acquisition and conversion unit 100 comprises a first input 101, a second input 102, a third input 103, a first output 111, and a second output 112.
The first input 101 is for receiving a three-phase voltage signal on the ac side of the flexible dc converter station.
The second input 102 is for receiving a three-phase current signal on the ac side of the flexible dc converter station.
The third input 103 is for receiving a synchronized phase angle signal.
The first output 111 is configured to output a voltage signal reflecting the operation state of the flexible direct current.
The second output 112 is configured to output a current signal reflecting the state of operation of the flexible direct current.
According to an embodiment, the adaptive island control unit 102 comprises a first input 201, a second input 202, a third input 203, a fourth input 204, a fifth input 211, a sixth input 212, a first output 261, a second output 262, a third output 263, a fourth output 264, a fifth output 265, a sixth output 266, a seventh output 267.
The first input terminal 201 is configured to receive a voltage setting reference value.
The second input 202 is used for receiving a synchronous phase angle signal generated by the frequency setting reference value to the third input of the acquisition and conversion unit and generating a reference wave.
The third input 203 is for receiving a voltage signal reflecting the state of operation of the flexible direct current.
The fourth input 204 is for receiving a current signal reflecting the state of operation of the flexible direct current.
The fifth input 211 is for receiving the dq-axis lower voltage signal.
The sixth input 212 is for receiving the dq-axis lower current signal.
The first output end 261, the second output end 262, the third output end 263, the fourth output end 264, the fifth output end 265 and the sixth output end 266 respectively output three-phase upper bridge arm reference waves and three-phase lower bridge arm reference waves of the adaptive island control unit.
The seventh output 267 is for outputting a synchronized phase angle signal.
According to an embodiment, referring to fig. 2, the first output 111 of the acquisition and conversion unit is connected to the fifth input 211 of the adaptive island control unit, the second output 112 of the acquisition and conversion unit is connected to the sixth input 212 of the adaptive island control unit, and the seventh output 267 of the adaptive island control unit is connected to the third input 103 of the acquisition and conversion unit.
The collection and conversion unit 100 is configured to convert the collected three-phase voltage and three-phase current on the flexible direct current and alternating current side into a dq-axis lower voltage Udq and a dq-axis lower voltage Idq through abc/dq according to the received azimuth signal, where the three-phase voltage and the three-phase current on the flexible direct current and alternating current side reach the collection and conversion unit 100 through a first input end 101 and a second input end 102 of the collection and conversion unit, respectively; the third input 103 of the acquisition and conversion unit 100 acquires the phase angle signal fed by the seventh output 267 of the adaptive island control unit 200.
According to an embodiment, optionally, the first output terminal 101 and the second output terminal 102 of the acquisition and conversion unit 100 can be combined into one output terminal to be sent to the adaptive island control unit 200, and accordingly, the fifth input terminal 211 and the sixth input terminal 212 of the adaptive island control unit 200 can be combined into one input terminal to receive the signal output by the acquisition and conversion unit 100.
Alternatively, the third input 203 and the fourth input 204 of the adaptive island control unit 200 can be combined to the fifth input 211 and the sixth input 212, the third 203 and the fourth input 204 are omitted, and the three-phase voltage signal and the three-phase current signal output by the first output 101 and the second output 102 of the acquisition unit 100 are directly transmitted to the fifth input 211 and the sixth input 212 of the adaptive island control unit 200.
The adaptive island control unit 200 is used for setting a reference value according to the received voltageAnd the dq-axis lower voltage Udq and current Idq are self-generated by self-adaptive island control according to three-phase voltage and current reflecting soft-straight running stateAnd adapting to island control bridge arm reference waves. The adaptive island control unit 200 generates a phase angle signal θ to the acquisition conversion unit 100 according to the received frequency setting reference value f_ref and generates a reference wave for use by itself. Voltage setting reference value +.>The frequency setting reference values f_ref, the dq-axis voltage Udq and the dq-axis current Idq are sent to the adaptive island control unit 200 via the first input terminal 201, the second input terminal 202, the fifth input terminal 211 and the sixth input terminal 212 of the adaptive control unit, respectively; the three-phase voltage and three-phase current signals reflecting the flexible direct current running state are respectively sent to the adaptive island control 200 through the third input end 203 and the fourth input end 204 of the adaptive control unit, the first output end 261, the second output end 262, the third output end 263, the fourth output end 264, the fifth output end 265 and the sixth output end 266 of the island control unit respectively output flexible direct current three-phase upper bridge arm and three-phase lower bridge arm reference waves and are sent to a flexible direct current valve control system (not shown), and the seventh output end 267 of the island control unit outputs a phase angle signal theta to the third input end 103 of the acquisition and conversion unit.
Fig. 3 shows a schematic structural diagram of an adaptive island control unit 200 of an adaptive island control system for connecting a flexible dc converter station to a new energy source according to an embodiment of the present application.
As shown in fig. 3, according to an exemplary embodiment, the adaptive island control unit 200 of the flexible dc power transmission converter station provided by the present application includes an island control module 210 with inner loop current control, an island control module 220 without inner loop current control, a frequency phase control module 230, an adaptive island control selection module 240, and a reference wave generation module 250.
Island control module 210 with inner loop current control is used to generate the dq-axis closed loop voltage reference wave.
Island control module 220 without inner loop current control is used to generate the dq-axis open loop voltage reference wave.
The frequency phase control module 230 is configured to generate a synchronous phase signal for use in abc/dq coordinate system conversion of the acquisition and conversion unit and reference wave generation module dq/abc coordinate system conversion.
The adaptive island control selection module 240 is configured to select an island control module with or without inner loop current control.
The reference wave generation module 250 is configured to receive the synchronous phase signal conversion dq/abc coordinate system of the frequency phase control module and generate six bridge arm reference waves.
According to an embodiment, island control module with inner loop current control 210 includes a first input 213, a second input 214, a third output 215, and a first output 217.
The first input terminal 213 is for receiving a voltage setting reference value.
The second input 214 is for receiving the dq-axis lower voltage signal.
The third input 215 is for receiving the dq-axis lower current signal.
The first output 217 is for outputting a dq-axis closed-loop voltage reference wave.
According to an embodiment, island control module 220 without inner loop current control includes a first input 221, a second input 222, and a first output 226.
A first input 221 for receiving a voltage setting reference value.
A second input 222 for receiving the dq axis lower voltage signal.
A first output 226 for outputting the dq-axis open-loop voltage reference wave.
According to an embodiment, the adaptive island control selection module includes a first input 241, a second input 242, a third input 243, a fourth input 244, and a first output 246.
The first input 241 is for receiving a voltage signal reflecting the state of operation of the flexible direct current.
The second input 242 is for receiving a current signal reflecting the state of operation of the flexible direct current.
The third input 243 is for receiving the dq-axis closed-loop voltage reference wave.
The fourth input 244 is for receiving the dq-axis open-loop voltage reference wave.
The first output 246 is for outputting an adaptive input reference wave voltage.
According to an embodiment, the island control module 210 with inner loop current control first output 217 is connected to the third input 243 of the adaptive island control selection module 240; the island control module 220 without inner loop current control has a first output 226 connected to a fourth input 244 of the adaptive island control selection module 240; the output 232 of the frequency phase control module 230 is connected to the second input 252 of the reference wave generating module; the first output 246 of the adaptive island control selection module 240 is connected to the first input 251 of the reference wave generation module.
According to an embodiment, the island control module 210 with inner loop current control is configured to set a reference value according to a received voltageAnd the dq-axis voltage Udq passes through the outer loop voltage controller to generate a current reference wave Idq_ref, and the current reference wave Idq_ref is fed into the third input end 243 of the adaptive island control selection module after the dq-axis voltage reference wave Udq_ref_cl with current closed-loop control generated by the dq-axis current Idq through the inner loop current controller; wherein the voltage is set to a reference value +.>The dq-axis voltage Udq and the dq-axis current Idq are fed to a first input 213, a second input 214 and a third input 215 of the island control module with inner loop current control.
According to an embodiment, the island control module 220 without inner loop current control is configured to set a reference value according to the received voltageAnd dq-axis voltage Udq is fed into a fourth input 244 of the adaptive island control selection module 240 via outer loop voltage control to generate a dq-axis open loop voltage reference wave Udq_ref_op without current closed loop control; wherein the voltage is set to a reference value +.>And the dq-axis voltage Udq is fed to the first input 221 and the second input 222 of the island control module without inner loop current control.
The frequency phase control module 230 is configured to generate a synchronous phase signal for use by the acquisition conversion module abc/dq conversion and the reference wave generation module dq/abc conversion according to the received frequency setting reference value f_ref. The frequency setting reference f_ref is coupled to the first input 231 of the frequency phase control module. The frequency phase control module first output 232 is coupled to the reference wave generation module third input 252.
The adaptive island control selection module 240 is configured to adaptively select a dq-axis closed-loop voltage reference wave udq_ref_cl with current closed-loop control or a dq-axis open-loop voltage reference wave udq_ref_op without current closed-loop control according to a flexible direct-current operation state, where the flexible direct-current operation state is adaptively determined and selected by three-phase voltage and three-phase current or a combination of three-phase voltage and three-phase current. The flexible dc operating state is connected by three-phase voltages and three-phase currents to the first input 241 and the second input 242 of the adaptive island control selection module. The dq-axis closed-loop voltage reference wave with current closed-loop control udq_ref_cl or the dq-axis open-loop voltage reference wave without current closed-loop control udq_ref_op are fed to the third input 243 and the fourth input 244 of the adaptive island control selection module, respectively. The adaptively input reference wave selected after the adaptive judgment according to the soft-straight running state is sent to the output end 246 of the adaptive island control selection module.
The reference wave generating module 250 is configured to convert dq/abc into abc coordinates according to the dq voltage reference wave and the synchronous phase signal of frequency phase control output by the adaptive island control selecting module, and then generate six bridge arm reference waves required by valve control. The dq-axis reference voltage of the output dq-axis of the adaptive island control selection module is fed to the first input end 251 of the reference wave generation module, and the six generated bridge arm reference waves are fed to the first output end 254 to the sixth output end 259 of the reference wave generation module, respectively.
The three-phase voltage Ux (x=a, b, c) reflecting the flexible-direct running state can be an alternating-current voltage in flexible-direct connection, the three-phase current Ix (x=a, b, c) can be an alternating-current, a valve side current or a bridge arm current, the running state can also be that the alternating-current voltage is multiplied by the current to obtain system power P, p=3ux×ix, and the flexible-direct running state adaptive selection module selects the dq-axis closed-loop voltage reference wave udq_ref_cl with current closed-loop control or the dq-axis open-loop voltage reference wave udq_ref_op without current closed-loop control according to the three-phase voltage, the three-phase current or the active power adaptive judgment, and the selection criterion is as follows:
according to an embodiment, when the system power P is met in a flexible dc-start unlocked and idle state<Pset1 or current peak value Ipeak<Iset1 orWhen the island control module 220 without the inner loop current control is selected to operate, otherwise, the island control module 210 with the inner loop current is automatically switched to operate, and Pset1 is less than or equal to 0.1pu, and Iset1 is less than or equal to 0.1pu.
When the voltage harmonic content us_h > us_hset or the current harmonic content i_h > iv_hset of the flexible direct system is detected under the control of the in-band inner loop current control module 210, the island control system without the inner loop current control module is automatically switched to an island control system without the inner loop current control module, wherein us_hset is more than or equal to 0.01pu, and iv_hset is more than or equal to 0.01pu.
When the zero sequence voltage U0> U0-set of the network side current or the net side current Is > IS-set or the bridge arm current Ib > Ib-set Is detected under the control of the current control module without the inner loop, the control module Is automatically switched to the current control module without the inner loop, U0-se t Is more than or equal to 0.05pu, IS-set Is more than or equal to 1.15pu, and Ib-set Is more than or equal to 1.15pu.
The dq-axis voltage Udq, the dq-axis current Idq,The command value, udq_ref_cl, udq_ref_op, represents a positive sequence component and a negative sequence component.
After receiving the dq-axis adaptive input reference wave and the synchronous phase angle signal, the input ends 251 and 252 of the reference wave generating module 250 respectively convert the dq-axis adaptive input reference wave and the synchronous phase angle signal to generate three-phase voltages ux_ref (a, b, c) for positive and negative sequence superposition, and then generate six bridge arm reference waves respectively through signal conversion Vxu _ref=udc/2-ux_ref (x=a, b, c) and vx_dref=udc/2-ux_ref, wherein Udc is a direct current voltage setting reference value.
The voltage outer loop control and current loop controller in the island control module with and without inner loop current control can be a PI controller or a PR controller.
Fig. 4 shows a block diagram of an electronic device of an adaptive island control system of a flexible direct current converter station connected with a new energy source according to an embodiment of the present application.
As shown in fig. 4, the electronic device 400 is embodied in the form of a general purpose computing device. The components of electronic device 400 may include, but are not limited to: at least one processing unit 410, at least one memory unit 420, a bus 430 connecting the different system components (including memory unit 420 and processing unit 410), a display unit 440, and the like.
In which a storage unit stores program code that can be executed by the processing unit 410, such that the processing unit 410 performs the methods according to various exemplary embodiments of the present application described in the present specification.
Bus 430 may be a local bus representing one or more of several types of bus structures including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or using any of a variety of bus architectures.
The electronic device 400 may also communicate with one or more external devices 500 (e.g., keyboard, pointing device, bluetooth device, etc.), one or more devices that enable a user to interact with the electronic device 400, and/or any device (e.g., router, modem, etc.) that enables the electronic device 400 to communicate with one or more other computing devices. Such communication may occur through an input/output (I/O) interface 450. Also, electronic device 400 may communicate with one or more networks such as a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the Internet, through network adapter 460. The network adapter 460 may communicate with other modules of the electronic device 400 via the bus 430. It should be appreciated that although not shown, other hardware and/or software modules may be used in connection with electronic device 400, including, but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, data backup storage systems, and the like.
According to the self-adaptive island control system, the self-adaptive island control method and the electronic equipment for the direct current converter station, the flexible direct current converter station control system connected with new energy sources can adaptively select the self-adaptive island control method adopting the current control mode with the inner ring or the current control mode without the inner ring according to the running state of the flexible direct current transmission system, the system can be stabilized by automatically switching to the current control without the inner ring due to the fact that negative resistance caused by delay such as sampling control is not existed, the problem of medium-high frequency oscillation caused by the fact that negative resistance component is introduced by closed-loop control is avoided, the risk of medium-high frequency oscillation is avoided, and fault current is controllable in a fault state.
The foregoing has outlined rather broadly the more detailed description of embodiments of the application in order that the detailed description of the principles and embodiments of the application may be implemented in conjunction with the detailed description of embodiments of the application that follows. Meanwhile, based on the idea of the present application, those skilled in the art can make changes or modifications on the specific embodiments and application scope of the present application, which belong to the protection scope of the present application. In view of the foregoing, this description should not be construed as limiting the application.
Claims (13)
1. An adaptive island control method for a direct current converter station, comprising:
three-phase voltage and three-phase current on the alternating current side of the flexible direct current convertor station are collected and converted into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system;
generating a self-adaptive island control bridge arm reference wave by selecting a control mode according to the received voltage set reference value, frequency set reference value, the dq-axis lower voltage signal and current signal, and the three-phase voltage signal and the three-phase current signal of the alternating current side of the flexible direct current converter station;
the selecting control mode includes selecting an island control mode with in-loop current control or selecting an island control mode without in-loop current control, wherein:
in the start-up unlocked and idle state, when the system power P is satisfied<P set1 Or the current peak value I peak <I set1 Or alternativelyWhen the island control mode without inner loop current control is selected to operate; otherwise, automatically switching to an island control mode adopting current control with an inner loop;
in the island control mode with inner loop current control, when detecting that the voltage harmonic content us_h > us_hset or the current harmonic content I_h > iv_hset at the network side, automatically switching to the island control mode without inner loop current control;
when the network side zero sequence voltage U is detected in the island control mode without inner loop current control 0 >U 0 Set or net side current Is>Is_set or bridge arm current I b >I b And (b) when_set is detected, automatically switching to an island control mode with inner loop current control.
2. The method according to claim 1, wherein said P set1 ≤0.1pu，I set1 ≤0.1pu。
3. The method of claim 1, wherein us_hset is ≡0.01pu and iv_hset is ≡0.01pu.
4. The method of claim 1, wherein the U 0 _set≥0.05pu，Is_set≥1.15pu，I b _set≥1.15pu。
5. An adaptive island control system for a dc converter station, comprising:
the acquisition conversion unit is used for converting the acquired three-phase voltage and three-phase current of the alternating-current side of the flexible direct-current converter station into a dq-axis lower voltage signal and a dq-axis lower current signal through an abc/dq coordinate system;
the self-adaptive island control unit is used for generating self-adaptive island control bridge arm reference waves according to the received voltage set reference value, frequency set reference value, the dq-axis lower voltage signal and current signal, and the three-phase voltage signal and the three-phase current signal of the alternating-current side of the flexible direct-current converter station;
the adaptive island control unit comprises:
the island control module with inner loop current control is used for generating dq axis closed loop voltage reference waves;
the island control module is not provided with inner loop current control and is used for generating dq axis open-loop voltage reference waves;
the frequency phase control module is used for generating synchronous phase signals for converting an abc/dq coordinate system of the acquisition and conversion unit and converting a dq/abc coordinate system of the reference wave generation module;
the self-adaptive island control selection module is used for selecting an island control module with inner loop current control or an island control module without inner loop current control; comprising the following steps:
in the start-up unlocked and idle state, when the system power P is satisfied<P set1 Or the current peak value I peak <I set1 Or alternativelySelecting to operate the island control module without inner loop current control; otherwise, automatically operating the island control module with the inner loop current control;
under the condition that the island control module with inner loop current control operates, when the network side voltage harmonic content us_h > us_hset or the current harmonic content I_h > iv_hset is detected, automatically operating the island control module without inner loop current control;
when the island control module without inner loop current control operates, the net side zero sequence voltage U is detected 0 >U 0 Set or net side current Is>Is_set or bridge arm current I b >I b When_set, automatically operating the island control module with the inner loop current control;
the reference wave generation module is used for receiving the synchronous phase signal conversion dq/abc coordinate system of the frequency phase control module and generating six bridge arm reference waves.
6. The system of claim 5, wherein the P set1 ≤0.1pu，I set1 ≤0.1pu。
7. The system of claim 5 wherein us_hset is greater than or equal to 0.01pu and iv_hset is greater than or equal to 0.01pu.
8. The system of claim 5, wherein the U 0 _set≥0.05pu，Is_set≥1.15pu，I b _set≥1.15pu。
9. The system of claim 5, wherein the island control module with in-loop current control comprises:
and converting the received voltage setting reference value, the dq-axis lower voltage signal and the dq-axis lower current signal into a dq-axis closed-loop voltage reference wave and outputting the dq-axis closed-loop voltage reference wave.
10. The system of claim 5, wherein the island control module without inner loop current control comprises:
and converting the voltage set reference value and the dq-axis lower voltage signal into a dq-axis open-loop voltage reference wave and outputting the dq-axis open-loop voltage reference wave.
11. The system of any one of claims 5 to 10, wherein the adaptive island control selection module comprises:
converting the three-phase voltage signal, the three-phase current signal and the dq-axis closed-loop voltage reference wave of the alternating-current side of the flexible direct-current converter station into self-adaptive input reference wave voltage and outputting the self-adaptive input reference wave voltage; or converting the three-phase voltage signal, the three-phase current signal and the dq-axis open-loop voltage reference wave on the alternating-current side of the flexible direct-current converter station into self-adaptive input reference wave voltage and outputting the self-adaptive input reference wave voltage.
12. The system of claim 5, wherein voltage and current outer loop controllers in both the island control module with and island control module without inner loop current control comprise PI and/or PR controllers.
13. An electronic device, comprising:
one or more processors;
a storage means for storing one or more programs;
the one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method of any of claims 1-4.
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| CN202110071233.0A CN114825419B (en) | 2021-01-19 | 2021-01-19 | Self-adaptive island control system and method for direct-current converter station and electronic equipment |
| PCT/CN2022/072571 WO2022156681A1 (en) | 2021-01-19 | 2022-01-18 | Control method and system for island operation of vsc-hvdc system |
| MX2023007693A MX2023007693A (en) | 2021-01-19 | 2022-01-18 | Control method and system for island operation of vsc-hvdc system. |
| EP22742160.9A EP4283816A1 (en) | 2021-01-19 | 2022-01-18 | Control method and system for island operation of vsc-hvdc system |
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