Disclosure of Invention
At present, the requirements of a power grid in each period are possibly different, the invention takes the power grid requirements as guidance, the problem of the actual power grid is solved through single energy storage, and the provided specific scheme is as follows:
an energy storage multi-scene application switching control method comprises the following steps:
s1, analyzing the power grid demand scene according to actual power grid data;
s2, dividing the demand scene into a demand scene with predictable planning and a demand scene with unpredictable planning;
s3, analyzing and determining the arrangement and the planning of all foreseeable planning demand scenes in the time period of the day through historical data and day-ahead data;
s4, determining a calculation method of the actual active output and the reactive output of the stored energy in each predictable and planned time interval of the demand scene;
s5, establishing an identification index to finish identification of the unpredictable planning demand scene;
and S6, establishing a switching index to judge whether the switching of the unpredictable planning demand scene is completed or not.
Preferably, the demand scenario that can be predicted to be planned in S2 may specifically be: peak regulation, steady state voltage regulation and steady state frequency modulation; the unpredictable planning demand scenario may specifically be: transient voltage regulation and transient frequency modulation.
Preferably, S3 specifically includes dividing the day into a main peak regulation period and a main voltage regulation period on a time scale, where the daytime is the main peak regulation period, and the nighttime is the main voltage regulation period.
Preferably, S4 is specifically, wherein peak shaving is mainly performed in the main peak shaving period, the PCS capacity first meets the peak shaving, an energy storage active output curve is obtained after determining a peak shaving line and a valley filling line through a load prediction curve, and an energy storage reactive margin curve for voltage regulation is obtained through energy storage planned output; in the main voltage regulation period, voltage regulation is mainly performed, the PCS meets the voltage regulation firstly, in order to meet the electric quantity balance, energy storage constant low power charging is set firstly until the main voltage regulation period is finished, charging is finished just, and a constant reactive margin is obtained according to the PCS residual capacity. And determining the required reactive power output according to whether the bus voltage exceeds the dead zone, and determining whether the energy storage singly undertakes the voltage regulation task or the energy storage auxiliary capacitor carries out fine voltage regulation or the energy storage auxiliary capacitor singly undertakes the voltage regulation according to the comparison between the reactive power margin and the required reactive power output, so as to obtain the final reactive power output of the energy storage. When the required reactive power output is not greater than the reactive margin, the energy storage independently undertakes the task of voltage regulation; if the required reactive power is larger than the reactive margin, firstly, judging whether the ratio of the required reactive power to the surplus value of the unit capacitor capacity and the unit capacitor capacity exceeds a set threshold value, if so, indicating that the capacitor voltage regulation causes overshoot or overshoot due to the limitation of the unit capacitor capacity, and finely regulating the voltage by using the energy storage auxiliary capacitor, otherwise, indicating that the capacitor voltage regulation is enough to realize the voltage regulation accuracy, and carrying out the voltage regulation work by using the capacitor alone.
Preferably, the demand scenario according to the unpredictable planning in S5 is transient frequency modulation and transient voltage regulation, and when the identification index of the transient frequency modulation exceeds a certain threshold, the demand scenario is identified as transient frequency modulation, and when the identification index of the transient voltage regulation exceeds a certain threshold, the demand scenario is identified as transient voltage regulation; the identification index may specifically be:
the identification index of the transient frequency modulation comprises a comprehensive frequency modulation identification index delta Fl:
Where Δ f is the frequency deviation, Δ f
iThe frequency offset corresponding to the real-time power offset,
the frequency change rate is a per unit value; mu.s
1,μ
2,μ
3Respectively, the weight, mu, between the three
1+μ
2+μ
31, determining the weight according to the simulation result of the system,
the frequency deviation delta f corresponding to the real-time power deviationiThe derivation formula is as follows:
wherein, KGAdjusting power for unit of the unit; kDAdjusting the effect coefficient for the frequency of the load; Δ p is the real-time power deviation;
the comprehensive frequency modulation identification index has the advantages that a series of misoperation such as frequency overshoot and reverse regulation of self-adaptive energy storage control is caused due to the fact that the time scale of frequency change of a conventional identification index is small and the system delay is large, real-time power deviation delta p is introduced into the comprehensive frequency modulation identification index so as to make up for the frequency deviation caused by power deviation outside a day-ahead plan, and misoperation including late action and over action during frequency modulation can be prevented;
the identification index of transient voltage regulation can be voltage deviation delta U in a conventional identification method or a comprehensive voltage regulation identification index delta Ut:
Δu=u(t)-uPCCN
Δui=∫(uPCCN-u(t))dt
Wherein u (t) is a real-time voltage value of a grid connection point; u. of
PCCNIs a grid-connected voltage rating; Δ u
iAccumulating the variation for the voltage;
is the rate of change of voltage; Δ u, Δ u
i,
Are per unit values.
The invention provides a multi-scene application switching control method based on a control strategy of a plurality of application scenes of the current energy storage access power grid and combined with the analysis of actual power grid requirements, aims to achieve the purpose of fully meeting the requirements of different power grids by accessing energy storage and performing adaptive transformation matched with different power grids, and can solve the problems of the current power grid as much as possible by accessing the energy storage and built-in control methods. Additional aspects and advantages 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.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
As can be seen from fig. 1, the method for controlling switching of energy storage multi-scenario applications provided in the embodiment of the present invention includes the following steps:
s1, analyzing the power grid demand scene according to actual power grid data;
s2, dividing the demand scene into a demand scene with predictable planning and a demand scene with unpredictable planning;
s3, analyzing and determining the arrangement and the planning of all foreseeable planning demand scenes in the time period of the day through historical data and day-ahead data;
s4, determining a calculation method of the actual active output and the reactive output of the stored energy in each predictable and planned time interval of the demand scene;
s5, establishing an identification index to finish identification of the unpredictable planning demand scene;
and S6, establishing a switching index to judge whether the switching of the unpredictable planning demand scene is completed or not.
The demand scenario that can be predicted to be planned in S2 may specifically be: peak regulation, steady state voltage regulation and steady state frequency modulation; the unpredictable planning demand scenario may specifically be: transient voltage regulation and transient frequency modulation.
In the embodiment, the power grid demand scenarios determined by the actual power grid data in the preset S1 include: peak regulation, steady state voltage regulation, transient state voltage regulation and transient state frequency modulation. According to the S2, the peak regulation and steady state pressure regulation scene is a demand scene which can be predicted and planned, and the transient state pressure regulation and transient state frequency regulation are a demand scene which can not be predicted and planned.
Wherein, the S3 may specifically be:
as can be seen from fig. 2, a typical day data is selected to perform the time interval arrangement and planning of the peak regulation and the steady-state voltage regulation on the day, and the following conclusions are obtained by combining the change rule of the peak regulation target parameter, i.e., the load, and the steady-state voltage regulation target parameter, i.e., the voltage, on the typical day:
1. the change rule of the total load of the region is consistent with the change rule of the load of the transformer substation. The load basically tends to rise in the morning (6: 00-11: 00), tends to fall in the evening (20: 00-4: 00), has a large peak and a small peak respectively at noon (11: 00-12: 00) and evening (18: 00-20: 00), and has a large trough in the early morning (2: 00-5: 00). Therefore, the energy storage installed on the 10kV bus of the transformer substation has no essential difference between peak clipping and valley filling of the total regional load and peak clipping and valley filling of the transformer substation load, and the same effect can be achieved.
2. The change rule of the load is basically opposite to the change rule of the bus voltage. The voltage drops when the load increases in the morning (6: 00-11: 00) and rises when the load decreases in the evening (20: 00-4: 00). When the load is at a higher level, the voltage is basically at a lower level, but the load crosses the peak clipping line for a plurality of times when the load is at the higher level, the maximum value is higher than the peak clipping line by a certain distance, the voltage is basically not lower than the lower voltage limit when the load is at the lower level, and a distance is reserved between the real-time voltage and the lower voltage limit when the load is at the two peak clipping areas; the voltage is substantially at a higher level when the load is at a lower level, the voltage also exceeds the upper voltage limit when the load crosses the valley fill line, and the voltage substantially crosses the limit in the valley fill region. Therefore, the stored energy does not need to be considered in the peak clipping region, but needs to be considered in the valley filling region.
It can be concluded that the voltage is at a higher level at load dips and is out of limit for a long time due to the absence of reactors at a number of substations in the grid. Too high a voltage will result in: the transformer is over-excited, so that the loss of an iron core is greatly increased; secondly, the aging of the electrical equipment is accelerated, and the service life is reduced; and causing damage to industrial equipment and unqualified industrial products. And because the valley filling period of the peak regulation scene is to solve the problem of electric quantity balance of the stored energy and generate positive influence on the voltage, but according to the voltage regulation formula, the longitudinal component of the voltage is far smaller than the transverse component of the voltage, and the influence of the reactive output of the stored energy on the system voltage is far larger than the active output of the stored energy, so that the switching control plan of the energy storage plan peak regulation/plan voltage regulation is provided without installing a reactor.
According to the conclusion, the switching control plan of energy storage plan peak shaving/plan voltage regulation may specifically be:
dividing the day into a main peak regulation time interval and a main peak regulation time interval on a time scale, wherein the daytime is the main peak regulation time interval, the nighttime is the main peak regulation time interval, and the specific time node division is obtained according to the following data analysis, as shown in table 1, counting the voltage and the load value from 0 point to 12 points of a typical day, determining the time corresponding to the intersection point of the voltage back and the upper voltage limit of 10.5kV and the time corresponding to the intersection point of the load line rising and the peak clipping line, determining the area where the time node switched between the main peak regulation time interval and the main peak regulation time interval is located to be 9:00-10:15 according to the time, and selecting a corresponding proper point as the switched time node in the area.
TABLE 1 scene Change time points
As can be seen from fig. 3, the step S4 may specifically be:
the method comprises the steps that peak shaving is mainly performed in the main peak shaving period, the PCS capacity meets the peak shaving firstly, an energy storage active output curve is obtained after a peak shaving line and a valley filling line are determined through a load prediction curve, and an energy storage reactive margin curve for voltage regulation is obtained through energy storage planned output; in the main voltage regulation period, voltage regulation is mainly performed, the PCS meets the voltage regulation firstly, in order to meet the electric quantity balance, energy storage constant low power charging is set firstly until the main voltage regulation period is finished, charging is finished just, and a constant reactive margin is obtained according to the PCS residual capacity. And determining the required reactive power output according to whether the bus voltage exceeds the dead zone, and determining whether the energy storage singly undertakes the voltage regulation task or the energy storage auxiliary capacitor carries out fine voltage regulation or the energy storage auxiliary capacitor singly undertakes the voltage regulation according to the comparison between the reactive power margin and the required reactive power output, so as to obtain the final reactive power output of the energy storage. When the required reactive power output is not greater than the reactive margin, the energy storage independently undertakes the task of voltage regulation; if the required reactive power is larger than the reactive margin, firstly, judging whether the ratio of the required reactive power to the surplus value of the unit capacitor capacity and the unit capacitor capacity exceeds a set threshold value, if so, indicating that the capacitor voltage regulation causes overshoot or overshoot due to the limitation of the unit capacitor capacity, and therefore, the energy storage auxiliary capacitor is used for finely regulating the voltage, otherwise, indicating that the capacitor voltage regulation is enough to realize the voltage regulation accuracy, and therefore, the capacitor is used for independently carrying out the voltage regulation work.
The unpredictable demand scenario in S5 includes transient frequency modulation and transient voltage regulation, where the identification index of the transient frequency modulation exceeds a certain threshold, and the identification index of the transient voltage regulation is transient voltage regulation; the identification index may specifically be:
1. identification index of transient frequency modulation
The frequency modulation identification index can be frequency deviation delta F in a conventional identification method, and can also be a comprehensive frequency modulation identification index delta Ft:
Where Δ f is the frequency deviation, Δ f
iThe frequency offset corresponding to the real-time power offset,
the frequency change rate is a per unit value; mu.s
1,μ
2,μ
3Respectively, the weight, mu, between the three
1+μ
2+μ
3And (1) determining the weight according to the simulation result of the system.
The frequency deviation delta f corresponding to the real-time power deviationiThe derivation formula is as follows:
wherein, KGAdjusting power for unit of the unit; kDAdjusting the effect coefficient for the frequency of the load; Δ p is the real-time power offset.
The comprehensive frequency modulation identification index has the advantages that a series of misoperation such as frequency overshoot and reverse regulation of self-adaptive energy storage control is caused due to the fact that the time scale of frequency change of a conventional identification index is small and the system delay is large, real-time power deviation delta p is introduced into the comprehensive frequency modulation identification index so as to make up for the frequency deviation caused by power deviation outside a day-ahead plan, and misoperation including late action and over action during frequency modulation can be prevented.
2. Identification index of transient voltage regulation
The voltage regulation identification index can be voltage deviation delta U in a conventional identification method, and can also be a comprehensive voltage regulation identification index delta Ut:
Δu=u(t)-uPCCN
Δui=∫(uPCCN-u(t))dt
Wherein u (t) is a real-time voltage value of a grid connection point; u. of
PCCNIs a grid-connected voltage rating; Δ u
iAccumulating the variation for the voltage;
as a change in voltageRate; Δ u, Δ u
i,
Are per unit values.
The advantages of the comprehensive pressure regulating identification index are the same as the comprehensive frequency modulation identification index.
Since it is necessary to confirm the influence on other scenes (especially the previous scene) and the result of participating in the scene after the energy storage participates in the scene when the transient frequency modulation scene or the transient voltage regulation scene is identified in S5, the switching index in S6 is used to determine whether the switching is completed, and the switching index may include influence factors on other scenes and result factors of the energy storage participating in the scene.
The switching index may be specifically represented by the following formula:
Z=γ1Rfro-bac-γ2Ifro-bac
wherein gamma is1And gamma2Weights for the result factor and the impact factor, respectively; rfro-bacAnd Ifro-bacResult silverson and influence factor respectively; Δ xbac-froThe method comprises the steps of obtaining the variable quantity of an original scene target parameter x before and after switching of an energy storage scene; Δ xfroDeviation of an original scene target parameter x before energy storage switching; Δ ybac-froThe variation of the target parameter y of the next scene before and after the energy storage scene is switched; Δ yfroAnd (4) the deviation of the next field through the target parameter y before the energy storage switching.
After the energy storage participates in the scene, the energy storage does not have great effect on other scenes except the previous scene and can be ignored, so that the influence factors are the exit of the previous scene and the addition of the sceneInfluence on the target parameters of the previous scene, namely the variation of the target parameters of the previous scene before and after switching; the result factor is the influence of the stored energy participating in the scene on the result of the scene target parameter, namely the variation of the scene target parameter before and after switching. And determining the relative weight of the parameters according to the priorities of the two parameters to obtain a switching index as follows, and determining whether scene switching is finished according to judgment of whether the switching index exceeds a set threshold value. If the previous application scene does not exist, namely the stored energy is not applied to the scene at present, the influence factor is 0, namely gamma2=0。
Wherein, γ1,γ2The determination of the weight may specifically be:
1. urgency index m
The urgency index is an index established for measuring the deviation degree of the scene target quantity, and is the severity reflecting the current scene.
2. Importance index n
The importance index is to measure the importance degree of pairwise comparison between scenes, for example, the known importance index of the frequency modulation scene is higher than that of the pressure regulating scene.
3. Comprehensive index
The composite index is defined as the product of the urgency index and the importance index.
λi=mi·ni
Determining gamma according to the composite index1,γ2The numerical value of (a) is as follows:
as can be seen from fig. 4, the specific step of S6 may be:
s7, identifying an unpredictable planning demand scene according to S5, if a single scene is identified, judging whether the output application of the predictable planning demand scene is currently carried out on stored energy, if not, directly entering the identified unpredictable planning demand scene, if so, calculating a switching index and comparing the switching index with a set threshold value to select whether to switch the scene;
and S8, if two demand scenes of transient voltage regulation and transient frequency modulation are identified, judging whether the output application of the demand scene which can be predicted and planned is carried out at present or not in the stored energy, if not, calculating the switching indexes of the two demand scenes of transient voltage regulation and transient frequency modulation and comparing the sizes of the two switching indexes, selecting one scene from the two demand scenes of transient voltage regulation and transient frequency modulation, if so, calculating the switching indexes of the two demand scenes of transient voltage regulation and transient frequency modulation and comparing the two switching indexes with the set threshold value, and selecting whether to switch to the transient voltage regulation scene or the transient frequency modulation scene or not.
As can be seen from fig. 5, the step of comparing the magnitudes of the switching indexes in S8 to select the entry scene may specifically be:
s9, calculating an influence factor and a result factor to obtain the size of a switching index;
s10, judging whether a transient voltage regulation scene and a transient frequency modulation scene are identified at the same time, if so, judging the numerical values of a transient voltage regulation/transient frequency modulation switching index and a set threshold, if the switching index of the transient voltage regulation is maximum, switching to the transient voltage regulation scene, if the switching index of the transient frequency modulation is maximum, switching to the transient frequency modulation scene, and if the set threshold is maximum, selecting not to switch; if not, judging the value between the switching index and the set threshold value, if the switching index is maximum, selecting to switch to the identified scene, and if the set threshold value is maximum, selecting not to switch.
Due to unpredictability and uncertainty of transient frequency modulation and steady frequency modulation scenes, energy storage electric quantity originally meeting a planned peak regulation scene is changed after participating in the frequency modulation scenes, the invention provides the following two methods for solving the problem of electric quantity conservation:
the method comprises the following steps: dividing the energy storage capacity into a virtual plan capacity and a virtual scheduling capacity, wherein the virtual plan capacity is used for determining the peak shaving plan output, and determining a peak shaving line and a valley filling line of a peak shaving scene according to the divided virtual plan capacity; the virtual scheduling capacity is used for additionally increasing or decreasing active power output of the frequency modulation scene, and if the virtual scheduling capacity is 0, the frequency modulation scene needs energy storage and discharge, the energy storage does not participate in the frequency modulation scene; and if the frequency modulation scene needs energy storage and charging when the virtual scheduling capacity is the maximum value, the energy storage does not participate in the frequency modulation scene.
The second method comprises the following steps: and setting a time interval to perform energy storage SOC (state of charge) return recovery. As shown in fig. 6, the following may be specifically mentioned:
if the primary frequency modulation consumes the electric quantity in the primary frequency modulation scene aiming at the condition of temporary frequency reduction, the stored energy is charged at the constant power in the electric quantity feedback area, as shown in the region I in the figure, the charging power is calculated as the following formula, and the charging time is t from t1At the beginning, at t1+ Δ t end; if the primary frequency modulation is aimed at the situation of sudden frequency increase, the primary frequency modulation scene stores electric quantity, the stored energy is discharged at constant power in the electric quantity feedback area, as shown in the region II in the figure, the discharge power is as follows, and the discharge time is t2At Δ t, starting at t2And (6) ending.
1. Region (power calculation)
(1) Objective function
max Δt
min Ppeak-P(t1+Δt)
(2) Constraint conditions
[Ppeak-P(t1+Δt)]Δt=Qre
0<Δt≤t2-t1
2. Region 2 power calculation
(1) Objective function
max Δt
min P(t2-Δt)-Pvalley
(2) Constraint conditions
[P(t2-Δt)-Pvalley]Δt=Qre
0<Δt≤t2-t1
Wherein, Δ t is the duration of the constant power electric quantity calibration; t is t1Starting time between main voltage regulating area and peak clipping area for energy storage inactive area;t2The end time of the energy storage non-action area between the main voltage regulating area and the peak clipping area; ppeakCutting a peak line for energy storage; pvalleyAnd filling valley lines for energy storage.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.