CN110086169B - Power distribution network control method - Google Patents

Power distribution network control method Download PDF

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CN110086169B
CN110086169B CN201910439217.5A CN201910439217A CN110086169B CN 110086169 B CN110086169 B CN 110086169B CN 201910439217 A CN201910439217 A CN 201910439217A CN 110086169 B CN110086169 B CN 110086169B
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converter
phase
target value
current
value
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CN110086169A (en
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由蕤
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Qingdao University
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Qingdao University
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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
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

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  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The application relates to a power distribution network control method, which is used for respectively controlling converters on two sides of an SOP module and comprises the following steps: according to the active current target value and the reactive current target value of the converter, obtaining a three-phase current target value of the converter; compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter; and controlling the on-off of a switching tube of the converter according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter. The method and the device can compensate the unbalanced load currents on two sides of the SOP module respectively, so that the three-phase voltages of the power grids on two sides of the SOP module tend to be balanced respectively.

Description

Power distribution network control method
Technical Field
The invention relates to the field of power systems, in particular to a power distribution network control method.
Background
At present, the intelligent soft switch SOP (Soft Open Point) technology facing the power distribution level is initiating a new round of research hot tide. The SOP technology aims to replace a traditional feeder interconnection switch based on a circuit breaker by a controllable power electronic converter, so that a normalized flexible soft connection between feeder lines is realized, and flexible, rapid and accurate power exchange control and power flow optimization capability can be provided.
The basic structure of the SOP can be described by a back-to-back AC/DC/AC converter consisting of high power fully controlled power electronics (e.g. insulated gate bipolar transistors IGBTs, etc.), a typical SOP structure is shown in fig. 1, where VSC1, VSC2 are voltage source converters. In general, the SOP two-sided converter is completely symmetrical in structure, and by implementing a proper control strategy, bidirectional flexible flow and accurate control of power can be realized according to a scheduling instruction. After SOP is adopted to replace a tie switch in the power distribution network, the power exchange of feeder lines at two sides can be controlled to influence or change the power flow distribution of the whole system, so that the operation scheduling of the power distribution network is more flexible.
Fig. 2 shows a typical application of a power distribution network in which a conventional tie switch is replaced by an SOP, and compared with a conventional network connection mode based on the tie switch, the SOP realizes normalized flexible interconnection between feeder lines, avoids potential safety hazards caused by frequent displacement of the switch, greatly improves the flexibility and rapidity of power distribution network control, and enables the power distribution network to have the advantages of open-loop operation and closed-loop operation.
Because the load in the distribution network is difficult to reach balance, the voltages at two sides of the SOP are unbalanced, the current solution is that the converter at one side of the SOP module is used for controlling the voltage of the direct current bus to be stable, the converter at the other side of the SOP module is used for controlling the flowing active power, the approach adjustment of the voltages at two sides of the SOP module is realized, namely, the three-phase voltages at one side are synchronously reduced, the three-phase voltages at the other side are synchronously increased, the voltages at two sides tend to be the same, but the control strategy can only synchronously increase or decrease the three-phase voltages at two sides, and the unbalance between the three-phase voltages at each side is not treated. The unbalanced three-phase voltage can increase the electric energy loss of a circuit, increase the electric energy loss of a distribution transformer and influence the safe operation of electric equipment.
Therefore, on the premise of meeting the voltage balance at two sides of the SOP module, the balance between the three-phase voltages is realized, which is a problem to be solved in the prior art.
Disclosure of Invention
The invention provides a power distribution network control method, which solves the problem of unbalance among three-phase voltages at one side of an SOP module in the prior art.
The technical scheme of the invention is realized as follows:
a power distribution network control method, the power distribution network comprising an SOP module, wherein one side converter of the SOP module is configured to control active power flow, the other side converter of the SOP module is configured to control direct current bus voltage, and the two side converters of the SOP module are respectively controlled, comprising:
according to the active current target value and the reactive current target value of the converter, obtaining a three-phase current target value of the converter;
compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter;
and controlling the on-off of a switching tube of the converter according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter.
Optionally, for a side converter configured to control active power flow, the active current target value of the converter is obtained from a difference between the active power target value and an actual active power value flowing through the converter.
Alternatively, for a side converter configured to control the dc bus voltage, the active current target value of the converter is obtained from the difference between the dc bus voltage target value and the dc bus voltage actual value.
Optionally, the reactive current target value of the converter is obtained according to the difference between the reactive power target value and the reactive power actual value of the converter output.
Optionally, the obtaining the three-phase current target value of the converter according to the active current target value and the reactive current target value of the converter includes:
and converting the active current target value and the reactive current target value of the converter from the dq axis to the abc axis according to the phase information of the three-phase voltage of the power grid, and obtaining the three-phase current target value of the converter.
Optionally, the compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter includes:
according to the phase information of the three-phase voltage of the power grid, converting an abc axis to a dq axis of the actual value of the three-phase current at the load side, and obtaining the dq axis component of the compensation current required to be provided by the converter through low-pass filtering and PI regulation;
performing coordinate transformation from a dq axis to an abc axis on the dq axis component of the compensation current according to the phase information of the three-phase voltage of the power grid to obtain a three-phase compensation current value;
and obtaining a final target value of the three-phase current of the converter according to the three-phase compensation current value and the target value of the three-phase current of the converter.
Optionally, the transforming the abc axis to dq axis according to the phase information of the three-phase voltage of the power grid includes: and after inverting the phase information of the three-phase voltage of the power grid, converting the actual value of the three-phase current at the load side from the abc axis to the phase information of the dq axis.
Optionally, the coordinate transformation from dq axis to abc axis of the dq axis component of the compensation current according to the phase information of the three-phase voltage of the power grid includes: after inverting the phase information of the three-phase voltage of the power grid, the dq axis component serving as the compensation current is converted from the dq axis to the phase information of the abc axis.
Optionally, the phase information of the three-phase voltage of the power grid is: and extracting positive sequence components of the power grid voltage, and obtaining the power grid voltage after phase locking by a phase-locked loop.
Optionally, the controlling the on-off of the converter switching tube according to the difference between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter includes: and the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter is controlled by hysteresis, and the comparison result is converted into a gate signal of a switching tube of the converter to control the on-off of the switching tube.
The beneficial effects of the invention are as follows:
(1) And respectively compensating the unbalance of load currents at two sides of the SOP module to obtain final target values of three-phase currents of converters at two sides, so that the three-phase currents of power grids at two sides of the SOP module tend to be balanced, and further, the three-phase voltages of the power grids at two sides of the SOP module tend to be balanced.
(2) The stability of the power grid is ensured, and the power supply quality is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a typical SOP structure;
FIG. 2 is a schematic diagram of a power distribution network employing SOP;
FIG. 3 is a schematic diagram of an alternative embodiment of a power distribution network;
fig. 4 is a schematic flow chart of a power distribution network control method according to an embodiment of the disclosure;
fig. 5 is a schematic block diagram of a power distribution network control method provided by an embodiment of the present disclosure;
fig. 6 is a schematic block diagram of a power distribution network control method provided by an embodiment of the present disclosure;
fig. 7 is a schematic block diagram of a power distribution network control system provided by an embodiment of the present disclosure.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Fig. 3 shows an alternative implementation of the distribution network.
V 1a 、V 1b 、V 1c Three-phase voltage, i of one of the power grids connected for the SOP module converter VSC1 s1,a 、i s1,b 、i s1,c For three-phase current of the converter VSC1, V 2a 、V 2b 、V 2c Three-phase voltage, i, of the other side network connected for the SOP module converter VSC2 s2,a 、i s2,b 、i s2,c For the three-phase current of the converter VSC2, the VSC controller outputs gate signals to VSC1 and VSC2 to control the on-off of the switching tubes. The Load side Load1 and the Load side Load2 of the power grid are respectively provided with a current sensor, and the actual value i of the three-phase current of the Load side is measured l1,a 、i l1,b 、i l1,c And i l2,a 、i l2,b 、i l2,c 。
In the embodiment of the disclosure, one side converter VSC1 of the SOP module is configured to control active power flow, the other side converter VSC2 of the SOP module is configured to control dc bus voltage, however, in other embodiments, the converter VSC2 of the SOP module may be configured to control active power flow, and the other side converter VSC1 of the SOP module may be configured to control dc bus voltage.
Fig. 4 shows an alternative embodiment of a power distribution network control method.
The embodiment of the disclosure provides a power distribution network control method, which respectively controls two side converters VSC1 and VSC2 of an SOP module, and includes: according to the active current target value and the reactive current target value of the converter, obtaining a three-phase current target value of the converter; compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter; and controlling the on-off of a switching tube of the converter according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter.
By adopting the embodiment, the unbalance of the load currents at the two sides of the SOP module is respectively compensated, and the final target value of the output three-phase currents of the converters at the two sides is obtained, so that the three-phase currents of the power grids at the two sides of the SOP module tend to be balanced, the three-phase voltages of the power grids at the two sides of the SOP module tend to be balanced, the stability of the power grid is ensured, and the power supply quality is improved.
Optionally, for a side converter configured to control active power flow, the active current target value of the converter is obtained from a difference between the active power target value and the active power actual value flowing through the converter.
Alternatively, for a side converter configured to control the dc bus voltage, the active current target value of the converter is obtained from the difference between the dc bus voltage target value and the dc bus voltage actual value.
Alternatively, for a side converter configured to control the flow of active power or a side converter configured to control the voltage of the dc bus, the reactive current target value of the converter is obtained from the difference between the converter output reactive power target value and the reactive power actual value.
Optionally, the obtaining the three-phase current target value of the converter according to the active current target value and the reactive current target value of the converter includes: and transforming the active current target value and the reactive current target value of the converter from the dq axis to the abc axis according to the phase information of the three-phase voltage of the power grid to obtain the three-phase current target value of the converter.
Optionally, the compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter includes: according to the phase information of the three-phase voltage of the power grid, converting an abc axis to a dq axis of the actual value of the three-phase current at the load side, and obtaining the dq axis component of the compensation current required to be provided by the converter through low-pass filtering and PI regulation; performing coordinate transformation from a dq axis to an abc axis on the dq axis component of the compensation current according to the phase information of the three-phase voltage of the power grid to obtain a three-phase compensation current value; and obtaining a final target value of the three-phase current of the converter according to the three-phase compensation current value and the target value of the three-phase current of the converter.
Optionally, the transforming the abc axis to the dq axis according to the actual value of the three-phase current on the load side according to the phase information of the three-phase voltage of the power grid includes: and after inverting the phase information of the three-phase voltage of the power grid, converting the actual value of the three-phase current at the load side from the abc axis to the phase information of the dq axis.
Optionally, the coordinate transformation from dq axis to abc axis of the dq axis component of the compensation current according to the phase information of the three-phase voltage of the power grid includes: after inverting the phase information of the three-phase voltage of the power grid, the dq axis component serving as the compensation current is converted from the dq axis to the phase information of the abc axis.
Optionally, the phase information of the three-phase voltage of the power grid is: and extracting positive sequence components of the power grid voltage, and obtaining the power grid voltage after phase locking by a phase-locked loop.
Fig. 5 shows a schematic block diagram of a power distribution network control method for controlling a side converter configured to control active power flow.
In some embodiments, a power distribution network control method includes: flow through active power target value P according to converter VSC1 * And the actual value P, obtaining an active current target value i of the converter VSC1 d1 * The method comprises the steps of carrying out a first treatment on the surface of the According to the converter VSC1 outputting a reactive power target value Q 1 * And reactive power actual value Q 1 Obtain the reactive current target value i of the converter VSC1 q1 * The method comprises the steps of carrying out a first treatment on the surface of the Acquiring three-phase voltage V of power grid 1a 、V 1b 、V 1c According to the phase information of the three-phase voltage V of the power grid 1a 、V 1b 、V 1c The phase information of (a) will be the active current target value i d1 * And reactive current target value i q1 * Conversion from dq axis to abc axis (inverse Parker transform) to obtain converter VSC1Three-phase current target value i a1 * 、i b1 * 、i c1 * The method comprises the steps of carrying out a first treatment on the surface of the According to the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c For VSC1 three-phase current target value i a1 * 、i b1 * 、i c1 * Compensating to obtain final target value i of three-phase current of converter VSC1 s1,a * 、i s1,b * 、i s1,c * The method comprises the steps of carrying out a first treatment on the surface of the According to the final target value i of the three-phase current of the converter VSC1 s1,a * 、i s1,b * 、i s1,c * Actual value i of three-phase current of VSC1 of AND converter s1,a 、i s1,b 、i s1,c And the switching on and off of a switching tube of the converter VSC1 are controlled.
The converter VSC1 is configured to control active power flow, to perform unbalance compensation on three-phase unbalance voltage of a power grid on the side of the VSC1, and to install a current sensor on the Load side Load1 of the power grid and to measure the actual value i of three-phase current on the Load side l1,a 、i l1,b 、i l1,c According to the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c For the three-phase current target value i of the converter VSC1 a1 * 、i b1 * 、i c1 * Compensating to make the side power grid three-phase voltage V 1a 、V 1b 、V 1c The balance tends to be between them.
Optionally, the compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter includes: obtaining the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase voltage V of the power network 1a 、V 1b 、V 1c For the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c Performing conversion from abc axis to dq axis (park conversion), low-pass filtering and PI regulation to obtain dq axis component i of compensation current to be provided by the converter ld1 * And i lq1 * The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase voltage V of the power network 1a 、V 1b 、V 1c The phase information of (2) is relative to the dq-axis component i of the compensation current ld1 * And i lq1 * Coordinate transformation (Pack inverse transformation) from dq axis to abc axis is performed to obtain three-phase compensation current value Δi a1 * 、Δi b1 * 、Δi c1 * The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase compensation current value delta i a1 * 、Δi b1 * 、Δi c1 * And a three-phase current target value i of the converter a1 * 、i b1 * 、i c1 * Obtaining a final target value i of three-phase current of the converter s1,a * 、i s1,b * 、i s1,c * 。
Optionally, the three-phase voltage V of the power grid is obtained 1a 、V 1b 、V 1c Comprises: extracting grid voltage V 1a 、V 1b 、V 1c The positive sequence component of (2) is phase-locked by a phase-locked loop PLL to obtain three-phase voltage V of the power grid 1a 、V 1b 、V 1c Is used for the phase information of the (c).
Optionally, the above-mentioned voltage V is based on the three-phase voltage of the power grid 1a 、V 1b 、V 1c For the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c Performing a conversion of the abc axis to the dq axis, comprising: with three-phase voltage V of the electric network 1a 、V 1b 、V 1c After inverting the phase information of (a), the three-phase current is taken as the actual value i of the load side three-phase current l1,a 、i l1,b 、i l1,c Phase information converted from abc axis to dq axis.
Optionally, the above-mentioned voltage V is based on the three-phase voltage of the power grid 1a 、V 1b 、V 1c The phase information of (2) is relative to the dq-axis component i of the compensation current ld1 * And i lq1 * Performing coordinate transformation from dq axis to abc axis, comprising: with three-phase voltage V of the electric network 1a 、V 1b 、V 1c After inverting the phase information of (a) as the dq-axis component i of the compensation current ld1 * And i lq1 * Phase information converted from dq axis to abc axis.
Optionally, the final target value i is based on three-phase current of the converter s1,a * 、i s1,b * 、i s1,c * And the actual value i of the three-phase current of the converter s1,a 、i s1,b 、i s1,c Control the switching of the switching tube of the converter VSC1, comprising: final target value i of three-phase current of converter s1,a * 、i s1,b * 、i s1,c * And the actual value i of the three-phase current of the converter s1,a 、i s1,b 、i s1,c The comparison result is converted into a gate signal of a switching tube of the converter VSC1 through hysteresis control, and the on-off of the switching tube is controlled.
Optionally, the active power target value P according to the power grid * And the actual value P, obtaining the active current target value i of the converter d1 * Comprising: the active power target value P of the power grid * The difference value between the current value and the actual value P is sent to a PI regulator, and after the output signal of the PI regulator passes through a limiting module, the active current target value i of the converter is obtained d1 * 。
Alternatively, the active power flow direction may pass through the active power target value P * Controlled by positive and negative of, e.g. P * Positive value means that active power is controlled to flow from VSC1 side to VSC2 side, P * Negative values indicate that active power is controlled to flow from the VSC2 side to the VSC1 side.
Optionally, the output reactive power target value Q according to the converter 1 * And reactive power actual value Q 1 Obtain the reactive current target value i of the converter q1 * Comprising: reactive power target value Q of converter 1 * And reactive power actual value Q 1 The difference value of (2) is sent to a PI regulator, and after the output signal of the PI regulator passes through a limiting module, the reactive current target value component i of the converter is obtained q1 * 。
Fig. 6 shows a schematic block diagram of a power distribution network control method for controlling a side converter configured to control the dc bus voltage.
In some embodimentsIn the method, a power distribution network control method comprises the following steps: according to the DC bus voltage target value V dc * And an actual value V dc Obtain the active current target value i of the converter VSC2 d2 * The method comprises the steps of carrying out a first treatment on the surface of the According to the converter VSC2 outputting a reactive power target value Q 2 * And actual value Q 2 Obtain the reactive current target value i of the converter VSC2 q2 * The method comprises the steps of carrying out a first treatment on the surface of the Acquiring three-phase voltage V of power grid 2a 、V 2b 、V 2c According to the phase information of the three-phase voltage V of the power grid 2a 、V 2b 、V 2c The phase information of (a) will be the active current target value i d2 * And reactive current target value i q2 * Conversion from dq axis to abc axis (inverse Parker transformation) to obtain three-phase current target value i of converter VSC2 a2 * 、i b2 * 、i c2 * The method comprises the steps of carrying out a first treatment on the surface of the According to the actual value i of the load-side three-phase current l2,a 、i l2,b 、i l2,c For VSC2 three-phase current target value i a2 * 、i b2 * 、i c2 * Compensating to obtain final target value i of three-phase current of converter VSC2 s2,a * 、i s2,b * 、i s2,c * The method comprises the steps of carrying out a first treatment on the surface of the According to the final target value i of the three-phase current of the converter VSC2 s2,a * 、i s2,b * 、i s2,c * Actual value i of three-phase current of VSC2 and converter s2,a 、i s2,b 、i s2,c And the switching on and off of a switching tube of the converter VSC2 are controlled.
The converter VSC2 is configured to control the voltage of a direct current bus, to perform unbalance compensation on the three-phase unbalance voltage of the VSC2 side power grid, and to install a current sensor on the Load side Load2 of the side power grid to measure the actual value i of the three-phase current on the Load side l2,a 、i l2,b 、i l2,c According to the actual value i of the load-side three-phase current l2,a 、i l2,b 、i l2,c For the three-phase current target value i of the converter VSC2 a2 * 、i b2 * 、i c2 * Compensating to make the side power grid three-phase voltage V 2a 、V 2b 、V 2c The balance tends to be between them.
Optionally, the compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter includes: obtaining the actual value i of the load-side three-phase current l2,a 、i l2,b 、i l2,c The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase voltage V of the power network 2a 、V 2b 、V 2c For the actual value i of the load-side three-phase current l2,a 、i l2,b 、i l2,c Performing conversion from abc axis to dq axis (park conversion), low-pass filtering and PI regulation to obtain dq axis component i of compensation current to be provided by the converter ld2 * And i lq2 * The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase voltage V of the power network 2a 、V 2b 、V 2c The phase information of (2) is relative to the dq-axis component i of the compensation current ld2 * And i lq2 * Coordinate transformation (Pack inverse transformation) from dq axis to abc axis is performed to obtain three-phase compensation current value Δi a2 * 、Δi b2 * 、Δi c2 * The method comprises the steps of carrying out a first treatment on the surface of the According to the three-phase compensation current value delta i a2 * 、Δi b2 * 、Δi c2 * And a three-phase current target value i of the converter a2 * 、i b2 * 、i c2 * Obtaining a final target value i of three-phase current of the converter s2,a * 、i s2,b * 、i s2,c * 。
Optionally, the three-phase voltage V of the power grid is obtained 2a 、V 2b 、V 2c Comprises: extracting grid voltage V 2a 、V 2b 、V 2c The positive sequence component of (2) is phase-locked by a phase-locked loop PLL to obtain three-phase voltage V of the power grid 2a 、V 2b 、V 2c Is used for the phase information of the (c).
Optionally, the above-mentioned voltage V is based on the three-phase voltage of the power grid 2a 、V 2b 、V 2c For the actual value i of the load-side three-phase current l2,a 、i l2,b 、i l2,c Performing a conversion of the abc axis to the dq axis, comprising: three phases of the power gridVoltage V 2a 、V 2b 、V 2c After inverting the phase information of (a), the three-phase current is taken as the actual value i of the load side three-phase current l2,a 、i l2,b 、i l2,c Phase information converted from abc axis to dq axis.
Optionally, the above-mentioned voltage V is based on the three-phase voltage of the power grid 2a 、V 2b 、V 2c The phase information of (2) is relative to the dq-axis component i of the compensation current ld2 * And i lq2 * Performing coordinate transformation from dq axis to abc axis, comprising: with three-phase voltage V of the electric network 2a 、V 2b 、V 2c After inverting the phase information of (a) as the dq-axis component i of the compensation current ld2 * And i lq2 * Phase information converted from dq axis to abc axis.
Alternatively, the final target value i is calculated according to the three-phase current s2,a * 、i s2,b * 、i s2,c * And three-phase current actual value i s2,a 、i s2,b 、i s2,c Control the switching of the switching tube of the converter VSC2, comprising: final target value i of three-phase current of converter s2,a * 、i s2,b * 、i s2,c * And the actual value i of the three-phase current of the converter s2,a 、i s2,b 、i s2,c The comparison result is converted into a gate signal of a switching tube of the converter VSC2 through hysteresis control, and the on-off of the switching tube is controlled.
Optionally, according to the DC bus voltage target value V dc * And an actual value V dc Obtain the active current target value i of the converter d2 * Comprising: the direct current bus voltage target value V dc * And an actual value V dc The difference value of (2) is sent to a PI regulator, and after the output signal of the PI regulator passes through a limiting module, the active current target value i of the converter is obtained d2 * 。
Optionally, the output reactive power target value Q according to the converter 2 * And reactive power actual value Q 2 Obtain the reactive current target value i of the converter q2 * Comprising: outputting reactive power target value Q of converter 2 * And reactive power actual value Q 2 The difference value of (2) is sent to a PI regulator, and after the output signal of the PI regulator passes through a limiting module, the reactive current target value component i of the converter is obtained q2 * 。
In other embodiments, the present application further provides a power distribution network control system, which controls the two side converters VSC1 and VSC2 of the SOP module respectively, including: a first unit configured to obtain an active current target value of the converter. A second unit configured to obtain a reactive current target value of the converter. And the third unit is configured to acquire phase information of three-phase voltage of the power grid. And a fourth unit configured to transform the active current target value and the reactive current target value from the dq axis to the abc axis (inverse Parker transformation) according to the phase information of the three-phase voltage of the power grid, and obtain a three-phase current target value of the converter. And a fifth unit configured to calculate a three-phase compensation current value for compensating the converter three-phase current target value based on the load-side three-phase current actual value. A sixth unit configured to obtain a final target value of the three-phase current of the inverter based on the target value of the three-phase current and the three-phase compensation current value; and controlling the on-off of a switching tube of the converter according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter.
Fig. 7 illustrates one embodiment of a power distribution network control system that controls a side converter configured to control active power flow.
The embodiment of the disclosure provides a power distribution network control system, which comprises: a first unit 10 configured to flow through the active power target value P in accordance with the converter VSC1 * And the actual value P, obtaining an active current target value i of the converter VSC1 d1 * . A second unit 20 configured to output a reactive power target value Q in accordance with the converter VSC1 1 * And reactive power actual value Q 1 Obtain the reactive current target value i of the converter VSC1 q1 * . A third unit 30 configured to obtain a grid three-phase voltage V 1a 、V 1b 、V 1c Is used for the phase information of the (c). Fourth stepA unit 40 configured to be dependent on the grid three-phase voltage V 1a 、V 1b 、V 1c The phase information of (a) will be the active current target value i d1 * And reactive current target value i q1 * Conversion from dq axis to abc axis (inverse Parker transformation) to obtain three-phase current target value i of converter VSC1 a1 * 、i b1 * 、i c1 * . A fifth unit 50 configured to, in accordance with the load-side three-phase current actual value i l1,a 、i l1,b 、i l1,c Calculating three-phase compensation current value delta i a1 * 、Δi b1 * 、Δi c1 * For VSC1 three-phase current target value i a1 * 、i b1 * 、i c1 * And compensating. A sixth unit 60 configured to respond to the converter three-phase current target value i a1 * 、i b1 * 、i c1 * And three-phase compensation current value Δi a1 * 、Δi b1 * 、Δi c1 * Obtaining a final target value i of three-phase current of the converter VSC1 s1,a * 、i s1,b * 、i s1,c * The method comprises the steps of carrying out a first treatment on the surface of the According to the final target value i of the three-phase current of the converter VSC1 s1,a * 、i s1,b * 、i s1,c * Actual value i of three-phase current of VSC1 of AND converter s1,a 、i s1,b 、i s1,c And the switching on and off of a switching tube of the converter VSC1 are controlled.
The converter VSC1 is configured to control active power flow for unbalance compensation of three-phase unbalanced voltage of the VSC1 side power grid, and the system further comprises a current sensor installed on the Load side Load1 of the side power grid for measuring the actual value i of three-phase current on the Load side l1,a 、i l1,b 、i l1,c According to the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c For the three-phase current target value i of the converter VSC1 a1 * 、i b1 * 、i c1 * Compensating to make the side power grid three-phase voltage V 1a 、V 1b 、V 1c The balance tends to be between them.
Optionally, the system passes the active power target value P * To control active power flow direction, e.g. P * Positive value means that active power is controlled to flow from VSC1 side to VSC2 side, P * Negative values indicate that active power is controlled to flow from the VSC2 side to the VSC1 side.
Optionally, the first unit 10 includes: PI regulator and limiter module, converter flowing through active power target value P * The difference value between the actual value P of the active power and the actual value P of the active power is sent to a PI regulator, and the output signal of the PI regulator passes through a limiting module to obtain the target value i of the active current of the converter d1 * 。
Optionally, the second unit 20 includes: PI regulator and amplitude limiting module, converter outputs reactive power target value Q 1 * And reactive power actual value Q 1 The difference value of (2) is sent to a PI regulator, and after the output signal of the PI regulator passes through a limiting module, the reactive current target value component i of the converter is obtained q1 * 。
Optionally, the third unit 30 includes: a positive sequence extraction module configured to extract a grid voltage V 1a 、V 1b 、V 1c Positive sequence component of (a); phase-locked loop PLL for converting the grid voltage V 1a 、V 1b 、V 1c After phase locking of the positive sequence component of (2), the three-phase voltage V of the power grid is obtained 1a 、V 1b 、V 1c Is used for the phase information of the (c).
Optionally, the fifth unit 50 includes: a load-side mounted current sensor configured to acquire a load-side three-phase current actual value i l1,a 、i l1,b 、i l1,c The method comprises the steps of carrying out a first treatment on the surface of the A first conversion unit 51 configured to convert the three-phase voltage V of the power grid 1a 、V 1b 、V 1c For the actual value i of the load-side three-phase current l1,a 、i l1,b 、i l1,c Performing a conversion from the abc axis to the dq axis (park conversion); a low-pass filter and PI regulator for low-pass filtering and PI regulating the output signal of the first conversion unit 51 to obtain the dq-axis component i of the compensation current that the converter is required to provide ld1 * And i lq1 * The method comprises the steps of carrying out a first treatment on the surface of the A second conversion unit 52 configured to convert the three-phase voltage V of the power grid 1a 、V 1b 、V 1c The phase information of (2) is relative to the dq-axis component i of the compensation current ld1 * And i lq1 * Coordinate transformation (Pack inverse transformation) from dq axis to abc axis is performed to obtain three-phase compensation current value Δi a1 * 、Δi b1 * 、Δi c1 * 。
Optionally, the first transforming unit 51 includes: with three-phase voltage V of the electric network 1a 、V 1b 、V 1c After inverting the phase information of (a), the three-phase current is taken as the actual value i of the load side three-phase current l1,a 、i l1,b 、i l1,c Phase information converted from abc axis to dq axis.
Optionally, the second transforming unit 52 includes: with three-phase voltage V of the electric network 1a 、V 1b 、V 1c After inverting the phase information of (a) as the dq-axis component i of the compensation current ld1 * And i lq1 * Phase information converted from dq axis to abc axis.
Optionally, the sixth unit 60 includes: hysteresis comparator for final target value i of three-phase current of converter s1,a * 、i s1,b * 、i s1,c * And the actual value i of the three-phase current of the converter s1,a 、i s1,b 、i s1,c The difference value of the voltage-regulating circuit is controlled by hysteresis, and the comparison result output by the hysteresis comparator is converted into a gate signal of a switching tube of the converter VSC1 to control the on-off of the switching tube.
In other embodiments, the distribution network control system controls a side converter VSC2 configured to control the dc bus voltage. Wherein the first unit 10, the direct current bus voltage target value V dc * And an actual value V dc Obtain the active current target value i of the converter VSC2 d2 * . A second unit 20 configured to output a reactive power target value Q in accordance with the converter VSC2 2 * And actual value Q 2 Obtain the reactive current target value i of the converter VSC2 q2 * . A third unit 30 configured toAcquiring three-phase voltage V of power grid 2a 、V 2b 、V 2c Is used for the phase information of the (c). A fourth unit 40 configured to be dependent on the grid three-phase voltage V 2a 、V 2b 、V 2c The phase information of (a) will be the active current target value i d2 * And reactive current target value i q2 * Conversion from dq axis to abc axis (inverse Parker transformation) to obtain three-phase current target value i of converter VSC2 a2 * 、i b2 * 、i c2 * . A fifth unit 50 configured to, in accordance with the load-side three-phase current actual value i l2,a 、i l2,b 、i l2,c Calculating three-phase compensation current value delta i a2 * 、Δi b2 * 、Δi c2 * For VSC2 three-phase current target value i a2 * 、i b2 * 、i c2 * And compensating. A sixth unit 60 configured to respond to the converter three-phase current target value i a2 * 、i b2 * 、i c2 * And three-phase compensation current value Δi a2 * 、Δi b2 * 、Δi c2 * Obtaining a final target value i of three-phase current of the converter VSC2 s2,a * 、i s2,b * 、i s2,c * The method comprises the steps of carrying out a first treatment on the surface of the According to the final target value i of the three-phase current of the converter VSC2 s2,a * 、i s2,b * 、i s2,c * Actual value i of three-phase current of VSC2 and converter s2,a 、i s2,b 、i s2,c And the switching on and off of a switching tube of the converter VSC2 are controlled.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (9)

1. A power distribution network control method, the power distribution network comprising an SOP module, wherein one side converter of the SOP module is configured to control active power flow, and the other side converter of the SOP module is configured to control direct current bus voltage, the method is characterized by respectively controlling converters on two sides of the SOP module, and the method comprises the following steps:
according to the active current target value and the reactive current target value of the converter, obtaining a three-phase current target value of the converter;
compensating the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter;
controlling the on-off of a switching tube of the converter according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter;
the compensation for the three-phase current target value of the converter according to the actual value of the three-phase current at the load side to obtain the final target value of the three-phase current of the converter comprises the following steps:
according to the phase information of the three-phase voltage of the power grid, converting an abc axis to a dq axis of the actual value of the three-phase current at the load side, and obtaining the dq axis component of the compensation current required to be provided by the converter through low-pass filtering and PI regulation;
performing coordinate transformation from a dq axis to an abc axis on the dq axis component of the compensation current according to the phase information of the three-phase voltage of the power grid to obtain a three-phase compensation current value;
and obtaining a final target value of the three-phase current of the converter according to the three-phase compensation current value and the target value of the three-phase current of the converter.
2. A power distribution network control method according to claim 1, wherein, for a side converter configured to control the flow of active power, the active current target value of the converter is obtained from a difference between the active power target value and the active power actual value flowing through the converter.
3. A power distribution network control method according to claim 1, characterized in that, for a converter on one side configured to control the dc bus voltage, the active current target value of the converter is obtained from the difference between the dc bus voltage target value and the dc bus voltage actual value.
4. A method of controlling a power distribution network according to claim 1, wherein the reactive current target value of the converter is obtained from a difference between the output reactive power target value and the actual reactive power value of the converter.
5. A power distribution network control method according to claim 1, wherein the obtaining the three-phase current target value of the converter based on the active current target value and the reactive current target value of the converter comprises:
and transforming the active current target value and the reactive current target value of the converter from the dq axis to the abc axis according to the phase information of the three-phase voltage of the power grid to obtain the three-phase current target value of the converter.
6. A power distribution network control method according to claim 1, wherein the transforming the actual value of the load-side three-phase current from the abc axis to the dq axis according to the phase information of the three-phase voltage of the power grid comprises: and after inverting the phase information of the three-phase voltage of the power grid, converting the actual value of the three-phase current at the load side from the abc axis to the phase information of the dq axis.
7. A power distribution network control method according to claim 1, wherein the coordinate transformation of the dq-axis component of the compensation current from the dq-axis to the abc-axis according to the phase information of the three-phase voltage of the power network comprises: after inverting the phase information of the three-phase voltage of the power grid, the dq axis component serving as the compensation current is converted from the dq axis to the phase information of the abc axis.
8. A power distribution network control method according to any one of claims 5 to 7, wherein the phase information of the three-phase voltage of the power grid is: and extracting positive sequence components of the power grid voltage, and obtaining the power grid voltage after phase locking by a phase-locked loop.
9. A power distribution network control method as recited in claim 1, wherein,
according to the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter, the on-off of a switching tube of the converter is controlled, and the method comprises the following steps: and the difference value between the final target value of the three-phase current of the converter and the actual value of the three-phase current of the converter is controlled by hysteresis, and the comparison result is converted into a gate signal of a switching tube of the converter to control the on-off of the switching tube.
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