CN111416377A - Flexible direct current control method and device for improving transient stability of power grid - Google Patents
Flexible direct current control method and device for improving transient stability of power grid 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
- 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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- 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
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Abstract
The invention discloses a flexible direct current control method and a flexible direct current control device for improving the transient stability of a power grid, wherein the method comprises the following steps: obtaining the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the system to the flexible direct current output through simulation; acquiring the angular speed variation of each generator when the system is in actual operation; obtaining an active index value and a reactive index value according to the active sensitivity, the reactive sensitivity and the angular speed variation; judging whether the active index value and the reactive index value are both in the dead zone, if so, maintaining the original control strategy unchanged; if not, when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is greater than or equal to the absolute value of the reactive index value, adopting an active power control priority strategy; and the other conditions adopt a reactive power control priority strategy. The invention can excavate the advantages of flexible direct current active and reactive control and improve the transient stability of the system.
Description
Technical Field
The invention relates to the technical field of power system operation control, in particular to a flexible direct current control method and device for improving transient stability of a power grid.
Background
In recent years, due to the flexible control of the flexible direct current and no risk of phase commutation failure, more and more flexible direct current projects are put into operation in China. In order to improve the operation safety of a large power grid, a transmitting-end power grid and a receiving-end power grid are more and more concerned by the domestic and foreign power industry and academia in a flexible direct current asynchronous interconnection mode, and a large amount of corresponding research work on a control method for improving the stability of a feed-in system by flexible direct current is carried out. The flexible direct current can realize active and reactive decoupling control to a great extent, and aiming at the characteristic of the flexible direct current, besides a conventional control strategy, the current corresponding flexible direct current control method for improving the system stability can be divided into an active control method and a reactive control method. The active control method mainly includes a virtual synchronous machine control method, a frequency control method and the like. The reactive control method mainly comprises a given reactive voltage curve method and the like. The methods mainly focus on considering active or reactive control, the coordination treatment of the active control and the reactive control is simpler, and the advantages brought by the active and reactive coordination control are not fully exploited.
Disclosure of Invention
The embodiment of the invention aims to provide a flexible direct current control method and a flexible direct current control device for improving the transient stability of a power grid, which can fully exploit the advantages of active and reactive coordinated control and provide a new control strategy for the existing flexible direct current control, thereby effectively improving the transient stability of the receiving-end power grid of a system.
In order to achieve the above object, an embodiment of the present invention provides a flexible dc control method for improving transient stability of a power grid, including the following steps:
obtaining the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the electric power alternating current system to the flexible direct current output through simulation;
acquiring the angular speed variation of the real-time angular speed of each generator relative to the angular speed of a reference system when the power alternating-current system is actually operated;
calculating to obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
judging whether the active index value and the reactive index value are both in a preset dead zone, if so, keeping an original control strategy unchanged; if not, the user can not select the specific application,
when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is greater than or equal to the absolute value of the reactive index value, adopting an active power control priority strategy;
and when the active index value is in the dead zone and the reactive index value is outside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is smaller than the absolute value of the reactive index value, adopting a reactive power control priority strategy.
Preferably, the obtaining, through simulation, active sensitivity and reactive sensitivity of electromagnetic power of each generator in the power ac system to the flexible dc output specifically includes:
in a simulation test, giving an active current step instruction to the flexible direct current to obtain an active power variation of the flexible direct current output and a first electromagnetic power variation of each generator, and obtaining the active sensitivity according to the ratio of the first electromagnetic power variation to the active power variation;
in a simulation test, a step instruction of reactive current is given to the flexible direct current to obtain the reactive power variation of the flexible direct current output and the second electromagnetic power variation of each generator, and the reactive sensitivity is obtained according to the ratio of the second electromagnetic power variation to the reactive power variation.
Preferably, the original control strategy is that the inverter side of the flexible direct current adopts a constant direct current voltage and constant reactive power control, and the rectifier side adopts a constant active power and constant reactive power control strategy; or the inversion side of the flexible direct current adopts a constant active power and constant reactive power control strategy, and the rectification side adopts constant direct current voltage and constant reactive power control.
Preferably, the active power control priority strategy is an active power control strategy according to the formula
Executing; wherein, Id_ref(t) is the active current command value of the active current at time t, Ivsc_maxMaximum current amplitude, I, for the flexible DC outputd_minIs the minimum value of active current in actual operation demand, Iq_minThe minimum adjustment range of the reactive current is the minimum adjustment range of the reactive current when the actual operation is required; i isd_ref0For a given current value in normal operation, KdFor a predetermined calculation coefficient, KdIs greater than 0; when x is more than or equal to 0, sign (x) takes 1, when x is less than 0, sign (x) takes-1;
the reactive power control strategy adopts constant alternating voltage control and meets the requirements
Wherein, VrefIs a command value of AC voltage, Vset1Is a preset first reference value, Iq(t) is the value of the reactive current at time t, IdAnd (t) is the current value of the active current at the moment t.
Preferably, the first and second electrodes are formed of a metal,the reactive power control priority strategy adopts constant alternating voltage control for the reactive power control strategy and meets the requirement of
Wherein, Vset2And Vset3Respectively are a preset second reference value and a preset third reference value;
active power control strategy according to formula Id_ref(t)＝Id_minAnd (6) executing.
Another embodiment of the present invention provides a flexible dc control device for improving transient stability of a power grid, including:
the sensitivity acquisition module is used for acquiring active sensitivity and reactive sensitivity of electromagnetic power of each generator in the electric power alternating current system to the flexible direct current output through simulation;
the angular speed variation acquisition module is used for acquiring the angular speed variation of the real-time angular speed of each generator relative to the angular speed of a reference system when the power alternating-current system is actually operated;
the index value calculation module is used for calculating and obtaining preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
the judging module is used for judging whether the active index value and the reactive index value are both in a preset dead zone, and if so, maintaining the original control strategy unchanged; if not, the user can not select the specific application,
an active priority module, configured to, when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and an absolute value of the active index value is greater than or equal to an absolute value of the reactive index value, adopt an active power control priority policy;
and the reactive power priority module is used for adopting a reactive power control priority strategy when the active index value is in the dead zone and the reactive index value is out of the dead zone, or when the active index value and the reactive index value are both out of the dead zone and the absolute value of the active index value is smaller than the absolute value of the reactive index value.
The invention further provides a device using the flexible direct current control method for improving the transient stability of the power grid, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the flexible direct current control method for improving the transient stability of the power grid according to any one of the above aspects.
Compared with the prior art, the flexible direct current control method and the flexible direct current control device for improving the transient stability of the power grid can fully exploit the advantages of active and reactive coordinated control and provide a new control strategy for the existing flexible direct current control, so that the transient stability of the receiving end power grid of the system is effectively improved, and the system is safer to operate.
Drawings
Fig. 1 is a schematic flowchart of a flexible dc control method for improving transient stability of a power grid according to an embodiment of the present invention;
fig. 2 is a simple flow chart diagram of a flexible dc control method for improving transient stability of a power grid according to an embodiment of the present invention;
FIG. 3 is a simplified schematic diagram of a flexible DC current provided by an embodiment of the present invention;
fig. 4 is a schematic diagram of a flexible dc control device for improving transient stability of a power grid according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an apparatus using a flexible dc control method for improving transient stability of a power grid according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, a schematic flow chart of a flexible dc control method for improving transient stability of a power grid according to an embodiment of the present invention is shown, where the method includes steps S1 to S6:
s1, obtaining the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the power alternating current system to the flexible direct current output through simulation;
s2, acquiring the angular speed variation of the real-time angular speed of each generator relative to the angular speed of a reference system when the power alternating-current system is actually operated;
s3, calculating to obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the electricityThe number of generators in the force alternator system;
s4, judging whether the active index value and the reactive index value are both in a preset dead zone, if so, keeping the original control strategy unchanged; if not, the user can not select the specific application,
s5, when the active index value is out of the dead zone and the reactive index value is in the dead zone, or when the active index value and the reactive index value are out of the dead zone and the absolute value of the active index value is greater than or equal to the absolute value of the reactive index value, adopting an active power control priority strategy;
and S6, when the active index value is in the dead zone and the reactive index value is out of the dead zone, or when the active index value and the reactive index value are both out of the dead zone and the absolute value of the active index value is smaller than the absolute value of the reactive index value, adopting a reactive power control priority strategy.
It should be noted that, in the operation of the power system, the alternating current may be decomposed into two decoupled components through coordinate transformation: component of D axis IdQ axis component Iq(ii) a Wherein, IdAlso known as active current, IqAlso known as reactive current. The active control and the reactive control of the flexible direct current output are respectively through controlling the I of the alternating current side current of the flexible direct current outputdAnd IqThe implementation is carried out; wherein, IdAnd IqThe following equation is satisfied:
in the above formula, Pvsc、QvscActive and reactive power, U, respectively, of a flexible DC outputacFor a flexible DC-AC side voltage, Ivsc_maxMaximum current amplitude, I, for a flexible DC outputd_minTo take into account I when actual operating requirementsdMinimum value, Iq_minTo take into account I when actual operating requirementsqMinimum adjustment range.
In particular, the invention is directed to a sending-end power gridAnd a receiving end power grid is asynchronously interconnected with the receiving end power grid through flexible direct current, wherein n generators are supposed to be arranged in a flexible direct current feed-in power system, n is greater than or equal to 1 and is G1、……、Gn. Obtaining each generator G in the power alternating current system through simulationiThe active sensitivity and the reactive sensitivity of the electromagnetic power to the flexible direct current output are that i is more than or equal to 1 and less than or equal to n.
Generator G for obtaining actual operation of power alternating current systemiThe change amount of the angular velocity of the reference frame relative to the real-time angular velocity of (1) is represented by [ delta ] omegaiAnd (4) showing.
Calculating to obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is as follows
The calculation formula of the reactive index value is as follows
ΔWpIs an active index value, kp_giActive sensitivity of the i-th generator, Δ WqAs a reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power ac system.
And judging whether the active index value and the reactive index value are both in a preset dead zone, wherein the dead zone is set through simulation calculation according to a specific power system. If so, maintaining the original control strategy which refers to the traditional control strategy; if not, different control strategies are selected according to the following different conditions.
And when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is greater than or equal to the absolute value of the reactive index value, adopting an active power control priority strategy. If the dead zone is used [ -F [ - ]band，Fband]Is shown in the specification, wherein Fband> 0, when Δ WpOutside the dead zone, Δ Wq∈[-Fband,Fband](ii) a Or but Δ Wp、ΔWqAre all outside the dead zone, and | Δ Wp|≥|ΔWqAnd if so, adopting an active power control priority strategy.
And when the active index value is in the dead zone, the reactive index value is out of the dead zone, or the active index value and the reactive index value are both out of the dead zone, and the absolute value of the active index value is smaller than the absolute value of the reactive index value, adopting a reactive power control priority strategy. That is, when Δ Wp∈[-Fband,Fband]，ΔWqOutside the dead zone; or but Δ Wp、ΔWqAre all outside the dead zone, and | Δ Wp|＜|ΔWqAnd if so, adopting a reactive power control priority strategy.
In order to more intuitively and clearly understand the implementation process of the present invention, refer to fig. 2, which is a simplified process diagram of the flexible dc control method for improving the transient stability of the power grid according to the embodiment of the present invention.
The flexible direct current control method for improving the transient stability of the power grid, provided by the embodiment 1 of the invention, can fully exploit the advantages of active and reactive coordinated control, and provide a new control strategy for the existing flexible direct current control, so that the transient stability of the receiving-end power grid of the system is effectively improved.
As an improvement of the above scheme, obtaining the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the power ac system to the flexible dc output through simulation specifically includes:
in a simulation test, giving an active current step instruction to the flexible direct current to obtain an active power variation of the flexible direct current output and a first electromagnetic power variation of each generator, and obtaining the active sensitivity according to the ratio of the first electromagnetic power variation to the active power variation;
in a simulation test, a step instruction of reactive current is given to the flexible direct current to obtain the reactive power variation of the flexible direct current output and the second electromagnetic power variation of each generator, and the reactive sensitivity is obtained according to the ratio of the second electromagnetic power variation to the reactive power variation.
Specifically, in a simulation test, an active current I is given to the flexible direct currentdStep instruction Id+ΔIdThe active power variation of the flexible direct current output and the first electromagnetic power variation of each generator can be obtained through calculation, the active sensitivity is obtained according to the ratio of the first electromagnetic power variation to the active power variation, and the active sensitivity is expressed by a mathematical expression
Wherein k isp_giActive sensitivity of the ith generator to active power of the flexible DC, Δ PvscActive power variation, Δ P, for flexible DC outpute_giIs the first electromagnetic power variation of the ith generator.
In a simulation test, a reactive current I is given to flexible direct currentqStep instruction Iq+ΔIqAnd obtaining reactive power variation of the flexible direct current output and second electromagnetic power variation of each generator, and obtaining reactive sensitivity according to the ratio of the second electromagnetic power variation to the reactive power variation. Expressed by a mathematical formula of
Wherein k isq_giFor reactive sensitivity of the ith generator to reactive power of the soft DC, Δ QvscVariation of reactive power, Δ P, for flexible DC outputf_giIs the second electromagnetic power variation of the ith generator.
As an improvement of the above scheme, the original control strategy is that the inversion side of the flexible direct current adopts a constant direct current voltage and constant reactive power control, and the rectification side adopts a constant active power and constant reactive power control strategy; or the inversion side of the flexible direct current adopts a constant active power and constant reactive power control strategy, and the rectification side adopts constant direct current voltage and constant reactive power control.
Fig. 3 is a simple schematic diagram of a flexible direct current provided by the embodiment of the present invention. Generally, the flexible direct current system level control is the highest level control of the flexible direct current transmission system, and can be divided into two categories according to the nature of the control quantity: 1) active power control, which mainly has the function of controlling active power exchanged with an alternating current system through a converter station and mainly comprises active power control, direct current voltage control and the like; 2) the reactive power control has the main function of controlling the reactive power exchanged with an alternating current system through a converter station, and mainly comprises reactive power control and alternating voltage control.
Specifically, the original control strategy is a conventional control strategy, namely, a constant direct current voltage and constant reactive power control is adopted on the inversion side of the flexible direct current, and a constant active power and constant reactive power control strategy is adopted on the rectification side; or the inversion side of the flexible direct current adopts a control strategy of fixed active power and fixed reactive power, and the rectification side adopts fixed direct current voltage and fixed reactive power for control.
It is worth noting that the flexible direct current is used for simultaneously carrying out active power type control and reactive power type control, and particularly, the active current I is controlleddAnd controlling the reactive current IqRealizing and controlling the active current IdThe active power control is realized, and the reactive current I is controlledqNamely, reactive power class control is realized.
As an improvement of the above scheme, the active power control priority strategy is an active power control strategy according to a formula
Executing; wherein, Id_ref(t) is the active current command value of the active current at time t, Ivsc_maxMaximum current amplitude, I, for the flexible DC outputd_minIs the minimum value of active current in actual operation demand, Iq_minThe minimum adjustment range of the reactive current is the minimum adjustment range of the reactive current when the actual operation is required; i isd_ref0For a given current value in normal operation, KdFor a predetermined calculation coefficient, KdIs greater than 0; when x is more than or equal to 0, sign (x) takes 1, when x is less than 0, sign (x) takes-1;
reactive power controlThe strategy adopts constant alternating voltage control and satisfies
Wherein, VrefIs a command value of AC voltage, Vset1Is a preset first reference value, Iq(t) is the value of the reactive current at time t, IdAnd (t) is the current value of the active current at the moment t.
It should be noted that, the active power control and the reactive power control are parallel, but they are constrained to each other, and it can be understood that: both active power control and reactive power control occupy certain 'control resources', and the total 'control resources' are limited, so that the active power control priority strategy is to enable the active power control to occupy more 'control resources', and the reactive power control to occupy less 'control resources'.
Specifically, the active power control priority strategy is an active power control strategy according to a formula
Executing; wherein, Id_ref(t) is the active current instruction value of the active current at the time t, different values are selected according to the above formula to adjust according to different calculation results, Ivsc_maxMaximum current amplitude, I, for a flexible DC outputd_minIs the minimum value of active current in actual operation demand, Iq_minThe minimum adjustment range of the reactive current is the minimum adjustment range of the reactive current when the actual operation is required; i isd_ref0For a given current value in normal operation, KdFor a predetermined calculation coefficient, KdIs greater than 0; sign (x) takes 1 when x ≧ 0, sign (x) takes-1 when x < 0.
The reactive power control strategy adopts constant alternating voltage control and meets the requirements
Wherein, VrefIs a command value of AC voltage, Vset1Is a preset first reference value, Iq(t) is the value of the reactive current at time t, IdAnd (t) is the current value of the active current at the moment t.
As an improvement of the scheme, the reactive power control priority strategy adopts constant alternating voltage control for the reactive power control strategy and meets the requirement of
Wherein, Vset2And Vset3Respectively are a preset second reference value and a preset third reference value;
active power control strategy according to formula Id_ref(t)＝Id_minAnd (6) executing.
Specifically, the priority strategy of reactive power control adopts constant alternating voltage control for the reactive power control strategy and meets the requirement of
Wherein, Vset2And Vset3Are respectively a preset second reference value and a third reference value, Iq(t) is the value of the reactive current at time t,. DELTA.WqIs a reactive index value;
active power control strategy according to formula Id_ref(t)＝Id_minExecution, i.e. the active current command value at time t of the active current is Id_min。
Referring to fig. 4, a flexible dc control device for improving transient stability of a power grid according to an embodiment of the present invention includes:
the sensitivity acquisition module 11 is configured to obtain, through simulation, active sensitivity and reactive sensitivity of electromagnetic power of each generator in the power ac system to the flexible dc output;
an angular velocity variation obtaining module 12, configured to obtain an angular velocity variation of a real-time angular velocity of each generator relative to an angular velocity of a reference system when the power ac system is actually operated;
an index value calculation module 13, configured to calculate and obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity, and the angular velocity variation; wherein the active index value is calculatedIs of the formula
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
a judging module 14, configured to judge whether the active index value and the reactive index value are both within a preset dead zone, and if so, maintain an original control strategy unchanged; if not, the user can not select the specific application,
an active priority module 15, configured to, when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and an absolute value of the active index value is greater than or equal to an absolute value of the reactive index value, adopt an active power control priority policy;
and a reactive power priority module 16, configured to, when the active index value is within the dead zone, the reactive index value is outside the dead zone, or when both the active index value and the reactive index value are outside the dead zone, and an absolute value of the active index value is smaller than an absolute value of the reactive index value, adopt a reactive power control priority policy.
The flexible direct current control device for improving the transient stability of the power grid provided by the embodiment of the invention can realize all the processes of the flexible direct current control method for improving the transient stability of the power grid described in any one of the embodiments, and the functions and the realized technical effects of each module and unit in the device are respectively the same as those of the flexible direct current control method for improving the transient stability of the power grid described in the embodiment, and are not repeated herein.
Referring to fig. 5, the apparatus using the flexible dc control method for improving transient stability of a power grid according to an embodiment of the present invention includes a processor 10, a memory 20, and a computer program stored in the memory 20 and configured to be executed by the processor 10, where the processor 10 implements the flexible dc control method for improving transient stability of a power grid according to any of the above embodiments when executing the computer program.
Illustratively, the computer program may be divided into one or more modules/units, which are stored in the memory 20 and executed by the processor 10 to implement the present invention. One or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program in a flexible direct current control method for improving the transient stability of the power grid. For example, the computer program may be divided into a sensitivity acquisition module, an angular velocity change amount acquisition module, an index value calculation module, a judgment module, an active priority module, and a reactive priority module, and each module has the following specific functions:
the sensitivity acquisition module 11 is configured to obtain, through simulation, active sensitivity and reactive sensitivity of electromagnetic power of each generator in the power ac system to the flexible dc output;
an angular velocity variation obtaining module 12, configured to obtain an angular velocity variation of a real-time angular velocity of each generator relative to an angular velocity of a reference system when the power ac system is actually operated;
an index value calculation module 13, configured to calculate and obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity, and the angular velocity variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
a judging module 14, configured to judge whether the active index value and the reactive index value are both within a preset dead zone, and if so, maintain an original control strategy unchanged; if not, the user can not select the specific application,
an active priority module 15, configured to, when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and an absolute value of the active index value is greater than or equal to an absolute value of the reactive index value, adopt an active power control priority policy;
and a reactive power priority module 16, configured to, when the active index value is within the dead zone, the reactive index value is outside the dead zone, or when both the active index value and the reactive index value are outside the dead zone, and an absolute value of the active index value is smaller than an absolute value of the reactive index value, adopt a reactive power control priority policy.
The device using the flexible direct current control method for improving the transient stability of the power grid can be computing equipment such as a desktop computer, a notebook computer, a palm computer and a cloud server. The device using the flexible direct current control method for improving the transient stability of the power grid can comprise, but is not limited to, a processor and a memory. It will be understood by those skilled in the art that the schematic diagram 5 is merely an example of an apparatus using the flexible dc control method for improving the transient stability of the power grid, and does not constitute a limitation of the apparatus using the flexible dc control method for improving the transient stability of the power grid, and may include more or less components than those shown in the drawings, or combine some components, or different components, for example, the apparatus using the flexible dc control method for improving the transient stability of the power grid may further include an input and output device, a network access device, a bus, and the like.
The Processor 10 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor 10 may be any conventional processor, etc., and the processor 10 is a control center of the apparatus using the flexible dc control method for improving the transient stability of the power grid, and various interfaces and lines are used to connect various parts of the entire apparatus using the flexible dc control method for improving the transient stability of the power grid.
The memory 20 may be used to store the computer programs and/or modules, and the processor 10 implements various functions of the apparatus using the flexible dc control method for improving the transient stability of the power grid by running or executing the computer programs and/or modules stored in the memory 20 and calling up data stored in the memory 20. The memory 20 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like. In addition, the memory 20 may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
Wherein, the device integrated module using the flexible direct current control method for improving the transient stability of the power grid can be stored in a computer readable storage medium if the device integrated module is realized in the form of a software functional unit and sold or used as an independent product. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium and can implement the steps of the embodiments of the method when the computer program is executed by a processor. The computer program includes computer program code, and the computer program code may be in a source code form, an object code form, an executable file or some intermediate form. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, U.S. disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution media, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, in accordance with legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunications signals.
The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, and when the computer program runs, the device where the computer-readable storage medium is located is controlled to execute the flexible direct current control method for improving transient stability of a power grid according to any one of the above embodiments.
In summary, the flexible direct current control method and the device for improving the transient stability of the power grid provided by the embodiment of the invention can fully exploit the advantages of active and reactive coordinated control, and provide a new control strategy for the existing flexible direct current control, thereby effectively improving the transient stability of the power grid at the receiving end of the system and ensuring that the system runs more safely.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (7)
1. A flexible direct current control method for improving transient stability of a power grid is characterized by comprising the following steps:
obtaining the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the electric power alternating current system to the flexible direct current output through simulation;
acquiring the angular speed variation of the real-time angular speed of each generator relative to the angular speed of a reference system when the power alternating-current system is actually operated;
calculating to obtain preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
judging whether the active index value and the reactive index value are both in a preset dead zone, if so, keeping an original control strategy unchanged; if not, the user can not select the specific application,
when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is greater than or equal to the absolute value of the reactive index value, adopting an active power control priority strategy;
and when the active index value is in the dead zone and the reactive index value is outside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and the absolute value of the active index value is smaller than the absolute value of the reactive index value, adopting a reactive power control priority strategy.
2. The method for controlling the flexible direct current to improve the transient stability of the power grid according to claim 1, wherein the obtaining, through simulation, the active sensitivity and the reactive sensitivity of the electromagnetic power of each generator in the power alternating current system to the flexible direct current output specifically comprises:
in a simulation test, giving an active current step instruction to the flexible direct current to obtain an active power variation of the flexible direct current output and a first electromagnetic power variation of each generator, and obtaining the active sensitivity according to the ratio of the first electromagnetic power variation to the active power variation;
in a simulation test, a step instruction of reactive current is given to the flexible direct current to obtain the reactive power variation of the flexible direct current output and the second electromagnetic power variation of each generator, and the reactive sensitivity is obtained according to the ratio of the second electromagnetic power variation to the reactive power variation.
3. The method for controlling the flexible direct current to improve the transient stability of the power grid according to claim 1, wherein the original control strategy is that a constant direct current voltage and a constant reactive power are used for an inverter side of the flexible direct current, and a constant active power and a constant reactive power are used for a rectifier side; or the inversion side of the flexible direct current adopts a constant active power and constant reactive power control strategy, and the rectification side adopts constant direct current voltage and constant reactive power control.
4. The flexible direct-current control method for improving transient stability of power grid according to claim 1, wherein the active power control priority strategy is an active power control strategy according to an equation
Executing; wherein, Id_ref(t) is the active current command value of the active current at time t, Ivsc_maxMaximum current amplitude, I, for the flexible DC outputd_minIs the minimum value of active current in actual operation demand, Iq_minThe minimum adjustment range of the reactive current is the minimum adjustment range of the reactive current when the actual operation is required; i isd_ref0For a given current value in normal operation, KdFor a predetermined calculation coefficient, KdIs greater than 0; when x is more than or equal to 0, sign (x) takes 1, when x is less than 0, sign (x) takes-1;
the reactive power control strategy adopts constant alternating voltage control and meets the requirements
Wherein, VrefIs a command value of AC voltage, Vset1Is a preset first reference value, Iq(t) is the value of the reactive current at time t, IdAnd (t) is the current value of the active current at the moment t.
5. The flexible direct-current control method for improving grid transient stability of claim 4, wherein the reactive power control priority strategy adopts constant alternating-current voltage control for the reactive power control strategy, and meets the requirement
Wherein, Vset2And Vset3Respectively are a preset second reference value and a preset third reference value;
active power control strategy according to formula Id_ref(t)＝Id_minAnd (6) executing.
6. A flexible direct current control device for improving transient stability of a power grid is characterized by comprising:
the sensitivity acquisition module is used for acquiring active sensitivity and reactive sensitivity of electromagnetic power of each generator in the electric power alternating current system to the flexible direct current output through simulation;
the angular speed variation acquisition module is used for acquiring the angular speed variation of the real-time angular speed of each generator relative to the angular speed of a reference system when the power alternating-current system is actually operated;
the index value calculation module is used for calculating and obtaining preset active index values and preset reactive index values according to the active sensitivity, the reactive sensitivity and the angular speed variation; wherein, the calculation formula of the active index value is
The calculation formula of the reactive index value is
ΔWpIs the active index value, kp_giActive sensitivity of the i-th generator, Δ WqIs the reactive index value, kq_giFor reactive sensitivity of the i-th generator, Δ ωiIs the angular speed variation of the ith generator; n is the number of generators in the power AC system;
the judging module is used for judging whether the active index value and the reactive index value are both in a preset dead zone, and if so, maintaining the original control strategy unchanged; if not, the user can not select the specific application,
an active priority module, configured to, when the active index value is outside the dead zone and the reactive index value is inside the dead zone, or when the active index value and the reactive index value are both outside the dead zone and an absolute value of the active index value is greater than or equal to an absolute value of the reactive index value, adopt an active power control priority policy;
and the reactive power priority module is used for adopting a reactive power control priority strategy when the active index value is in the dead zone and the reactive index value is out of the dead zone, or when the active index value and the reactive index value are both out of the dead zone and the absolute value of the active index value is smaller than the absolute value of the reactive index value.
7. An apparatus using a flexible direct current control method for improving transient stability of a power grid, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the flexible direct current control method for improving transient stability of a power grid according to any one of claims 1 to 5.
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