Primary frequency regulation optimization control method applicable to photovoltaic and energy storage power stations

Abstract

The present invention discloses a primary frequency regulation optimization control method applicable to photovoltaic and energy storage power stations, including: setting a variable sliding window based on the system frequency of a periodically sampled power grid, calculating the frequency change rate within the sliding window time, screening out the frequency change rate that deviates from the power frequency, and calculating a first power deviation; calculating a second power deviation through a segmented P‑F droop control algorithm based on the system frequency of the periodically sampled power grid; summing the current power, the first power deviation, and the second power deviation to construct a new target power; distributing the target power to form a power regulation instruction and sending it to each power output device, and the power output device adjusts its own power to the command power according to the power regulation instruction, and actually outputs the power to the grid connection point. The present invention provides a primary frequency regulation optimization control method applicable to photovoltaic and energy storage power stations, optimizes conventional new energy P‑F droop control, and improves the transient regulation capability of the primary frequency regulation algorithm of photovoltaic power stations and energy storage power stations.

Description

Technical Field

[0001] The invention relates to a primary frequency regulation optimization control method applicable to photovoltaic and energy storage power stations, and belongs to the technical field of primary frequency regulation of new energy photovoltaic power stations and energy storage power stations. Background Art

[0002] In recent years, with the rapid development of new energy in the power grid, the proportion of new energy installed capacity in the total installed capacity has increased year by year. New energy has become the second largest installed power source in the grid. The increasing penetration rate of new energy has squeezed the space of conventional thermal and power units with rotational inertia. At the same time, the fast and stable power regulation capability of new energy microgrids has also become an important part of measuring the power quality of the power grid. For this reason, new energy stations must have primary frequency regulation capabilities.

[0003] Photovoltaic power stations, energy storage power stations, etc. do not have the ability to regulate inertia themselves, but their response speed is generally relatively fast. Their primary frequency regulation function can be optimized and their transient regulation capability can be improved to enhance the role of photovoltaic and energy storage power stations when frequency fluctuations occur in the entire power grid.

[0004] There are three operating conditions that require improved transient capability: the frequency deviates significantly from 50 Hz, the frequency deviates from 50 Hz and has a trend of further deviation, and the frequency has a large trend of deviating from 50 Hz. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a primary frequency regulation optimization control method suitable for photovoltaic and energy storage power stations. For working conditions requiring frequency regulation, the conventional new energy PF droop control is optimized to improve the transient regulation capability of the primary frequency regulation algorithm of photovoltaic power stations and energy storage power stations.

[0006] To achieve the above object, the present invention provides a primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations, comprising the following steps:

[0007] A variable sliding window is set based on the system frequency of the power grid sampled periodically, the frequency change rate within the sliding window time is calculated, the frequency change rate that deviates from the power frequency is screened out, and the first power deviation generated by the frequency change rate is calculated accordingly;

[0008] Based on the system frequency of the periodically sampled power grid, a second power deviation generated by a frequency variation is calculated by a segmented PF droop control algorithm;

[0009] The current power, the first power deviation and the second power deviation are summed to construct a new target power;

[0010] The target power is distributed to form power adjustment instructions and sent to each power output device. The power output device adjusts its own power to the command power according to the power adjustment instructions and actually outputs the power to the grid connection point.

[0011] Furthermore, the sampling period is less than or equal to 10 milliseconds.

[0012] Furthermore, the variable sliding window includes:

[0013] t window = k × t sample ;

[0014] Among them, t window is the window time; k is the sliding coefficient, k≥1. When the sliding coefficient increases, the sensitivity decreases and the stability increases; t sample is the sampling period of the frequency device.

[0015] Furthermore, the value range of k is 5-10.

[0016] Furthermore, the frequency change rate that deviates from the power frequency is screened out, including:

[0017] The frequency change rate that deviates from the power frequency of 50 Hz is retained, and the frequency change rate that returns to the power frequency of 50 Hz is removed.

[0018] Further, calculating a first power deviation generated by the frequency change rate includes:

[0019] Get the upper and lower dead zones of the frequency change rate and calculate the first power deviation:

[0020]

[0021] Among them, P radio (r) is the first power deviation; r is the frequency change rate at the current moment; k r is the power coefficient of the frequency change rate; P n is the rated power of the system; f is the frequency of the system; r dead+ is the upper dead zone, r dead- The lower dead zone.

[0022] Furthermore, the upper and lower dead zones of the frequency change rate are obtained, including:

[0023]

[0024] Among them, r dead± The upper and lower dead zones of the frequency change rate are two values ​​that are opposite to each other, r dead+ represents the upper dead zone, r dead- Represents the lower dead zone; r min represents the minimum absolute value of the dead zone; f is the frequency of the system; fr-max is the maximum value of the dynamic change of frequency, f r-max The effect is: the frequency f exceeds 50±f r-max When k rd is the dynamic dead zone coefficient.

[0025] Further, the second power deviation generated by the frequency variation is calculated based on the segmented PF droop control algorithm, including:

[0026] The PF droop curve is segmented in the frequency deviation band to construct a multi-segment segmented PF droop curve;

[0027] The second power deviation is calculated based on a multi-segment segmented PF droop curve.

[0028] Furthermore, the frequency deviation band is a frequency difference interval between the system frequency and 50 Hz.

[0029] Furthermore, a three-segment segmented PF droop curve is constructed to calculate the second power deviation:

[0030]

[0031] Among them, P f (f) is the second power deviation; f is the frequency of the system; f max 、f min Represents the upper and lower dead zones of the frequency response, f u1 、f u2 、f u3 、f d1 、f d2 、f d3 are frequency bands respectively. u1 , k u2 , k u3 , k d1 , k d2 , k d3 Respectively represent the power coefficient corresponding to each frequency band; P n is the rated power of the system.

[0032] The beneficial effects achieved by the present invention are:

[0033] The present invention improves the traditional PF droop control algorithm, adds a segmented adjustment function to the algorithm, and adds an adjustment amount that is positively correlated with the frequency change rate, thereby improving the system's adjustment effect under the conditions of frequency mutation and large frequency change rate. At the same time, in order to optimize the effect of the adjustment amount, a variable sliding window calculation is added to the frequency change rate, the direction of the frequency change rate is determined, and the dead zone of the frequency change rate is dynamically set, thereby improving the adjustment effect when the frequency deviates from the power frequency by 50Hz.

[0034] In addition to being able to stably regulate the power station power under normal working conditions, the present invention still has a good regulating effect under conditions of rapid frequency changes or large frequency changes, so that the system can cope with different types of working conditions.

[0035] The present invention is applicable to the primary frequency modulation control system of new energy photovoltaic power stations, energy storage stations and photovoltaic storage integrated power stations, and can realize rapid regulation of active power under abnormal frequency conditions to ensure the stability of the station output power and improve the output power quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a program flow chart of a primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations provided by an embodiment of the present invention;

[0037] Figure 2 It is a comparison diagram of sliding coefficients k=2 and k=10 in the primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations provided by an embodiment of the present invention;

[0038] Figure 3 It is a segmented PF droop curve divided into three sections in the primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations provided in an embodiment of the present invention;

[0039] Figure 4 It is a functional relationship curve of frequency and frequency change rate dead zone in the primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations provided by an embodiment of the present invention;

[0040] Figure 5 It is a step diagram of a primary frequency regulation optimization control method applicable to photovoltaic and energy storage power stations provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0042] The embodiment of the present invention provides a primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations, such as Figures 1 to 5As shown, the present invention improves the traditional PF droop control algorithm, adds a segmented adjustment function to the algorithm, and adds an adjustment amount that is positively correlated with the frequency change rate, thereby improving the system's adjustment effect under conditions of sudden frequency changes and large frequency change rates. At the same time, in order to optimize the effect of the adjustment amount, a variable sliding window calculation is added to the frequency change rate, the direction of the frequency change rate is determined, and the dead zone of the frequency change rate is dynamically set to improve the adjustment effect when the frequency deviates from the power frequency by 50Hz; in addition to being able to stably adjust the power of the power station under conventional working conditions, the present invention still has a good adjustment effect under conditions of rapid frequency changes or large frequency changes, so that the system can cope with different types of working conditions; the present invention is suitable for the primary frequency regulation control system of new energy photovoltaic power stations, energy storage power stations and integrated photovoltaic and storage power stations, and can realize rapid adjustment of active power under abnormal frequency conditions to ensure the stability of the output power of the station and improve the output power quality.

[0043] Specifically, the present invention provides a primary frequency modulation optimization control method for photovoltaic and energy storage power stations, such as Figure 1 and Figure 5 As shown, the following steps are included:

[0044] Step 1: Calculate the first power deviation caused by the frequency change rate:

[0045] 1.1: The high-precision system frequency of the photovoltaic and energy storage power station grid is obtained periodically and in real time from the frequency measurement device. The sampling period of the frequency device is t sample No more than 10 milliseconds. Set a variable sliding window for the acquired frequency and calculate the frequency change rate within the sliding window time, where the window time of the sliding window is: t window = k × t sample ;

[0046] Among them, t window represents the window time, t sample Indicates the sampling period of the frequency device, k is the sliding coefficient, requiring k ≥ 1. When k is at least 1, the system has the maximum sensitivity and minimum stability. When k increases, the sensitivity of the system decreases and the stability increases. Generally, the value of k is between 5 and 10; when k = 2 and k = 10, the comparison effect is shown in Figure 2 When k=2, the frequency change rate calculated by the sliding window changes very sensitively. When k=10, the frequency change rate calculated by the sliding window changes relatively slowly. According to step 1.2, the sensitivity / smoothness of the frequency change rate will directly affect the sensitivity / smoothness of the final target power. Note: Figure 2 The middle frequency uses the right axis.

[0047] 1.2: According to the frequency change rate calculated in step 1.1, the frequency change rate that deviates from the power frequency is screened, and the first power deviation is calculated according to the screened frequency change rate.

[0048] First, calculate the upper and lower dead zones of the frequency change rate:

[0049]

[0050] Among them, r dead± The upper and lower dead zones of the frequency change rate are two values ​​that are opposite to each other, r dead+ represents the upper dead zone, r dead- Represents the lower dead zone; r min represents the minimum absolute value of the dead zone; f is the frequency of the system; f r-max is the maximum value of the dynamic change of frequency, f r-max The effect is: the frequency f exceeds 50±f r-max When k rd is the dynamic dead zone coefficient.

[0051] Figure 4 For r min =0.05Hz, f r-max =0.1Hz, k rd = 0.7 when the frequency change rate dead zone and frequency relationship.

[0052] Then calculate the power deviation caused by the frequency change rate, which is the first power deviation:

[0053]

[0054] Among them, P radio (r) represents the first power deviation caused by the frequency change rate; r is the frequency change rate at the current moment; k r The power factor that represents the rate of change of frequency; P n Represents the rated power of photovoltaic and energy storage power stations; Note: In the calculation process here, r does not need to subtract the dead zone value.

[0055] Step 2: Calculate the second power deviation caused by the frequency change:

[0056] 2.1: Preset segment PF droop curve:

[0057] The PF droop curve is segmented in the frequency deviation band to construct a multi-segment segmented PF droop curve. The frequency deviation band is the frequency difference interval between the system frequency and 50 Hz, such as Figure 3As shown, the present invention can set the number of segments according to the actual site and is suitable for different application scenarios. Specifically, in the embodiment of the present invention, in the part where the frequency is higher or lower than 50 Hz, the PF droop curve is divided into 3 segments to construct a 3-segment segmented PF droop curve; compared with the smooth curve or adaptive curve used in other methods, the present invention uses a segmented curve to construct a segmented function with a clear structure, which is very suitable for writing programs for calculations; the parameter setting is simple and intuitive, which is convenient for on-site operation and maintenance personnel to set and debug.

[0058] 2.2: The high-precision system frequency of the photovoltaic and energy storage power station grid is obtained periodically and in real time from the frequency measurement device. The power deviation caused by the frequency change is calculated by the preset segmented PF droop control algorithm, which is the second power deviation. Taking three segments as an example, the power calculation formula is:

[0059]

[0060] Where f represents the system frequency, P f (f) represents the power deviation caused by frequency, f max 、f min Represents the upper and lower dead zones of the frequency response, f u1 、f u2 、f u3 、f d1 、f d2 、f d3 are frequency bands respectively. u1 , k u2 , k u3 , k d1 , k d2 , k d3 Respectively represent the power coefficient corresponding to each frequency band; P n Indicates the rated power of photovoltaic and energy storage power stations.

[0061] Step 3: Substitute the first power deviation P obtained in step 1 and step 2 radio (r) and the second power deviation P f (f) and the current system frequency P 0 The target power is added together to obtain the current target power of the system, and the target power is distributed to form a power adjustment instruction and sent to each power output device. The power output device adjusts its own power to the command power according to the power adjustment instruction and actually outputs the power to the grid connection point, thereby optimizing the primary frequency regulation optimization control method of photovoltaic and energy storage power stations.

[0062] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0063] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0064] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0065] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations, characterized in that: The steps include: A variable sliding window is set based on the system frequency of the power grid sampled periodically, the frequency change rate within the sliding window time is calculated, the frequency change rate that deviates from the power frequency is screened out, and the first power deviation generated by the frequency change rate is calculated accordingly; Based on the system frequency of the periodically sampled power grid, a second power deviation generated by a frequency variation is calculated by a segmented PF droop control algorithm; The current power, the first power deviation and the second power deviation are summed to construct a new target power; The target power is distributed to form a power adjustment instruction and sent to each power output device. The power output device adjusts its own power to the command power according to the power adjustment instruction and actually outputs the power to the grid connection point; The sampling period is less than or equal to 10 milliseconds; Calculating a first power deviation generated by the frequency change rate includes: Get the upper and lower dead zones of the frequency change rate and calculate the first power deviation: ； in, is the first power deviation; is the frequency change rate at the current moment; is the power coefficient of the frequency change rate; is the rated power of the system; is the frequency of the system; is the upper dead zone, is the lower dead zone; The second power deviation generated by the frequency variation is calculated based on the segmented PF droop control algorithm, including: The PF droop curve is segmented in the frequency deviation band to construct a multi-segment segmented PF droop curve; Calculating a second power deviation based on a multi-segment segmented PF droop curve; Construct a three-segment piecewise PF droop curve and calculate the second power deviation: ； in, is the second power deviation; is the frequency of the system; , Indicates the upper and lower dead zones of the frequency response, , , , , , They are frequency bands; , , , , , Respectively represent the power coefficient corresponding to each frequency band; is the rated power of the system.

2. The primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations according to claim 1 is characterized in that: Variable sliding windows, including: ； in, is the window time; is the sliding coefficient, , when the sliding coefficient increases, the sensitivity decreases and the stability increases; is the sampling period of the frequency device.

3. The primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations according to claim 2 is characterized in that: The value range is 5-10.

4. The primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations according to claim 1 is characterized in that: Filter out the frequency change rate that deviates from the power frequency, including: The frequency change rate that deviates from the power frequency of 50 Hz is retained, and the frequency change rate that returns to the power frequency of 50 Hz is removed.

5. The primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations according to claim 1 is characterized in that: Get the upper and lower dead zones of the frequency change rate, including: ； in, The upper and lower dead zones representing the frequency change rate are two values ​​that are opposite to each other. Indicates the upper dead zone, Indicates lower dead zone; Indicates the minimum absolute value of the dead zone; is the frequency of the system; is the maximum value of the dynamic change of frequency, The role of: frequency More than 50± When , the dead zone no longer decreases; is the dynamic dead zone coefficient.

6. The primary frequency modulation optimization control method applicable to photovoltaic and energy storage power stations according to claim 1 is characterized in that: The frequency deviation band is the frequency difference range between the system frequency and 50 Hz.

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