CN110137999B - Direct-current power coordination control method and system with participation of receiving-end wind power plant - Google Patents
Direct-current power coordination control method and system with participation of receiving-end wind power plant Download PDFInfo
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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
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- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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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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Abstract
The invention discloses a direct-current power coordination control method and system for participation of a receiving-end wind power plant, and belongs to the field of power system control. In the active power control strategy, when the active power transmitted by the direct current system changes, the active power transmitted by each converter can be reasonably distributed on the inversion side according to the state of the alternating current system connected with the inversion side; in the reactive power control strategy, in order to reduce voltage fluctuation caused by reactive disturbance, an additional reactive power control strategy is provided, reactive power consumed by a converter of a direct current transmission system is controlled by controlling an arc extinguishing angle of the converter, meanwhile, a direct current voltage deviation value is introduced into d-axis constant voltage control of an outer ring of a fan control system, additional control of alternating current voltage deviation is introduced into q-axis constant reactive power control, and currents of d and q axes of each fan rotor in a wind power plant are controlled, so that reactive power consumed by each fan converter in the wind power plant is controlled, the direct current voltage is maintained stable, and the probability of phase change failure is reduced.
Description
Technical Field
The invention belongs to the field of power system control, and particularly relates to a direct-current power coordination control method and system with participation of a receiving-end wind power plant.
Background
In recent years, with the continuous development of new energy power generation technology, ultra-high voltage direct current transmission becomes a mature and reliable technology capable of economically realizing large-capacity and long-distance transmission of electric energy, and is beneficial to realizing efficient utilization of large energy bases and clean energy such as photovoltaic and wind power in China. With the construction and operation of extra-high voltage direct current transmission projects of more and more middle-east power grids of the drop points, the middle-east receiving end alternating current system gradually evolves to a multi-feed-in direct current access system. In order to solve the problems caused by multi-feed-in direct current, domestic scholars put forward an access mode of an extra-high voltage direct current layered access receiving end power grid from the power grid structure.
The normal fixed arc-quenching angle control and the fixed voltage control which are usually adopted by the inversion side of the conventional extra-high voltage direct current system are controlled according to poles, and each converter of the same pole adopts a unified trigger instruction. In the layered access mode, although the pole-based control mode can still be adopted, the transmission power of each converter on the inversion side cannot be independently controlled in the mode, and the advantage that the receiving-end alternating-current power grid load flow is reasonably distributed in the layered access mode cannot be well played.
In order to solve the problem, the conventional control strategy of the extra-high voltage direct current system needs to be correspondingly improved. At present, the research on the control strategy of +/-1100 kV extra-high voltage direct current at home and abroad mainly focuses on the influence of the faults of a transmitting and receiving end alternating current system on the running characteristics of an alternating current and direct current system, the difference between a control and protection system configuration scheme and a conventional extra-high voltage direct current system and the like. Guo Long, etc., an additional power-voltage control strategy is proposed, in which a constant power control is adopted on a rectification side and an additional power-voltage control is adopted on an inversion side, which may cause both sides of a system to operate in a constant power control mode, resulting in no stable static operating point when the system operates for a long time.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to solve the technical problems that the arc extinguishing angle margin is small, the probability of commutation failure is increased, the stable operation of an alternating current system and a direct current system is influenced, and the voltage disturbance of the direct current system is caused when the reactive power of the system is disturbed in the emergency control process of the transmission of active power of the direct current system.
In order to achieve the above object, in a first aspect, an embodiment of the present invention provides a method for coordinated control of dc power of a receiving wind farm, where the method includes the following steps:
s1, judging whether the active power of direct current transmission changes, if so, acquiring the active power transmitted by each converter at the inversion side, the direct current voltage of each converter and the arc extinguishing angle of each converter in real time, transmitting a total power demand signal of the inversion side to the converter at the rectification side when the transmitted active power needs to change, and entering a step S2, otherwise, entering a step S5;
s2, after the target active power is determined, the active power of a step value is changed in a stepwise mode by the rectifier side converter station; each current converter on the inversion side determines a transmission power instruction of each current converter according to the power distribution coefficient, and active power of a step value is changed in a stepwise manner;
s3, judging whether at least one converter arc-quenching angle on the inversion side is smaller than or equal to a threshold value, if so, reducing the power back to the previous step, finishing the active power promotion, and entering the step S5; otherwise, directly entering S4;
s4, judging whether the inversion side converter station reaches the target active power, if so, finishing the active power promotion, and entering a step S5, otherwise, entering a step S2;
s5, judging whether the direct current voltage of at least one converter on the inversion side is disturbed, if so, simultaneously changing the arc extinguishing angle of the disturbed converter and the current of each fan rotor participating in adjustment in the wind power field to keep the direct current voltage and the active power stable, and finishing the power coordination control after the additional reactive power control is finished after the direct current voltage recovers the original value, otherwise, directly finishing the power coordination control;
the method aims at an extra-high voltage direct current transmission system and simultaneously meets the following conditions:
1) The rectification side alternating current system is connected with the direct current converter station through a converter transformer;
2) The inversion side is connected into an alternating current system in a layered connection mode;
3) And an alternating current system at the inversion side is accessed by a wind power field.
Specifically, the threshold value ranges from [7 °,12 ° ].
Specifically, the disturbed inverter-side converter arc-quenching angle refers to an inverter-side converter arc-quenching angle when the dc voltage signal is inconsistent with a reference value given by a dispatcher.
Specifically, when the direct current voltage is higher than a reference value, the inverter-side converter arc-quenching angle is increased; when the direct-current voltage is lower than the reference value, reducing the arc extinguishing angle of the inverter side converter; and comparing the reference value with a direct-current voltage reference value, and obtaining the reference value of the extinction angle of each converter in the additional reactive voltage control of each converter through a proportional integral controller and a proportional integral link.
Specifically, the control strategy of the fan grid side converter of the receiving end wind power plant is divided into an outer ring control part and an inner ring control part, wherein the outer ring control part comprises: d-axis fixed direct-current voltage control, q-axis fixed reactive power control and additional control; wherein the content of the first and second substances,
a control mode of d-axis constant DC voltage is adopted to convert the reference value U of the DC voltage dc_ref And a measured value U of DC voltage dc After difference comparison, the difference is input into a PI controller to obtain a reference value of the rotor current of the inner ring control d shaft
The method adopts the modes of fixed reactive power control and additional control on a Q axis, and firstly, a reference value Q of the reactive power of a current converter of the fan is set s_ref And the actual reactive power Q of the fan is obtained through measurement s Comparing the difference to obtain a value and a reference value U of an inversion side alternating current bus connected with the fan in additional control AC_ref And the actual value U AC The difference values are added and then input into a PI controller to obtain a reference value of the inner loop control q-axis rotor current
And then enters the inner loop control.
Specifically, in the inner loop control, the reference value of the d-axis rotor current
And d actual value i of the axis rotor current dr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner ring control d-axis rotor voltage' dr Plus the voltage deviation value Deltau dr Then an actual d-axis rotor voltage instruction value u is obtained through an amplitude limiting control link dr (ii) a Reference value for the q-axis rotor current>
And the actual value i of the q-axis rotor current qr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner loop control q-axis rotor voltage' qr Plus the voltage deviation value Deltau qr Then an actual q-axis rotor voltage instruction value u is obtained through an amplitude limiting control link qr ；
u dr And u qr And after dq-abc conversion, the power is transmitted to a fan converter, the reactive power transmitted by the converter and the voltage of the converter are controlled, and the converter of the wind power field at the receiving end does reactive power under the condition of reactive power disturbance, so that the converter participates in power disturbance of a balance system.
In a second aspect, an embodiment of the present invention provides a dc power coordination control system for a receiving-end wind farm, where the system includes:
the power signal acquisition unit is used for acquiring a transmission power instruction of each converter on the inversion side;
the time delay unit is used for transmitting the power transmission instruction acquired by the inversion side to the rectification side through a time delay link;
the stepped power regulating unit is used for actually transmitting active power of each converter when the transmission power instruction value of the converter is changed according to a stepped regulating mode;
the power distribution coefficient determining unit is used for determining the power distribution coefficient of each converter on the inversion side in real time and reasonably distributing power regulating quantity in the power regulating process;
and the additional power-voltage coordination controller adopts additional power-voltage control on the inversion side, and determines the reference value of the voltage in the constant-voltage control of each converter through proportional-integral regulation by receiving the instruction value and the actual value of the transmission power of each converter on the inversion side.
And the additional reactive voltage controller is used for comparing the collected DC voltage signals of the inverter side converters with DC voltage reference values and determining the reference values of the extinction angles of the converters in the additional reactive voltage control of the converters through proportional integral regulation.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the method for coordination and control of direct current power participated by an end wind farm according to the first aspect is implemented.
Generally, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
the direct current power coordination control method of the invention is divided into two aspects of active power control strategy and reactive power control strategy. In the active power control strategy, when the active power transmitted by the direct current system changes, the active power transmitted by each converter can be reasonably distributed on the inversion side according to the state of the alternating current system connected with the inversion side. In the reactive power control strategy, in order to reduce voltage fluctuation caused by reactive disturbance, an additional reactive power control strategy is provided, the reactive power consumed by a converter of a direct current transmission system is controlled by controlling the arc extinguishing angle of the converter, meanwhile, a direct current voltage deviation value is introduced into the d-axis constant voltage control of an outer ring of a fan control system, the additional control of alternating current voltage deviation is introduced into the q-axis constant reactive power control, and the currents of d and q axes of each fan rotor in a wind power plant are controlled, so that the reactive power consumed by each fan converter in the wind power plant is controlled, and the direct current voltage is maintained to be stable. The converter connected with each alternating current system can be ensured to maintain larger extinction angle margin, and the probability of phase commutation failure is reduced.
Drawings
Fig. 1 is a flowchart of a method for coordinated control of dc power participated by a receiving-end wind farm according to an embodiment of the present invention;
fig. 2 is a topology structure diagram of an extra-high voltage direct current transmission system with an inverting side connected to a receiving end in a layered manner according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a control strategy of a fan grid side converter of a receiving-end wind farm according to an embodiment of the present invention;
FIG. 4 (a) is a U employing three different control methods according to an embodiment of the present invention dc1 A graph of time;
FIG. 4 (b) is a U employing three different control methods according to an embodiment of the present invention dc2 Graph over time.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, a method for coordinated control of dc power participated by a receiving wind farm includes the following steps:
s1, judging whether the active power of direct current transmission changes, if so, acquiring the active power transmitted by each converter at the inversion side, the direct current voltage of each converter and the arc extinguishing angle of each converter in real time, transmitting a total power demand signal of the inversion side to the converter at the rectification side when the transmitted active power needs to change, and entering a step S2, otherwise, entering a step S5;
s2, after the target active power is determined, the active power of a step value is changed in a stepwise manner by the rectifier side converter station; each current converter on the inverting side determines a transmission power instruction of each current converter according to the power distribution coefficient, and active power of a step value is changed in a stepwise manner;
s3, judging whether at least one converter arc-quenching angle on the inversion side is smaller than or equal to a threshold value, if so, reducing the power back to the previous step, finishing the active power promotion, and entering the step S5; otherwise, directly entering S4;
s4, judging whether the inversion side converter station reaches the target active power, if so, finishing the active power promotion, and entering a step S5, otherwise, entering a step S2;
s5, judging whether the direct current voltage of at least one converter on the inversion side is disturbed, if so, simultaneously changing the arc extinguishing angle of the disturbed converter and the current of each fan rotor participating in adjustment in the wind power field to keep the direct current voltage and the active power stable, and finishing the power coordination control after the additional reactive power control is finished after the direct current voltage recovers the original value, otherwise, directly finishing the power coordination control;
the aimed system needs to satisfy the following conditions at the same time:
1) The rectification side alternating current system is connected with the direct current converter station through a converter transformer;
2) The inversion side is connected into an alternating current system in a layered connection mode;
3) And an alternating current system at the inversion side is accessed by a wind power field.
As shown in FIG. 2The ultra-high voltage direct current transmission system with the inverting side connected to the receiving end in a layered mode comprises: a rectifying side, a dc transmission line and an inverter side. Wherein, U dc Indicating the positive DC voltage measured on the inverting side, being equal to the sum of the DC voltages of the two converters on the positive side, i.e. U dc ＝U dc1 +U dc2 . The wind power plant is connected with the inverter side alternating current system 1, and a fan converter is arranged in the wind power plant.
The rectification side comprises: the system comprises a rectification side alternating current system, an alternating current filter and a rectification side converter station (comprising four converters, namely a positive pole high-end converter, a positive pole low-end converter, a negative pole high-end converter and a positive pole low-end converter). The alternating current filter is directly connected with a rectifying side alternating current system bus, and the rectifying side alternating current system is connected with the direct current transmission line through the rectifying side converter station.
The DC transmission line includes: line equivalent resistance R d And a dc filter. Wherein, the direct current circuit is directly connected with the rectifying side converter station and the inversion side converter station.
The inverter includes: inverting side AC systems 1, 2; the system comprises an inversion side converter station (comprising four converters, namely a positive pole high-end converter, a positive pole low-end converter, a negative pole high-end converter and a positive pole low-end converter), an alternating current filter and a receiving end wind power plant. The wind power plant is connected with the inversion side alternating current system 1 through a fan current converter, and the wind power plant is composed of dozens of to hundreds of fans.
Step S1, judging whether the active power of direct current transmission changes, if so, acquiring the active power transmitted by each converter at the inversion side, the direct current voltage of each converter and the arc extinguishing angle of each converter in real time, transmitting a total power demand signal of the inversion side to the converter at the rectification side when the transmitted active power needs to change, and entering step S2, otherwise, entering step S5.
The change of the active power of the direct current transmission can be caused by the following reasons: the alternating current system connected with the inversion side changes or the requirement of manual instruction changes. No matter what reason causes the direct current transmission active power to change, the change transition is smooth through the direct current power coordination control, and sudden change or oscillation is prevented.
And transmitting the obtained converter transmission power signal to a rectifier side converter through a first-order delay link, and then entering the subsequent steps. Namely, the target active power value of the inversion side is transmitted to the rectification side with a certain time delay. The total power of the inversion side is equal to the sum of the transmission active power of each converter. And the total power demand signal of the inversion side is the target active power of the converter station of the rectification side.
S2, after the target active power is determined, the active power of a step value is changed in a stepwise manner by the rectifier side converter station; and determining the transmission power instruction of each converter on the inverting side according to the power distribution coefficient, and changing the active power of a step value according to a step.
When the transmission power instruction value of the current converter changes, the active power actually transmitted by each current converter is changed in a step mode.
Specifically, the step amplitude Δ P is changed within the duration Δ t of receiving the power increase or decrease instruction of the inverter side, the transmission power instruction is the sum of the dc base transmission power and the step amplitude Δ P, and the value of Δ P is 0.02 per unit.
And calculating the power distribution coefficient in real time according to the equivalent voltage amplitude and the sine value of the arc extinguishing angle of the alternating current system connected with each converter on the inverting side. And each current converter on the inversion side adopts additional power-voltage control to carry out step-by-step promotion on the power instruction. The additional power-voltage control means that a voltage reference value of constant voltage control of the converter is formed through proportional integral adjustment according to a difference value of a transmission power signal and a transmission power instruction of each converter on the inversion side.
S3, judging whether at least one converter on the inversion side has an arc extinguishing angle smaller than or equal to a threshold value, if so, reducing the power back to the last step, finishing the active power promotion, and entering the step S5; otherwise, go directly to S4.
In engineering practice, it is believed that commutation failure of the dc system will occur when the extinction angle is below 7 °. In order to ensure that each converter has a certain margin, the minimum value of the arc quenching angle degree in each converter on the inversion side is lower than a threshold value alpha, the minimum value is used as a criterion for stopping the power of the converter, and the value range of the alpha is [7 degrees, 12 degrees ].
If the criterion is established, the extinction angle of a converter valve connected in series in the same pole is reduced to a lower value, the power lifting process is stopped, and the power is reduced back by one step. Therefore, the arc extinguishing angle of each converter in the power emergency lifting process is ensured to have larger margin, and the probability of phase commutation failure is reduced.
And S4, judging whether the inverter side converter station reaches the target active power, if so, finishing the active power promotion, and entering the step S5, otherwise, entering the step S2.
And S5, judging whether the direct current voltage of at least one converter on the inversion side is disturbed, if so, enabling the direct current voltage and the active power to be stable through the arc extinguishing angle of the converter which is disturbed simultaneously and the current of each fan rotor participating in adjustment in the wind power field, and finishing the power coordination control after the additional reactive power control is finished after the direct current voltage recovers the original value, otherwise, directly finishing the power coordination control.
And the arc extinguishing angle of the inverter side converter is changed, so that the converter consumes reactive power. And the reactive power absorbed by the wind power plant is obtained through the current of each fan rotor participating in adjustment in the wind power plant.
The arc extinguishing angle of the inverter side converter with disturbance refers to that: and if the direct-current voltage signal is inconsistent with the reference value given by the dispatcher, the converter on the inverting side has an arc extinguishing angle. Specifically, when the direct current voltage is higher than a reference value, the inverter-side converter arc-quenching angle is increased; and when the direct-current voltage is lower than the reference value, reducing the arc extinguishing angle of the inverter side converter. And comparing the reference value with a direct-current voltage reference value, and obtaining the reference value of the extinction angle of each converter in the additional reactive voltage control of each converter through a proportional integral controller and a proportional integral link.
As shown in fig. 3, the control strategy of the wind turbine grid side converter of the receiving-end wind farm is divided into an outer ring control part and an inner ring control part, wherein the outer ring control part comprises: d-axis fixed direct voltage control, q-axis fixed reactive power control and additional control.
In the outer ring control, a d-axis constant DC voltage control mode is adopted to control the reference value U of the DC voltage dc_ref And a DC voltageMeasured value U dc After difference comparison, the difference is input into a PI controller to obtain a reference value of the rotor current of the inner ring control d shaft
Adopting a fixed reactive power control and additional control mode for the Q axis, firstly, using a reference value Q of the reactive power of a current converter of the fan s_ref And the actual reactive power Q of the fan obtained by measurement s Comparing the difference, and comparing the obtained value with the reference value U of the alternating current bus at the inversion side connected with the fan in the additional control AC_ref And the actual value U AC The difference values are added and then input into a PI controller to obtain a reference value of the inner loop control q-axis rotor current>
And then the inner loop control is started.
Reference value of d-axis rotor current in inner loop control
And d actual value i of the axis rotor current dr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner ring control d-axis rotor voltage' dr Plus the voltage deviation value Deltau dr Then an actual d-axis rotor voltage instruction value u is obtained through an amplitude limiting control link dr (ii) a Reference value for the q-axis rotor current>
And the actual value i of the q-axis rotor current qr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner loop control q-axis rotor voltage' qr Plus the voltage deviation value Deltau qr Then an actual q-axis rotor voltage instruction value u is obtained through an amplitude limiting control link qr 。
u dr And u qr And after dq-abc conversion, the power is transmitted to a fan converter, the reactive power transmitted by the converter and the voltage of the converter are controlled, and the converter of the wind power field at the receiving end is enabled to participate in power disturbance of a balance system under the condition of reactive disturbance.
A system for coordinated control of dc power with participation by a receiving wind farm, the system comprising:
the power signal acquisition unit is used for acquiring a transmission power instruction of each converter on the inversion side;
the time delay unit is used for transmitting the power transmission instruction acquired by the inversion side to the rectification side through a time delay link;
the stepped power regulating unit is used for actually transmitting active power of each converter when the transmission power instruction value of the converter is changed according to a stepped regulating mode;
the power distribution coefficient determining unit is used for determining the power distribution coefficient of each converter on the inversion side in real time and reasonably distributing power regulating quantity in the power regulating process;
and the additional power-voltage coordination controller adopts additional power-voltage control on the inversion side, and determines the reference value of the voltage in the constant-voltage control of each converter through proportional-integral regulation by receiving the instruction value and the actual value of the transmission power of each converter on the inversion side.
And the additional reactive voltage controller is used for comparing the collected direct-current voltage signals of the inverter side converters with direct-current voltage reference values and determining the reference values of the extinction angles of the converters in the additional reactive voltage control of the converters through proportional-integral regulation.
U employing three different control methods, as shown in FIG. 4 (a) dc1 Graph over time. U employing three different control methods, as shown in FIG. 4 (b) dc2 Graph over time. It can be seen that after the control method of the single wind field participation of the receiving end is adopted, after the whole system is disturbed by reactive power, the direct current voltage U of the two converters on the positive pole of the inversion side dc1 、U dc2 The method can quickly recover to the original value, only adopts a control method participated by an inverter side converter, the recovery speed of the direct current voltage is slow, and if a reactive power control strategy is not adopted, after a system receives reactive power disturbance, the direct current voltage U is obtained dc 、U dc2 There is no way to restore to the initial value, thereby verifying the proposed control of the participation of the receiving wind farmThe effectiveness of the method. It should be noted that the specific control effect is directly related to the magnitude of the reactive power that can be provided by the receiving-end wind farm, and the higher the reactive power that can be provided by the receiving-end wind farm is, the better the control effect is.
The above description is only for the preferred embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (8)
1. A direct current power coordination control method participated by a receiving end wind power plant is characterized by comprising the following steps:
s1, judging whether the active power of direct current transmission changes, if so, acquiring the active power transmitted by each converter at the inversion side, the direct current voltage of each converter and the arc extinguishing angle of each converter in real time, transmitting a total power demand signal of the inversion side to the converter at the rectification side when the transmitted active power needs to change, and entering a step S2, otherwise, entering a step S5;
s2, after the target active power is determined, the active power of a step value is changed in a stepwise mode by the rectifier side converter station; each current converter on the inverting side determines a transmission power instruction of each current converter according to the power distribution coefficient, and active power of a step value is changed in a stepwise manner;
s3, judging whether at least one converter arc-quenching angle on the inversion side is smaller than or equal to a threshold value, if so, reducing the power back to the previous step, finishing the active power promotion, and entering the step S5; otherwise, directly entering S4;
s4, judging whether the inversion side converter station reaches the target active power, if so, finishing the active power promotion, and entering a step S5, otherwise, entering a step S2;
s5, judging whether the direct current voltage of at least one converter on the inversion side is disturbed, if so, simultaneously changing the arc extinguishing angle of the disturbed converter and the current of each fan rotor participating in adjustment in the wind power field to keep the direct current voltage and the active power stable, and finishing the power coordination control after the additional reactive power control is finished after the direct current voltage recovers the original value, otherwise, directly finishing the power coordination control;
the method aims at an extra-high voltage direct current transmission system and simultaneously meets the following conditions:
1) The rectifying side alternating current system is connected with the direct current converter station through a converter transformer;
2) The inversion side is connected into an alternating current system in a layered connection mode;
3) And an alternating current system at the inversion side is accessed by a wind power field.
2. The method of claim 1, wherein the threshold value ranges from [7 °,12 ° ].
3. The method of claim 1, wherein the disturbed inverter-side converter arc-quench angle is an inverter-side converter arc-quench angle when the dc voltage signal is not consistent with a reference value given by a dispatcher.
4. A method according to any one of claims 1 to 3, wherein when the direct-current voltage is higher than a reference value, the inverter-side converter arc-quenching angle is increased; when the direct-current voltage is lower than the reference value, reducing the arc extinguishing angle of the inverter side converter; and comparing the reference value with a direct-current voltage reference value, and obtaining the reference value of the extinction angle of each converter in the additional reactive voltage control of each converter through a proportional integral controller and a proportional integral link.
5. The method according to any one of claims 1 to 3, wherein a wind turbine grid side converter control strategy of a receiving wind farm is divided into an outer loop control and an inner loop control, and the outer loop control comprises the following steps: d-axis fixed direct-current voltage control, q-axis fixed reactive power control and additional control; wherein, the first and the second end of the pipe are connected with each other,
a control mode of d-axis constant DC voltage is adopted to convert the reference value U of the DC voltage dc_ref And a measured value U of DC voltage dc After difference comparison, the difference is input into a PI controller to obtain a reference value of the rotor current of the inner ring control d shaft
The method adopts the modes of fixed reactive power control and additional control on a Q axis, and firstly, a reference value Q of the reactive power of a current converter of the fan is set s_ref And the actual reactive power Q of the fan obtained by measurement s Comparing the difference to obtain a value and a reference value U of an inversion side alternating current bus connected with the fan in additional control AC_ref And the actual value U AC The difference values are added and then input into a PI controller to obtain a reference value of the inner loop control q-axis rotor current
And then the inner loop control is started.
6. Method according to claim 5, characterized in that in the inner loop control the reference value for the d-axis rotor current
And d actual value i of the axis rotor current dr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner ring control d-axis rotor voltage' dr Plus the voltage deviation value Deltau dr Then an actual d-axis rotor voltage instruction value u is obtained through an amplitude limiting control link dr (ii) a Reference value for the q-axis rotor current>
And the actual value i of the q-axis rotor current qr After difference is made, the obtained value enters a PI controller to obtain a reference value u 'of the inner loop control q-axis rotor voltage' qr Plus the voltage deviation value Deltau qr Then an actual q-axis rotor voltage instruction value u is obtained through an amplitude limiting control link qr ；
u dr And u qr After dq-abc conversion, the obtained product is transmitted to a fan converter to convert the currentThe reactive power transmitted by the converter and the voltage of the converter are controlled, and the converter of the wind power plant at the receiving end is subjected to reactive power output under the condition of reactive power disturbance, so that the converter participates in power disturbance of a balance system.
7. A direct current power coordination control system participated by a receiving end wind power plant is characterized by comprising:
the power signal acquisition unit is used for acquiring a transmission power instruction of each converter on the inversion side;
the time delay unit is used for transmitting the power transmission instruction acquired by the inversion side to the rectification side through a time delay link;
the stepped power regulating unit is used for regulating the active power actually transmitted by each converter when the transmission power instruction value of the converter is changed according to a stepped regulating mode;
the power distribution coefficient determining unit is used for determining the power distribution coefficient of each converter on the inversion side in real time and reasonably distributing power regulating quantity in the power regulating process;
the additional power-coordination controller adopts additional power-voltage control on an inversion side, and determines a reference value of voltage in constant voltage control of each converter through proportional-integral regulation by receiving an instruction value and an actual value of transmission power of each converter on the inversion side;
the additional reactive voltage controller is used for comparing the collected direct-current voltage signals of the inverter side converters with direct-current voltage reference values and determining the reference values of the extinction angles of the converters in the additional reactive voltage control of the converters through proportional-integral regulation; the method specifically comprises the following steps: judging whether the direct current voltage of at least one converter on the inversion side is disturbed, if so, simultaneously changing the arc extinguishing angle of the disturbed converter and the current of each fan rotor participating in adjustment in the wind power field to keep the direct current voltage and the active power stable, and finishing the power coordination control after the direct current voltage recovers the original value and finishing the additional reactive power control;
the aimed system needs to satisfy the following conditions at the same time:
1) The rectifying side alternating current system is connected with the direct current converter station through a converter transformer;
2) The inversion side is connected into an alternating current system in a layered connection mode;
3) And an alternating current system at the inversion side is accessed by a wind power field.
8. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program which, when being executed by a processor, implements the method for coordinated direct current power control with participation of a terminated wind farm according to any of the claims 1 to 6.
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| CN112421662B (en) * | 2019-08-22 | 2022-07-22 | 南京南瑞继保电气有限公司 | Power voltage coordination control method of direct current energy consumption device |
| CN113381438B (en) * | 2020-03-10 | 2024-01-23 | 北京金风科创风电设备有限公司 | Power reduction control method and device for wind turbine generator |
| CN111725843B (en) * | 2020-06-30 | 2022-05-27 | 广东电网有限责任公司电力科学研究院 | Voltage control method and device based on virtual synchronous generator |
| CN113394788B (en) * | 2021-06-15 | 2023-03-24 | 南方电网科学研究院有限责任公司 | Control method and device for AC/DC parallel two-region system |
| CN113489045B (en) * | 2021-07-20 | 2023-06-16 | 华南理工大学 | MMC-HVDC hybrid controller switching fault ride-through control method |
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