CN110504694B - Frequency modulation parameter acquisition method and device, computer equipment and readable storage medium - Google Patents
Frequency modulation parameter acquisition method and device, computer equipment and readable storage medium Download PDFInfo
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Abstract
The application provides a method and a device for acquiring frequency modulation parameters, computer equipment and a readable storage medium, wherein the method comprises the following steps: the method comprises the steps of obtaining an optimization objective function of a frequency modulation parameter obtaining model of the flexible direct current transmission interconnected power grid system, determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct current transmission interconnected power grid systems, obtaining a frequency modulation parameter obtaining model of the flexible direct current transmission interconnected power grid system according to the optimization objective function and the constraint conditions, solving the frequency modulation parameter obtaining model to obtain comprehensive performance indexes, and determining frequency modulation parameters according to the comprehensive performance indexes.
Description
Technical Field
The present application relates to the field of power system operation, and in particular, to a method and an apparatus for obtaining frequency modulation parameters, a computer device, and a readable storage medium.
Background
With the gradual merging of new energy electric fields, the scale of the power system is continuously enlarged, and the form of the power system is gradually changed to the interconnection of a multi-region power grid.
In the traditional technology, alternating current transmission technology is adopted among all regional alternating current subsystems, and frequency modulation parameter acquisition of a multi-regional system can be realized. However, the conventional techniques cannot make reasonable use of frequency modulation of each regional system, thereby reducing the frequency stability of the multi-regional system.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a method, an apparatus, a computer device and a readable storage medium for acquiring frequency modulation parameters, which can improve frequency stability of a multi-zone system.
The embodiment of the application provides a frequency modulation parameter acquisition method, which comprises the following steps:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
In one embodiment, the obtaining an optimized objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected grid system includes: and obtaining the optimized objective function according to the normalized stable frequency deviation of the flexible direct-current power transmission interconnected grid system, the normalized frequency modulation active power unbalance degree during frequency adjustment and the weight coefficient.
In one embodiment, the method further comprises:
obtaining stable frequency deviation of a key load subsystem contained in the flexible direct current transmission interconnected power grid system;
acquiring frequency modulation active power distributed by different frequency modulation resources when adjusting frequency;
obtaining an imbalance index of the frequency modulation active power according to the frequency modulation active power;
normalizing the stable frequency deviation and the frequency modulation active power unbalance index to obtain a normalization function;
and obtaining the normalized stable frequency deviation and the normalized frequency modulation active power imbalance degree when the frequency is adjusted according to the normalization function.
In one embodiment, the determining a constraint condition corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload, and the power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems includes:
and determining the constraint condition according to the active power output by the unit, the node voltage of an alternating current subsystem, the node voltage of a direct current subsystem, the capacity overload of the transmission line of the alternating current subsystem, the capacity overload of the transmission line of the direct current subsystem, the positive frequency deviation of the power grid system and the negative frequency deviation of the power grid system in different flexible direct current transmission interconnected power grid systems.
In one embodiment, the obtaining the frequency modulation parameter obtaining model of the flexible dc power transmission interconnected grid system according to the optimization objective function and the constraint condition includes:
and performing fusion processing on the optimization objective function, the constraint condition and the power flow constraint equation of the flexible direct-current power transmission interconnected grid system to obtain the frequency modulation parameter acquisition model of the flexible direct-current power transmission interconnected grid system.
In one embodiment, the solving the frequency modulation parameter obtaining model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index includes:
and solving the frequency modulation parameter acquisition model by using the comprehensive performance index as an optimization target and adopting a Newton-Raphson algorithm to obtain the comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
In one embodiment, the determining the frequency modulation parameter according to the comprehensive performance index includes:
according to the comprehensive performance index, adjusting the variable of the alternating current subsystem, the variable of the direct current subsystem and the loss variable of the flexible direct current transmission converter station in the flexible direct current transmission interconnected power grid system, and continuously updating the comprehensive performance index according to an adjustment result to obtain an optimal comprehensive performance index;
and determining the optimal frequency modulation parameters according to the optimal comprehensive performance index.
The embodiment of the application provides a frequency modulation parameter acquisition device, the device includes:
the system comprises an acquisition module, a frequency modulation parameter acquisition module and a frequency modulation parameter acquisition module, wherein the acquisition module is used for acquiring an optimization objective function of a frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system, and the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
the determining module is used for determining constraint conditions corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload and the power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
the fusion module is used for obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system according to the optimization objective function and the constraint condition;
and the solving module is used for solving the frequency modulation parameter obtaining model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
The embodiment of the application provides a computer device, which comprises a memory and a processor, wherein a computer program capable of running on the processor is stored in the memory, and the processor executes the computer program to realize the following steps:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
An embodiment of the application provides a readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, implements the following steps:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
In order to perform frequency adjustment in a flexible dc-interconnected multi-zone ac power system by using local frequency modulation resources or other regional grid frequency modulation resources interconnected by a flexible dc power transmission line, so as to ensure stable frequency of each ac subsystem, and implement adaptive tracking of net load fluctuation of power grid system generated power, the method, device, computer device, and readable storage medium according to the embodiments of the present invention, can obtain frequency modulation parameters during a frequency adjustment process, and further perform frequency adjustment of a multi-zone system according to the frequency modulation parameters, so as to improve frequency stability of the multi-zone system.
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Fig. 1 is a schematic flow chart of a method for acquiring frequency modulation parameters according to an embodiment;
fig. 2 is a schematic view of a detailed flow chart of a method for acquiring frequency modulation parameters according to another embodiment;
fig. 3 is a schematic structural diagram of a frequency modulation parameter obtaining apparatus according to an embodiment;
FIG. 4 is an internal block diagram of a computer device, provided in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.
The frequency modulation parameter obtaining method provided by the embodiment can be applied to computer equipment. The computer device may be an electronic device with a data processing function, such as a smart phone, a tablet computer, a notebook computer, a desktop computer, or a personal digital assistant, and the specific form of the computer device is not limited in this embodiment.
It should be noted that, in the frequency modulation parameter obtaining method provided in the embodiment of the present invention, the execution main body may be a frequency modulation parameter obtaining apparatus, and the apparatus may be implemented as part or all of a computer device by software, hardware, or a combination of software and hardware. Optionally, the computer device may be an electronic device with a data processing function, such as a smart phone, a tablet computer, a notebook computer, a desktop computer, or a personal digital assistant, and the specific form of the computer device is not limited in this embodiment. The execution subjects of the method embodiments described below are described taking a computer device as an example.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention are further described in detail by the following embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 1 is a schematic flow chart of a method for acquiring frequency modulation parameters according to an embodiment. The embodiment relates to a process for acquiring frequency modulation parameters in a frequency adjustment process of a multi-region asynchronous interconnected power grid system. As shown in fig. 1, the method may include the steps of:
s101, obtaining an optimization objective function of a frequency modulation parameter obtaining model of the flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment.
The step of obtaining an optimized objective function of a frequency modulation parameter obtaining model of the flexible direct current power transmission interconnected grid system may specifically include: and obtaining the optimized objective function according to the normalized stable frequency deviation of the flexible direct-current power transmission interconnected grid system, the normalized frequency modulation active power unbalance degree during frequency adjustment and the weight coefficient.
Specifically, the values of the normalized frequency modulation increase or decrease active power imbalance degree and the normalized stable frequency deviation in the frequency adjustment process can be 0-1. In the present embodiment, the above-mentioned optimization objective function Obj can be characterized by formula (1), i.e.
Obj＝λ1·gΔf+λ2·gPS (1)；
Wherein λ is1And λ2Are all weight coefficients, and the weight coefficient is lambda1And λ2The sum may be equal to 1, gΔfThe normalized stable frequency deviation, g, can be characterizedPSThe normalized frequency modulation increase or decrease active power imbalance degree when the frequency is adjusted can be represented.
It should be noted that, the optimization objective function Obj can also be characterized by an optimal overall performance index. Optionally, the above-mentioned overall performance index may consider two aspects, on one hand, when a frequency event occurs, different frequency modulation resources output active power by adjusting so that the frequency deviation of the ac subsystem is small, and on the other hand, for frequency events at different positions and with different power shortage, different frequency modulation resources may reasonably allocate active power adjustment amounts according to their own adjustment capacities or other economic operation indexes, that is, on the one hand, the operation index of the power grid system is reflected, and on the other hand, the economy of the power grid system is reflected.
And S102, determining constraint conditions corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload and the power grid system frequency deviation of different flexible direct current transmission interconnected power grid systems.
Specifically, when different flexible direct-current transmission interconnected power grid systems operate, the operating constraints of unit output, node voltage, transmission line capacity overload and power grid system frequency deviation can be different. Optionally, the constraint condition corresponding to the frequency adjustment of the power grid system may be obtained according to the operation constraints of different flexible direct-current transmission interconnected power grid systems, such as the output of the unit, the node voltage, the capacity overload of the power transmission line, the frequency deviation of the power grid system, and the like.
S103, obtaining the frequency modulation parameter acquisition model of the flexible direct current transmission interconnected power grid system according to the optimization objective function and the constraint condition.
Specifically, the computer device may combine the optimization objective function obtained in step S101 and the constraint condition corresponding to the optimization objective function obtained in step S102 to obtain a frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system.
S104, solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
Specifically, the frequency modulation parameter obtaining model may be a set of nonlinear equations, and the method for solving the nonlinear equations may be an iteration method, a quadratic interpolation method, a chebyshev iteration method, an attenken acceleration method, or the like. Optionally, the computer device may determine the frequency modulation parameter according to the optimized comprehensive performance index.
The method for obtaining frequency modulation parameters, the device, the computer equipment and the readable storage medium provided by the embodiment are used for obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected grid system, determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, power transmission line capacity overload and grid system frequency deviation of different flexible direct current power transmission interconnected grid systems, obtaining the frequency modulation parameter obtaining model of the flexible direct current power transmission interconnected grid system according to the optimization objective function and the constraint conditions, solving the frequency modulation parameter obtaining model to obtain comprehensive performance indexes, and determining the frequency modulation parameters according to the comprehensive performance indexes, so that frequency modulation is performed by using local frequency modulation resources or other regional power grid resources interconnected by the flexible direct current power transmission lines in a flexible direct current interconnected multi-region alternating current power system, the method can acquire frequency modulation parameters in the frequency adjustment process, and further carry out frequency adjustment of the multi-region system according to the frequency modulation parameters so as to improve the frequency stability of the multi-region system.
Fig. 2 is a schematic specific flow chart of a frequency modulation parameter obtaining method according to another embodiment, as shown in fig. 2, before the step of obtaining the optimized objective function of the frequency modulation parameter obtaining model of the flexible direct current power transmission interconnected grid system in S101, the method may further include the following steps:
and S105, obtaining the stable frequency deviation of the flexible direct current transmission interconnected power grid system including the key load subsystem.
Specifically, the flexible dc power transmission interconnected grid system may include a plurality of different subsystems, and each subsystem may include a different load. Optionally, in the flexible direct-current transmission interconnected power grid system, different stable frequency deviations β including the critical load subsystemΔfCan be kept within a certain reasonable range. Optionally, the stable frequency deviation β of the critical load subsystem in different regions of different flexible dc power transmission interconnected grid systemsΔfThe reasonable range to be maintained may be different, and the reasonable range may be determined according to national grid standards.
It should be noted that if a plurality of stable frequency deviations β including the critical load sub-system are includedΔfAll kept within a certain reasonable range, then the frequency deviation beta can be stabilized from a plurality ofΔfSelecting the minimum stable negative frequency deviation betaΔf-Or maximum stable positive frequency offset betaΔf+I.e. characterized by formula (2) and formula (3), respectively:
wherein i canThe flexible direct current transmission interconnected power grid system is characterized by comprising the number of key load subsystems, i.e. i can be equal to 1,2, …, NAC。
S106, acquiring frequency modulation active power distributed by different frequency modulation resources when the frequency is adjusted.
Specifically, the capacity of increasing or decreasing the active power of different frequency modulation resources in different regions and different types during the frequency adjustment may be different, and the frequency modulation increasing or decreasing active power that needs to be reasonably allocated for different frequency modulation resources may also be different. Optionally, the frequency modulation active power may represent a frequency modulation increase or decrease active power P.
It should be noted that N is in the grid systemGThe proportion of the active power P of the frequency modulation increasing or decreasing of the individual units can be represented by formula (4), wherein kp1，kp2，…，kpNGThe expected active power distribution proportion can be represented, the specific numerical values of the distribution proportion can be corrected according to the rated capacity, the spare capacity, the adjustment cost and the like of the frequency modulation resource, and the formula (4) is
And S107, obtaining the imbalance index of the frequency modulation active power according to the frequency modulation active power.
In this embodiment, the active power imbalance indicator β can be modulated by frequency modulationPSThe deviation of the proportion of the frequency modulation increasing or decreasing active power P and the expected adjustment power of different frequency modulation resources during the frequency adjustment is represented by a formula (5); wherein, betaPSThe method can represent the unbalanced distribution of the active power of the frequency modulation resources, and can also represent that the power variation of different frequency modulation resources in the frequency modulation period conforms to the expected distribution proportion, betaPSMay be as
And S108, carrying out normalization processing on the stable frequency deviation and the frequency modulation active power unbalance index to obtain a normalization function.
Specifically, the computer device may adopt a normalization function to correct the stable frequency deviation β of the critical load subsystem in the flexible dc power transmission interconnected grid systemΔfAnd the index beta of the imbalance of active power of frequency modulationPSAnd (6) carrying out normalization processing.
In this embodiment, the normalization function may include two types, which are respectively characterized by formula (6) and formula (7), i.e.
Wherein, tau1And τ2The attenuation coefficient can be characterized, and the calculation method can be characterized by formula (8) and formula (9); beta can represent the original value of the variable before normalization and the stable frequency deviation betaΔfAnd the frequency modulation active power imbalance indicator betaPSβ in the normalization function may be substituted; beta is a0A reference value for the normalization variable can be characterized, and can be determined according to national grid standards,
in addition, β issReference values for another normalizing variable can be characterized if β is taken as βsTime, normalization function gN1Or gN2The value may be equal to 0.95. Optionally, the closer the normalization function value is to 1, the corresponding performance indexThe better the quality; if beta is beta0The time performance index is 0, and the corresponding performance index is poor. Wherein, if the original variable value is larger and the performance index is better, the normalization function can select gN1(ii) a If the original variable value is smaller and the performance index is better, the normalization function can select gN2。
It can be appreciated that the steady negative frequency deviation betaΔf-When larger, the frequency deviation beta is stabilizedΔfThe absolute value is small, the characteristic frequency adjustment performance is good, and the corresponding normalization function can be gN1Conversely, the positive frequency offset difference β is stabilizedΔf+When smaller, the frequency modulation active power imbalance index betaPSThe characteristic frequency adjustment performance is better at the moment, and the corresponding normalization function can be gN2。
S109, obtaining the normalized stable frequency deviation and the normalized frequency modulation active power unbalance degree when the frequency is adjusted according to the normalization function.
Specifically, different normalization variables are substituted into the normalization function gN1And gN2In (3), a normalized variable expression can be obtained as shown in equations (10) to (12).
The method, apparatus, computer device and readable storage medium for obtaining frequency modulation parameters provided in this embodiment, performs normalization processing on a stable frequency deviation and a normalized frequency modulation active power imbalance degree when adjusting frequency, further obtains an optimization objective function through the obtained normalized stable frequency deviation and the normalized frequency modulation active power imbalance degree when adjusting frequency, determines a constraint condition corresponding to the optimization objective function, obtains a frequency modulation parameter obtaining model of a flexible dc power transmission interconnected grid system according to the optimization objective function and the constraint condition, solves the frequency modulation parameter obtaining model to obtain a comprehensive performance index, and then determines frequency modulation parameters according to the comprehensive performance index, so as to perform frequency modulation in a flexible dc interconnected multi-region ac power system by using local frequency modulation resources or other regional power grid resources interconnected by a flexible dc power transmission line, the method can acquire frequency modulation parameters in the frequency adjustment process, and further carry out frequency adjustment of the multi-region system according to the frequency modulation parameters so as to improve the frequency stability of the multi-region system.
In one embodiment, the step of determining the constraint condition corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload, and the power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems in S102 specifically includes: and determining the constraint condition according to the active power output by the unit, the node voltage of an alternating current subsystem, the node voltage of a direct current subsystem, the capacity overload of the transmission line of the alternating current subsystem, the capacity overload of the transmission line of the direct current subsystem, the positive frequency deviation of the power grid system and the negative frequency deviation of the power grid system in different flexible direct current transmission interconnected power grid systems.
In particular, the method comprises the following steps of,
(1) for the flexible direct-current transmission interconnected power grid system, the active power P output by any ith synchronous machine set, wind turbine generator set, photovoltaic module or energy storage device and other machine sets can meet the constraint condition, namely
0≤PGi≤PGi,max (13)；
Wherein, PGiCan characterize the output of the ith unit, PGi,maxThe maximum output of the ith unit can be characterized. Optionally, synchronous generator set, wind turbine generator set, photovoltaic module or energy storage device and other generator setsThe corresponding numbers are not deterministic, however, there may only be one corresponding number per unit.
(2) For any ith node in the flexible direct current transmission interconnected power grid system, the voltage of the ith node needs to meet the safe operation range, and the node voltage constraint of the alternating current subsystem and the node voltage constraint of the direct current subsystem can be respectively expressed as follows:
wherein, Vi、Vi,minAnd Vi,maxThe voltage, the lower voltage limit and the upper voltage limit of the ith node can be respectively represented; b isACAnd BDCThe alternating current subsystem node set and the direct current subsystem node set can be characterized respectively. Optionally, there is no corresponding relationship between the nodes and the units, and one node may be accessed to multiple units or not accessed to any unit.
(3) For any power transmission line connecting the node i and the node j in the flexible direct-current power transmission interconnected power grid system, the power transmission line capacity overload constraint needs to be considered, and the power transmission line capacity overload constraint of the alternating-current subsystem and the capacity overload constraint of the direct-current subsystem can be respectively expressed as follows:
wherein S isijAnd Sij,maxCan represent the upper limit of the power and the transmission capacity of the alternating current transmission line, PDCijAnd PDCij,maxThe upper limit of the power and the transmission capacity of the direct current transmission line can be represented.
(4) In a flexible direct-current transmission interconnected power grid system, if a large-frequency event occurs, in order to prevent the power grid system from generating low-frequency load shedding or high-frequency generator tripping, the power grid system stabilizes the negative frequency deviation betaΔf-May be greater than a preset minimum low frequency threshold beta0_Δf-To stabilize the positive frequency deviation betaΔf+May be less than a maximum high frequency threshold beta0_Δf+The corresponding low and high frequency constraints can be expressed by equations (18) and (19), i.e.
βΔf-≥β0_Δf- (18)；
βΔf+≤β0_Δf+ (19)。
Optionally, the step of obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system according to the optimization objective function and the constraint condition in S103 may specifically include: and performing fusion processing on the optimization objective function, the constraint condition and the power flow constraint equation of the flexible direct-current power transmission interconnected grid system to obtain the frequency modulation parameter acquisition model of the flexible direct-current power transmission interconnected grid system.
It should be noted that the power flow constraint equation of the flexible direct current transmission interconnected power grid system can be expressed by the formula (20), that is, the power flow constraint equation
Wherein f isACCan represent a set of equations, f, associated with the AC subsystemDCCan represent a set of equations, f, associated with the DC subsystemACDCA set of equations relating to the flexible dc transmission converter station may be expressed. Meanwhile, the unbalance equation can comprise an unbalance equation of an alternating current subsystem, an unbalance equation of a direct current subsystem and a loss unbalance equation of the flexible direct current transmission converter station. In addition, the above x may be equal to [ x ]AC,xDC,xcL]，xACCan be equal to
xDCMay be equal to VDC，xcLMay be equal to PcL。
It can be understood that the power flow constraint equation of the flexible direct current transmission interconnected grid system can also be referred to as an unbalance equation. Optionally, the imbalance equation is expanded according to taylor series, and a power flow equation for frequency adjustment of the asynchronous interconnected power grid system can be obtained, that is, the power flow equation is obtained
Wherein, Δ PAC、ΔQAC、ΔPDC、ΔPACDCAnd Δ DACDCThe method can respectively express an active power unbalance equation of an alternating current subsystem, a reactive power unbalance equation of the alternating current subsystem, a power unbalance equation of a direct current subsystem, an active power conservation equation of a flexible direct current transmission converter station and a droop control strategy equation of the flexible direct current transmission converter station, and J can be called as a Jacobian matrix.
It will also be appreciated that the fusion process described above may characterize the binding process and is not substantial fusion. Optionally, the computer device may perform fusion processing on the optimization objective function, the constraint condition, and the power flow constraint equation of the flexible direct-current transmission interconnected grid system to obtain a frequency modulation parameter acquisition model of the flexible direct-current transmission interconnected grid system, which is expressed by a formula (22), that is, the frequency modulation parameter acquisition model is expressed by a formula (22)
Wherein, f (x) can represent a power flow constraint equation of the flexible direct current transmission interconnected power grid system.
In order to perform frequency adjustment in a flexible dc-interconnected multi-zone ac power system by using local frequency modulation resources or other regional grid frequency modulation resources interconnected by a flexible dc power transmission line, so as to ensure stable frequency of each ac subsystem, and implement adaptive tracking of net load fluctuation of power grid system generated power, the method, device, computer device, and readable storage medium according to the embodiments of the present invention, can obtain frequency modulation parameters during a frequency adjustment process, and further perform frequency adjustment of a multi-zone system according to the frequency modulation parameters, so as to improve frequency stability of the multi-zone system.
In one embodiment, the step of solving the frequency modulation parameter obtaining model in S104 to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index may include: and solving the frequency modulation parameter acquisition model by using the comprehensive performance index as an optimization target and adopting a Newton-Raphson algorithm to obtain the comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
The step of determining the frequency modulation parameter according to the comprehensive performance index may specifically include: according to the comprehensive performance index, adjusting the variable of the alternating current subsystem, the variable of the direct current subsystem and the loss variable of the flexible direct current transmission converter station in the flexible direct current transmission interconnected power grid system, and continuously updating the comprehensive performance index according to an adjustment result to obtain an optimal comprehensive performance index; and determining the optimal frequency modulation parameters according to the optimal comprehensive performance index.
In this embodiment, the comprehensive performance index in the frequency modulation parameter acquisition model is used as an optimization target, and the frequency modulation parameter acquisition model is solved by using a newton-raphson algorithm to obtain an optimal comprehensive performance index. Optionally, the larger the value of the comprehensive performance index is, the better the comprehensive performance index is. Optionally, the computer device may continuously and cyclically adjust the variable of the ac subsystem, the variable of the dc subsystem, and the loss variable of the flexible dc transmission converter station in the flexible dc transmission interconnected grid system according to the comprehensive performance index to change the power flow constraint equation of the flexible dc transmission interconnected grid system, further continuously update the comprehensive performance index according to the adjustment result to obtain an optimal comprehensive performance index, and determine an optimal frequency modulation parameter in the variable adjustment process according to the optimal comprehensive performance index. Optionally, in an optimal case, a value of the optimal comprehensive performance index may be equal to 1.
In order to perform frequency adjustment in a flexible dc-interconnected multi-zone ac power system by using local frequency modulation resources or other regional grid frequency modulation resources interconnected by a flexible dc power transmission line, so as to ensure stable frequency of each ac subsystem, and implement adaptive tracking of net load fluctuation of power grid system generated power, the method, device, computer device, and readable storage medium according to the embodiments of the present invention, can obtain frequency modulation parameters during a frequency adjustment process, and further perform frequency adjustment of a multi-zone system according to the frequency modulation parameters, so as to improve frequency stability of the multi-zone system.
It should be understood that although the various steps in the flowcharts of fig. 1-2 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 1-2 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performing the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.
For the specific definition of the frequency modulation parameter obtaining device, reference may be made to the above definition of the frequency modulation parameter obtaining method, which is not described herein again. All or part of the modules in the frequency modulation parameter acquisition device in the computer equipment can be realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
Fig. 3 is a schematic structural diagram of a frequency modulation parameter obtaining apparatus according to an embodiment. As shown in fig. 3, the apparatus may include: an acquisition module 11, a determination module 12, a fusion module 13, and a solution module 14.
Specifically, the obtaining module 11 is configured to obtain an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct-current power transmission interconnected grid system, where the optimization objective function includes a normalized stable frequency deviation of the flexible direct-current power transmission interconnected grid system and a normalized frequency modulation active power imbalance degree when adjusting a frequency;
the determining module 12 is configured to determine a constraint condition corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload, and the power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
the fusion module 13 is configured to obtain the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system according to the optimization objective function and the constraint condition;
the solving module 14 is configured to solve the frequency modulation parameter obtaining model to obtain a comprehensive performance index, and determine the frequency modulation parameter according to the comprehensive performance index.
The frequency modulation parameter obtaining apparatus provided in this embodiment may implement the method embodiments, and the implementation principle and the technical effect are similar, which are not described herein again.
In one embodiment, a computer device is provided, the internal structure of which may be as shown in FIG. 4. The computer device includes a processor, a memory, a network interface, a display screen, and an input system connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The network interface of the computer device is used for communicating with an external terminal through a network connection. The computer program is executed by a processor to implement a method of frequency modulation parameter acquisition. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input system of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.
Those skilled in the art will appreciate that the configuration shown in fig. 4 is a block diagram of only a portion of the configuration associated with the present application and does not constitute a limitation on the computing device to which the present application may be applied, and that a particular computing device may include more or less components than those shown in fig. 4, or may combine certain components, or have a different arrangement of components.
In one embodiment, a computer device is provided, comprising a memory and a processor, the memory having a computer program stored therein, the processor implementing the following steps when executing the computer program:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
In one embodiment, a readable storage medium is provided, having stored thereon a computer program which, when executed by a processor, performs the steps of:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function comprises a normalized stable frequency deviation of the flexible direct current power transmission interconnected power grid system and a normalized frequency modulation active power imbalance degree during frequency adjustment;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, and determining the frequency modulation parameter according to the comprehensive performance index.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for acquiring frequency modulation parameters is characterized by comprising the following steps:
obtaining an optimization objective function of a frequency modulation parameter obtaining model of a flexible direct current power transmission interconnected power grid system, wherein the optimization objective function is used for carrying out weighted summation on a stable frequency deviation normalized by the flexible direct current power transmission interconnected power grid system, a frequency modulation active power imbalance normalized when the frequency is adjusted and a weight coefficient, and the flexible direct current power transmission interconnected power grid system comprises a plurality of alternating current subsystems;
determining constraint conditions corresponding to the optimization objective function according to unit output, node voltage, transmission line capacity overload and power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected power grid system according to the optimization objective function and the constraint condition;
and solving the frequency modulation parameter acquisition model to obtain a comprehensive performance index, adjusting the variable of an alternating current subsystem, the variable of a direct current subsystem and the loss variable of the flexible direct current transmission converter station in the flexible direct current transmission interconnected power grid system according to the comprehensive performance index, continuously updating the comprehensive performance index according to an adjustment result to obtain an optimal comprehensive performance index, and determining an optimal frequency modulation parameter according to the optimal comprehensive performance index.
2. The method of claim 1, further comprising:
obtaining stable frequency deviation of a key load subsystem contained in the flexible direct current transmission interconnected power grid system;
acquiring frequency modulation active power distributed by different frequency modulation resources when adjusting frequency;
obtaining an imbalance index of the frequency modulation active power according to the frequency modulation active power;
normalizing the stable frequency deviation and the frequency modulation active power unbalance index to obtain a normalization function;
and obtaining the normalized stable frequency deviation and the normalized frequency modulation active power imbalance degree when the frequency is adjusted according to the normalization function.
3. The method according to claim 1, wherein the determining the constraint condition corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload and the grid system frequency deviation of different flexible direct-current transmission interconnected grid systems comprises:
and determining the constraint condition according to the active power output by the unit, the node voltage of an alternating current subsystem, the node voltage of a direct current subsystem, the capacity overload of the transmission line of the alternating current subsystem, the capacity overload of the transmission line of the direct current subsystem, the positive frequency deviation of the power grid system and the negative frequency deviation of the power grid system in different flexible direct current transmission interconnected power grid systems.
4. The method according to claim 1, wherein obtaining the frequency modulation parameter acquisition model of the flexible direct current transmission interconnected grid system according to the optimization objective function and the constraint condition comprises:
and performing fusion processing on the optimization objective function, the constraint condition and the power flow constraint equation of the flexible direct-current power transmission interconnected grid system to obtain the frequency modulation parameter acquisition model of the flexible direct-current power transmission interconnected grid system.
5. The method of claim 1, wherein solving the frequency modulation parameter acquisition model to obtain a composite performance indicator comprises:
and solving the frequency modulation parameter acquisition model by using the comprehensive performance index as an optimization target and adopting a Newton-Raphson algorithm to obtain the comprehensive performance index.
6. A frequency modulation parameter acquisition apparatus, comprising:
the system comprises an acquisition module, a frequency modulation parameter acquisition module and a frequency modulation parameter acquisition module, wherein the acquisition module is used for acquiring an optimization objective function of a frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system, the optimization objective function is used for carrying out weighted summation on a normalized stable frequency deviation of the flexible direct current power transmission interconnected grid system, a normalized frequency modulation active power imbalance degree during frequency adjustment and a weight coefficient, and the flexible direct current power transmission interconnected grid system comprises a plurality of alternating current subsystems;
the determining module is used for determining constraint conditions corresponding to the optimization objective function according to the unit output, the node voltage, the transmission line capacity overload and the power grid system frequency deviation of different flexible direct-current transmission interconnected power grid systems;
the fusion module is used for obtaining the frequency modulation parameter acquisition model of the flexible direct current power transmission interconnected grid system according to the optimization objective function and the constraint condition;
and the solving module is used for solving the frequency modulation parameter obtaining model to obtain a comprehensive performance index, adjusting the variable of an alternating current subsystem, the variable of a direct current subsystem and the loss variable of the flexible direct current transmission converter station in the flexible direct current transmission interconnected power grid system according to the comprehensive performance index, continuously updating the comprehensive performance index according to an adjusting result to obtain an optimal comprehensive performance index, and determining an optimal frequency modulation parameter according to the optimal comprehensive performance index.
7. The apparatus according to claim 6, wherein the determining module is specifically configured to determine the constraint condition according to active power output by the unit, an ac subsystem node voltage, a dc subsystem node voltage, an ac subsystem power transmission line capacity overload, a dc subsystem power transmission line capacity overload, the grid system positive frequency deviation, and the grid system negative frequency deviation in different flexible dc power transmission interconnected grid systems.
8. The apparatus according to claim 6, wherein the fusion module is specifically configured to perform fusion processing on the optimization objective function, the constraint condition, and a power flow constraint equation of the flexible direct-current power transmission interconnected grid system to obtain the frequency modulation parameter acquisition model of the flexible direct-current power transmission interconnected grid system.
9. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the method of any one of claims 1 to 5 when executing the computer program.
10. A 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 5.
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