CN112803450A - Wind power plant energy storage regulation and control method and system considering overhead line electric thermal coupling characteristics - Google Patents
Wind power plant energy storage regulation and control method and system considering overhead line electric thermal coupling characteristics Download PDFInfo
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Abstract
本公开提出了考虑架空线电热耦合特性的风电场储能调控方法及系统，包括：基于电热耦合及温度电阻的相关性建立架空线路的电热耦合模型；基于该模型计算出线路达到最高允许温度时所能够传输的功率，记为风电场的最大出力；实时计算风电场的实际出力，风电场的实际出力大于风电场的最大出力时，将超出的风能进行存储，小于该风电场的最大出力，将存储的风能释放并网。力求最大限度挖掘输电元件的利用效率。
The present disclosure proposes a wind farm energy storage regulation method and system considering the electric-thermal coupling characteristics of overhead lines, including: establishing an electric-thermal coupling model of overhead lines based on the correlation between electric-thermal coupling and temperature resistance; calculating based on the model when the line reaches the maximum allowable temperature The power that can be transmitted is recorded as the maximum output of the wind farm; the actual output of the wind farm is calculated in real time. When the actual output of the wind farm is greater than the maximum output of the wind farm, the excess wind energy will be stored, which is less than the maximum output of the wind farm. Release stored wind energy into the grid. Strive to maximize the utilization efficiency of power transmission components.
Description
Technical Field
The disclosure belongs to the technical field of wind power, and particularly relates to a wind power plant energy storage regulation and control method and system considering the electric-heat coupling characteristic of an overhead line.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
With the gradual depletion of traditional fossil energy, clean energy represented by wind energy and solar energy is rapidly developed, the technology is mature continuously, and the cost is reduced gradually. In China, 70% of load centers are intensively distributed in the middle and east regions, while new energy bases are mainly intensively distributed in the 'three north regions', the installed capacity of the new energy bases accounts for 70% of the installed capacity of wind power in China, and due to the characteristic that clean energy and power loads are reversely distributed, the wind power generation and photovoltaic power generation bases adopting 'large-scale development and centralized grid connection' become an important form of new energy development. The overhead transmission line bears the important task of transmitting electric energy from a new energy base to a load center by using the absolute economic advantages of the overhead transmission line, and the efficient operation of the overhead transmission line plays an important role in the new energy consumption and the safety and stability of the whole transmission system. Therefore, the method has practical significance for the research on the mining of the transmission capacity of the overhead line and the related regulation and control strategy thereof.
The electric energy storage technology is a product under the rapid development of scientific technology. At present, under the background of energy interconnection, electric energy storage plays an increasingly important role, the energy storage application plays an active role in the aspects of system peak regulation, frequency modulation, voltage regulation, accident standby and the like, renewable energy sources are matched with corresponding energy storage measures to realize efficient utilization of resources at present when new energy sources are widely applied, and the energy storage investment of a wind power station has important significance for improving the consumption capacity of wind power generation and the wind power utilization ratio. At present, the electric energy storage technology is widely applied to power distribution networks with different voltage grades, so that the electric energy storage has a wide development prospect.
The inventor discovers in research that due to the limitation of self physical characteristics, the temperature of an overhead line cannot exceed a corresponding thermal limit value, once the temperature exceeds the thermal limit value, the self physical structure of the overhead line can be damaged, or the sag is caused to be overlarge to generate a safety problem, along with the continuous increase of output power of a power plant side, the current flowing on the overhead line is also increased, and further the generated heat can be increased continuously, so that the temperature of the overhead line is increased, meanwhile, the influence of the change of ambient environment parameters is caused, the temperature of the overhead line is also influenced by the heat exchange between the overhead line and the ambient environment, when the temperature of the overhead line exceeds the thermal limit value, the line can be damaged irreversibly, and a series of safety problems are generated.
Because the generated output of the wind power plant has the characteristics of intermittency and randomness, the output of the wind power plant cannot be actively controlled according to various preset limits. Therefore, when wind power is abundant at a certain moment, the power of the wind power is merged into the power grid, which is very likely to cause the temperature of the overhead line to exceed the maximum temperature allowed by the safe operation, at this moment, wind abandon is often generated, generally speaking, the electrothermal coupling effect is not considered when the maximum transmission power of the overhead line is calculated, and thus, the waste of resources is caused.
Disclosure of Invention
In order to overcome the defects of the prior art, the wind power plant energy storage regulation and control method considering the electric-thermal coupling characteristics of the overhead line is provided, and the utilization rate of wind energy is improved.
In order to achieve the above object, one or more embodiments of the present disclosure provide the following technical solutions:
in a first aspect, a wind power plant energy storage regulation and control method considering the electric and thermal coupling characteristics of an overhead line is disclosed, and comprises the following steps:
establishing an electrothermal coupling model of the overhead line based on the correlation of electrothermal coupling and temperature resistance;
calculating the power which can be transmitted when the line reaches the highest allowable temperature based on the model, and recording the power as the maximum output of the wind power plant;
and calculating the actual output of the wind power plant in real time, storing the exceeded wind energy when the actual output of the wind power plant is greater than the maximum output of the wind power plant, and releasing and connecting the stored wind energy to the grid when the actual output of the wind power plant is less than the maximum output of the wind power plant.
According to the further technical scheme, before the electric heating coupling model of the overhead line is established, an electric model of the overhead transmission line is established based on a power transmission theory, a thermal physical model of the overhead line is established based on a thermal balance equation, and then the electric heating coupling model of the overhead line is established based on the electric heating coupling theory and the correlation of temperature resistance as a bridge.
According to the technical scheme, a system based on the electric-thermal coupling model of the overhead line is a simplified test system, during simplification, the electric power system is subjected to regional processing, the wind power plant and the main system are equivalent to two independent nodes and are connected through a wind power access channel, and each node has independent environmental parameters.
In a further aspect, the electrical model of the overhead line comprises:
a power equation of per unit values of a power plant and a receiving end expressed based on a power transmission principle;
generating a network loss power equation on a line when power is transmitted from a wind power plant side to a main network end of a system;
a series resistance and reactance equation on the overhead tie line;
a reference value of system impedance and a reference value equation of three-phase current.
According to the further technical scheme, the value of the network loss power equation is equal to the difference between the generated power and the receiving end power, and is also equal to the generated heat value of the current flowing through the line resistor.
In a further technical scheme, the thermal balance equation in the thermal physical model of the overhead line considers that the temperature of the overhead line is influenced by various meteorological factors and the properties of the overhead line.
According to the further technical scheme, the electric heating coupling model of the overhead line considers that when current flows through the overhead line, heat generated by the current on a resistor interacts with heat exchange between the overhead line and the external environment to jointly determine the temperature of the line.
In a second aspect, a wind farm energy storage regulation and control system considering overhead line electric thermal coupling characteristics is disclosed, comprising:
the electric-thermal coupling model building module is used for building an electric-thermal coupling model of the overhead line based on the correlation of electric-thermal coupling and temperature resistance;
the maximum output calculation module is used for calculating the power which can be transmitted when the line reaches the highest allowable temperature based on the model and recording the power as the maximum output of the wind power plant;
and the energy storage module is used for calculating the actual output of the wind power plant in real time, storing the exceeded wind energy when the actual output of the wind power plant is greater than the maximum output of the wind power plant, releasing the stored wind energy to be connected to the grid when the actual output of the wind power plant is less than the maximum output of the wind power plant.
The above one or more technical solutions have the following beneficial effects:
according to the technical scheme, according to an electrothermal coupling theory, environment variables are introduced into wind power generation grid-connected analysis and calculation, environment parameters in the actual running state of the overhead line are introduced into power transmission limit value analysis, the power which can be transmitted when the line reaches the highest allowable temperature is calculated, whether energy storage and compensation are needed or not is judged by taking the power as a standard, and the utilization efficiency of a power transmission element is sought to the maximum.
The technical scheme disclosed by the invention is to equivalently obtain the two-node test model according to the actual engineering needs, and analyze the two-node test model on the basis of the two-node test model. Modeling is performed according to the power transmission theory. And then establishing an electric-thermal coupling model of the overhead line by taking the correlation between the temperature and the resistance as a bridge according to a thermal equilibrium expression under the IEEE-738 standard. An energy storage strategy considering line electrothermal elasticity is provided according to the current power grid development situation and the characteristics of a new energy technology, and example design is carried out according to various parameters of an actual wind power plant, so that the feasibility of the method is fully verified.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
FIG. 1 is a simplified test system schematic of an embodiment of the present disclosure;
FIG. 2 is a schematic illustration of wind farm output without compensation;
FIG. 3 is a schematic diagram of wind farm output when compensation is performed according to an embodiment of the disclosure;
FIG. 4 is a schematic diagram comparing before and after an input energy storage strategy;
fig. 5 is a schematic diagram of stored electrical energy over time according to an embodiment of the disclosure.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Example one
The embodiment discloses a wind power plant energy storage regulation and control method considering the electric-thermal coupling characteristics of an overhead line, and provides the wind power plant energy storage regulation and control method and system based on the principle that the electric-thermal coupling characteristics of the overhead line are comprehensively considered from the aspect of wind power plant energy storage economic regulation and control, and environmental parameters are introduced into power limit analysis. Firstly, a simplified model of a test system is provided, and then an electric model of the overhead transmission line is established based on a power transmission theory. Then, a thermal physical model of the overhead line is established on the basis of a thermal balance equation under IEEE-738std, and then an electric-thermal coupling model of the overhead line is established on the basis of an electric-thermal coupling theory and the correlation of temperature resistance as a bridge. On the basis, a wind power plant energy storage strategy considering the electric heating elasticity of an overhead line is provided by combining the current wind power plant output prediction technology, and finally, the feasibility of the provided regulation and control strategy is verified by using 795kcmil26/7Drake ACSR steel-cored aluminum stranded wire and wind power plant operation parameter design examples.
In a specific embodiment, the test system is simplified: because large-scale wind power bases are often located in remote areas far away from the main grid frame, electric energy sent by the large-scale wind power bases needs to be connected to the grid by a special overhead power transmission line and transmitted to a load center. However, the embodiment mainly focuses on the power generation and transmission links of the wind power plant, so that for convenience of analysis, the power system is subjected to regional processing, the wind power plant and the main system are equivalent to two independent nodes and are connected through a special wind power access channel, and each node has independent environmental parameters. In a modern power system, various reactive power compensation devices (such as a series capacitor TCSC, a static var generator SVC and a unified power flow controller UPFC) are widely applied, and sufficient reactive power support of the system is ensured. According to the national standard, various nodes which are centrally connected to the wind power base station should provide sufficient dynamic reactive power compensation equipment. In this case, since the system can ensure sufficient reactive power, the node voltage amplitudes can be assumed to be clamped around the rated voltage (1.0 p.u.). As shown in fig. 1, the two-node equivalent system is a model in which a wind power base W and a main system S are connected by an overhead line.
In a specific embodiment mode, 795kcmil26/7Drake ACSR steel-cored aluminum strand is selected as a research object, dynamic processes of energy storage and compensation are simulated, and data subjected to scene simulation in the embodiment are actual operation parameters of a wind power plant, so that the method has a high reference value. The parameters in the examples are shown in Table 2.
TABLE 2 test System parameters
Based on the test module, an electric model of the overhead line is established, the current on the line can be calculated clearly, a heat balance equation is brought in, coupling of electric quantity and thermal physical quantity is formed, as shown in fig. 1, a wind power base and a system receiving end are respectively positioned at two positions, power is transmitted between two nodes through the overhead line, and a per unit value power equation of a power plant and the receiving end can be expressed as follows according to a power transmission principle:
when power is transmitted from a wind power plant side to a main grid end of a system, grid loss power can be generated on a line, the value of the grid loss power is equal to the difference between generated power and received end power, meanwhile, the grid loss power is also equal to the heat generation value of current flowing through a line resistor, and specific power can be expressed as follows:
in the formula, PwAnd PsRespectively representing the active power generated by the wind power plant and the power received by the receiving end of the system, UwAnd UsRespectively represent the voltage of a wind power base node and a system receiving end node, theta is the phase angle difference of the voltage between the two nodes, R and X represent series resistance and reactance on an overhead connecting line, and the series resistance and reactance can be obtained by the following formulas 3 and 4:
wherein L represents the length of an overhead line connecting a wind power base and a main system, r and x represent the series resistance and reactance of the line per unit length, respectively, and ZBA reference value representing the system impedance, which may be represented by
The equations 5 and 6 are obtained simultaneously.
In the formula, SBReference value, U, representing the system powerBAnd IBWhich represent the reference values of the three-phase voltages and currents, respectively. Since there are sufficient reactive compensation devices at both nodes, the node voltage can be considered approximately equal to the rated voltage, at which time UwAnd UsThis can be taken as 1.0p.u, which is substituted into formula 1 to yield:
since overhead lines are generally connected in a star connection during long-distance power transmission, the line current is equal to the phase current, which can be determined from equation 8.
The square of the current amplitude can be derived from equation 8:
further, replacing all named values in the formula with per unit values can obtain:
based on the test module, a thermophysical model of the overhead line is established, and the influence of environmental factors on the temperature of the overhead line can be determined.
Currently, the regulations on the overhead line heat balance equation are mainly divided into two types, one is the heat balance equation under the IEEE standard, and the other is the heat balance equation under the GIGRE standard. Through comparison of the two, the heat balance equation under the IEEE standard performs a lot of simplification processing on weather conditions, and the heat balance equation under the GIGRE standard has more strict requirements on weather conditions. Because this document does not focus on theoretical studies, but instead focuses on engineering practices, the thermal equilibrium equations under the IEEE standard were chosen.
When the power system operates in a steady state, the heat absorption capacity and the heat dissipation capacity of the power transmission line are equal at the same moment, so that the temperature of the line is approximately stabilized at a certain determined value, and the overhead line is in a dynamic heat balance state at the moment. The thermal process of the overhead line is divided into two processes of heat absorption and heat dissipation for analysis.
For the heat dissipation process, two factors mainly influence the heat dissipation capacity, firstly, the line temperature is not equal to the environment temperature any more due to factors such as air temperature change, and heat conduction can occur at the moment; secondly, convective heat dissipation caused by changes in wind speed. For the heat absorption process, there are two main reasons for influencing the magnitude of the heat absorption: firstly, the temperature rise caused by the thermal power on the resistor generates heat absorption; secondly, radiation absorption due to the change in the amount of solar radiation.
A number of factors together determine the temperature of the overhead line, which is mainly influenced by a number of meteorological factors and the nature of the overhead line itself. The thermal equilibrium of the overhead line is disrupted and its temperature fluctuates up and down, and the thermal equilibrium equation is expressed as:
where m is the mass of the overhead line per unit length, CpThe specific heat capacity of the material used for the overhead line, T is the average temperature of the surface of the overhead line, T is the time required for the corresponding temperature change to occur, I is the per unit value of the current flowing through the line, and r is the resistance corresponding to the line per unit length. q. q.ss、qcAnd q isrRespectively representing the heat absorption and heat dissipation of the line caused by various factors, which are respectively related to different environmental parameters and electric quantities, and formula 12 represents qs、qcAnd q isrA brief expression of (a).
Following pair of qs、qcAnd q isrThe specific meaning and solving equation of (a):
1) convection heat radiation qc
According to the IEEE-738 standard, convective heat dissipation is mainly influenced by a plurality of factors such as wire temperature, ambient temperature, wire diameter, altitude, wind speed and wind direction angle, and the value of the convective heat dissipation is natural convective heat dissipation qcnAnd forced convection heat dissipation qcfThe larger one in between.
The forced convection mode is influenced by the wind speed, and has different expression forms when the wind speed V around the overhead linelWhen the heat dissipation is more than 7m/s, the formula of forced convection heat dissipation is
When wind speed VlWhen the heat dissipation is less than 7m/s, the formula of forced convection heat dissipation at this time is:
wherein N isRERepresenting the Reynolds coefficient, which is related to the wind speed, and the specific formula is shown in the formula 15.
Convection heat radiation qcnThe expression of (a) is:
in equations 14-16, D represents the diameter of the overhead line conductor, T represents the temperature of the conductor, and T represents the temperature of the conductoraRepresenting the ambient temperature in the vicinity of the overhead line. And rhof、μfAnd kfIs a parameter related to the air condition.
Wherein the air density ρfThe solving formula of (2) is as follows:
thermal conductivity of air kfThe solving formula of (2) is as follows:
air viscosity coefficient mufThe expression of (a) is:
h in formulae 17 to 19eRepresentative of altitude, TfRepresents the mean of ambient temperature and wire temperature, i.e.:
Tf＝(T+Ta)/2 (20)
since the difference of wind direction will also cause the change of convection heat dissipation, when considering convection heat dissipation, it is often necessary to multiply by the wind direction factor KaCorrection is made, KaAngle to wind direction only
It is related.
Ka＝1.194-cos(φ)+0.194cos(2φ)+0.368sin(3φ) (21)
By analyzing the convective heat dissipation, the conclusion can be drawn: a) natural convection heat dissipation is more severe in places with high altitude, and the higher the temperature is, the less natural convection heat dissipation is, so the higher the temperature and altitude can have negative effects on the heat dissipation of the overhead line. b) The wind direction correction coefficient is only related to a wind direction angle, and when the overhead line is in an actual operation process, the wind direction changes along with time, which inevitably influences the heat dissipation process of the line.
2) Radiation heat radiation qr
From equation 12, the radiation heat dissipation is mainly affected by the material and diameter of the overhead line, and the specific solving process is as follows:
wherein epsilon is the radiance, mainly determined by the material of the overhead line, compared with the light heat absorption described below, the two heat exchange modes are the same in the radiance mode, but the generated effects are not opposite, the former is favorable for reducing the temperature of the overhead line, and the latter is favorable for increasing the temperature of the line
3) Light absorbing heat qs
In the IEEE-738 standard, the light heat absorption capacity q of the wire per unit length is obtained by taking both the direct incidence and the diffusion of the sun into considerationsComprises the following steps:
qs＝αDKsQssinθs (23)
similar to the wind direction correction factor, KsThe correction factor of the sun altitude is only related to the altitude, and the specific expression is shown in the formula 24.
The altitude range of human life is between 0 and 3000 m, and as the altitude rises, KsIncrease continuously, thereby leading to the heat absorption q of illuminationsAlso rises with it, thetasFor the illumination angle of incidence, it can be expressed as:
θs＝arccos(cosHc·cosZa) (25)
solar altitude angle ZaSee expressions 26 and 27.
In the above formula, D represents the diameter of the wire, α is the absorptivity of the wire to light, HcRepresenting the angle between the sun's rays and the ground, which is between 0 and 90 deg.. ZlAnd ZcAzimuth angle of the line and sun, L respectivelyaRepresenting latitude, N being the number of days accumulated in the year, δ being the solar declination angle, which generally varies in magnitude between-23.46 and 23.46, expressed as:
Qsthe intensity of the solar and radiant heat is expressed, and the equation is solved as in equation 27.
Polynomial coefficient A in the formula0-A6The specific value is determined by the actual operating environment of the overhead line and is shown in table 1.
TABLE 1 polynomial coefficient value-taking table
Based on above-mentioned two models, establish overhead line's electric heat coupling model, the temperature of overhead line receives two aspects effects of self current-carrying capacity and natural environment, and overhead line's heat dissipation can exert an influence to ambient temperature equally, has interact between the two. The series impedance of the overhead line can change along with the temperature change of the overhead line, and the traditional analysis shows that the reactance of the overhead line is mainly influenced by factors such as three-phase distance, conductor radius, the number of split conductors and the like, and is slightly influenced by the temperature, so that the resistance of the overhead line is focused on the condition that the resistance changes along with the temperature. The temperature resistance is used as a bridge correspondingly, the electrical parameter is connected with the thermal parameter, an electrical-thermal coupling model of the overhead line is established, the model is specifically an equation (30-4), the left side of the equation represents the effect of the environmental factor, the right side of the equation represents the electrical property of the overhead line power transmission, and the environmental parameter and the electrical parameter can be coupled for analysis through the coupling relation.
In past research, the series resistance in the power system is considered to be constant, and the influence of temperature change on the change of the resistance value is ignored. In practical situations, the resistance is linear with temperature, the temperature has a great influence on the resistance, and the relationship can be expressed as:
r＝Rl+σ(T-Tl) (30)
in the formula, RlRepresentative of temperature TlThe corresponding resistance, σ, represents the linear coefficient of dependence of temperature and resistance, which is related to the material of the conductor. The electric heating coupling model of the overhead line is that in short, when current flows through the overhead line, heat generated by the current on a resistor interacts with heat exchange between the overhead line and the external environment, and the temperature of the line is determined together.
According to the electric-thermal coupling theory of the overhead line, the temperature of the line is determined by two aspects, the line is heated and heated by the self current heat effect, meanwhile, the line temperature is reduced by heat exchange and heat dissipation with the ambient environment, the relation is described in a heat balance equation under the IEEE-738 standard, wherein the heat exchange value Q of the lead and the ambient environment is as follows:
Q＝qs-qr-qc (30-2)
in the long term, the demand of the power system changes slowly and can be analyzed by the static heat balance equation, so that:
Q+I×IB 2r＝0 (30-3)
the current can be obtained by the power transmission theory, and Q is obtained by carrying in (30-3):
the left side of the equation (30-4) represents the effect of environmental factors, the right side of the equation is the electrical property of the overhead line power transmission, and the environmental parameters and the electrical quantity parameters can be coupled for analysis through the coupling relation.
After the model is built, when the wind power plant energy storage capacity evaluation considering the electric thermal elasticity of the overhead line is realized, the specific mode is as follows:
according to the heat balance equation of the overhead line, since the temperature change is a slow process, the maximum temperature T is reached by the temperatureTLThen, it can be approximated that the temperature no longer varies with time, when the left side of equation 11 equals zero, i.e.:
0＝(I·IB)2r+qs-qr-qc (31)
according to equation 31, given various environmental parameters, the current at the corresponding environmental parameter is calculated, that is:
the value of the current obtained is taken into formula 10 according to formula 32, and the temperature T reached can be obtainedTLUnder the corresponding environmental parameters, the phase angle difference of the current and the voltage flowing on the corresponding line is as follows:
carry the calculation result of equation 33 into equation 7sThe current value when the temperature reaches the limit value can be obtained; the obtained current value is brought into formula 10, and further the temperature T is obtainedTLThe maximum output P of the corresponding wind power plantmax. Once the actual output of the wind power plant is greater than the output, the residual wind energy needs to be stored, and once the actual output is less than the output, the stored wind energy is released and connected to the grid, so that the utilization rate of the wind energy can be improved.
In concrete implementation, various environmental parameters such as wind speed, environmental temperature and the like need to be acquired, and then (30-4) is carried out to calculate the phase angle difference cosObtaining T by post-substitution (7)TLP ofmax. In addition, the actual output at the stage can be directly obtained from the wind power plant, the output of the wind power plant within 15 minutes in the future can be obtained according to the existing wind power prediction technology, the output of the wind power plant within 15 minutes is considered to be linearly changed in the technical scheme disclosed by the invention, and the real-time output of the wind power plant is approximately obtained from the linear change.
More specifically, to better explain the implementation effect of the above scheme, the present embodiment first selects the environmental parameters of the whole year of a certain place, samples the environmental parameters every 15 minutes, approximates the change of various environmental parameters to linear within 15 minutes, then carries the environmental parameters at each time into formula 33 to calculate, obtains the phase angle difference in the past year, takes the minimum value of the phase angle difference, and brings the minimum value into formula 7 to obtain PsAs a criterion P of this yearjud。
Once the output of the wind power plant exceeds PjudStoring the excess electrical energy, once the wind farm output is less than PjudThe resulting deficit is compensated for. This, although it may introduce errors, may ensure that the temperature of the overhead line is below the maximum allowable temperature.
Because various environmental parameters (such as temperature, wind speed and the like) influencing the output of the wind power plant are slowly converted, the existing technology can basically predict various environmental parameters in a short time, so that the wind power output which is accurate in the future 15 minutes can be obtained, and the output of the wind power plant in the future 15 minutes is assumed to be linearly changed in the research, so that the output P of the wind power plant at the moment is passed throughnowAnd predicted future 15 minutes PfurForce and P ofjudA comparison was made to determine, based on the analysis, that there were a total of four cases, as shown in table 3.
TABLE 3 energy storage situation judgment table
Whether energy still exists in the energy storage device or not needs to be judged in advance during each compensation, if energy storage exists, when the power is smaller than the judgment power, the energy in the energy storage device is merged into the system, and if energy storage does not exist, the energy storage cannot be carried out.
Calculating the judgment power through a program according to the output of the wind power plant and the environmental condition in the last year of a certain place, taking the judgment power as a reference, selecting 25 time points for calculation, carrying out example simulation, and simultaneously carrying out comparative analysis according to P before and after strategy compensationsThe variation of (2). When compensation is not being put into effect, PsAnd PjudAs shown in fig. 2. From the simulation results, it can be found that the output of the wind farm is compared to the expected output PjudThere is a considerable offset.
When compensation is put into effect, PsAnd PjudAs shown in fig. 3. According to the simulation result, after compensation is input, ideal wind power output can be obtained, but the ideal output cannot be completely achieved due to the limitation of the total output of the wind power plant, and a good peak clipping and valley filling effect can be obtained.
FIGS. 4 and 5 show the comparison of the output of the wind farm and the unused energy storage strategy and the stored electric energy P according to the energy storage strategystoAccording to the change situation along with time, the energy storage strategy can effectively adjust the output of the wind power plant through analysis, and the full utilization of energy is realized.
Example two
It is an object of this embodiment to provide a computing device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the above method when executing the program.
EXAMPLE III
An object of the present embodiment is to provide a computer-readable storage medium.
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 above-mentioned method.
Example four
The object of this embodiment is to provide a wind power plant energy storage regulation and control system considering overhead line electric thermal coupling characteristic, includes:
the electric-thermal coupling model building module is used for building an electric-thermal coupling model of the overhead line based on the correlation of electric-thermal coupling and temperature resistance;
the maximum output calculation module is used for calculating the power which can be transmitted when the line reaches the highest allowable temperature based on the model and recording the power as the maximum output of the wind power plant;
and the energy storage module is used for calculating the actual output of the wind power plant in real time, storing the exceeded wind energy when the actual output of the wind power plant is greater than the maximum output of the wind power plant, releasing the stored wind energy to be connected to the grid when the actual output of the wind power plant is less than the maximum output of the wind power plant.
The steps involved in the apparatuses of the above second, third and fourth embodiments correspond to the first embodiment of the method, and the detailed description thereof can be found in the relevant description of the first embodiment. The term "computer-readable storage medium" should be taken to include a single medium or multiple media containing one or more sets of instructions; it should also be understood to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor and that cause the processor to perform any of the methods of the present disclosure.
Those skilled in the art will appreciate that the modules or steps of the present disclosure described above can be implemented using general purpose computer means, or alternatively, they can be implemented using program code executable by computing means, whereby the modules or steps may be stored in memory means for execution by the computing means, or separately fabricated into individual integrated circuit modules, or multiple modules or steps thereof may be fabricated into a single integrated circuit module. The present disclosure is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (10)
1. The wind power plant energy storage regulation and control method considering the electric and thermal coupling characteristics of the overhead line is characterized by comprising the following steps of:
establishing an electrothermal coupling model of the overhead line based on the correlation of electrothermal coupling and temperature resistance;
calculating the power which can be transmitted when the line reaches the highest allowable temperature based on the model, and recording the power as the maximum output of the wind power plant;
and calculating the actual output of the wind power plant in real time, storing the exceeded wind energy when the actual output of the wind power plant is greater than the maximum output of the wind power plant, and releasing and connecting the stored wind energy to the grid when the actual output of the wind power plant is less than the maximum output of the wind power plant.
2. A wind power plant energy storage regulation and control method considering overhead line electric-thermal coupling characteristics according to claim 1, characterized in that before an electric-thermal coupling model of an overhead line is established, an electric model of an overhead transmission line is established based on a power transmission theory, a thermal-physical model of the overhead line is established based on a thermal balance equation, and then an electric-thermal coupling model of the overhead line is established based on the electric-thermal coupling theory and a correlation of temperature resistance is taken as a bridge.
3. A wind farm energy storage regulation and control method considering overhead line electrical thermal coupling characteristics as claimed in claim 1, characterized in that the system on which the electrical thermal coupling model of the overhead line is based is a simplified test system, during simplification, the electric power system is regionalized, the wind farm and the main system are equivalent to two independent nodes, and are connected through a wind power access channel, and each node has independent environmental parameters.
4. A wind farm energy storage regulation and control method taking into account overhead line electro-thermal coupling characteristics as claimed in claim 2, characterized in that the electrical model of the overhead line comprises:
a power equation of per unit values of a power plant and a receiving end expressed based on a power transmission principle;
generating a network loss power equation on a line when power is transmitted from a wind power plant side to a main network end of a system;
a series resistance and reactance equation on the overhead tie line;
a reference value of system impedance and a reference value equation of three-phase current.
5. A wind farm energy storage regulation and control method considering overhead line thermoelectric coupling characteristics as claimed in claim 4, characterized in that the grid loss power equation has a value equal to the difference between the generated power and the receiving end power and also equal to the heat generation value of the current when flowing through the line resistance.
6. A wind farm energy storage regulation and control method considering overhead line thermoelectric coupling characteristics as claimed in claim 2, characterized in that the thermal balance equation in the thermophysical model of the overhead line takes into account that the temperature of the overhead line is influenced by various meteorological factors and the properties of the overhead line itself.
7. A wind farm energy storage regulation and control method considering overhead line electrical and thermal coupling characteristics as claimed in claim 1, characterized in that the electric heating coupling model of the overhead line considers that when current flows through the overhead line, heat generated by the current on a resistor interacts with the overhead line in heat exchange with the external environment to jointly determine the temperature of the line.
8. Wind power plant energy storage regulation and control system considering overhead line electric thermal coupling characteristics is characterized by comprising:
the electric-thermal coupling model building module is used for building an electric-thermal coupling model of the overhead line based on the correlation of electric-thermal coupling and temperature resistance;
the maximum output calculation module is used for calculating the power which can be transmitted when the line reaches the highest allowable temperature based on the model and recording the power as the maximum output of the wind power plant;
and the energy storage module is used for calculating the actual output of the wind power plant in real time, storing the exceeded wind energy when the actual output of the wind power plant is greater than the maximum output of the wind power plant, releasing the stored wind energy to be connected to the grid when the actual output of the wind power plant is less than the maximum output of the wind power plant.
9. A computing device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps of the method of any of claims 1 to 7 when executing the program.
10. 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 of any one of the preceding claims 1 to 7.
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