CN115940193A - Combined determination method and system for inertia-primary frequency modulation capacity requirement of power system - Google Patents
Combined determination method and system for inertia-primary frequency modulation capacity requirement of power system Download PDFInfo
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Abstract
The invention discloses a method and a system for jointly determining the inertia-primary frequency modulation capacity requirement of a power system, wherein the method comprises the following steps: determining model parameters; establishing T representing inertia-primary frequency modulation capability requirement j -a K plane; a first analytical relationship based on a frequency steady state deviation constraint, at said T j -determining a first feasible region on the K plane; a second analytical relationship based on a frequency rate of change maximum constraint, at said T j -determining a second feasible region on the K plane; determining a system frequency dynamic curve, and determining a maximum value of transient frequency deviation according to the current system frequency dynamic curve; when the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, at T j -determining a third feasible region on the K plane; when the current system frequency dynamic curve satisfiesWhen the oscillation is constrained at T j -determining a fourth feasible region on the K plane; and determining the system inertia-primary frequency modulation capacity requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
Description
Technical Field
The invention relates to the technical field of power system simulation and analysis, in particular to a method and a system for jointly determining inertia-primary frequency modulation capacity requirements of a power system.
Background
The frequency stability of the system is related to inertia and primary frequency modulation capability, so the inertia-frequency modulation combined requirement of the system comes from the frequency stability constraint. Because synchronous generators provide sufficient inertia in conventional power systems, frequency stability constraints are typically reflected in the need for system primary modulation capability. In recent years, power electronic power supplies such as wind power, photovoltaic and direct current are connected to a power grid on a large scale. On one hand, different from a conventional power supply synchronous generator, the unit rotating speed and the injection power of the inverter grid-connected power supply are decoupled from the system frequency, and effective inertia cannot be provided for a power grid. On the other hand, the active frequency control technology of new energy and direct current expands the source of the frequency modulation capability of the system. Therefore, the necessity of determining the inertia-frequency modulation combined demand is widely concerned in a high-proportion new energy power system with the new characteristics of insufficient inertia and flexible frequency modulation control.
The minimum inertia requirement of the system has already received a certain attention, but the existing evaluation of the minimum inertia requirement of the system is usually carried out under the given frequency modulation capability, and cannot be applied to the new characteristic of flexible frequency modulation control of a high-proportion new energy power system. Because the partial frequency problem cannot be reflected in the specific frequency modulation capacity, the frequency constraint cannot be considered comprehensively, and the conventional constraint conditions such as the frequency change rate, the out-of-limit frequency deviation transient value and the like are usually concerned, and the constraint conditions such as the frequency oscillation risk constraint, the out-of-limit steady-state frequency deviation and the like in the scene of frequency emphasis and low inertia are less involved.
In order to solve the problems, a method for jointly determining the inertia-primary frequency modulation capacity requirement of the power system is urgently needed.
Disclosure of Invention
The invention provides a method and a system for jointly determining the inertia-primary frequency modulation capacity requirement of an electric power system, and aims to solve the problem of how to efficiently determine the inertia-primary frequency modulation capacity requirement of the electric power system.
In order to solve the above problem, according to an aspect of the present invention, there is provided a method for jointly determining an inertia-primary modulation capability requirement of a power system, the method including:
acquiring power system operation data, and determining model parameters based on the power system operation data and a system frequency response analysis model;
establishing T representing inertia-primary frequency modulation capability requirement based on system equivalent inertia time constant and equivalent power generation frequency modulation coefficient in model parameters j -a K plane;
a first analytical relationship based on a frequency steady state deviation constraint, at said T j -determining a first feasible region on the K plane;
a second analytical relationship based on a frequency rate of change maximum constraint, at said T j -determining a second feasible region on the K plane;
determining a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determining a maximum value of transient frequency deviation according to the current system frequency dynamic curve;
when the maximum value of the current transient frequency deviation is equal to a preset transient frequency deviation threshold value, at T j -determining a third feasible region on the K plane;
when the current system frequency dynamic curve meets the oscillation constraint, at T j -determining a fourth feasible region on the K plane;
and determining the system inertia-primary frequency modulation capacity requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
Preferably, wherein said determining model parameters based on said power system operating data and system frequency response analysis model comprises:
where α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the equivalent inertia time constant of the system; s. the GNi Capacity of the ith grid-connected synchronous machine; t is ji Inertia time constant of ith grid-connected synchronous machineCounting;
the average inertia time constant of the grid-connected synchronous machine is obtained; s. the L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k is G The equivalent power generation frequency modulation coefficient; />
Average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p of i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is calculated; />
The average available frequency modulation capacity is the ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameters of the ith grid-connected synchronous machine; and n is the number of the units.
Preferably, wherein said first analytical relationship based on frequency steady state deviation constraint, at said T j -determining a first feasible region on the K-plane, comprising:
at the T j -the first feasible region on the K plane satisfies:
Δf s ≤Δf sc ，
wherein, Δ P Gmax Available modulated capacity for equivalent power generation; k is G The equivalent power generation frequency modulation coefficient; Δ f s Is the steady state frequency deviation; Δ f sc Is a preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k L Frequency modulation coefficient for load；Δf lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
Preferably, wherein said second analytical relationship based on a frequency rate of change maximum constraint is at said T j -determining a second feasible region on the K-plane, comprising:
at the T j -the second feasible region in the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is j Is the system equivalent inertia time constant.
Preferably, wherein the method further comprises:
when the maximum value of the current transient frequency deviation is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is determined again, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value of the transient frequency deviation is determined at T j -determining a third feasible region on the K plane.
Preferably, wherein the method further comprises:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to ensure that the system does not oscillate and the system does not oscillate at the T j -determining a fourth feasible region on the K plane.
According to another aspect of the present invention, there is provided a system for jointly determining inertia-primary modulation capability requirements of a power system, the system comprising:
the model parameter determining unit is used for acquiring the operating data of the power system and determining model parameters based on the operating data of the power system and a system frequency response analysis model;
T j -a K-plane establishing unit for establishing T characterizing inertia-primary modulation capability requirements based on system equivalent inertia time constants and equivalent generation modulation coefficients in the model parameters j -a K plane;
a first feasible region determining unit, configured to determine a first analytic relationship based on a frequency steady-state deviation constraint at the T j -determining a first feasible region on the K plane;
a second feasible region determining unit for determining a second analytic relationship based on a frequency change rate maximum constraint at the T j -determining a second feasible region on the K plane;
the transient frequency deviation maximum value determining unit is used for determining a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determining a transient frequency deviation maximum value according to the current system frequency dynamic curve;
a third feasible region determination unit for determining a current transient frequency deviation maximum value at T when the current transient frequency deviation maximum value is equal to a preset transient frequency deviation threshold value j -determining a third feasible region on the K plane;
a fourth feasible region determining unit, configured to determine the current system frequency dynamic curve at the T when the current system frequency dynamic curve satisfies the oscillation constraint j -determining a fourth feasible region on the K plane;
and the requirement determining unit is used for determining the system inertia-primary frequency modulation capability requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
Preferably, the model parameter determination unit determines the model parameters based on the power system operation data and the system frequency response analysis model, including:
wherein α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the equivalent inertia time constant of the system; s GNi Capacity of the ith grid-connected synchronous machine; t is a unit of ji An inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k G The equivalent power generation frequency modulation coefficient; />
Average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is obtained; />
The average available frequency modulation capacity is the ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameters of the ith grid-connected synchronous machine; and n is the number of the units.
Preferably, the first feasible region determining unit determines the first feasible region based on a first analytical relationship constrained by a steady-state deviation of frequency at the T j -determining the first feasibility in the K planeA region, comprising:
at the T j -the first feasible region in the K plane satisfies:
Δf s ≤Δf sc ，
wherein, Δ P Gmax Available frequency modulation capacity for equivalent power generation; k G The equivalent power generation frequency modulation coefficient; Δ f s Is a steady state frequency deviation; Δ f sc A preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k L Is the load frequency modulation coefficient; Δ f lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
Preferably, the second feasible region determining unit determines the second feasible region based on a second analytical relationship constrained by a maximum value of a frequency change rate at the time T j -determining a second feasible region on the K-plane, comprising:
at the T j -the second feasible region on the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is j Is the system equivalent inertia time constant.
Preferably, the third feasible region unit is further configured to:
when the maximum value of the current transient frequency deviation is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is determined again, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value of the transient frequency deviation is determined at T j -determining a third feasible region on the K plane.
Preferably, the fourth feasible region unit is further configured to:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to enable the system not to oscillate and to be in the T state j -determining a fourth feasible region on the K plane.
Based on another aspect of the invention, a computer-readable storage medium is provided, having stored thereon a computer program which, when being executed by a processor, carries out the steps of any one of the methods for jointly determining a power system inertia-primary modulation capability requirement.
Based on another aspect of the present invention, the present invention provides an electronic device comprising:
the computer-readable storage medium described above; and
one or more processors to execute the program in the computer-readable storage medium.
The invention provides a method and a system for jointly determining the inertia-primary frequency modulation capacity requirement of a power system, wherein the method comprises the following steps: acquiring power system operation data, and determining model parameters based on the power system operation data and a system frequency response analysis model; establishing T representing inertia-primary frequency modulation capability requirement based on system equivalent inertia time constant and equivalent power generation frequency modulation coefficient in model parameters j -a K plane; a first analytical relationship based on a frequency steady state deviation constraint, at said T j -determining a first feasible region on the K plane; a second analytical relationship based on a frequency rate of change maximum constraint, at said T j -determining a second feasible region on the K plane; determining a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determining a maximum value of transient frequency deviation according to the current system frequency dynamic curve; when the maximum value of the current transient frequency deviation is equal to a preset transient frequency deviation threshold value, at T j -determining a third feasible region on the K plane; when the current system frequency dynamic curve meets the oscillation constraint, at T j -determining a fourth feasible region on the K planeA domain; and determining the system inertia-primary frequency modulation capacity requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region. Parameter equivalence is carried out through a system frequency response analysis model, detailed modeling for all elements can be avoided, and the calculation speed is increased; under the condition of considering different degrees of frequency modulation capability of the new energy power system, the minimum inertia requirement of the system under multiple constraints of frequency oscillation, out-of-limit and the like is quickly judged, a feasible region of equivalent inertia time constant-equivalent frequency modulation coefficient meeting all the constraints is obtained, and a basis can be provided for the coordination configuration of inertia and frequency adjustment resources of a high-proportion new energy system; the obtained system inertia-frequency modulation combined demand can adapt to the characteristic of flexible configuration of the frequency modulation capacity of a high-proportion new energy power system, has better adaptability and practicability, and simultaneously comprehensively considers frequency oscillation risk constraint and multiple frequency dynamic characteristic key index out-of-limit constraint under the scene of 'frequency emphasis and low inertia', so that the referential performance is stronger.
Drawings
Exemplary embodiments of the invention may be more completely understood in consideration of the following drawings:
FIG. 1 is a flow chart of a method 100 for jointly determining power system inertia-primary modulation capability requirements, according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for determining a combined system inertia and frequency modulation requirement according to an embodiment of the invention;
FIG. 3 is a schematic diagram of an improved system frequency response analysis model according to an embodiment of the present invention;
FIG. 4 is a diagram illustrating frequency stability constraints according to an embodiment of the present invention;
FIG. 5 is a schematic illustration of dominant constraints according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of frequency modulation integration requirements according to an embodiment of the present invention;
FIG. 7 is a schematic illustration of a combined system inertia-frequency modulation requirement according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of a system 800 for jointly determining inertia-primary modulation capability requirements of an electric power system according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flow chart of a method 100 for jointly determining inertia-primary modulation capability requirements of a power system according to an embodiment of the present invention. As shown in fig. 1, the method for jointly determining the inertia-primary frequency modulation capability requirement of the power system provided by the embodiment of the invention performs parameter equivalence through a system frequency response analysis model, so that detailed modeling for all elements can be avoided, and the calculation speed can be increased; under the condition that the frequency modulation capability degrees of the new energy power system are different, the minimum inertia requirement of the system under multiple constraints of frequency oscillation, out-of-limit and the like is quickly judged, a feasible region of equivalent inertia time constant-equivalent frequency modulation coefficient meeting all the constraints is obtained, and a basis can be provided for the coordination configuration of inertia and frequency modulation resources of a high-proportion new energy system; the obtained system inertia-frequency modulation combined demand can adapt to the characteristic of flexible configuration of the frequency modulation capacity of a high-proportion new energy power system, has better adaptability and practicability, and simultaneously comprehensively considers frequency oscillation risk constraint and multiple frequency dynamic characteristic key index out-of-limit constraint under the scene of 'frequency emphasis and low inertia', so that the referential performance is stronger. The method 100 for jointly determining the inertia-primary frequency modulation capacity requirement of the power system provided by the embodiment of the invention starts from step 101, obtains the operation data of the power system in step 101, and determines the model parameters based on the operation data of the power system and the system frequency response analysis model.
Preferably, wherein said determining model parameters based on said power system operating data and system frequency response analysis model comprises:
where α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the system equivalent inertia time constant; s GNi Capacity of the ith grid-connected synchronous machine; t is ji The inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k G The equivalent power generation frequency modulation coefficient; />
Average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p i Occupying the rated capacity of the unit for the available frequency modulation capacity of the ith grid-connected synchronous machineThe ratio of the amounts; />
Is the average available frequency modulation capacity ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L High-pressure cylinder power natural overshoot coefficient lambda and high-pressure cylinder power ratio F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameter of the ith grid-connected synchronous machine; and n is the number of the units.
Referring to fig. 2, in the present invention, the following parameters are extracted according to the grid data: load capacity S L Load frequency modulation coefficient K L Capacity S of grid-connected synchronous machine GNi Time constant of inertia T ji The proportion delta p of the available frequency modulation capacity to the rated capacity of the unit i Frequency modulation coefficient K of generator Gi And the relevant parameters of the speed regulator simplified model. In detail, the relevant parameters of the simplified model of the speed regulator further comprise a proportional coefficient K of the servomotor mi And the opening/closing time constant T of the servomotor mi Time constant T of feedback link of oil-driven engine stroke Li Natural overshoot factor lambda of high pressure cylinder power i High pressure cylinder power ratio F HPi Reheater time constant T RHi Time constant of steam volume T CHi . In particular, the generator frequency modulation factor K Gi The ratio of the regulated power of the generator to the variation of the frequency is defined as the inverse of the regulating coefficient. Then, a system frequency response analysis model is established, and generator related parameters are subjected to equivalent aggregation to obtain a system equivalent inertia time constant T j Equivalent power generation frequency modulation coefficient K G Equivalent power generation available frequency modulation capacity delta P Gmax And equivalent parameters of the speed regulator. In detail, the equivalent parameter of the speed regulator comprises a proportional coefficient K of the servomotor m And the opening/closing time constant T of the servomotor m Time constant T of feedback link of oil-driven engine stroke L The power of the high-pressure cylinder naturally overshoots the coefficient lambda and the power proportion F of the high-pressure cylinder HP Reheater time constant T RH Time constant of steam volume T CH 。
In the invention, a System Frequency Response analysis model is improved on the basis of a System Frequency Response (SFR) model, and the low inertia characteristic of a high-proportion new energy power System scene and the actual characteristic of steam turbine load Frequency control are respectively considered. One is to preserve the necessary integration and hysteresis as shown in fig. 3. The SFR model cannot reflect the system oscillation problem because only the generator reheating time constant T is reserved in the SFR model RH And the inertia time constant T of the synchronous machine j The premise that the two time constants are far larger than those of other hysteresis links is that the two time constants are kept as dominant time constants, but in a high-proportion new energy power system, the equivalent inertia time of the system is reduced along with the reduction of the voltage of the startup ratio of the synchronous machine, and especially when the frequency oscillation problem is researched, necessary integral and hysteresis link time constants need to be kept. And the natural over-regulation coefficient of the power of the high-pressure cylinder of the thermal power generating unit is calculated. The traditional SFR model adopts a classical IEEE turbine power model, does not consider the natural overshoot phenomenon of the high-pressure cylinder power, and the mechanical power of the SFR model can only reach 30-40% of a target adjustment value in the initial stage after disturbance, and is greatly different from 60-70% of a field actual achievable target value.
In the present invention, the polymerization equivalent method is: inertia time constant T of grid-connected synchronous machine ji Frequency modulation coefficient K of generator Gi And taking the rated capacity of the generator as a weight coefficient to obtain a weighted average. The equivalent parameter of the speed regulator is the generator coefficient K Gi The product of the weighted average and the rated capacity of the generator is used as a weight coefficient to obtain a weighted average. And for convenient calculation, unify with the total load capacity S of the system L For reference, expressed in per-unit values. The method specifically comprises the following steps:
wherein α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the system equivalent inertia time constant; s GNi Capacity of the ith grid-connected synchronous machine; t is ji The inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k G The equivalent power generation frequency modulation coefficient; />
Average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is obtained; />
Is the average available frequency modulation capacity ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameter of the ith grid-connected synchronous machine; and n is the number of the units.
In step 102, a system equivalent inertia time constant and an equivalent power generation frequency modulation coefficient are established based on the model parametersT characterizing inertia-primary modulation capability requirement j -K plane.
In the invention, after the model parameters are determined, the equivalent inertia time constant T of the system is used j And equivalent power generation frequency modulation coefficient K G Two parameters are used as independent variables to establish T representing the requirement of inertia-primary frequency modulation capacity j -K plane.
At step 103, a first analytical relationship based on a frequency steady state deviation constraint is determined, at T j -determining a first feasible region on the K plane.
Preferably, wherein said first analytical relationship based on frequency steady state deviation constraint, at said T j -determining a first feasible region on the K-plane, comprising:
at the T j -the first feasible region in the K plane satisfies:
Δf s ≤Δf sc ，
wherein, Δ P Gmax Available frequency modulation capacity for equivalent power generation; k is G The equivalent power generation frequency modulation coefficient; Δ f s Is a steady state frequency deviation; Δ f sc Is a preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k L Is the load frequency modulation coefficient; Δ f lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
At step 104, a second analytical relationship based on a frequency rate of change maximum constraint, at said T j -determining a second feasible region on the K plane.
Preferably, the second analytical relationship based on frequency change rate maximum constraint is at T j -determining a second feasible region on the K plane, comprising:
at the T j -the second feasible region in the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is a unit of j Is the system equivalent inertia time constant.
In step 105, a system frequency dynamic curve is determined based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and a transient frequency deviation maximum value is determined according to the current system frequency dynamic curve.
In step 106, when the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, at T j -determining a third feasible region on the K plane.
Preferably, wherein the method further comprises:
when the maximum value of the current transient frequency deviation is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is determined again, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value of the transient frequency deviation is determined at T j -determining a third feasible region on the K plane.
In step 107, when the current system frequency dynamic curve satisfies the oscillation constraint, at T j -determining a fourth feasible region on the K plane.
Preferably, wherein the method further comprises:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to enable the system not to oscillate and to be in the T state j -determining a fourth feasible region on the K plane.
Referring to fig. 3, in the present invention, the technical characteristics such as the equipment frequency ride-through capability, the setting threshold of the grid frequency safety and stability control device, etc. are considered comprehensively, and the system frequency safety and stability constraint conditions and criteria are refined. As shown in fig. 4, the method includes:
(1) and (3) restraining the steady-state frequency deviation: steady state frequency deviationΔf s Not exceeding a threshold value deltaf sc ；(Δf s ≤Δf sc )；
(2) Frequency rate of change maximum constraint: frequency rate of change maximum (df/dt) max Not exceeding a threshold value (df/dt) c ；((df/dt) max ＜(df/dt) c )；
(3) The maximum value constraint of the transient frequency deviation is as follows: maximum value of transient frequency deviation Δ f tmax Not exceeding a threshold value deltaf tc ；(Δf tmax ＜Δf tc )；
(4) And (3) frequency oscillation constraint: after the dynamic process is finished, the frequency can be maintained at the unchanged frequency, continuous periodic fluctuation does not occur, namely the frequency change rate tends to 0; (t → ∞ time df/dt → 0).
Referring to FIG. 5, in the present invention, an analytical relationship of frequency steady state deviation is established, based on a steady state frequency deviation threshold, at T j Obtaining a feasible frequency modulation coefficient area A1 on a K plane, wherein the feasible frequency modulation coefficient area A1 meets the following conditions:
wherein, Δ f lim Indicating the frequency deviation corresponding to the maximum available fm capacity. Generally, the frequency modulation coefficient of a single generator is set to be between 20 and 50, and when the maximum available frequency modulation capacity is considered according to 10 percent, the delta f lim Generally about 0.1-0.25 Hz.
Referring to FIG. 5, in the present invention, an analytical relationship of frequency change rate maximum value constraint is established, based on a frequency change rate maximum value threshold, at T j -obtaining a feasible region A2 of the inertia time constant on the K plane, the feasible region A2 satisfying:
in the invention, the analytic solution of the transient frequency deviation is difficult to solve after the amplitude limiting link is introduced, so that the lowest/high point on the dynamic curve of the system frequency is corresponding to the maximum value of the transient frequency deviation through the iterative solution of the model value.
Referring to fig. 5, in the present invention, it is determined whether the maximum value of the transient frequency deviation of the system is equal to the threshold Δ f according to the dynamic curve of the system frequency tc If not, keeping the inertia time constant unchanged, adjusting the equivalent power generation frequency modulation coefficient, repeating the previous step, re-determining the system frequency dynamic curve and the maximum value of the system transient frequency deviation, and finally enabling the maximum value of the system transient frequency deviation to be just equal to the threshold value delta f tc Thus at T j -determining a feasible region A3 on the K plane.
Referring to fig. 5, in the present invention, it is determined whether the system satisfies the oscillation constraint according to the system frequency dynamic curve, if not, the inertia time constant is maintained unchanged, the frequency modulation coefficient is reduced, so that the system can just not oscillate, thereby generating a frequency modulation coefficient at T j -determining a feasible region A4 on the K plane.
In step 108, a system inertia time constant-primary frequency modulation capability requirement is determined based on an intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
With reference to fig. 6, in the present invention, an intersection a of four feasible regions A1, A2, A3, and A4 is taken to obtain an equivalent inertia time constant-equivalent frequency modulation coefficient feasible region that satisfies all constraints, and each point (inertia time constant, frequency modulation coefficient) on the boundary is the minimum inertia time constant-primary frequency modulation capability requirement of the system, thereby determining the system inertia-primary frequency modulation capability requirement represented by the system equivalent inertia time constant-equivalent power generation frequency modulation coefficient under the constraint of system frequency stability.
The system inertia time constant-frequency modulation combined demand obtained by calculation by the method can adapt to the characteristic of flexible configuration of the frequency modulation capability of a high-proportion new energy power system, and has better adaptability and practicability; the system inertia time constant-frequency modulation combined requirement obtained by calculation by the method comprehensively considers frequency oscillation risk constraint and multiple frequency dynamic characteristic key index out-of-limit constraint under the scene of 'emphasis frequency low inertia', and has stronger referential property.
The following specifically exemplifies embodiments of the present invention
Constructing an equivalent system, wherein the load level is 3000MW, the feed-in direct current power is 300MW, the starting capacity of a conventional unit is 3000MW under the initial working condition, and obtaining the equivalent inertia time constant T of the system according to a polymerization formula j Is 10s, equivalent frequency modulation coefficient K Gmax Is 20, equivalent FM capacity Δ P Gmax The value is 6%, and the polymerization results of the governor control parameters are shown in table 1.
Table 1 speed governor control parameter aggregate results
| Parameter (Unit) | Value taking |
| T m /K m (s) | 0.04 |
| T L (s) | 0.02 |
| λ | 1.2 |
| F HP | 0.3 |
| T RH (s) | 20 |
| T CH (s) | 0.2 |
When the system has a direct current blocking fault, 10% of power shortage occurs, the frequency of the system is reduced, the inertia time constant and the frequency modulation are required to work together to prevent the frequency from being reduced, and the frequency is restored to a certain level. In order to avoid low-frequency load shedding and frequency collapse, the technical characteristics of equipment frequency ride-through capability, a set threshold value of a power grid frequency safety and stability control device and the like are comprehensively considered, and the extracted system frequency safety and stability constraint conditions and criteria are as follows:
(1) supposing that the secondary frequency modulation reserve level of the power grid can only adjust the frequency from 49.5Hz to the allowable frequency range in the normal state, in order to avoid the frequency being unable to recover to the rated frequency for a long time, a steady-state frequency deviation threshold value delta f is preferably adopted sc Is-0.5 Hz.
(2) In order to avoid disordered disconnection of grid-connected equipment, the minimum intersection of frequency change rate ranges allowed by the grid-connected equipment is preferably taken as the maximum threshold of the frequency change rate, and the frequency change rate is taken as 1Hz/s in the example.
(3) Assuming that the first-round action threshold value of the system low-frequency load shedding is 49.0Hz, in order to avoid the low-frequency load shedding action, the maximum value threshold value delta f of the transient frequency deviation is taken tc Is-1.0 Hz;
(4) generally, it is considered that the dynamic process of the system frequency is finished after 2min, and the frequency should be stable and maintained at a constant frequency, and no continuous periodic fluctuation occurs, i.e. the frequency change rate tends to 0.
According to steady state frequency deviation constraints
Obtaining available FM capacity delta P Gmax Not less than 8.8%, Δ f is set in this example lim At 0.15Hz, at which K G Must be greater than 29.4, whereby K G >29.4 is the A1 region.
According to maximum value constraint of frequency change rate
System inertia time constant T j It is required not to fall below 5s, whereby T j >5 is the A2 region.
Because the analytic solution of the transient frequency deviation is difficult to solve after the amplitude limiting link is introduced, a system frequency dynamic curve is obtained through model value iterative solution according to an improved model and a polymerization equivalent parameter method shown in fig. 3, the frequency deviation corresponding to the lowest/high point on the curve is the maximum value of the transient frequency deviation, and whether the system oscillates can be judged according to the curve shape.
Under different values of inertia time constant, the frequency modulation coefficient is adjusted to make the maximum value of the transient frequency deviation of the system just equal to the threshold value delta f tc And determining a feasible region A3. Similarly, under different values of inertia time constant, the frequency modulation coefficient is adjusted to ensure that the system does not oscillate, and a feasible region A4 meeting the frequency oscillation can be determined. The intersection a of A1, A2, A3 and A4 is taken, and the obtained inertia-primary frequency modulation capacity combined requirement is shown in fig. 7.
Fig. 8 is a schematic structural diagram of a system 800 for jointly determining inertia-primary modulation capability requirements of an electric power system according to an embodiment of the present invention. As shown in fig. 8, a system 800 for jointly determining inertia-primary modulation capability requirement of an electrical power system according to an embodiment of the present invention includes: model parameter determination units 801, T j A K-plane establishing unit 802, a first feasible region determining unit 803, a second feasible region determining unit 804, a maximum value of transient frequency deviation determining unit 805, a third feasible region determining unit 806, a fourth feasible region determining unit 807, and a demand determining unit 808.
Preferably, the model parameter determining unit 801 is configured to acquire power system operation data, and determine a model parameter based on the power system operation data and a system frequency response analysis model.
Preferably, the model parameter determining unit 801, based on the power system operation data and the system frequency response analysis model, determines the model parameters, including:
where α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the equivalent inertia time constant of the system; s GNi Capacity of the ith grid-connected synchronous machine; t is ji The inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s. the L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k is G The equivalent power generation frequency modulation coefficient; />
Average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is calculated; />
Is the average available frequency modulation capacity ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameters of the ith grid-connected synchronous machine; and n is the number of the units.
Preferably, said T j A K-plane establishing unit 802 for establishing a system equivalent inertia time constant and an equivalent power generation based on the system equivalent inertia time constant and the equivalent power generation in the model parametersFrequency modulation coefficient establishment T representing inertia-primary frequency modulation capability requirement j -K plane.
Preferably, the first feasible region determining unit 803 is configured to determine a first analytical relationship based on a frequency steady-state deviation constraint at T j -determining a first feasible region on the K plane.
Preferably, the first feasible region determining unit 803 is configured to determine the first feasible region at T based on a first analytic relationship constrained by a steady-state deviation of frequency j -determining a first feasible region on the K plane, comprising:
at the T j -the first feasible region in the K plane satisfies:
Δf s ≤Δf sc ，
wherein, Δ P Gmax Available frequency modulation capacity for equivalent power generation; k G The equivalent power generation frequency modulation coefficient; Δ f s Is a steady state frequency deviation; Δ f sc Is a preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k is L Is the load frequency modulation coefficient; Δ f lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
Preferably, the second feasible region determining unit 804 is configured to determine a second analytic relationship based on a frequency change rate maximum constraint at T j -determining a second feasible region on the K plane.
Preferably, the second feasible region determining unit 804 determines the second analysis relationship based on the maximum frequency change rate constraint at T j -determining a second feasible region on the K-plane, comprising:
at the T j -the second feasible region in the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is j Is the system equivalent inertia time constant.
Preferably, the maximum transient frequency deviation determining unit 805 is configured to determine a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determine a maximum transient frequency deviation according to the current system frequency dynamic curve.
Preferably, the third feasible region determining unit 806 is configured to determine the value of the current transient frequency deviation at T when the value is equal to a preset transient frequency deviation threshold, and the value is maximum j -determining a third feasible region on the K plane.
Preferably, the third feasible region unit 806 is further configured to:
when the maximum value of the current transient frequency deviation is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is determined again, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value of the transient frequency deviation is determined at T j -determining a third feasible region on the K plane.
Preferably, the fourth feasible region determining unit 807 is configured to determine the current system frequency dynamic curve at T when the current system frequency dynamic curve satisfies the oscillation constraint j -determining a fourth feasible region on the K plane.
Preferably, wherein the fourth feasible region unit 807 is further configured to:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to ensure that the system does not oscillate and the system does not oscillate at the T j -determining a fourth feasible region on the K plane.
Preferably, the requirement determining unit 808 is configured to determine the system inertia-primary frequency modulation capability requirement based on an intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
Based on another aspect of the invention, a computer-readable storage medium is provided, having stored thereon a computer program which, when being executed by a processor, carries out the steps of any one of the methods for jointly determining a power system inertia-primary modulation capability requirement.
Based on another aspect of the present invention, the present invention provides an electronic device comprising:
the computer-readable storage medium described above; and
one or more processors to execute the program in the computer-readable storage medium.
The system 800 for jointly determining the inertia-primary frequency modulation capability requirement of the power system according to the embodiment of the present invention corresponds to the method 100 for jointly determining the inertia-primary frequency modulation capability requirement of the power system according to another embodiment of the present invention, and is not described herein again.
Based on another aspect of the invention, a computer-readable storage medium is provided, having stored thereon a computer program which, when being executed by a processor, carries out the steps of any one of the methods for jointly determining a power system inertia-primary modulation capability requirement.
Based on another aspect of the present invention, the present invention provides an electronic device comprising:
the computer-readable storage medium described above; and
one or more processors to execute the program in the computer-readable storage medium.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (14)
1. A method for jointly determining inertia-primary modulation capability requirements of a power system is characterized by comprising the following steps:
acquiring power system operation data, and determining model parameters based on the power system operation data and a system frequency response analysis model;
establishing T representing inertia-primary frequency modulation capability requirement based on system equivalent inertia time constant and equivalent power generation frequency modulation coefficient in model parameters j -a K plane; wherein, T j Representing inertia requirement, and K representing primary frequency modulation capability requirement;
a first analytical relationship based on a frequency steady state deviation constraint, at said T j -determining a first feasible region on the K plane;
a second analytical relationship based on a frequency rate of change maximum constraint, at said T j -determining a second feasible region on the K plane;
determining a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determining a maximum value of transient frequency deviation according to the current system frequency dynamic curve;
when the maximum value of the current transient frequency deviation is equal to a preset transient frequency deviation threshold value, at T j -determining a third feasible region on the K plane;
when the current system frequency dynamic curve meets the oscillationWhen constrained, at said T j -determining a fourth feasible region on the K plane;
and determining the system inertia-primary frequency modulation capacity requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
2. The method of claim 1, wherein determining model parameters based on the power system operating data and a system frequency response analysis model comprises:
wherein α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the equivalent inertia time constant of the system; s GNi Capacity of the ith grid-connected synchronous machine; t is ji The inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k G The equivalent power generation frequency modulation coefficient;
average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available modulated capacity for equivalent power generation; Δ p i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is obtained; />
Is the average available frequency modulation capacity ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameters of the ith grid-connected synchronous machine; and n is the number of the units.
3. The method of claim 1, wherein the first analytical relationship based on a frequency steady state deviation constraint is at T j -determining a first feasible region on the K-plane, comprising:
at the T j -the first feasible region on the K plane satisfies:
wherein, Δ P Gmax Available frequency modulation capacity for equivalent power generation; k G The equivalent power generation frequency modulation coefficient; Δ f s Is a steady state frequency deviation; Δ f sc Is a preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k L Load frequency modulation coefficient; Δ f lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
4. The method of claim 1, wherein the second analytical relationship based on a frequency rate of change maximum constraint is at the T j -determining a second feasible region on the K-plane, comprising:
at the T j -the second feasible region in the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is j Is the system equivalent inertia time constant.
5. The method of claim 1, further comprising:
when the maximum value of the current transient frequency deviation is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is re-determined, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value of the transient frequency deviation is determined at T j -determining a third feasible region on the K plane.
6. The method of claim 1, further comprising:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to ensure that the system does not oscillate and the system does not oscillate at the T j -determining a fourth feasible region on the K plane.
7. A system for jointly determining an inertia-primary modulation capability requirement of an electrical power system, the system comprising:
the model parameter determining unit is used for acquiring the operating data of the power system and determining model parameters based on the operating data of the power system and a system frequency response analysis model;
T j -a K-plane building unit for building a model based on the system in the model parametersT for establishing characteristic inertia-primary frequency modulation capability requirement by integrating equivalent inertia time constant and equivalent power generation frequency modulation coefficient j -K plane wherein T j Representing inertia requirements, and K representing primary frequency modulation capacity requirements; (ii) a
A first feasible region determining unit, configured to determine a first analytic relationship based on a frequency steady-state deviation constraint at the T j -determining a first feasible region on the K plane;
a second feasible region determining unit for determining a second analytic relationship based on frequency change rate maximum constraint at the T j -determining a second feasible region on the K plane;
the transient frequency deviation maximum value determining unit is used for determining a system frequency dynamic curve based on the system equivalent inertia time constant and the equivalent power generation frequency modulation coefficient, and determining a transient frequency deviation maximum value according to the current system frequency dynamic curve;
a third feasible region determination unit for determining a current transient frequency deviation maximum value at T when the current transient frequency deviation maximum value is equal to a preset transient frequency deviation threshold value j -determining a third feasible region on the K plane;
a fourth feasible region determining unit, configured to determine the current system frequency dynamic curve at the T when the current system frequency dynamic curve satisfies the oscillation constraint j -determining a fourth feasible region on the K plane;
and the requirement determining unit is used for determining the system inertia-primary frequency modulation capability requirement based on the intersection of the first feasible region, the second feasible region, the third feasible region and the fourth feasible region.
8. The system of claim 7, wherein the model parameter determination unit determines model parameters based on the power system operating data and a system frequency response analysis model, comprising:
wherein α represents a ratio of the power generation capacity to the load capacity, i.e., a power generation load ratio, T j Is the equivalent inertia time constant of the system; s. the GNi The capacity of the ith grid-connected synchronous machine is set; t is ji The inertia time constant of the ith grid-connected synchronous machine is obtained;
the average inertia time constant of the grid-connected synchronous machine is obtained; s L Is the load capacity; k Gi Adjusting a frequency coefficient for the ith grid-connected synchronous machine; k G The equivalent power generation frequency modulation coefficient;
average frequency modulation coefficient of the grid-connected synchronous machine; delta P Gmax Available frequency modulation capacity for equivalent power generation; Δ p i The proportion of the available frequency modulation capacity of the ith grid-connected synchronous machine to the rated capacity of the unit is calculated; />
Is the average available frequency modulation capacity ratio; x represents a governor equivalent parameter, including: proportional coefficient K of oil-driven machine m And the opening/closing time constant T of the servomotor m Time constant T of stroke feedback link of servomotor L Natural overshoot coefficient lambda of high-pressure cylinder power and high-pressure cylinder power proportion F HP Reheater time constant T RH And vapor volume time constant T CH (ii) a Subscript i represents the parameter of the ith grid-connected synchronous machine; and n is the number of the units.
9. The system of claim 7, wherein the first feasible region determination unit is configured to determine the first feasible region based on a first analytical relationship constrained by a steady-state deviation of frequency at the T j -determining a first feasible region on the K-plane, comprising:
at the T j -the first feasible region in the K plane satisfies:
wherein, Δ P Gmax Available frequency modulation capacity for equivalent power generation; k G The equivalent power generation frequency modulation coefficient; Δ f s Is a steady state frequency deviation; Δ f sc A preset steady-state frequency deviation threshold; delta P d Is the disturbance power; k L Load frequency modulation coefficient; Δ f lim The frequency deviation corresponding to the maximum available frequency modulation capacity.
10. The system according to claim 7, wherein the second feasible region determining unit determines the second analytic relationship at the T based on a frequency change rate maximum constraint j -determining a second feasible region on the K-plane, comprising:
at the T j -the second feasible region in the K plane satisfies:
wherein, the frequency change rate maximum value (df/dt) max Less than a predetermined frequency rate of change threshold (df/dt) c ；ΔP d Is the disturbance power; t is a unit of j Is the system equivalent inertia time constant.
11. The system of claim 7, wherein the third feasible region unit is further configured to:
when the current transient frequency deviationWhen the maximum value is not equal to the preset transient frequency deviation threshold value, the inertia time constant is kept unchanged, the equivalent power generation frequency modulation coefficient is adjusted, the system frequency dynamic curve is determined again, the maximum value of the transient frequency deviation is determined according to the current system frequency dynamic curve until the maximum value of the current transient frequency deviation is equal to the preset transient frequency deviation threshold value, and the maximum value is determined at T j -determining a third feasible region on the K plane.
12. The system of claim 7, wherein the fourth feasible region unit is further configured to:
when the current system frequency dynamic curve does not meet the oscillation constraint, the inertia time constant is kept unchanged, and the equivalent power generation frequency modulation coefficient is adjusted to ensure that the system does not oscillate and the system does not oscillate at the T j -determining a fourth feasible region on the K plane.
13. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 6.
14. An electronic device, comprising:
the computer-readable storage medium recited in claim 13; and
one or more processors to execute the program in the computer-readable storage medium.
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