Power grid stability control method and system based on combination of power tracking and frequency adjustment

Abstract

The invention relates to a power grid stability control method and system based on combination of power tracking and frequency regulation, and the method comprises the steps: setting a power tracking point of a target power grid, and monitoring the real-time power change of the power tracking point; obtaining a power change value of an electronic load according to the real-time power change, and controlling the electronic load to carry out power compensation on the target power grid based on the power change value; and if the electronic load capacity in the target power grid is smaller than the electronic load capacity required by a power change value, dynamically adjusting the power change value by adopting a frequency-assisted adjustment linear difference algorithm, and continuously performing power compensation on the target power grid through the dynamically adjusted power change value. And completing the stable control of the target power grid until the power of the power tracking point reaches a preset power threshold. According to the invention, through active power tracking and auxiliary frequency adjustment, a rapid stepless electronic load based on a high-voltage high-power power electronic technology is adopted to realize stable control of a power grid.

Description

Technical Field

[0001] The present invention relates to the technical field of power system automation, and in particular to a power grid stability control method and system based on the combination of power tracking and frequency regulation, which is suitable for islanded power grids, in particular, isolated grid systems with small units and limited regulation capabilities. Background Art

[0002] In the power grid in island operation, the limited installed capacity of generators and small rotating reserve limit the regulation capacity of the power grid. When the high-power load suddenly disappears due to fault tripping, large impact load withdrawal, etc., it far exceeds the regulation capacity of the generator, and the power grid frequency rises rapidly, which will cause the generator overspeed protection, high-frequency shedding, and low-frequency load shedding to alternately act, and even cause black network events in severe cases. This phenomenon is particularly prominent in the isolated grid system of 2 to 4 units. The number of generators and loads in the isolated grid system is small, and the power regulation means are relatively few. Therefore, when load shedding occurs, it is easier to cause the accident to expand.

[0003] Traditional coping methods include machine-grid coordination systems, stability control systems, and switch-type electric load balancing systems. Among them, the machine-grid coordination system is generally regulated and controlled based on frequency changes. The frequency itself changes slowly and has dead zones, and the generator regulation capacity is limited, with slow regulation speed and low precision. In an isolated grid, the units and loads have large capacities and small numbers, and the stability control system has few operational resources, large granularity, serious over-cutting and under-cutting problems, and large limitations on stability control actions. Switch-type electric loads are based on frequency or power, and adopt a hierarchical and group switching method, single feedforward control, single function, and inflexible control methods. Therefore, the present invention proposes a power grid stability control method based on the combination of power tracking and frequency regulation. Summary of the invention

[0004] The purpose of the present invention is to provide a power grid stability control method and system based on the combination of power tracking and frequency regulation, and to achieve stable control of the power grid by using a fast stepless electronic load based on high-voltage and high-power power electronics technology.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The grid stability control method based on the combination of power tracking and frequency regulation includes:

[0007] Setting a power tracking point of a target power grid and monitoring real-time power changes of the power tracking point;

[0008] Acquiring a power change value of the electronic load according to the real-time power change, and controlling the electronic load to perform power compensation on the target power grid based on the power change value;

[0009] If the electronic load capacity in the target power grid is less than the electronic load required by the power change value, the frequency-assisted regulation linear difference algorithm is used to dynamically adjust the power change value, and the power change value obtained by the dynamic adjustment is used to continuously compensate the power of the target power grid until the power of the power tracking point reaches the preset power threshold, thereby completing the stable control of the target power grid.

[0010] Optionally, the power tracking point includes a fixed power value tracking point and an average power value tracking point, wherein the fixed power value tracking point is used for loads with fixed power in the target power grid, and the average power value tracking point is used for loads with large power variations in the target power grid.

[0011] Optionally, acquiring a power change value of the electronic load according to the real-time power change includes:

[0012] If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value;

[0013] If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

[0014] Optionally, dynamically adjusting the power change value by using the frequency-assisted linear difference adjustment algorithm includes:

[0015] Set the frequency point and the corresponding power value;

[0016] Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value;

[0017] The found power value is superimposed on the power change value to obtain an adjusted power change value.

[0018] To further achieve the above-mentioned purpose, the present invention also provides a power grid stability control system based on the combination of power tracking and frequency regulation, including: a power tracking module, a power compensation module, and a frequency auxiliary module, wherein the power tracking module is used to set the power tracking point of the target power grid and monitor the real-time power changes of the power tracking point; the power compensation module is used to obtain the power change value of the electronic load according to the real-time power change, and control the electronic load to perform power compensation on the target power grid based on the power change value; the frequency auxiliary module is used to dynamically adjust the power change value by using a frequency-assisted regulation linear difference algorithm when the electronic load capacity in the target power grid is less than the electronic load required by the power change value, and continuously perform power compensation on the target power grid by using the power change value obtained by the dynamic adjustment until the power of the power tracking point reaches a preset power threshold, thereby completing the stable control of the target power grid.

[0019] Optionally, the power tracking points of the target power grid set in the power tracking module include fixed power value tracking points and average power value tracking points, wherein the fixed power value tracking points are used for loads with fixed power in the target power grid, and the average power value tracking points are used for loads with large power variations in the target power grid.

[0020] Optionally, the power compensation module acquires the power change value of the electronic load according to the real-time power change, including:

[0021] If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value;

[0022] If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

[0023] Optionally, the frequency auxiliary module adopts a frequency auxiliary regulation linear difference algorithm to dynamically adjust the power change value, including:

[0024] Set the frequency point and the corresponding power value;

[0025] Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value;

[0026] The found power value is superimposed on the power change value to obtain an adjusted power change value.

[0027] To further achieve the above objectives, the present invention also provides a processor, which is used to run a program, wherein when the program is running, a power grid stability control method based on the combination of power tracking and frequency regulation is executed.

[0028] To further achieve the above-mentioned purpose, the present invention also provides an electronic device, comprising one or more memories and a processor, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement a grid stability control method based on the combination of power tracking and frequency regulation.

[0029] The beneficial effects of the present invention are:

[0030] The present invention realizes that the isolated grid system can actively realize disturbance-free complete compensation when the load is lost in most cases through active power tracking; and the frequency-assisted regulation can cope with some special situations, such as when the load is lost or the amplitude of the fluctuation exceeds the capacity of the electronic load, or when the reserve power is insufficient due to negative sequence compensation, reduced capacity operation, etc. The frequency-assisted regulation function can ensure that the electronic load has the mobility of dynamic regulation instead of staying at a fixed value, which greatly increases the flexibility of electronic load control and improves the control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A flow chart of a power tracking control method according to an embodiment of the present invention;

[0033] Figure 2 This is a control curve variation diagram of the power tracking mode 1 of an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the electronic load power increase at a constant rate according to an embodiment of the present invention;

[0035] Figure 4 A flow chart of a method for power tracking mode 1 according to an embodiment of the present invention;

[0036] Figure 5 This is a control curve variation diagram of power tracking mode 2 of an embodiment of the present invention;

[0037] Figure 6A schematic diagram of a specific setting of a frequency-assisted linear difference adjustment algorithm according to an embodiment of the present invention;

[0038] Figure 7 A curve diagram showing the suppressing effect of the electronic load input on the frequency oscillation according to an embodiment of the present invention;

[0039] Figure 8 is a curve diagram of the damping suppression effect of the electronic load under different coefficients of an embodiment of the present invention;

[0040] Fig. 9 This is a flow chart of a grid stability control method based on the combination of power tracking and frequency regulation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] This embodiment provides a power grid stability control method based on the combination of power tracking and frequency regulation, including:

[0044] The grid stability control method based on the combination of power tracking and frequency regulation includes:

[0045] Setting a power tracking point of a target power grid and monitoring real-time power changes of the power tracking point;

[0046] Acquiring a power change value of the electronic load according to the real-time power change, and controlling the electronic load to perform power compensation on the target power grid based on the power change value;

[0047] If the electronic load capacity in the target power grid is less than the electronic load required by the power change value, the frequency-assisted regulation linear difference algorithm is used to dynamically adjust the power change value, and the power change value obtained by the dynamic adjustment is used to continuously compensate the power of the target power grid until the power of the power tracking point reaches the preset power threshold, thereby completing the stable control of the target power grid.

[0048] Specifically, this embodiment realizes that the isolated grid system can actively achieve disturbance-free complete compensation when the load is lost in most cases through active power tracking; and the frequency-assisted regulation can deal with some special situations, such as when the load is lost or the amplitude of the fluctuation exceeds the capacity of the electronic load, or when the reserve power is insufficient due to negative sequence compensation, reduced capacity operation, etc., the frequency-assisted regulation function can ensure that the electronic load has the mobility of dynamic regulation instead of staying at a fixed value, which greatly increases the flexibility of electronic load control and improves the control effect.

[0049] Furthermore, the power tracking point includes a fixed power value tracking point and an average power value tracking point, wherein the fixed power value tracking point is used for loads with fixed power in the target power grid, and the average power value tracking point is used for loads with large power variations in the target power grid.

[0050] Further, obtaining the power change value of the electronic load according to the real-time power change includes:

[0051] If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value;

[0052] If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

[0053] Specifically, the electronic load can monitor the power of the load in real time. When the power mutation exceeds a certain set value, the corresponding power can be immediately put into or out to achieve total power constancy.

[0054] like Figure 1 , P ref is the reference value of power tracking, i.e. the target value to be kept constant, P Track is the actual power P at the tracking point ord is the power command that the electronic load actually needs to output, P DB is the dead zone size. When the power of the tracking point decreases and exceeds the dead zone, the power of the electronic load will increase accordingly to ensure that the total power remains constant. Dead zone control is to reserve a certain space for the power fluctuation of the tracking point, allowing it to vary within a certain range. ref The electronic load has two tracking modes.

[0055] Mode 1, tracking a fixed reference value, is achieved by setting a fixed power value tracking point:

[0056] like Figure 2As shown, in this mode, P ref A set constant. This situation is more suitable for tracking loads with relatively fixed power, such as industrial ore-heating furnaces, melting furnaces, electrolytic aluminum, etc. When these loads have tripping, material collapse, anode effect, etc., resulting in a sudden drop in power, the electronic load immediately compensates for the missing power.

[0057] This mode can also be used to start and stop large loads. Large load startup process: First, set the normal operating power of the large load after it is put into operation. After setting, the electronic load will slowly climb to the set value at a certain slope. Figure 3 As shown, and then start the large load, after the large load is started, the electronic load will immediately exit the corresponding power to ensure smooth and impact-free startup of the large load. The shutdown process of the large load is similar to the startup process.

[0058] Mode 2, tracking average power, is achieved by setting the average power value tracking point:

[0059] Tracking average power means that the electronic load uses the average power of the tracking point as its reference value, without setting another reference value. The specific method is: open a time window, take a 240s time window as an example, the electronic load collects the average power of the tracking point at a fixed time interval and puts it into the time window, and then uses the average value of the total power in the time window as the reference value. The data in the time window will gradually replace the oldest data with new data over time.

[0060] like Figure 4 As shown, the mode of tracking the average power value is suitable for tracking occasions with relatively large power changes, such as the interconnection line between two regional power grids, impact loads, and the interconnection line of weakly connected power plants.

[0061] like Figure 5 As shown in the figure, when the tie line power is relatively stable, the tie line average power reference value is basically equal to the actual value it tracks. When the tie line power suddenly decreases, the average power reference value is taken as the average value over a period of time, so the reference value remains basically unchanged. At this time, the electronic load will immediately compensate for the shortfall in the actual value. As time goes by, the average value gradually becomes the same as the actual value, and the output of the electronic load will gradually drop to zero. This process is equivalent to the electronic load acting as a buffer damper, which helps to cooperate with the generator to slowly reduce the output without causing high frequency and system oscillation.

[0062] Further, dynamically adjusting the power change value by using the frequency-assisted linear difference adjustment algorithm includes:

[0063] Set the frequency point and the corresponding power value;

[0064] Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value;

[0065] The found power value is superimposed on the power change value to obtain an adjusted power change value.

[0066] Specifically, active power tracking can ensure that the power grid operates normally and stably without disturbances, and can cooperate with large loads to be put into and withdrawn without disturbances. In principle, active power tracking control can achieve stable and disturbance-free operation of the power grid, and the generator can hardly feel the process of large load withdrawal, ensuring that the frequency of the power grid does not change. However, since the capacity of the electronic load is limited, for economic reasons, the capacity of the electronic load is designed to meet the load loss situation in most cases, but not all load loss situations can be covered. When the load loss is large and far exceeds the capacity of the electronic load, it will still induce high frequency and system oscillation in the power grid. In the process of system oscillation, if the power shortage is always greater than the capacity of the electronic load, the electronic load will show that the full power remains unchanged. This situation cannot provide damping for the system oscillation, so it is necessary to introduce the system frequency as a means of auxiliary control.

[0067] Power tracking mode and frequency auxiliary control such as Fig. 9 As shown in the figure, P ord P is the power command value, which refers to the electronic load command calculated in the power tracking mode; act is the current actual power of the electronic load; K op is the open-loop control proportional gain; K p / K i is the closed-loop control proportional / integral gain; f act is the actual frequency of the system; P max / P min The upper and lower limits of the output power are generally determined by the power limit instruction.

[0068] Auxiliary control of frequency, namely "primary frequency modulation" function. The purpose of adding auxiliary frequency control to the main control loop of the electronic load is to ensure that the electronic load can take into account the changes in system frequency when executing other strategies. The instructions of the auxiliary frequency control are superimposed on the instructions of the open-loop and closed-loop control to form the final instructions. "Primary frequency modulation" is a differential regulation, that is, there will be a corresponding instruction only when there is a difference between the actual frequency and the set value.

[0069] Frequency auxiliary control uses a linear interpolation algorithm to convert the actual frequency of the target power grid system into the final power command. There are a total of 2×6 parameters that need to be set in the linear interpolation link, namely X1-X6 and Y1-Y6, where X1-X6 represents the frequency point and Y1-Y6 represents the power value at the corresponding frequency.

[0070] The specific settings of the frequency-assisted linear difference algorithm are as follows: Figure 6 As shown, X3-X4 corresponds to the frequency fluctuation range allowed in the steady state of the target power grid system; the X1-X2-X3 interval corresponds to the negative power command at low frequency; and X4-X5-X6 corresponds to the positive power command at high frequency. It should be noted that although the electronic load cannot output negative power, in the linear difference link of the frequency auxiliary control, when the frequency is lower than the dead zone value, a negative power command will be output. This command is equivalent to reducing the power command when superimposed with the power active tracking command, so that the processing can be appropriately reduced when oscillating to low frequency to achieve a damping effect.

[0071] The suppression effect of electronic load input on frequency oscillation is as follows Figure 7 As shown in the figure, the damping suppression effect of the electronic load under different coefficients is as follows Figure 8 As shown, frequency auxiliary control can be regarded as a "safety net" measure to ensure the frequency of the power grid. The electronic load is passively adjusted according to the change of frequency to ensure that positive damping is always maintained during the frequency oscillation process, ensuring the correctness of the electronic load response.

[0072] To further optimize the technical solution, the present embodiment also provides a power grid stability control system based on the combination of power tracking and frequency regulation, including: a power tracking module, a power compensation module, and a frequency auxiliary module, wherein the power tracking module is used to set the power tracking point of the target power grid and monitor the real-time power changes of the power tracking point; the power compensation module is used to obtain the power change value of the electronic load according to the real-time power change, and control the electronic load to perform power compensation on the target power grid based on the power change value; the frequency auxiliary module is used to dynamically adjust the power change value by using a frequency-assisted regulation linear difference algorithm when the electronic load capacity in the target power grid is less than the electronic load required by the power change value, and continuously perform power compensation on the target power grid by using the power change value obtained by the dynamic adjustment until the power of the power tracking point reaches a preset power threshold, thereby completing the stable control of the target power grid.

[0073] Furthermore, the power tracking points of the target power grid set in the power tracking module include fixed power value tracking points and average power value tracking points, wherein the fixed power value tracking points are used for loads with fixed power in the target power grid, and the average power value tracking points are used for loads with large power variations in the target power grid.

[0074] Furthermore, the power compensation module obtains the power change value of the electronic load according to the real-time power change, including:

[0075] If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value;

[0076] If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

[0077] Furthermore, the frequency auxiliary module adopts a frequency auxiliary regulation linear difference algorithm to dynamically adjust the power change value, including:

[0078] Set the frequency point and the corresponding power value;

[0079] Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value;

[0080] The found power value is superimposed on the power change value to obtain an adjusted power change value.

[0081] In order to further optimize the technical solution, this embodiment also provides a processor, which is used to run a program, wherein the program executes a power grid stability control method based on the combination of power tracking and frequency regulation when running.

[0082] To further optimize the technical solution, this embodiment also provides an electronic device, including one or more memories and a processor, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement a grid stability control method based on the combination of power tracking and frequency regulation.

[0083] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A grid stability control method based on the combination of power tracking and frequency regulation, characterized in that: include: Setting a power tracking point of a target power grid and monitoring real-time power changes of the power tracking point; Acquiring a power change value of the electronic load according to the real-time power change, and controlling the electronic load to perform power compensation on the target power grid based on the power change value; If the electronic load capacity in the target power grid is less than the electronic load required by the power change value, the frequency-assisted regulation linear difference algorithm is used to dynamically adjust the power change value, and the power change value obtained by the dynamic adjustment is used to continuously compensate the power of the target power grid until the power of the power tracking point reaches the preset power threshold, thereby completing the stable control of the target power grid.

2. The power grid stability control method based on the combination of power tracking and frequency regulation according to claim 1 is characterized in that: The power tracking points include fixed power value tracking points and average power value tracking points, wherein the fixed power value tracking points are used for loads with fixed power in the target power grid, and the average power value tracking points are used for loads with large power variations in the target power grid.

3. The power grid stability control method based on the combination of power tracking and frequency regulation according to claim 2 is characterized in that: Acquiring the power change value of the electronic load according to the real-time power change includes: If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value; If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

4. The grid stability control method based on combining power tracking and frequency regulation according to claim 1 is characterized in that: The method of dynamically adjusting the power change value by using the frequency-assisted linear difference adjustment algorithm includes: Set the frequency point and the corresponding power value; Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value; The found power value is superimposed on the power change value to obtain an adjusted power change value.

5. A power grid stability control system based on the combination of power tracking and frequency regulation, characterized in that: include: A power tracking module, a power compensation module, and a frequency auxiliary module, wherein the power tracking module is used to set a power tracking point of a target power grid and monitor the real-time power change of the power tracking point; the power compensation module is used to obtain a power change value of an electronic load according to the real-time power change, and control the electronic load to perform power compensation on the target power grid based on the power change value; the frequency auxiliary module is used to dynamically adjust the power change value by using a frequency-assisted linear difference adjustment algorithm when the electronic load capacity in the target power grid is less than the electronic load required by the power change value, and continuously perform power compensation on the target power grid by using the power change value obtained by the dynamic adjustment until the power of the power tracking point reaches a preset power threshold, thereby completing stable control of the target power grid.

6. The power grid stability control system based on the combination of power tracking and frequency regulation according to claim 5 is characterized in that: The power tracking points of the target power grid set in the power tracking module include fixed power value tracking points and average power value tracking points, wherein the fixed power value tracking points are used for loads with fixed power in the target power grid, and the average power value tracking points are used for loads with large power variations in the target power grid.

7. The power grid stability control system based on the combination of power tracking and frequency regulation according to claim 6, characterized in that: The power compensation module acquires the power change value of the electronic load according to the real-time power change, including: If it is a fixed power value tracking point, obtaining a first real-time power change value of the fixed power value tracking point according to a preset fixed power value, and obtaining a first power change value of the electronic load according to the first real-time power change value; If it is an average power value tracking point, the second real-time power change value of the average power value tracking point is obtained according to the average power value within a preset time, and the second power change value of the electronic load is obtained according to the second real-time power real-time change value.

8. The power grid stability control system based on the combination of power tracking and frequency regulation according to claim 5, characterized in that: The frequency auxiliary module dynamically adjusts the power change value by using a frequency auxiliary adjustment linear difference algorithm, including: Set the frequency point and the corresponding power value; Acquire the real-time power and the corresponding real-time frequency of the power tracking point, map the real-time frequency to the frequency, and find the corresponding power value; The found power value is superimposed on the power change value to obtain an adjusted power change value.

9. A processor, characterized in that: The processor is used to run a program, wherein the program executes the method according to any one of claims 1 to 4 when running.

10. An electronic device, characterized in that: The invention comprises one or more memories and processors, wherein the memories are used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 4.

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