CN114362195B - Method and system for regulating voltage of low-voltage bus of flexible AC/DC hybrid distribution network substation - Google Patents
Method and system for regulating voltage of low-voltage bus of flexible AC/DC hybrid distribution network substation Download PDFInfo
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Abstract
The invention discloses a voltage regulating method and a system for a low-voltage bus of a flexible alternating-current/direct-current hybrid distribution network transformer substation, which are used for measuring the position of a main transformer sub-joint, the voltage amplitude of a main transformer high-voltage side and the real-time data of the active load of the low-voltage bus, calculating the equivalent topological parameter of the main transformer, calculating the corresponding reactive power transmission ideal value according to the ideal value of the voltage of the low-voltage bus of the transformer substation, judging whether the reactive power regulation capacity of the transformer substation is enough or not, locking AVC and regulating the reactive power set value of the converter if the reactive power regulation capacity of the transformer substation is enough, indicating the AVC action if the reactive power regulation capacity of the transformer substation is insufficient, and repeating the steps after the AVC action until the voltage of the low-voltage bus is regulated to the ideal value, realizing the continuous voltage regulation of the flexible alternating-current/direct-current hybrid distribution network without independently increasing power electronic devices, improving the equipment utilization rate and reducing the system operation cost.
Description
Technical Field
The invention relates to the technical field of operation and maintenance of distribution networks, in particular to a voltage regulating method and system for a low-voltage bus of a flexible alternating current-direct current hybrid distribution network transformer substation.
Background
The voltage offset is an important index for measuring the quality of electric energy, on the distribution network side, various electric equipment is designed and manufactured according to rated voltage, and excessive voltage offset can cause equipment damage or even damage to affect users. Therefore, the accurate regulation of the voltage of the low-voltage bus of the transformer substation has great significance for the operation of the distribution network.
The prior art realizes the purpose of high-efficiency accurate alternating current voltage regulation and voltage stabilization through power electronic devices such as an additional power transistor, for example, a multistage high-efficiency linear accurate alternating current voltage regulation and voltage stabilization device disclosed in Chinese patent CN110162129A, and the design structure of the existing power transformer is changed greatly although the high-efficiency accurate voltage regulation is realized, the running loss of a system is increased, and the additional power electronic conversion device can greatly improve the manufacturing cost of power distribution equipment.
Disclosure of Invention
The invention provides a voltage regulating method and a system for a low-voltage bus of a flexible AC/DC hybrid distribution network transformer substation, which are used for solving the technical problems that the design structure of the existing power transformer is greatly changed, the running loss of the system is increased, and the manufacturing cost of distribution equipment is greatly increased by adding power electronic devices such as power transistors and the like to realize the purposes of high-efficiency and accurate AC voltage regulation and voltage stabilization in the prior art.
In view of the above, the first aspect of the present invention provides a voltage regulating method for a low-voltage bus of a flexible ac/dc hybrid distribution network substation, comprising the following steps:
s1, acquiring the active load data of a main transformer sub-joint position, a main transformer high-voltage side voltage amplitude and a low-voltage bus at the moment before voltage regulation in a dispatching automation system;
s2, calculating the equivalent topology parameters of the main transformer according to the equipment parameters on the nameplate of the main transformer, wherein the equivalent topology parameters of the main transformer comprise the resistance and reactance of the equivalent impedance of the main transformer;
s3, calculating reactive power transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation according to the equivalent topological parameter of the main transformer, the position of a main transformer tap, the amplitude of the high-voltage side voltage of the main transformer, the active load data of the low-voltage bus and the ideal value of the low-voltage bus voltage of the transformer substation;
s4, judging whether the reactive power regulation capacity of the converter station is enough or not according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, executing the step S5, otherwise, executing the step S6;
s5, locking an automatic voltage reactive power control strategy of the transformer substation, and adjusting a reactive power set value of the converter station to be the difference between reactive power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation and reactive power transmitted by the low-voltage bus of the current transformer substation, so that the voltage of the low-voltage bus of the transformer substation is adjusted to the ideal value;
and S6, indicating the automatic voltage reactive power control strategy action of the transformer substation, and returning to the step S1 after the automatic voltage reactive power control strategy action of the transformer substation until the voltage of the low-voltage bus of the transformer substation is regulated to an ideal value.
Optionally, step S2 specifically includes:
the main transformer is equivalent to an equivalent model consisting of impedance and an ideal transformer;
according to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Resistance, X, being the main variable equivalent impedance T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Is the rated voltage marked on the nameplate of the main transformer.
Optionally, step S3 specifically includes:
obtaining ideal value U of low-voltage bus voltage of transformer substation 2 ；
According to the main transformer ratio k determined by the main transformer sub-joint position, the ideal value U of the low-voltage bus voltage of the transformer substation 2 The voltage amplitude converted to the high-voltage side is obtained, and the voltage amplitude U 'converted to the high-voltage side of the transformer substation is obtained' 2 ＝kU 2 ；
According to the collected voltage amplitude of the high-voltage side of the main transformer, converting the voltage amplitude into the voltage amplitude U 'of the high-voltage side of the transformer substation' 2 Equivalent topology parameters of main transformer and active load data of low-voltage bus, and calculating reactive power transmission power Q corresponding to ideal value of low-voltage bus voltage of transformer substation 2 The calculation formula is as follows:
wherein P is 2 Is the active load data of the low-voltage bus, U 1 The amplitude of the main transformer high-voltage side voltage is acquired.
Optionally, step S4 specifically includes:
according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, calculating the |Q 2 -(Q Net +Q Valve ) Whether or not to meet
If yes, judging that the reactive power regulation capacity of the converter station is enough, executing a step S5, otherwise, executing a step S6, wherein P is the same as that of the reactive power regulation capacity of the converter station Valve For setting the active power of the alternating current side of the converter station, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter.
The second aspect of the application provides a flexible AC/DC hybrid distribution network transformer substation low-voltage bus voltage regulating system, which comprises the following modules:
the data acquisition module is used for acquiring the main transformer sub-joint position, the main transformer high-voltage side voltage amplitude and the low-voltage bus active load data at the moment before voltage regulation in the dispatching automation system;
the main transformer parameter calculation module is used for calculating the equivalent topology parameters of the main transformer according to the equipment parameters on the main transformer nameplate, wherein the equivalent topology parameters of the main transformer comprise the resistance and the reactance of the equivalent impedance of the main transformer;
the reactive power transmission power calculation module is used for calculating reactive power transmission corresponding to the ideal value of the voltage of the low-voltage bus of the transformer substation according to the equivalent topological parameter of the main transformer, the position of the main transformer substation connector, the voltage amplitude of the high-voltage side of the main transformer, the active load data of the low-voltage bus and the ideal value of the voltage of the low-voltage bus of the transformer substation;
the reactive capacity judging module is used for judging whether the reactive regulation capacity of the converter station is enough or not according to the reactive transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, triggering the first action module, and if not, triggering the second action module;
the first action module is used for locking an automatic voltage reactive power control strategy of the transformer substation, adjusting a reactive power set value of the converter station to be the difference between reactive power corresponding to an ideal value of the voltage of the low-voltage bus of the transformer substation and reactive power transmitted by the current low-voltage bus of the transformer substation, and enabling the voltage of the low-voltage bus of the transformer substation to be adjusted to the ideal value;
the second action module is used for indicating the action of the automatic voltage reactive power control strategy of the transformer substation, and re-triggering the data acquisition module after the action of the automatic voltage reactive power control strategy of the transformer substation.
Optionally, the main transformer parameter calculation module is specifically configured to:
the main transformer is equivalent to an equivalent model consisting of impedance and an ideal transformer;
according to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Resistance, X, being the main variable equivalent impedance T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Is the rated voltage marked on the nameplate of the main transformer.
Optionally, the reactive power transmission calculation module is specifically configured to:
obtaining ideal value U of low-voltage bus voltage of transformer substation 2 ；
Based on the determination of the position of the main-transformer tapThe transformation ratio k is used for obtaining the ideal value U of the low-voltage bus voltage of the transformer substation 2 The voltage amplitude converted to the high-voltage side is obtained, and the voltage amplitude U 'converted to the high-voltage side of the transformer substation is obtained' 2 ＝kU 2 ；
According to the collected voltage amplitude of the high-voltage side of the main transformer, converting the voltage amplitude into the voltage amplitude U 'of the high-voltage side of the transformer substation' 2 Equivalent topology parameters of main transformer and active load data of low-voltage bus, and calculating reactive power transmission power Q corresponding to ideal value of low-voltage bus voltage of transformer substation 2 The calculation formula is as follows:
wherein P is 2 Is the active load data of the low-voltage bus, U 1 The amplitude of the main transformer high-voltage side voltage is acquired.
Optionally, the reactive capacity judging module is specifically configured to:
according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, calculating the |Q 2 -(Q Net +Q Valve ) Whether or not I satisfies
If yes, judging that the reactive power regulation capacity of the converter station is enough, executing a step S5, otherwise, executing a step S6, wherein P is the same as that of the reactive power regulation capacity of the converter station Valve For setting the active power of the alternating current side of the converter station, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter.
According to the technical scheme, the voltage regulating method and the system for the low-voltage bus of the flexible AC/DC hybrid distribution network transformer substation have the following advantages:
according to the method and the system for regulating the voltage of the low-voltage bus of the flexible AC/DC hybrid distribution network transformer substation, provided by the invention, the position of the main transformer tap, the voltage amplitude of the high-voltage side of the main transformer and the real-time data of the active load of the low-voltage bus are measured, the equivalent topological parameter of the main transformer is calculated, the corresponding reactive power transmission ideal value is calculated according to the ideal value of the low-voltage bus voltage of the transformer substation, whether the reactive power regulation capacity of the transformer substation is enough is judged, if the reactive power regulation capacity of the transformer substation is enough, the AVC is locked, the reactive power set value of the transformer is regulated to be the difference between the reactive power transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation and the reactive power transmission power of the current low-voltage bus of the transformer substation, if the reactive power regulation capacity of the transformer substation is insufficient, the AVC is indicated, the steps are repeated after the AVC is acted until the low-voltage bus voltage is regulated to the ideal value, the design structure of the existing power transformer is not required to be changed, the continuous voltage regulation of the flexible AC/DC hybrid distribution network is realized under the condition that the power electronic device is not increased alone, the system operating cost is reduced, the power electronic device operating cost is high, the power electronic device is greatly improved, the power electronic device is designed to realize high-efficient accurate voltage regulation and the voltage regulation is realized by the power electronic device.
Meanwhile, by combining with the existing AVC strategy, the large-range continuous and accurate voltage regulation capability of the low-voltage bus of the transformer substation is improved, the problem that the adjustment capacity of the power electronic continuous voltage regulation device is low due to the current capacity of the power electronic device is solved, the wide-range economic voltage regulation is realized by utilizing the limited reactive compensation capacity of the converter, and the method has engineering application and popularization values.
Drawings
For a clearer description of embodiments of the invention or of solutions according to the prior art, the figures which are used in the description of the embodiments or of the prior art will be briefly described, it being obvious that the figures in the description below are only some embodiments of the invention, from which, without the aid of inventive efforts, other relevant figures can be obtained for a person skilled in the art.
Fig. 1 is a schematic flow chart of a voltage regulating method for a low-voltage bus of a flexible ac/dc hybrid distribution network substation;
fig. 2 is a schematic diagram of a topology structure of a flexible ac/dc hybrid distribution network connected between a typical transformer substation and a converter station according to the present invention;
fig. 3 is a schematic diagram of a main transformer equivalent model of a transformer substation provided by the invention;
fig. 4 is a schematic structural diagram of a low-voltage bus voltage regulating system of a flexible ac/dc hybrid distribution network substation.
Detailed Description
In order to make the present invention better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, 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.
The invention provides a voltage regulating method for a low-voltage bus of a flexible AC/DC hybrid distribution network transformer substation, which is based on a flexible AC/DC hybrid distribution network topological structure of a typical transformer substation and a converter station, wherein the typical topology comprises an AC main network, an AC transformer substation main transformer, a high-voltage bus, a low-voltage bus and the converter station. Wherein P is Net 、Q Net Representing active and reactive loads except for a converter station borne by a low-voltage bus of an alternating-current transformer substation, P Valve 、Q Valve Respectively representing the set values of active power and reactive power of the alternating current side of the converter station by adjusting the set value Q of the reactive power Valve The voltage of the low-voltage bus is continuously regulated.
For easy understanding, referring to fig. 1, the embodiment of the invention provides a voltage regulating method for a low-voltage bus of a flexible ac/dc hybrid distribution network substation, which includes:
and step 101, acquiring the active load data of the main transformer sub-joint position, the voltage amplitude of the main transformer high-voltage side and the low-voltage bus at the moment before voltage regulation in the dispatching automation system.
The main transformer sub-joint position, the main transformer high-voltage side voltage amplitude and the low-voltage bus active load data at the moment before voltage regulation can be directly obtained from the dispatching automation system.
The main transformer of the transformer station can be equivalent to an equivalent model consisting of impedance and ideal transformer as shown in figure 3,
and->
The voltage vectors of the high-voltage bus and the low-voltage bus respectively connected with the main transformer of the transformer substation are S 1 And S is 2 The power values transmitted by the high-voltage side and the low-voltage side of the main transformer are respectively, and the positive direction is that the high-voltage side points to the low-voltage side, and k:1 is the main transformer ratio calculated according to the current main transformer sub joint position, R T +jX T Is the main variable equivalent impedance.
According to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Electric power with main variable equivalent impedanceResistance, X T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Is the rated voltage marked on the nameplate of the main transformer.
And step 103, calculating reactive power transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation according to the equivalent topological parameter of the main transformer, the position of the main transformer tap, the amplitude of the high-voltage side voltage of the main transformer, the active load data of the low-voltage bus and the ideal value of the low-voltage bus voltage of the transformer substation.
The ideal value of the low-voltage bus voltage of the transformer substation can be set manually, namely the target voltage regulation value. Assume that the ideal value of the voltage of the low-voltage bus of the transformer substation set by manpower is U 2 U is known according to the current transformer transformation ratio k 1 2 Voltage amplitude U 'converted to high voltage side' 2 The method comprises the following steps:
U' 2 ＝kU 2
according to the basic concept of power transmission, the ideal value U of the low-voltage bus voltage can be accurately calculated 2 Corresponding reactive power transmission Q 2 . The specific calculation process is as follows:
first, the longitudinal component DeltaU 'of the voltage drop on the main variable equivalent impedance is written in columns' 2 And a transverse component δU' 2 Is represented by the expression:
wherein P is 2 Is the active load data of the low-voltage bus.
The collected voltage amplitude U of the high-voltage side of the main transformer 1 And the voltage amplitude U 'converted to the high voltage side' 2 The relationship between them is expressed as:
thus, it is possible to obtain:
as can be seen from the above equation, the above equation only contains the ideal value U of the low-voltage bus voltage 2 Corresponding reactive power transmission Q 2 This unique unknown quantity thus allows the determination of the ideal value U of the low-voltage bus voltage 2 Corresponding reactive power transmission Q 2 。
And 104, judging whether the reactive power regulation capacity of the converter station is enough according to the reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, executing the step 105, otherwise, executing the step 106.
And 105, locking an automatic voltage reactive power control strategy of the transformer substation, and adjusting the reactive power set value of the converter station to be the difference between reactive power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation and reactive power transmitted by the current low-voltage bus of the transformer substation, so that the voltage of the low-voltage bus of the transformer substation is adjusted to the ideal value.
And step 106, indicating the automatic voltage reactive power control strategy action of the transformer substation, and returning to step 101 after the automatic voltage reactive power control strategy action of the transformer substation until the voltage of the low-voltage bus of the transformer substation is regulated to an ideal value.
Specifically, according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, whether the following formula is satisfied is calculated:
wherein P is Valve For setting the active power of the alternating current side of the converter station, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter.
And if the above formula is met, judging that the reactive power regulation capacity of the converter station is enough, otherwise, judging that the reactive power regulation capacity of the converter station is insufficient.
Reactive power regulation in a converter stationIf the capacity is enough, the reactive power set value of the converter station is adjusted to be the reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation and the reactive power transmission (Q) of the low-voltage bus of the current transformer substation Net +Q Valve ) The difference, i.e. the reactive power set point of the converter station is adjusted to |Q 2 -(Q Net +Q Valve ) And I, so that the voltage of the low-voltage bus of the transformer substation reaches an ideal value, and the voltage regulation is finished.
And if the reactive power regulation capacity of the converter station is insufficient, indicating the action of an automatic voltage reactive power control strategy (Automatic Voltage Control, AVC) of the transformer substation, carrying out coordinated optimization automatic closed-loop control on the reactive power device by changing the transformation ratio of the transformer, switching a capacitor and other measures, and returning to the step 101 after the action of the automatic voltage reactive power control strategy of the transformer substation until the voltage of the low-voltage bus of the transformer substation is regulated to an ideal value.
According to the flexible AC/DC hybrid distribution network transformer substation low-voltage bus voltage regulating method provided by the invention, the position of a main transformer tap, the voltage amplitude of a main transformer high-voltage side and real-time data of a low-voltage bus active load are measured, the equivalent topological parameter of the main transformer is calculated, the corresponding reactive power transmission ideal value is calculated according to the ideal value of the transformer substation low-voltage bus voltage, whether the reactive power regulating capacity of a converter station is enough or not is judged, if the reactive power regulating capacity of the converter station is enough, the AVC is blocked, the reactive power set value of the converter is regulated to be the difference between the reactive power transmission power corresponding to the transformer substation low-voltage ideal value and the reactive power transmission reactive power of the current transformer substation low-voltage bus, if the reactive power regulating capacity of the converter station is insufficient, the AVC is indicated to act, the steps are repeated after the AVC acts until the low-voltage bus voltage is regulated to the ideal value, the design structure of the existing power transformer is not required to be changed, the continuous voltage regulating of the flexible AC/DC hybrid distribution network is realized under the condition that the power electronic device is not increased independently, the system operation cost is reduced, the high-efficiency accurate AC voltage regulating of the power distribution network is realized through the power electronic devices such as additional power transistors, the power electronic device is improved, the power consumption of the existing power transformer is greatly designed, and the power transformer voltage regulating device is greatly increased.
Meanwhile, by combining with the existing AVC strategy, the large-range continuous and accurate voltage regulation capability of the low-voltage bus of the transformer substation is improved, the problem that the adjustment capacity of the power electronic continuous voltage regulation device is low due to the current capacity of the power electronic device is solved, the wide-range economic voltage regulation is realized by utilizing the limited reactive compensation capacity of the converter, and the method has engineering application and popularization values.
For easy understanding, referring to fig. 4, an embodiment of a low-voltage bus voltage regulating system of a flexible ac/dc hybrid distribution network substation is provided in the present invention, which includes the following modules:
the data acquisition module is used for acquiring the main transformer sub-joint position, the main transformer high-voltage side voltage amplitude and the low-voltage bus active load data at the moment before voltage regulation in the dispatching automation system;
the main transformer parameter calculation module is used for calculating the equivalent topology parameters of the main transformer according to the equipment parameters on the main transformer nameplate, wherein the equivalent topology parameters of the main transformer comprise the resistance and the reactance of the equivalent impedance of the main transformer;
the reactive power transmission power calculation module is used for calculating reactive power transmission corresponding to the ideal value of the voltage of the low-voltage bus of the transformer substation according to the equivalent topological parameter of the main transformer, the position of the main transformer substation connector, the voltage amplitude of the high-voltage side of the main transformer, the active load data of the low-voltage bus and the ideal value of the voltage of the low-voltage bus of the transformer substation;
the reactive capacity judging module is used for judging whether the reactive regulation capacity of the converter station is enough or not according to the reactive transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, triggering the first action module, and if not, triggering the second action module;
the first action module is used for locking an automatic voltage reactive power control strategy of the transformer substation, adjusting a reactive power set value of the converter station to be the difference between reactive power corresponding to an ideal value of the voltage of the low-voltage bus of the transformer substation and reactive power transmitted by the current low-voltage bus of the transformer substation, and enabling the voltage of the low-voltage bus of the transformer substation to be adjusted to the ideal value;
the second action module is used for indicating the action of the automatic voltage reactive power control strategy of the transformer substation, and re-triggering the data acquisition module after the action of the automatic voltage reactive power control strategy of the transformer substation.
The main transformer parameter calculation module is specifically used for:
the main transformer is equivalent to an equivalent model consisting of impedance and an ideal transformer;
according to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Resistance, X, being the main variable equivalent impedance T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Is the rated voltage marked on the nameplate of the main transformer.
The reactive power transmission calculation module is specifically used for:
obtaining ideal value U of low-voltage bus voltage of transformer substation 2 ；
According to the main transformer ratio k determined by the main transformer sub-joint position, the ideal value U of the low-voltage bus voltage of the transformer substation 2 The voltage amplitude converted to the high-voltage side is obtained, and the voltage amplitude U 'converted to the high-voltage side of the transformer substation is obtained' 2 ＝kU 2 ；
According to the collected voltage amplitude of the high-voltage side of the main transformer, converting the voltage amplitude into the voltage amplitude U 'of the high-voltage side of the transformer substation' 2 Equivalent topology parameters of main transformer and active load data of low-voltage bus, and calculating reactive power transmission power Q corresponding to ideal value of low-voltage bus voltage of transformer substation 2 The calculation formula is as follows:
wherein P is 2 Is the active load data of the low-voltage bus, U 1 The amplitude of the main transformer high-voltage side voltage is acquired.
The reactive capacity judging module is specifically used for:
according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, calculating the |Q 2 -(Q Net +Q Valve ) Whether or not to meet
If yes, judging that the reactive power regulation capacity of the converter station is enough, executing a step S5, otherwise, executing a step S6, wherein P is the same as that of the reactive power regulation capacity of the converter station Valve For setting the active power of the alternating current side of the converter station, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter.
According to the flexible AC/DC hybrid distribution network transformer substation low-voltage bus voltage regulating system provided by the invention, the position of a main transformer tap, the voltage amplitude of a main transformer high-voltage side and real-time data of a low-voltage bus active load are measured, the equivalent topological parameter of the main transformer is calculated, the corresponding reactive power transmission ideal value is calculated according to the ideal value of the transformer substation low-voltage bus voltage, whether the reactive power regulating capacity of the transformer substation is enough is judged, if the reactive power regulating capacity of the transformer substation is enough, the AVC is blocked, the reactive power set value of the transformer is regulated to be the difference between the reactive power transmission power corresponding to the transformer substation low-voltage ideal value and the reactive power transmission reactive power of the current transformer substation, if the reactive power regulating capacity of the transformer substation is insufficient, the AVC is indicated to act, the steps are repeated after the AVC acts until the low-voltage bus voltage is regulated to the ideal value, the design structure of the existing power transformer is not required to be changed, the continuous voltage regulating of the flexible AC/DC hybrid distribution network is realized under the condition that the power electronic devices are not increased independently, the utilization rate of the power distribution network equipment is improved, the system running cost is reduced, the high-efficiency accurate AC voltage regulating is realized through the power electronic devices such as additional power transistors, the power electronic devices in the prior art, the power transformer voltage regulating device is greatly designed, the power transformer voltage stabilizing device is greatly lost, and the power transformer running cost is greatly increased.
Meanwhile, by combining with the existing AVC strategy, the large-range continuous and accurate voltage regulation capability of the low-voltage bus of the transformer substation is improved, the problem that the adjustment capacity of the power electronic continuous voltage regulation device is low due to the current capacity of the power electronic device is solved, the wide-range economic voltage regulation is realized by utilizing the limited reactive compensation capacity of the converter, and the method has engineering application and popularization values.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (2)
1. The voltage regulating method for the low-voltage bus of the flexible AC/DC hybrid distribution network transformer substation is characterized by comprising the following steps of:
s1, acquiring the active load data of a main transformer sub-joint position, a main transformer high-voltage side voltage amplitude and a low-voltage bus at the moment before voltage regulation in a dispatching automation system;
s2, calculating the equivalent topology parameters of the main transformer according to the equipment parameters on the nameplate of the main transformer, wherein the equivalent topology parameters of the main transformer comprise the resistance and reactance of the equivalent impedance of the main transformer;
s3, calculating reactive power transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation according to the equivalent topological parameter of the main transformer, the position of a main transformer tap, the amplitude of the high-voltage side voltage of the main transformer, the active load data of the low-voltage bus and the ideal value of the low-voltage bus voltage of the transformer substation;
s4, judging whether the reactive power regulation capacity of the converter station is enough or not according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, executing the step S5, otherwise, executing the step S6;
s5, locking an automatic voltage reactive power control strategy of the transformer substation, and adjusting a reactive power set value of the converter station to be the difference between reactive power corresponding to the ideal value of the low-voltage bus voltage of the transformer substation and reactive power transmitted by the low-voltage bus of the current transformer substation, so that the voltage of the low-voltage bus of the transformer substation is adjusted to the ideal value;
s6, indicating the automatic voltage reactive power control strategy action of the transformer substation, and returning to the step S1 after the automatic voltage reactive power control strategy action of the transformer substation until the voltage of the low-voltage bus of the transformer substation is regulated to an ideal value;
the step S2 specifically comprises the following steps:
the main transformer is equivalent to an equivalent model consisting of impedance and an ideal transformer;
according to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Resistance, X, being the main variable equivalent impedance T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Rated voltage marked on a main transformer nameplate;
the step S3 specifically comprises the following steps:
obtaining ideal value U of low-voltage bus voltage of transformer substation 2 ；
According to the main transformer ratio k determined by the main transformer sub-joint position, the ideal value U of the low-voltage bus voltage of the transformer substation 2 The voltage amplitude converted to the high-voltage side is obtained, and the voltage amplitude U 'converted to the high-voltage side of the transformer substation is obtained' 2 ＝kU 2 ；
According to the collected voltage amplitude of the high-voltage side of the main transformer, converting the voltage amplitude into the voltage amplitude U 'of the high-voltage side of the transformer substation' 2 Equivalent topology parameters of main transformer and active load data of low-voltage bus, and calculating reactive power transmission power Q corresponding to ideal value of low-voltage bus voltage of transformer substation 2 The calculation formula is as follows:
wherein P is 2 Is the active load data of the low-voltage bus, U 1 The amplitude of the collected main transformer high-voltage side voltage is used;
the step S4 specifically comprises the following steps:
according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, calculating the |Q 2 -(Q Net +Q Valve ) Whether or not I satisfies
If yes, judging that the reactive power regulation capacity of the converter station is enough, executing a step S5, otherwise, executing a step S6, wherein P is the same as that of the reactive power regulation capacity of the converter station Valve For converters of converter stationsSet value of active power of alternating current side, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter.
2. A low-voltage bus voltage regulating system of a flexible AC/DC hybrid distribution network transformer substation is characterized by comprising the following modules:
the data acquisition module is used for acquiring the main transformer sub-joint position, the main transformer high-voltage side voltage amplitude and the low-voltage bus active load data at the moment before voltage regulation in the dispatching automation system;
the main transformer parameter calculation module is used for calculating the equivalent topology parameters of the main transformer according to the equipment parameters on the main transformer nameplate, wherein the equivalent topology parameters of the main transformer comprise the resistance and the reactance of the equivalent impedance of the main transformer;
the reactive power transmission power calculation module is used for calculating reactive power transmission corresponding to the ideal value of the voltage of the low-voltage bus of the transformer substation according to the equivalent topological parameter of the main transformer, the position of the main transformer substation connector, the voltage amplitude of the high-voltage side of the main transformer, the active load data of the low-voltage bus and the ideal value of the voltage of the low-voltage bus of the transformer substation;
the reactive capacity judging module is used for judging whether the reactive regulation capacity of the converter station is enough or not according to the reactive transmission power corresponding to the ideal value of the low-voltage bus voltage of the transformer station, if so, triggering the first action module, and if not, triggering the second action module;
the first action module is used for locking an automatic voltage reactive power control strategy of the transformer substation, adjusting a reactive power set value of the converter station to be the difference between reactive power corresponding to an ideal value of the voltage of the low-voltage bus of the transformer substation and reactive power transmitted by the current low-voltage bus of the transformer substation, and enabling the voltage of the low-voltage bus of the transformer substation to be adjusted to the ideal value;
the second action module is used for indicating the action of the automatic voltage reactive power control strategy of the transformer substation, and re-triggering the data acquisition module after the action of the automatic voltage reactive power control strategy of the transformer substation;
the main transformer parameter calculation module is specifically used for:
the main transformer is equivalent to an equivalent model consisting of impedance and an ideal transformer;
according to the equivalent model and the equipment parameters on the main transformer nameplate, calculating the equivalent topology parameters of the main transformer, wherein the equation for calculating the equivalent topology parameters of the main transformer is as follows:
wherein R is T Resistance, X, being the main variable equivalent impedance T Reactance, deltaP, of the main variable equivalent impedance S For short-circuit loss marked on main transformer nameplate, U S % is the impedance voltage percentage marked on the nameplate of the main transformer, S N For the rated capacity marked on the nameplate of the main transformer, U N Rated voltage marked on a main transformer nameplate;
the reactive power transmission calculation module is specifically used for:
obtaining ideal value U of low-voltage bus voltage of transformer substation 2 ；
According to the main transformer ratio k determined by the main transformer sub-joint position, the ideal value U of the low-voltage bus voltage of the transformer substation 2 The voltage amplitude converted to the high-voltage side is obtained, and the voltage amplitude U 'converted to the high-voltage side of the transformer substation is obtained' 2 ＝kU 2 ；
According to the collected voltage amplitude of the high-voltage side of the main transformer, converting the voltage amplitude into the voltage amplitude U 'of the high-voltage side of the transformer substation' 2 Equivalent topology parameters of main transformer and active load data of low-voltage bus, and calculating reactive power transmission power Q corresponding to ideal value of low-voltage bus voltage of transformer substation 2 The calculation formula is as follows:
wherein P is 2 Is the active load data of the low-voltage bus, U 1 The amplitude of the collected main transformer high-voltage side voltage is used;
the reactive capacity judging module is specifically used for:
according to reactive power transmission corresponding to the ideal value of the low-voltage bus voltage of the transformer substation, calculating the |Q 2 -(Q Net +Q Valve ) Whether or not I satisfies
If yes, judging that the reactive power regulation capacity of the converter station is enough, executing a step S5, otherwise, executing a step S6, wherein P is the same as that of the reactive power regulation capacity of the converter station Valve For setting the active power of the alternating current side of the converter station, Q Valve For setting reactive power of alternating current side of converter station, Q Net Reactive load except for converter station borne by low-voltage bus of alternating-current transformer station, S Valve N Is the rated capacity of the converter. />
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