An analytic calculation method and system for abandoned power rate of a water-light complementary system

Abstract

The present application relates to the cross field of clean renewable energy utilization and reservoir scheduling, and discloses a kind of analytical calculation method and system for water-light complementary system abandoned electricity rate. Including the following steps: step S1. Based on daily average photovoltaic output, using quadratic function to fit the hourly scale photovoltaic output process of each day;Step S2. Using analytical method to obtain the daily abandoned electricity rate of water-light complementary system based on boundary conditions;Step S3. Verify the accuracy of the analytical calculation method of the obtained abandoned electricity rate. The present application uses quadratic function to fit the photovoltaic output process, proposes an estimation method for describing the photovoltaic hourly output process based on daily average photovoltaic output, obtains the analytical calculation method for daily scale abandoned electricity rate of water-light complementary system, reasonably calculates the daily abandoned electricity rate of water-light complementary system, and provides a new way for evaluating the abandoned electricity risk of water-light complementary system.

Description

TECHNICAL FIELD

[0001] The application belongs to the cross field of clean renewable energy utilization and reservoir scheduling, and relates to an analytic calculation method and system for abandoned electricity rate of a water-light complementary system. BACKGROUND

[0002] Developing new energy such as wind and light is one of the effective measures to alleviate the impact of climate change. However, due to the randomness, uncertainty and intermittence of wind and light resources, large-scale access of non-adjustable wind and light power will bring great challenges to the stability and safety of the power system. Joint scheduling of light and power and water power with flexible adjustment capacity to form a water-light complementary system can effectively promote the consumption of light and power. The calculation of abandoned electricity rate and the accurate identification of abandoned electricity risk are one of the core problems of the scheduling and operation of the water-light complementary system.

[0003] At present, the calculation method of the abandoned electricity rate of the water-light complementary system mostly uses the numerical calculation method of simulating the scheduling process by constructing a model, and lacks an analytic calculation method of the abandoned electricity quantity of the water-light complementary system based on theoretical derivation. Based on this, the application provides an analytic calculation method for the abandoned electricity rate of the water-light complementary system. SUMMARY

[0004] In view of the fact that the existing method mostly uses the numerical calculation method of simulating the scheduling process by constructing a model, and lacks an analytic calculation method of the abandoned electricity quantity of the water-light complementary system based on theoretical derivation, the application provides an analytic calculation method for the abandoned electricity rate of the water-light complementary system, which provides a new way for reasonably evaluating the short-term abandoned electricity risk of the water-light complementary system.

[0005] To solve the above technical problems, the application adopts the following technical solutions:

[0006] An analytic calculation method for the abandoned electricity rate of a water-light complementary system comprises the following steps:

[0007] Step S1. Based on daily average photovoltaic output, a quadratic function is used to fit the hourly photovoltaic output process of each day.

[0008] Step S2. An analytic method is used to derive the daily abandoned electricity rate of the water-light complementary system based on boundary conditions.

[0009] Step S3. The accuracy of the derived analytic calculation method for the abandoned electricity rate is verified.

[0010] Further, in step S1, to quantitatively describe the hourly photovoltaic output process, a quadratic function is first used to fit the hourly photovoltaic output process of each day.

[0011] (1)

[0012] In the formula, is the photovoltaic output of the photovoltaic power station at the hourly output, , , are three parameters of the quadratic function used for fitting, respectively, is the daily average photovoltaic output; secondly, the relationship between the three parameters of the quadratic function used for fitting and the daily average photovoltaic output is established:

[0013]

[0014] wherein: , , , , , are parameters of linear fitting of the three parameters of the quadratic function with the daily average photovoltaic output .

[0015] Further, the boundary condition in the step S2 is that the total daily output of water and electricity is known; the typical daily load curve of the water-light complementary system is unimodal, and the peak segment of the load curve covers the photovoltaic output time period.

[0016] Further, the step S2 specifically comprises the following sub-steps:

[0017] Step S21: average the photovoltaic output process, and adjust the water and electricity to meet the formulated day-ahead generation plan; under the given load rate, i.e. the ratio of the average value to the maximum value of the load curve, and the peak segment length of the load curve, the peak segment load and the valley segment load of the first day-ahead generation plan are calculated;

[0018] Step S22: compare the peak segment load of the first day-ahead generation plan calculated in the step S21 with the transmission capacity of the water-light complementary system ; if the peak segment load of the first day-ahead generation plan is greater than the transmission capacity of the water-light complementary system , the step S23 is executed, otherwise the step S24 is executed;

[0019] Step S23: adjust the day-ahead generation plan downward, and are the peak segment and valley segment loads of the second day-ahead generation plan after adjustment, respectively, and part of the photovoltaic power, i.e. the first photovoltaic power is abandoned, and the step S25 is continued to be executed;

[0020] Step S24: if the peak segment load of the first day-ahead generation plan is less than or equal to the transmission capacity of the water-light complementary system If the second step does not need to adjust the day-ahead generation plan, the amount of abandoned electricity is 0, and step S25 is continued.

[0021] Step S25: The intra-day hourly step photovoltaic output process quantitatively described in step S1 by the daily average photovoltaic output Substitute and compare the maximum photovoltaic output with the peak load of the second day-ahead generation plan If That is, the photovoltaic output alone has already exceeded the load demand, so part of the photovoltaic power, i.e., the second photovoltaic power, needs to be continuously abandoned If the day-ahead generation plan remains unchanged, the required hydroelectric output will increase Since the available daily hydroelectric output is fixed, the day-ahead generation plan needs to be continuously adjusted downward;

[0022] Step S26: The day-ahead generation plan is continuously adjusted downward to , The peak load of the third day-ahead generation plan, and part of the photovoltaic power, i.e., the third photovoltaic power, needs to be continuously abandoned So that the required hydroelectric output is exactly equal to the available hydroelectric output, and the third photovoltaic power is solved .

[0023] Further, in the step S21,

[0024]

[0025] In the formula, and are the peak load and the valley load of the first day-ahead generation plan, respectively; and are the daily average hydroelectric output and the daily average photovoltaic output, respectively; is the proportion of the peak period of the day-ahead generation plan to the total length of a day.

[0026] Further, in the step S23,

[0027] (4)

[0028] In the formula, and are the peak load and the valley load of the second day-ahead generation plan, respectively; is the first photovoltaic power abandoned for the first time ; is the transmission capacity of the hybrid system; is the daily average photovoltaic output remaining after the first time of abandoned electricity is deducted.

[0029] Further, in the step S24,

[0030] (5)

[0031] In the formula: and These are the peak and off-peak loads of the power generation plan for the second day prior; The first optoelectronics company to be abandoned ; For the transmission capacity of the water-solar hybrid system; This refers to the average daily output of photovoltaic power remaining after deducting the first instance of power curtailment.

[0032] Furthermore, in step S26,

[0033] The system of equations is constructed as follows:

[0034]

[0035] In the formula This refers to the average daily output of photovoltaic power remaining after deducting the second instance of power curtailment. The peak load of the power generation plan is three days prior; For the photoelectric effect that needs to be discarded in the third step, equation (6) can be transformed into equation (6) concerning the photoelectric effect that needs to be discarded in the third step. The cubic equation of one variable:

[0036]

[0037] Solving equation (7), we obtain the following solution within the domain:

[0038]

[0039] Find Then, the amount of electricity wasted in the fourth step is .

[0040] Furthermore, in step S3, in order to verify the accuracy of the proposed analytical calculation method for the curtailment rate, the method of describing the hourly photovoltaic output process using the daily average photovoltaic output is first tested based on historical long-sequence hourly step photovoltaic data. Then, the curtailment rate obtained by optimized scheduling is compared with the curtailment rate obtained by the analytical calculation method to verify the accuracy of the proposed analytical calculation method for the curtailment rate.

[0041] Furthermore, the correlation coefficient was used. The accuracy of the evaluation method The closer the value is to 1, the more accurate the calculation of the curtailment rate.

[0042] This invention also provides an analytical calculation system for the curtailment rate of a water-solar hybrid system, characterized in that it includes:

[0043] Module one, which adopts quadratic function to fit the hourly photovoltaic output process based on daily average photovoltaic output;

[0044] Module two, which adopts an analytical method to calculate the daily curtailment rate of the water-light complementary system based on boundary conditions:

[0045] Module three, which verifies the accuracy of the analytical calculation method of the calculated curtailment rate.

[0046] Compared with the prior art, the present application has the following beneficial effects:

[0047] The present application adopts quadratic function to fit the photovoltaic output process, proposes an estimation method for describing the hourly photovoltaic output process through daily average photovoltaic output, calculates the daily scale curtailment rate of the water-light complementary system by an analytical method, and reasonably calculates the daily curtailment rate of the water-light complementary system, thereby providing a new way for evaluating the curtailment risk of the water-light complementary system. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0049] Figure 1 The flowchart of the method of the present application.

[0050] Figure 2 The schematic diagram of the curtailment process of the present application.

[0051] Figure 3 The simulation result of the hourly photovoltaic process of the Yalong River Jinping first-stage water-light complementary system.

[0052] Figure 4 The analytical calculation result of the curtailment rate of the Yalong River Jinping first-stage water-light complementary system. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0054] In the description of the present application, it needs to be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0055] In the description of the present application, it needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] As Figure 1 shown, the present application comprises the following flow:

[0057] Step S1. Based on daily average photovoltaic output, quadratic function is used to fit daily hourly scale photovoltaic output process; in order to quantitatively describe the hourly photovoltaic output process, first of all, quadratic function is used to fit the daily hourly scale photovoltaic output process:

[0058] (1)

[0059] In the formula: is the output of photovoltaic power station at the first hour, , , , are three parameters of the quadratic function used for fitting, is daily average photovoltaic output; secondly, the relationship between three parameters of the fitted quadratic function and daily average photovoltaic output is established:

[0060]

[0061] In the formula: , , , , , are parameters used for linear fitting three parameters of the quadratic function with daily average photovoltaic output .

[0062] Step S2. The daily curtailment rate of the water-light complementary system is calculated based on the boundary conditions, wherein the boundary conditions are: the total daily output of the water power is known; the typical daily load curve of the water-light complementary system is unimodal, and the peak segment of the load curve covers the photovoltaic output period:

[0063] Step S3. The accuracy of the calculated curtailment rate is verified.

[0064] As shown in Figure 2 , step S2 specifically includes the following sub-steps:

[0065] Step S21: The photovoltaic output process is averaged, and the water power is adjusted to meet the formulated day-ahead generation plan. Under the given load rate, i.e., the ratio of the average value to the maximum value of the load curve, and the peak segment length of the load curve, the peak segment load and the valley segment load of the first day-ahead generation plan are calculated.

[0066] Step S22: The peak segment load of the first day-ahead generation plan calculated in step S21 is compared with the transmission capacity of the water-light complementary system. If the peak segment load of the first day-ahead generation plan is greater than the transmission capacity of the water-light complementary system, as shown in step 1 in Figure 2 , step S23 is performed, otherwise step S24 is performed.

[0067] Step S23: The day-ahead generation plan is adjusted downward, and are the peak segment and valley segment loads of the second day-ahead generation plan after adjustment, and part of the photovoltaic power, i.e., the first photovoltaic power , is curtailed, as shown in step 2 in Figure 2 , and step S25 is continued.

[0068] Step S24: If the peak segment load of the first day-ahead generation plan is less than or equal to the transmission capacity of the water-light complementary system, the day-ahead generation plan does not need to be adjusted in the second step, and the curtailment amount is 0, and step S25 is continued.

[0069] Step S25: The photovoltaic output process in hourly steps within a day quantitatively described by the daily average photovoltaic output in step S1 is substituted into , and the maximum photovoltaic output is compared with the peak segment load of the second day-ahead generation plan. If , i.e., the photovoltaic output alone has already exceeded the load demand, part of the photovoltaic power, i.e., the second photovoltaic power ; but if the day-ahead generation schedule remains unchanged, the required hydro power output will increase , since the available daily hydro power output is fixed, the day-ahead generation schedule needs to be adjusted downward continuously, as shown in step 3 in Figure 2 ;

[0070] Step S26: the day-ahead generation schedule is continuously adjusted downward to , is the third daily peak load of the day-ahead generation schedule, and the part of the photovoltaic power that is continuously abandoned is the third photovoltaic power so that the required hydro power output is exactly equal to the available hydro power output, the third photovoltaic power is solved, as shown in step 4 in Figure 2 .

[0071] Taking the Yalong River Jinping I water-photovoltaic complementary system as an example, the hourly photovoltaic power output data from 1980 to 2019, the hourly reservoir inflow and outflow, upstream and downstream water level, system load demand and other dispatching operation data from 2016 to 2017 are input, the parameters for describing the hourly photovoltaic power process by the daily average photovoltaic power are calibrated and verified, and then the analytical method is used to calculate the daily abandoned power rate of the water-photovoltaic complementary system, and compared with the numerical calculation method of constructing the model to simulate the dispatching process to verify the accuracy of the analytical method.

[0072] Figure 3 The results of simulating the hourly photovoltaic power process by the daily average photovoltaic power of the Yalong River Jinping I water-photovoltaic complementary system are shown, wherein the calibration period is from 1980 to 1999, and the verification period is from 2000 to 2019. As shown in the attached Figure 3 , the three parameters of the quadratic function used to fit the hourly photovoltaic power of each day and the daily average photovoltaic power are all greater than 0.9, and all show a significant linear correlation; in addition, the average value of the method for simulating the hourly photovoltaic power process by the daily average photovoltaic power in the calibration period and the verification period is higher than 0.85 in different months, indicating that the simulation method is good. The attached shows the comparison results of the abandoned power rate of the Yalong River Jinping I water-photovoltaic complementary system from 2016 to 2017 obtained by the analytical calculation method proposed in the present application and the numerical calculation method of constructing the model to simulate the dispatching process under different load rates. The results show that the abandoned power rate results of the two methods under different load rates

[0073] are all greater than 0.998, the abandoned power rate analytical calculation method of the water-photovoltaic complementary system proposed can accurately calculate the daily abandoned power rate of the system, especially when the abandoned power rate is greater than 60%, the abandoned power rate calculation result is the most accurate. Figure 4

[0074] ​​The research method proposes a method for simulating hourly photovoltaic output process by using daily photovoltaic output, deduces an analytical calculation method for abandoned electricity rate of the water-light complementary system, and improves the identification method for abandoned electricity risk of the water-light complementary system, thereby providing a new way for reasonably evaluating the abandoned electricity risk of the water-light complementary system.

[0075] The above is the specific embodiment of the technical scheme of the present application and the technical principle used. Any modification or supplement or equivalent replacement made by the person skilled in the art on the basis of the embodiment is within the scope claimed by the claims of the present application.

Claims

1. An analytical calculation method for the curtailment rate of a hydro-solar hybrid system, characterized in that, Includes the following steps: Step S1. Based on the daily average photovoltaic output, a quadratic function is used to fit the daily hourly photovoltaic output process; Step S2. Calculate the daily curtailment rate of the hydro-solar hybrid system based on boundary conditions using analytical methods; specifically including the following sub-steps: Step S21: Average the photovoltaic power output process and adjust the hydropower to meet the established day-ahead power generation plan. Given the load factor (the ratio of the average to the maximum value of the load curve) and the peak duration of the load curve, calculate the peak load of the first day-ahead power generation plan. and valley load ; Step S22: Calculate the peak load of the first day's planned power generation from step S21. Transmission capacity of water-solar complementary system For comparison, if the peak load of the power generation plan on the first day is... Greater than the transmission capacity of the water-solar hybrid system If yes, proceed to step S23; otherwise, proceed to step S24. Step S23: Adjust the day-ahead power generation plan downwards. and These are the peak and off-peak loads of the adjusted power generation plan for the second day, respectively, with a portion of the photovoltaic power being discarded, i.e., the first photovoltaic power generation. Continue with step S25; Step S24: If the peak load of the power generation plan is on the first day Smaller than the transmission capacity of water-solar complementary systems If so, the second step does not require adjusting the day-ahead power generation plan, and the amount of abandoned power is 0, then continue to execute step S25; Step S25: Quantify the intraday hourly photovoltaic output process described in Step S1 using the daily average photovoltaic output. Substitute and compare the maximum output of photovoltaic power. Peak load of power generation plan the day before Size, if This means that the output of photovoltaic power alone already exceeds the load demand, therefore it is necessary to continue to discard some photovoltaic power, i.e., a second photovoltaic power generation. However, if the current power generation plan remains unchanged, the required hydropower output will increase. Since the available daily hydropower output is fixed, it is necessary to continue to adjust the day-ahead power generation plan downward. Step S26: Further adjust the day-ahead power generation plan downwards to , To meet the peak load of the power generation plan three days prior, a portion of the photovoltaic power will be curtailed, i.e., the third photovoltaic power generation. Solve for the third photoelectric power source so that the required hydroelectric output is exactly equal to the available hydroelectric output. ; Step S3. Verify the accuracy of the analytical calculation method for the derived power curtailment rate.

2. The analytical calculation method for the curtailment rate of a hydro-solar hybrid system according to claim 1, characterized in that: In step S1, to quantitatively describe the hourly photovoltaic power output process, a quadratic function is first used to fit the daily hourly photovoltaic power output process: (1) In the formula: For photovoltaic power stations in the first Hours of effort, , , These are the three parameters of the quadratic function used for fitting. The first step is to determine the average daily photovoltaic output; the second step is to establish the relationship between the three parameters of the fitted quadratic function and the average daily photovoltaic output. The relationship between them: In the formula: , , , , , They are respectively based on the average daily photovoltaic output The parameters of the three parameters of the linearly fitted quadratic function.

3. The analytical calculation method for the curtailment rate of a hydro-solar hybrid system according to claim 1, characterized in that: The boundary conditions in step S2 are: the total daily output of hydropower is known; the typical daily load curve of the hydro-solar hybrid system is single-peak type, and the peak segment of the load curve covers the time period of photovoltaic output.

4. The analytical calculation method for the curtailment rate of a water-solar hybrid system according to claim 1, characterized in that: In the formula, and These are the peak and off-peak loads of the power generation plan for the first day; and These are the average daily power output of hydropower and the average daily power output of photovoltaic power, respectively. This refers to the proportion of peak hours in the daily power generation plan to the total daily time.

5. The analytical calculation method for the curtailment rate of a water-solar hybrid system according to claim 1, characterized in that: In step S23 (4) In the formula: and These are the peak and off-peak loads of the power generation plan for the second day prior; The first optoelectronics company to be abandoned ; For the transmission capacity of the water-solar hybrid system; The remaining average daily output of photovoltaic power after deducting the first instance of power curtailment; In step S24 （5） In the formula: and These are the peak and off-peak loads of the power generation plan for the second day prior; The first optoelectronics company to be abandoned ; For the transmission capacity of the water-solar hybrid system; This refers to the average daily output of photovoltaic power remaining after deducting the first instance of power curtailment.

6. The analytical calculation method for the curtailment rate of a hydro-solar hybrid system according to claim 1, characterized in that: In step S26 The system of equations is constructed as follows: In the formula This refers to the average daily output of photovoltaic power remaining after deducting the second instance of power curtailment. The peak load of the power generation plan is three days prior; For the photoelectric effect that needs to be discarded in the third step, equation (6) can be transformed into equation (6) concerning the photoelectric effect that needs to be discarded in the third step. The cubic equation of one variable: Solving equation (7), we obtain the following solution within the domain: Find Then, the amount of electricity wasted in the fourth step is .

7. The analytical calculation method for the curtailment rate of a hydro-solar hybrid system according to claim 1, characterized in that: In step S3, to verify the accuracy of the proposed analytical calculation method for the curtailment rate, the method of describing the hourly photovoltaic output process using the daily average photovoltaic output is first tested based on historical long-sequence hourly step photovoltaic data. Then, the curtailment rate obtained by optimized scheduling is compared with the curtailment rate obtained by the analytical calculation method to verify the accuracy of the proposed analytical calculation method for the curtailment rate.

8. The analytical calculation method for the curtailment rate of a water-solar hybrid system according to claim 7, characterized in that: Using correlation coefficient The accuracy of the evaluation method The closer the value is to 1, the more accurate the calculation of the curtailment rate.

9. An analytical calculation system for the curtailment rate of a hydro-solar hybrid system, characterized in that: include Module 1 uses a quadratic function to fit the daily hourly photovoltaic output process based on the average daily photovoltaic output. Module Two employs an analytical method to deduce the daily curtailment rate of the hydro-solar hybrid system based on boundary conditions. Specifically, it includes the following sub-steps: Step S21: Average the photovoltaic power output process and adjust the hydropower to meet the established day-ahead power generation plan. Given the load factor (the ratio of the average to the maximum value of the load curve) and the peak duration of the load curve, calculate the peak load of the first day-ahead power generation plan. and valley load ; Step S22: Calculate the peak load of the first day's planned power generation from step S21. Transmission capacity of water-solar complementary system For comparison, if the peak load of the power generation plan on the first day is... Greater than the transmission capacity of the water-solar hybrid system If yes, proceed to step S23; otherwise, proceed to step S24. Step S23: Adjust the day-ahead power generation plan downwards. and These are the peak and off-peak loads of the adjusted power generation plan for the second day, respectively, with a portion of the photovoltaic power being discarded, i.e., the first photovoltaic power generation. Continue with step S25; Step S24: If the peak load of the power generation plan is on the first day Smaller than the transmission capacity of water-solar complementary systems If so, the second step does not require adjusting the day-ahead power generation plan, and the amount of abandoned power is 0, then continue to execute step S25; Step S25: Quantify the intraday hourly photovoltaic output process described in Step S1 using the daily average photovoltaic output. Substitute and compare the maximum output of photovoltaic power. Peak load of power generation plan the day before Size, if This means that the output of photovoltaic power alone already exceeds the load demand, therefore it is necessary to continue to discard some photovoltaic power, i.e., a second photovoltaic power generation. However, if the current power generation plan remains unchanged, the required hydropower output will increase. Since the available daily hydropower output is fixed, it is necessary to continue to adjust the day-ahead power generation plan downward. Step S26: Further adjust the day-ahead power generation plan downwards to , To meet the peak load of the power generation plan three days prior, a portion of the photovoltaic power will be curtailed, i.e., the third photovoltaic power generation. Solve for the third photoelectric power source so that the required hydroelectric output is exactly equal to the available hydroelectric output. ; Module 3 verifies the accuracy of the analytical calculation method for the derived curtailment rate.

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