Power supply system and control method thereof

Abstract

The embodiment of the present application discloses a power supply system and its control method. The power supply system includes N distributed power sources and at least one detection control unit. The N distributed power sources are connected to the power grid in parallel or in series, and N is an integer greater than 1; the detection control unit is used to obtain the power compensation control ratio of each distributed power source based on the impedance of each distributed power source to the grid connection point of the power supply system when it detects that the oscillation of the power supply system exceeds a preset threshold range. The power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system; the detection control unit is also used to control the power output ratio of each distributed power source based on the power compensation control ratio. By adopting the embodiment of the present application, it is possible to suppress the oscillation of the power supply system and ensure the normal and stable operation of the power supply system without changing the original control circuit or adding additional equipment, so the implementation is low in complexity and low in cost.

Description

Technical Field

[0001] The present application relates to the field of electronic power technology, and in particular to a power supply system and a control method thereof. Background Art

[0002] As the proportion of wind and solar power generation continues to increase, and the application of power electronics continues to grow, the problem of broadband oscillations in emerging power systems is becoming increasingly prominent. Oscillations in power systems can be defined as the multi-timescale dynamic interactions between renewable energy generators, AC / DC converters, and their control systems, formed through complex grid coupling. The control elements in power electronics have wide response timescales (ranging from <1ms to seconds). This results in broadband oscillations with frequencies ranging from several hertz to kHz in emerging power systems that widely use power electronics.

[0003] Broadband oscillations in power supply systems have the following hazards: (1) Damage to equipment. Oscillations spread rapidly in the system and can trigger overvoltage and overcurrent in equipment before the protective relay operates. (2) Weakening power supply reliability. Oscillations can cause machine trips, resulting in loss of power generation at renewable energy stations and even large-scale power outages, affecting the safety and stability of the system power supply. (3) Affecting power quality. Oscillations can generate large harmonics and interharmonics. Therefore, in order to improve the reliability of power supply systems such as photovoltaic power stations, energy storage power stations, and microgrids, it is necessary to have broadband oscillation suppression technology. However, existing solutions for suppressing broadband oscillations have poor system stability, high implementation complexity, and high implementation costs. Summary of the Invention

[0004] The embodiments of the present application provide a power supply system and a control method thereof, which can suppress oscillation of the power supply system and ensure normal and stable operation of the power supply system.

[0005] In a first aspect, an embodiment of the present application provides a power supply system comprising N distributed power sources and at least one detection and control unit, wherein the N distributed power sources are connected to a power grid in parallel or in series, where N is an integer greater than 1. The detection and control unit is configured to, upon detecting that an oscillation in the power supply system exceeds a preset threshold range, obtain a power compensation control ratio for each distributed power source based on the impedance of each distributed power source to a grid connection point of the power supply system, the power compensation control ratio being the ratio of the power output of each distributed power source to the total power output of the power supply system; and the detection and control unit is further configured to control the power output ratio of each distributed power source based on the power compensation control ratio.

[0006] When power supply system oscillation is detected exceeding a preset threshold, the system adjusts the power compensation control ratio of each distributed power source based on the impedance of each distributed power source to the grid connection point. Based on the adjusted power compensation control ratio, the power output ratio of each distributed power source is controlled. This suppresses power supply system oscillations and ensures normal and stable operation. This system also eliminates the need to modify existing control circuits or add additional equipment, resulting in low complexity and low cost.

[0007] In one possible design, the detection and control unit is further configured to control the active power output by the first distributed power source to be less than a first preset power when the impedance from the first distributed power source to the grid connection point is greater than a first threshold value; or the detection and control unit is further configured to control the active power output by the first distributed power source to be greater than or equal to the first preset power when the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value. That is, if the impedance from any one of the N distributed power sources to the grid connection point is greater, the active power output by the distributed power source is smaller. If the impedance from any one of the N distributed power sources to the grid connection point is smaller, the active power output by the distributed power source is greater. By adjusting the active power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0008] In another possible design, the detection and control unit is further configured to control the reactive power output by the second distributed power source to be greater than a second preset power when the impedance from the second distributed power source to the grid connection point is greater than a second threshold value; or the detection and control unit is further configured to control the reactive power output by the second distributed power source to be less than or equal to the second preset power when the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value. That is, the greater the impedance from any one of the N distributed power sources to the grid connection point, the greater the reactive power output by that distributed power source. The smaller the impedance from any one of the N distributed power sources to the grid connection point, the smaller the reactive power output by that distributed power source. By adjusting the reactive power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0009] In another possible design, the detection and control unit is further configured to, upon detecting that the power supply system oscillates beyond a preset threshold, control the sum of the active power output by the N distributed power supplies to be equal to the total active power output by the power supply system before the oscillation exceeded the preset threshold; and control the sum of the reactive power output by the N distributed power supplies to be equal to the total reactive power output by the power supply system before the oscillation exceeded the preset threshold. That is, without changing the total active power and total reactive power output by the power supply system, the active power and reactive power output by each distributed power supply are adjusted, thereby suppressing oscillations in the power supply system and ensuring that the power supply system resumes normal and stable operation.

[0010] In another possible design, the power compensation control ratio includes an active power compensation control ratio, which is the ratio of the active power output by each distributed power source to the total active power output by the power supply system. The detection and control unit is further configured to, upon detecting that an oscillation in the power supply system exceeds a preset threshold range, number each distributed power source based on the impedance from each distributed power source to the grid connection point in ascending order, obtain the active power compensation control ratio of each distributed power source based on the number and N of each distributed power source, and control the active power output of each distributed power source based on the active power compensation control ratio.

[0011] In another possible design, the active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is p(k) satisfy:

[0012]

[0013] The active power P output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0014] P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc

[0015] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K p_p is the first proportional coefficient, K p_i is the first integral coefficient, s is the Laplace operator, P all is the total active power output by the power supply system, SOC ave is the average state of charge SOC of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc is the transfer function.

[0016] In another possible design, the power compensation control ratio includes a reactive power compensation control ratio, which is the ratio of the reactive power output by each distributed power source to the total reactive power output by the power supply system. The detection and control unit is further configured to, upon detecting that an oscillation in the power supply system exceeds a preset threshold, number each distributed power source in ascending order based on the impedance from each distributed power source to the grid connection point, obtain a reactive power compensation control ratio for each distributed power source based on the number and N of each distributed power source, and control the reactive power output of each distributed power source based on the reactive power compensation control ratio.

[0017] In another possible design, the reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is q(k) satisfy:

[0018]

[0019] The reactive power Q output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0020] Q ref(k) =Q all ε q(k) ;

[0021] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K q_p is the second proportional coefficient, K q_i is the second integral coefficient, s is the Laplace operator, Q all It is the total reactive power output by the power supply system.

[0022] In the above, the distributed power sources are numbered in the order of the impedance from the distributed power source to the grid connection point from small to large. The smaller the impedance from the distributed power source to the grid connection point, the smaller the distributed power source number and the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε q(k) The smaller it is, the greater the active power output of the distributed power supply, and the smaller the reactive power output of the distributed power supply. Alternatively, the greater the impedance from the distributed power supply to the grid connection point, the larger the number of the distributed power supply, and the greater the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε q(k) The larger the value, the smaller the active power output of the distributed power supply, and the larger the reactive power output of the distributed power supply. By dynamically adjusting the active power and reactive power output of each distributed power supply, oscillation of the power supply system is suppressed and the power supply system is guaranteed to resume normal and stable operation.

[0023] In another possible design, the detection control unit is also used to collect the current and voltage of the grid connection point of the power supply system, and obtain the effective value of the oscillation component of the voltage, the effective value of the oscillation component of the current, and the effective value of the oscillation component of the system frequency based on the voltage and current of the grid connection point; the detection control unit is also used to obtain that the oscillation of the power supply system exceeds the preset threshold range when the effective value of the oscillation component of the voltage is greater than the third threshold value, the effective value of the oscillation component of the current is greater than the fourth threshold value, and / or the effective value of the oscillation component of the system frequency is greater than the fifth threshold value. By collecting the current and voltage of the grid connection point, it is detected whether the oscillation of the power supply system exceeds the preset threshold range, thereby ensuring the accuracy of detecting the oscillation of the power supply system. Therefore, when it is detected that the oscillation of the power supply system exceeds the preset threshold range, the reactive power output by the distributed power supply is adjusted to suppress the oscillation of the power supply system, thereby ensuring that the power supply system resumes normal and stable operation.

[0024] In the second aspect, an embodiment of the present application provides a power control method for a power supply system, which is applicable to at least one detection control unit in the power supply system. The power supply system also includes N distributed power sources, which are connected to the power grid in parallel or in series, and N is an integer greater than 1; in this method, when it is detected that the power supply system oscillates beyond a preset threshold range, the power compensation control ratio of each distributed power source is obtained based on the impedance of each distributed power source to the grid connection point of the power supply system, and the power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system; based on the power compensation control ratio, the power output ratio of each distributed power source is controlled.

[0025] When power supply system oscillation is detected exceeding a preset threshold, the system adjusts the power compensation control ratio of each distributed power source based on the impedance of each distributed power source to the grid connection point. Based on the adjusted power compensation control ratio, the power output ratio of each distributed power source is controlled. This suppresses power supply system oscillations and ensures normal and stable operation. This system also eliminates the need to modify existing control circuits or add additional equipment, resulting in low complexity and low cost.

[0026] In one possible design, when the impedance from the first distributed power source among the N distributed power sources to the grid connection point is greater than a first threshold value, the active power output by the first distributed power source is controlled to be less than a first preset power; or when the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value, the active power output by the first distributed power source is controlled to be greater than or equal to the first preset power. That is, if the impedance from any distributed power source among the N distributed power sources to the grid connection point is greater, the active power output by the distributed power source is smaller. If the impedance from any distributed power source among the N distributed power sources to the grid connection point is smaller, the active power output by the distributed power source is greater. By adjusting the active power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system returns to normal and stable operation.

[0027] In another possible design, when the impedance from the second distributed power source among the N distributed power sources to the grid connection point is greater than a second threshold value, the reactive power output by the second distributed power source is controlled to be greater than a second preset power; or when the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value, the reactive power output by the second distributed power source is controlled to be less than or equal to the second preset power. That is, the greater the impedance from any distributed power source among the N distributed power sources to the grid connection point, the greater the reactive power output by that distributed power source. The smaller the impedance from any distributed power source among the N distributed power sources to the grid connection point, the smaller the reactive power output by that distributed power source. By adjusting the reactive power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system returns to normal and stable operation.

[0028] In another possible design, when it is detected that the power supply system is oscillating beyond a preset threshold, the sum of the active power output by the N distributed power sources is controlled to be equal to the total active power output by the power supply system before the oscillation exceeded the preset threshold; and the sum of the reactive power output by the N distributed power sources is controlled to be equal to the total reactive power output by the power supply system before the oscillation exceeded the preset threshold. That is, without changing the total active power and total reactive power output by the power supply system, the active power and reactive power output by each distributed power source are dynamically adjusted, thereby suppressing oscillations in the power supply system and ensuring that the power supply system resumes normal and stable operation.

[0029] In another possible design, the power compensation control ratio includes an active power compensation control ratio, which is the ratio of the active power output by each distributed power source to the total active power output by the power supply system; when it is detected that the oscillation of the power supply system exceeds a preset threshold range, each distributed power source is numbered in ascending order based on the impedance from each distributed power source to the grid connection point, and based on the number and N of each distributed power source, the active power compensation control ratio of each distributed power source is obtained, and the active power output of each distributed power source is controlled based on the active power compensation control ratio.

[0030] In another possible design, the active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is p(k) satisfy:

[0031]

[0032] The active power P output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0033] P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc

[0034] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K p_p is the first proportional coefficient, K p_i is the first integral coefficient, s is the Laplace operator, P all is the total active power output by the power supply system, SOC ave is the average state of charge SOC of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc is the transfer function.

[0035] In another possible design, the power compensation control ratio includes a reactive power compensation control ratio, which is the ratio of the reactive power output by each distributed power source to the total reactive power output by the power supply system. When an oscillation in the power supply system is detected that exceeds a preset threshold range, each distributed power source is numbered in ascending order of impedance from the distributed power source to the grid connection point. Based on the number and N of each distributed power source, the reactive power compensation control ratio of each distributed power source is obtained, and the reactive power output of each distributed power source is controlled based on the reactive power compensation control ratio.

[0036] In another possible design, the reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is q(k) satisfy:

[0037]

[0038] The reactive power Q output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0039] Q ref(k) =Q all ε q(k) ;

[0040] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K q_p is the second proportional coefficient, K q_i is the second integral coefficient, s is the Laplace operator, Q all It is the total reactive power output by the power supply system.

[0041] In the above, the distributed power sources are numbered in the order of the impedance from the distributed power source to the grid connection point from small to large. The smaller the impedance from the distributed power source to the grid connection point, the smaller the distributed power source number and the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε q(k) The smaller it is, the greater the active power output of the distributed power supply, and the smaller the reactive power output of the distributed power supply. Alternatively, the greater the impedance from the distributed power supply to the grid connection point, the larger the number of the distributed power supply, and the greater the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε q(k) The larger the value, the smaller the active power output of the distributed power supply, and the larger the reactive power output of the distributed power supply. By dynamically adjusting the active power and reactive power output of each distributed power supply, oscillation of the power supply system is suppressed and the power supply system is guaranteed to resume normal and stable operation.

[0042] In another possible design, the current and voltage of the grid connection point of the power supply system are collected, and based on the voltage and current of the grid connection point, the effective value of the oscillation component of the voltage, the effective value of the oscillation component of the current, and the effective value of the oscillation component of the system frequency are obtained; when the effective value of the oscillation component of the voltage is greater than the third threshold value, the effective value of the oscillation component of the current is greater than the fourth threshold value, and / or the effective value of the oscillation component of the system frequency is greater than the fifth threshold value, it is determined that the oscillation of the power supply system exceeds the preset threshold range. By collecting the current and voltage of the grid connection point, it is detected whether the oscillation of the power supply system exceeds the preset threshold range, thereby ensuring the accuracy of detecting the oscillation of the power supply system. Therefore, when it is detected that the oscillation of the power supply system exceeds the preset threshold range, the reactive power output of the distributed power supply is adjusted to suppress the oscillation of the power supply system, thereby ensuring that the power supply system resumes normal and stable operation.

[0043] In a third aspect, the present application provides a power supply system, which includes a photovoltaic array and a detection and control unit provided in the first aspect and any possible embodiment of the first aspect, which is connected to the photovoltaic array. The photovoltaic array is used to supply the converted electrical energy to the power grid. In the detection and control unit, by detecting the voltage and current at the grid connection point, it is detected whether the oscillation of the power supply system exceeds a preset threshold range. When it is detected that the oscillation of the power supply system exceeds the preset threshold range, the power compensation control ratio of each distributed power source is adjusted based on the impedance of each distributed power source to the grid connection point of the power supply system. Based on the adjusted power compensation control ratio, the power output ratio of each distributed power source is controlled. This suppresses the oscillation of the power supply system and ensures the normal and stable operation of the power supply system. In addition, there is no need to change the original control circuit or add additional equipment, so the implementation complexity is low and the implementation cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0045] Figure 1 This is a schematic diagram of an application scenario of the power supply system provided by this application;

[0046] Figure 2 This is a schematic diagram of another application scenario of the power supply system provided by this application;

[0047] Figure 3 This is a schematic diagram of the structure of a radial wiring method of a power supply system provided by the present application;

[0048] Figure 4 This is a schematic diagram of the structure of a T-type wiring method of a power supply system provided by this application;

[0049] Figure 5This is a structural diagram of the power supply system provided by this application;

[0050] Figure 6 This is a flow chart of a power control method for a power supply system provided in this application. DETAILED DESCRIPTION

[0051] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0052] The power supply system provided in this application can be applied to new energy stations. According to the different types of new energy stations, it can be divided into the new energy intelligent microgrid field, the power transmission and distribution field or the new energy field (such as the photovoltaic grid-connected field or the wind grid-connected field), the photovoltaic storage power generation field (such as power supply to household appliances (such as refrigerators, air conditioners) or power grids), or the wind storage power generation field, or the high-power converter field (such as converting direct current into high-power high-voltage alternating current) and other application fields. The specific application fields can be determined according to the actual application scenario and are not limited here. The power supply system provided in this application can be adapted to different application scenarios, such as photovoltaic storage power supply application scenarios, wind storage power supply application scenarios, pure energy storage power supply application scenarios or other application scenarios. The energy storage power supply application scenario will be used as an example for explanation below, and no further details will be given below.

[0053] Figure 1 This is a schematic diagram of an application scenario of the power supply system provided by this application. In the pure energy storage power supply application scenario, such as Figure 1 As shown, the power supply system includes a battery pack and a detection control unit. When the battery pack supplies power to the load, the detection control unit can detect the voltage and current at the grid connection point of the power supply system and control the battery pack to supply power to loads such as communication base stations or household appliances in the power grid based on the detected voltage and current. The detection control unit can be a new energy station controller, including a new energy power station controller, energy storage station controller, micro-electric controller, or active distribution network controller.

[0054] Figure 2 This is another application scenario diagram of the power supply system provided by this application. In the photovoltaic system application scenario, the output end of the photovoltaic array can be connected to the power grid, and the detection control unit can detect the voltage and current of the grid connection point of the power supply system. According to the detected voltage and current, the photovoltaic array is controlled to supply power to the battery, communication base station or household appliances and other electrical appliances in the power grid. Figure 2 In the photovoltaic system shown, the photovoltaic array can be a photovoltaic module group. A photovoltaic module group can be composed of one or more photovoltaic strings connected in parallel, and a photovoltaic string can be obtained by connecting one or more photovoltaic modules in series. The photovoltaic modules here can be solar panels, photovoltaic panels, or energy storage batteries. In other words, in Figure 2In the photovoltaic system shown, a photovoltaic string can be a photovoltaic string obtained by connecting one or more solar panels, photovoltaic panels, or energy storage batteries in series. The output current of the multiple photovoltaic strings is used by electrical devices such as batteries in the power grid, communication base stations, or household appliances.

[0055] The following will be combined Figures 3 and 4 The power supply system provided in this application and its working principle are illustrated. In the embodiments of this application, "and / or" may represent one of them, or may represent some or all of them. For example, DG1, DG2, and / or DG3 may represent any one of DG1, DG2, and DG3, or any two of DG1, DG2, and DG3, or DG1, DG2, and DG3.

[0056] The wiring methods of distributed generation (DG) in power supply systems can be divided into radial wiring and T-type wiring. Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of a radial connection mode of a power supply system provided by the present application. The power supply system includes N DGs (DG1, DG2, ..., DG N ) 10 and at least one detection control unit 20. N DGs are connected in parallel to the power grid. Taking one detection control unit 20 as an example, one end of the detection control unit 20 is connected to the grid connection point of the power supply system, and the other end of the detection control unit 20 is connected to the control end of each DG. There is an impedance between each DG and the grid connection point of the power supply system. The impedance between DG1 and the grid connection point is L1, the impedance between DG2 and the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N . Wherein, N is an integer greater than or equal to 1.

[0057] like Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of a T-type connection method of a power supply system provided by this application. The power supply system includes N DGs (DG1, DG2, ..., DG N ) 10 and at least one detection control unit 20. There is an impedance between each two adjacent DGs, the impedance between DG1 and the grid point is L1, the impedance between DG1 and DG2 is L2, ..., DG N With DG N-1 The impedance between N L1 and DG1 can form a DG unit 1, L2 and DG2 can form a DG unit 2, ..., L N and DG NN DG units can be connected in series to form a DG unit. Taking a detection control unit 20 as an example, one end of the detection control unit 20 is connected to the grid connection point of the power supply system, and the other end of the detection control unit 20 is connected to the control terminal of each DG. Impedance, which can be composed of resistance, inductance, and capacitance, acts as an obstacle to AC power.

[0058] The detection control unit 20 may include various logic devices, such as a proportional-integral controller, a second-order general integrator phase-locked loop (SOGI-PLL), a threshold comparator, a high-frequency filter, a compensator, a root mean square (RMS) detector, and a balancing control loop regulator. The detection control unit is used to detect the voltage and current at the grid connection point of the power supply system and control each DG to output active power and reactive power to the grid based on the detected voltage and current.

[0059] On the one hand, the detection control unit 20 is used to obtain the power compensation control ratio of each distributed power source when it is detected that the power supply system is working normally and stably. The power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system. Control the power output ratio of each distributed power source. By controlling the active power and reactive power output of each distributed power source according to the state of charge (SOC) balancing control method, the SOC of each distributed power source is maintained at the average SOC of N distributed power sources. Among them, normal and stable operation of the system can be represented by the power supply system not oscillating, or the power supply system oscillation does not exceed the preset threshold range. The specific implementation method is as follows:

[0060] In a possible implementation, the detection control unit 20 is further configured to obtain the active power compensation control ratio of each distributed power source when it is detected that the system is operating normally and stably. Control the active power output of each distributed power source Among them, P ref(k) is the active power output by the distributed power supply numbered k among the N distributed power supplies, P all is the total active power output by the power supply system, SOC ave is the average SOC value of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc is a transfer function, which may be a transfer function of a balancing control loop regulator.

[0061] In another possible implementation, the detection control unit 20 is further configured to obtain the reactive power compensation control ratio of each distributed power source when detecting that the system is operating normally and stably. Control the active power output of each distributed power source Among them, Q ref(k) is the reactive power output by the distributed power supply numbered k among the N distributed power supplies, Q all It is the total reactive power output by the power supply system.

[0062] On the other hand, the detection control unit 20 is used to obtain the power compensation control ratio of each distributed power source based on the impedance of each distributed power source to the grid connection point of the power supply system when it is detected that the oscillation of the power supply system exceeds a preset threshold range, wherein the power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system. Figure 3 As shown, the impedance from DG1 to the grid connection point is L1, the impedance from DG2 to the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N Another example Figure 4 As shown, the impedance from DG1 to the grid connection point is L1, and the impedance from DG2 to the grid connection point is L1+L2, ..., DG N The impedance to the grid connection point is L1+L2+…+L N Because the impedances of the N DGs to the grid connection point are different, the power compensation control ratios of the N DGs are also different. The detection control unit 20 is also used to control the power output ratio of each distributed power source based on the power compensation control ratio, thereby suppressing oscillations in the power supply system and ensuring that the power supply system returns to normal and stable operation. In addition, there is no need to change the original control circuit or add additional equipment, which reduces the complexity and cost of implementation. The specific implementation method is as follows:

[0063] In one possible implementation, the detection control unit 20 is further configured to control the active power output by the first distributed power source to be less than a first preset power when the impedance from the first distributed power source to the grid connection point among the N distributed power sources is greater than a first threshold value; or to control the active power output by the first distributed power source to be greater than or equal to the first preset power when the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value. The first distributed power source is any one of the N distributed power sources. That is, if the impedance from any one of the N distributed power sources to the grid connection point is greater, the active power output by the distributed power source is smaller. If the impedance from any one of the N distributed power sources to the grid connection point is smaller, the active power output by the distributed power source is greater. By adjusting the active power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0064] In another possible implementation, the detection control unit 20 is further configured to control the reactive power output by the second distributed power source to be greater than a second preset power when the impedance from the second distributed power source to the grid connection point among the N distributed power sources is greater than a second threshold value. Alternatively, when the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value, control the reactive power output by the second distributed power source to be less than or equal to the second preset power. The second distributed power source is any one of the N distributed power sources. That is, if the impedance from any one of the N distributed power sources to the grid connection point is greater, the reactive power output by the distributed power source is greater. If the impedance from any one of the N distributed power sources to the grid connection point is smaller, the reactive power output by the distributed power source is smaller. By adjusting the reactive power output by the distributed power sources, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0065] In another possible implementation, the detection control unit 20 is further configured to, upon detecting that the power supply system oscillation exceeds a preset threshold range, control the sum of the active power output by the N distributed power supplies to be equal to the total active power output by the power supply system before the oscillation exceeds the preset threshold range; and control the sum of the reactive power output by the N distributed power supplies to be equal to the total reactive power output by the power supply system before the oscillation exceeds the preset threshold range. That is, without changing the total active power and total reactive power output by the power supply system, the active power and reactive power output by each distributed power supply are adjusted, thereby suppressing oscillations in the power supply system and ensuring that the power supply system resumes normal and stable operation.

[0066] In another possible implementation, the power compensation control ratio includes an active power compensation control ratio, where the active power compensation control ratio is the ratio of the active power output by each distributed power source to the total active power output by the power supply system. The detection control unit 20 is further configured to, upon detecting that an oscillation in the power supply system exceeds a preset threshold range, number each distributed power source based on the impedance from the distributed power source to the grid connection point from small to large, obtain the active power compensation control ratio of each distributed power source based on the number and N of each distributed power source, and control the active power output of each distributed power source based on the active power compensation control ratio.

[0067] For example, Figure 3 As shown, the impedance from DG1 to the grid connection point is L1, the impedance from DG2 to the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N , among which L1 <L2<L3<……<L NTherefore, according to the impedance from DG to the grid connection point, the N DGs are numbered in order, DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N. For example Figure 4 As shown, the impedance from DG1 to the grid connection point is L1, and the impedance from DG2 to the grid connection point is L1+L2, ..., DG N The impedance to the grid connection point is L1+L2+…+L N Among them, L1 <L1+L2<L1+L2+L3<……<L1+L2+L3+……+L N Therefore, the N DGs are numbered in the order of the impedance from DG to the grid connection point from small to large. DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N.

[0068] Among them, the active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies p(k) satisfy:

[0069]

[0070] The active power P output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0071] P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc

[0072] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K p_p is the first proportional coefficient, K p_i is the first integral coefficient, s is the Laplace operator, P all is the total active power output by the power supply system, SOC ave is the average SOC of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc The first proportional coefficient may be a proportional coefficient of a proportional-integral controller, the first integral coefficient may be an integral coefficient of a proportional-integral controller, and the transfer function may be a transfer function of a balanced control loop regulator.

[0073] In another possible implementation, the power compensation control ratio includes a reactive power compensation control ratio, where the reactive power compensation control ratio is the ratio of the reactive power output by each distributed power source to the total reactive power output by the power supply system. The detection control unit 20 is further configured to, upon detecting that an oscillation in the power supply system exceeds a preset threshold range, number each distributed power source in ascending order based on the impedance from each distributed power source to the grid connection point, obtain a reactive power compensation control ratio for each distributed power source based on the number and N of each distributed power source, and control the reactive power output of each distributed power source based on the reactive power compensation control ratio.

[0074] For example, Figure 3 As shown, the impedance from DG1 to the grid connection point is L1, the impedance from DG2 to the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N , among which L1 <L2<L3<……<L N Therefore, according to the impedance from DG to the grid connection point, the N DGs are numbered in order, DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N. For example Figure 4 As shown, the impedance from DG1 to the grid connection point is L1, and the impedance from DG2 to the grid connection point is L1+L2, ..., DG N The impedance to the grid connection point is L1+L2+…+L N Among them, L1 <L1+L2<L1+L2+L3<……<L1+L2+L3+……+L N Therefore, the N DGs are numbered in the order of the impedance from DG to the grid connection point from small to large. DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N.

[0075] Among them, the reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is q(k) satisfy:

[0076]

[0077] The reactive power Q output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0078] Q ref(k) =Q all ε q(k) ;

[0079] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, N is the total number of distributed power sources, K q_p is the second proportional coefficient, Kq_i is the second integral coefficient, s is the Laplace operator, Q all The second proportional coefficient may be a proportional coefficient of a proportional-integral controller, and the second integral coefficient may be an integral coefficient of a proportional-integral controller.

[0080] In summary, the distributed power sources are numbered in the order of the impedance from the distributed power source to the grid connection point from small to large. The smaller the impedance from the distributed power source to the grid connection point, the smaller the number of the distributed power source, and the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε q(k) The smaller it is, the greater the active power output of the distributed power supply, and the smaller the reactive power output of the distributed power supply. Alternatively, the greater the impedance from the distributed power supply to the grid connection point, the larger the number of the distributed power supply, and the greater the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε q(k) The larger the value, the smaller the active power output of the distributed power supply, and the larger the reactive power output of the distributed power supply. By dynamically adjusting the active power and reactive power output of each distributed power supply, oscillation of the power supply system is suppressed and the power supply system is guaranteed to resume normal and stable operation.

[0081] Of course, the embodiment of the present application can also number the distributed power sources in descending order of the impedance from the distributed power source to the grid point. The smaller the impedance from the distributed power source to the grid point, the larger the number of the distributed power source, and the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε q(k) The smaller the distributed power supply, the greater the active power output, and the smaller the reactive power output. The greater the impedance from the distributed power supply to the grid connection point, the smaller the number of the distributed power supply, and the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε q(k) The larger it is, the smaller the active power output of the distributed power supply is, and the larger the reactive power output of the distributed power supply is.

[0082] It should be noted that the calculation of active power compensation control ratio ε p(k) and reactive power compensation control ratio ε q(k) The formula is not limited to the above formula. As long as the impedance from the distributed power source to the grid point is greater, the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε p(k) Alternatively, the smaller the impedance from the distributed power source to the grid connection point, the greater the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε p(k) The smaller the formula, the more it falls within the scope of protection of this application.

[0083] In another possible implementation, the detection control unit 20 is further configured to collect the current and voltage at the grid connection point of the power supply system, and obtain the effective value of the voltage oscillation component, the effective value of the current oscillation component, and the effective value of the system frequency oscillation component based on the voltage and current at the grid connection point; when the effective value of the voltage oscillation component is greater than a third threshold value, the effective value of the current oscillation component is greater than a fourth threshold value, and / or the effective value of the system frequency oscillation component is greater than a fifth threshold value, it is determined that the power supply system oscillates beyond a preset threshold range. When the effective value of the voltage oscillation component is not greater than the third threshold value, the effective value of the current oscillation component is not greater than the fourth threshold value, and the effective value of the system frequency oscillation component is not greater than the fifth threshold value, it is determined that the power supply system is operating normally and stably. The effective value of the voltage oscillation component may be the RMS value of the voltage oscillation component, the effective value of the current oscillation component may be the RMS value of the current oscillation component, and the effective value of the system frequency oscillation component may be the RMS value of the system frequency oscillation component.

[0084] For example, the detection control unit 20 can collect the voltage V pcc and current I pcc , extract voltage V pcc Phase θ g , calculate the system frequency ω g And generate a dq rotating coordinate system, and calculate V in the rotating coordinate system through Park transformation pcc Components and I pcc Components, respectively for V pcc Components and I pcc The voltage amplitude E is obtained by taking the square root of the components m and the current amplitude I m Then the phase θ is filtered by high-pass filter. g , voltage amplitude E m and the current amplitude is I m The voltage oscillation component, current oscillation component and system frequency oscillation component are processed and the RMS value of the voltage oscillation component, current oscillation component and system frequency oscillation component are calculated and recorded as E m,ripple , I m,ripple 、ω g,ripple Among them, E m,ripple Corresponding threshold value E m,ripple_threshold , I m,ripple Corresponding threshold value I m,ripple_threshold ,ω g,ripple Corresponding threshold value ω g,ripple_threshold . E m,ripple , I m,ripple 、ω g,rippleCompared with the corresponding threshold value, when E m,ripple , I m,ripple and ω g,ripple When any one of the above exceeds the corresponding threshold value, it is determined that the power supply system oscillation exceeds the preset threshold range. m,ripple , I m,ripple and ω g,ripple When the oscillation of the power supply system exceeds the preset threshold range, the threshold comparator can output Flag emg =1, based on the impedance of each distributed power source to the grid connection point of the power supply system, adjust the power compensation control ratio of each distributed power source, and control the distributed power source output active power and reactive power based on the adjusted power compensation control ratio. When the power supply system is working normally and stably, the threshold comparator can output Flag emg =0, the active power and reactive power output of each distributed power source are controlled according to the SOC balance control method.

[0085] It should be noted that by adjusting the active power and reactive power output by each distributed power source, suppressing the oscillation of the power supply system and ensuring that the power supply system resumes normal and stable operation, the integrator of the compensator in the detection control unit 20 can be cleared to ensure that the next time the power supply system is detected to have oscillations exceeding the preset threshold range, the compensator can maintain a slow start to achieve continuous power control.

[0086] See Figure 5 , Figure 5 This is a schematic diagram of the power supply system provided by this application. Figure 5As shown, the power supply system includes a power supply module 30 and a detection control unit 40. The power supply module 30 can be composed of N distributed power sources, and the input end of the detection control unit 40 can be connected to the grid connection point of the power supply module 30. In the pure energy storage power supply application scenario, the power supply module 30 can be composed of multiple battery packs connected in series and parallel, and a battery pack can be composed of one or more battery cells (the voltage of the battery cell is usually between 2.5V and 4.2V) connected in series and parallel to form a minimum energy storage and management unit. Optionally, the above-mentioned power supply module can also be a power generation component, which may include but is not limited to a solar power generation component, a wind power generation component, a hydrogen power generation component, and an oil engine power generation component. In the photovoltaic storage hybrid power supply scenario, the power supply module 30 is a photovoltaic array, which can be composed of a plurality of photovoltaic strings connected in series and parallel, wherein one photovoltaic string may include a plurality of photovoltaic components (also referred to as solar panels or photovoltaic panels). The detection control unit 40 can detect the current and voltage of the grid connection point of the power supply module 30, and determine whether the oscillation of the power supply system exceeds a preset threshold range based on the detected current and voltage of the grid connection point of the power supply module 30. When it is detected that the oscillation of the power supply system exceeds the preset threshold range, the power compensation control ratio of each distributed power source is obtained based on the impedance of each distributed power source to the grid connection point of the power supply system, and the power output ratio of each distributed power source is controlled based on the power compensation control ratio. This suppresses the oscillation of the power supply system and ensures that the power supply system resumes normal and stable operation.

[0087] like Figure 6 As shown, Figure 6 This is a flow chart of a power control method for a power supply system provided in the present application. The method is applicable to at least one detection control unit in the power supply system. The power supply system also includes N distributed power sources, which are connected to the power grid in parallel or in series, and N is an integer greater than 1.

[0088] S601, collecting current and voltage at the grid connection point of the power supply system.

[0089] In a possible implementation, the current and voltage of the grid connection point of the power supply system may be collected in real time.

[0090] In another possible implementation, the current and voltage of the grid connection point of the power supply system may be collected according to a preset sampling period.

[0091] In another possible implementation, a user input instruction may be received, and the current and voltage of the grid connection point of the power supply system may be collected based on the input instruction.

[0092] S602 : Obtain an effective value of an oscillating component of voltage, an effective value of an oscillating component of current, and an effective value of an oscillating component of system frequency based on the voltage and current at the grid connection point.

[0093] Specifically, the voltage V of the grid connection point can be collected pcc and current I pcc , extract voltage V pcc Phase θ g , calculate the system frequency ω g And generate a dq rotating coordinate system, and calculate V in the rotating coordinate system through Park transformation pcc Components and I pcc Components, respectively for V pcc Components and I pcc The voltage amplitude E is obtained by taking the square root of the components m and the current amplitude I m Then, the phase θ is filtered by high-pass filter. g , voltage amplitude E m and the current amplitude is I m The voltage oscillation component, current oscillation component and system frequency oscillation component are processed and the RMS value of the voltage oscillation component, current oscillation component and system frequency oscillation component are calculated and recorded as E m,ripple , I m,ripple and ω g,ripple The effective value of the oscillating component of the voltage may be the RMS value of the oscillating component of the voltage, the effective value of the oscillating component of the current may be the RMS value of the oscillating component of the current, and the effective value of the oscillating component of the system frequency may be the RMS value of the oscillating component of the system frequency.

[0094] S603: Determine whether the oscillation of the power supply system exceeds a preset threshold range. If the oscillation of the power supply system exceeds the preset threshold range, execute S604; if the power supply system is working normally and stably, execute S605.

[0095] Specifically, when the effective value of the voltage oscillation component is greater than a third threshold value, the effective value of the current oscillation component is greater than a fourth threshold value, and / or the effective value of the system frequency oscillation component is greater than a fifth threshold value, it is determined that the power supply system oscillates beyond a preset threshold range. When the effective value of the voltage oscillation component is not greater than the third threshold value, the effective value of the current oscillation component is not greater than the fourth threshold value, and the effective value of the system frequency oscillation component is not greater than the fifth threshold value, it is determined that the power supply system is operating normally and stably.

[0096] For example, E m,ripple Corresponding threshold value E m,ripple_threshold , I m,ripple Corresponding threshold value I m,ripple_threshold ,ω g,ripple Corresponding threshold value ω g,ripple_threshold . E m,ripple , Im,ripple 、ω g,ripple Compared with the corresponding threshold value, when E m,ripple , I m,ripple and ω g,ripple When any one of the above exceeds the corresponding threshold value, it is determined that the power supply system oscillation exceeds the preset threshold range. m,ripple , I m,ripple and ω g,ripple When the corresponding threshold values ​​are not exceeded, it is determined that the power supply system is operating normally and stably.

[0097] S604 , obtaining a power compensation control ratio of each distributed power source based on the impedance of each distributed power source to the grid connection point of the power supply system, and controlling the power output ratio of each distributed power source based on the power compensation control ratio.

[0098] In one possible implementation, when the impedance from a first distributed power source among the N distributed power sources to the grid connection point is greater than a first threshold value, the active power output by the first distributed power source is controlled to be less than a first preset power; alternatively, when the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value, the active power output by the first distributed power source is controlled to be greater than or equal to the first preset power. The first distributed power source is any one of the N distributed power sources. That is, if the impedance from any one of the N distributed power sources to the grid connection point is greater, the active power output by the distributed power source is smaller. If the impedance from any one of the N distributed power sources to the grid connection point is smaller, the active power output by the distributed power source is greater. By adjusting the active power output by each distributed power source, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0099] In another possible implementation, when the impedance from a second distributed power source among the N distributed power sources to the grid connection point is greater than a second threshold value, the reactive power output by the second distributed power source is controlled to be greater than a second preset power; alternatively, when the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value, the reactive power output by the second distributed power source is controlled to be less than or equal to the second preset power. The second distributed power source is any one of the N distributed power sources. That is, the greater the impedance from any one of the N distributed power sources to the grid connection point, the greater the reactive power output by that distributed power source. The smaller the impedance from any one of the N distributed power sources to the grid connection point, the smaller the reactive power output by that distributed power source. By regulating the reactive power output by the distributed power sources, oscillations in the power supply system are suppressed, ensuring that the power supply system resumes normal and stable operation.

[0100] In another possible implementation, when it is detected that the power supply system oscillates beyond a preset threshold, the sum of the active power output by the N distributed power supplies is controlled to be equal to the total active power output by the power supply system before the oscillation exceeded the preset threshold; and the sum of the reactive power output by the N distributed power supplies is controlled to be equal to the total reactive power output by the power supply system before the oscillation exceeded the preset threshold. That is, without changing the total active power and total reactive power output by the power supply system, the active power and reactive power output by each distributed power supply are adjusted, thereby suppressing oscillations in the power supply system and ensuring that the power supply system resumes normal and stable operation.

[0101] In another possible implementation, the power compensation control ratio includes an active power compensation control ratio, where the active power compensation control ratio is the ratio of the active power output by each distributed power source to the total active power output by the power supply system. When it is detected that an oscillation in the power supply system exceeds a preset threshold range, each distributed power source is numbered in ascending order of impedance from each distributed power source to the grid connection point. Based on the number and N of each distributed power source, the active power compensation control ratio of each distributed power source is obtained, and the active power output of each distributed power source is controlled based on the active power compensation control ratio.

[0102] For example, Figure 3 As shown, the impedance from DG1 to the grid connection point is L1, the impedance from DG2 to the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N , among which L1 <L2<L3<……<L N Therefore, according to the impedance from DG to the grid connection point, the N DGs are numbered in order, DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N. For example Figure 4 As shown, the impedance from DG1 to the grid connection point is L1, and the impedance from DG2 to the grid connection point is L1+L2, ..., DG N The impedance to the grid connection point is L1+L2+…+L N Among them, L1 <L1+L2<L1+L2+L3<……<L1+L2+L3+……+L N Therefore, the N DGs are numbered in the order of the impedance from DG to the grid connection point from small to large. DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N.

[0103] Among them, the active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies p(k) satisfy:

[0104]

[0105] The active power P output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0106] P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc

[0107] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, K p_p is the first proportional coefficient, K p_i is the first integral coefficient, s is the Laplace operator, P all is the total active power output by the power supply system, SOC ave is the average SOC of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc The first proportional coefficient may be a proportional coefficient of a proportional-integral controller, the first integral coefficient may be an integral coefficient of a proportional-integral controller, and the transfer function may be a transfer function of a balanced control loop regulator.

[0108] In another possible implementation, the power compensation control ratio includes a reactive power compensation control ratio, where the reactive power compensation control ratio is the ratio of the reactive power output by each distributed power source to the total reactive power output by the power supply system. When an oscillation in the power supply system is detected that exceeds a preset threshold range, each distributed power source is numbered in ascending order based on the impedance from each distributed power source to the grid connection point. Based on the number and N of each distributed power source, the reactive power compensation control ratio of each distributed power source is obtained, and the reactive power output of each distributed power source is controlled based on the reactive power compensation control ratio.

[0109] For example, Figure 3 As shown, the impedance from DG1 to the grid connection point is L1, the impedance from DG2 to the grid connection point is L2, ..., DG N The impedance to the grid connection point is L N , among which L1 <L2<L3<……<L N Therefore, according to the impedance from DG to the grid connection point, the N DGs are numbered in order, DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N. For example Figure 4 As shown, the impedance from DG1 to the grid connection point is L1, and the impedance from DG2 to the grid connection point is L1+L2, ..., DG NThe impedance to the grid connection point is L1+L2+…+L N Among them, L1 <L1+L2<L1+L2+L3<……<L1+L2+L3+……+L N Therefore, the N DGs are numbered in the order of the impedance from DG to the grid connection point from small to large. DG1 is numbered 1, DG2 is numbered 2, ..., DG N The number is N.

[0110] Among them, the reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies is q(k) satisfy:

[0111]

[0112] The reactive power Q output by the distributed power supply numbered k among N distributed power supplies ref(k) satisfy:

[0113] Q ref(k) =Q all ε q(k) ;

[0114] Wherein, k is an integer greater than or equal to 1 and less than or equal to N, N is the total number of distributed power sources, K q_p is the second proportional coefficient, K q_i is the second integral coefficient, s is the Laplace operator, Q all The second proportional coefficient may be a proportional coefficient of a proportional-integral controller, and the second integral coefficient may be an integral coefficient of a proportional-integral controller.

[0115] It should be noted that the calculation of active power compensation control ratio ε p(k) and reactive power compensation control ratio ε q(k) The formula is not limited to the above formula. As long as the impedance from the distributed power source to the grid point is greater, the active power compensation control ratio ε p(k) The smaller the reactive power compensation control ratio ε p(k) Alternatively, the smaller the impedance from the distributed power source to the grid connection point, the greater the active power compensation control ratio ε p(k) The larger the reactive power compensation control ratio ε p(k) The smaller the formula, the more it falls within the scope of protection of this application.

[0116] S605 , controlling the power output ratio of each distributed power source according to the SOC balancing control method.

[0117] Specifically, when it is detected that the power supply system is working normally and stably, the power compensation control ratio of each distributed power source is obtained. The power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system. Control the active power and reactive power output of each distributed power source. By controlling the active power and reactive power output of each distributed power source in accordance with the state of charge (SOC) balancing control method, the SOC of each distributed power source is maintained at the average SOC of N distributed power sources. Among them, normal and stable operation of the system can be represented by the fact that the power supply system does not oscillate, or the oscillation of the power supply system does not exceed the preset threshold range. The specific implementation method is as follows:

[0118] In a possible implementation, when it is detected that the system is working normally and stably, the active power compensation control ratio of each distributed power source is obtained as Control the active power output of each distributed power source Among them, P ref(k) is the active power output by the distributed power supply numbered k among the N distributed power supplies, P all is the total active power output by the power supply system, SOC ave is the average SOC value of N distributed power sources, SOC k is the SOC of the distributed power supply numbered k, G pi_soc is a transfer function, which may be a transfer function of a balancing control loop regulator.

[0119] In another possible implementation, when it is detected that the system is working normally and stably, the reactive power compensation control ratio of each distributed power source is obtained as Control the active power output of each distributed power source Among them, Q ref(k) is the reactive power output by the distributed power supply numbered k among the N distributed power supplies, Q all It is the total reactive power output by the power supply system.

[0120] It should be noted that after controlling the active power and reactive power output of each distributed power source, S601-S605 can be repeatedly executed to detect whether the oscillation of the power supply system exceeds a preset threshold range and use different power control methods to control the active power and reactive power output of each distributed power source.

[0121] In an embodiment of the present application, by detecting the current and voltage at the power supply system's grid connection point, it is determined whether the power supply system's oscillation exceeds a preset threshold range. When it is detected that the power supply system's oscillation exceeds the preset threshold range, the power compensation control ratio of each distributed power source is obtained based on the impedance of each distributed power source to the power supply system's grid connection point. Based on the power compensation control ratio, the power output ratio of each distributed power source is controlled. This suppresses the power supply system's oscillation and ensures that the power supply system resumes normal and stable operation.

[0122] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A power supply system, characterized in that: The power supply system includes N distributed power sources and at least one detection control unit, wherein the N distributed power sources are connected in parallel or in series to the power grid, where N is an integer greater than 1; The detection control unit is used to obtain the power compensation control ratio of each distributed power source based on the impedance of each distributed power source in the N distributed power sources to the grid connection point of the power supply system when it is detected that the oscillation of the power supply system exceeds a preset threshold range. The power compensation control ratio is the ratio of the power output of each distributed power source to the total power output of the power supply system. The power compensation control ratio includes an active power compensation control ratio and a reactive power compensation control ratio. The active power compensation control ratio is the ratio of the active power output of each distributed power source to the total active power output of the power supply system. The reactive power compensation control ratio is the ratio of the reactive power output of each distributed power source to the total reactive power output of the power supply system, including: when the impedance of the distributed power source to the grid connection point of the power supply system is L1, the active power compensation control ratio is ε 1p(k) , the reactive power compensation control ratio is ε 1q(k) When the impedance of the distributed power supply to the grid point of the power supply system is L2, the active power compensation control ratio is ε 2p(k) , the reactive power compensation control ratio is ε 2q(k) ; When L1 is greater than L2, ε 1p(k) Less than ε 2p(k) , ε 1q(k) Greater than ε 2q(k) ; The detection control unit is further configured to control the power output ratio of each distributed power source based on the power compensation control ratio.

2. The system according to claim 1, wherein: The detection control unit is further configured to control the active power output by a first distributed power source among the N distributed power sources to be less than a first preset power when the impedance from the first distributed power source to the grid connection point is greater than a first threshold value; or The detection control unit is further configured to control the active power output by the first distributed power source to be greater than or equal to the first preset power when the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value.

3. The system according to claim 1, wherein: The detection control unit is further configured to control the reactive power output by a second distributed power source among the N distributed power sources to be greater than a second preset power when the impedance from the second distributed power source to the grid connection point is greater than a second threshold value; or The detection control unit is further configured to control the reactive power output by the second distributed power source to be less than or equal to the second preset power when the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value.

4. The system according to claim 1, wherein: The detection control unit is further configured to, when detecting that the oscillation of the power supply system exceeds the preset threshold range, control the sum of the active powers output by the N distributed power supplies to be equal to the total active power output by the power supply system before the oscillation of the power supply system exceeds the preset threshold range; Furthermore, the sum of the reactive powers output by the N distributed power sources is controlled to be equal to the total reactive power output by the power supply system before the power supply system oscillates beyond the preset threshold range.

5. The system according to any one of claims 1 to 4, characterized in that: The detection control unit is further configured to, when it is detected that the oscillation of the power supply system exceeds a preset threshold range, number each distributed power supply based on the impedance from each distributed power supply to the grid connection point in ascending order, obtain the active power compensation control ratio of each distributed power supply based on the number of each distributed power supply and N, and control the active power output of each distributed power supply based on the active power compensation control ratio.

6. The system according to claim 5, characterized in that The active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies p(k) satisfy: The active power P output by the distributed power supply numbered k among the N distributed power supplies ref(k) satisfy: P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc Wherein, k is an integer greater than or equal to 1 and less than or equal to N, The K p_p is the first proportional coefficient, the K p_i is the first integral coefficient, s is the Laplace operator, and P all is the total active power output by the power supply system, the SOC ave is the average value of the state of charge SOC of the N distributed power sources, the SOC k is the SOC of the distributed power supply numbered k, the G pi_soc is the transfer function.

7. The system according to any one of claims 1 to 4, characterized in that: The detection control unit is further configured to, when it is detected that the power supply system oscillates beyond a preset threshold range, number each distributed power supply in ascending order based on the impedance from each distributed power supply to the grid connection point, obtain the reactive power compensation control ratio of each distributed power supply based on the number of each distributed power supply and N, and control the reactive power output of each distributed power supply based on the reactive power compensation control ratio.

8. The system according to claim 7, characterized in that The reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies q(k) satisfy: The reactive power Q output by the distributed power supply numbered k among the N distributed power supplies ref(k) satisfy: Q ref(k) =Q all ε q(k) ; Wherein, k is an integer greater than or equal to 1 and less than or equal to N, The K q_p is the second proportional coefficient, the K q_i is the second integral coefficient, s is the Laplace operator, and Q all is the total reactive power output by the power supply system.

9. The system according to any one of claims 1 to 4, characterized in that: The detection control unit is further configured to collect the current and voltage of the grid connection point of the power supply system, and obtain the effective value of the oscillation component of the voltage, the effective value of the oscillation component of the current, and the effective value of the oscillation component of the system frequency based on the voltage and current of the grid connection point; The detection control unit is further configured to obtain that the power supply system oscillates beyond the preset threshold range when the effective value of the oscillating component of the voltage is greater than a third threshold value, the effective value of the oscillating component of the current is greater than a fourth threshold value, and / or the effective value of the oscillating component of the system frequency is greater than a fifth threshold value.

10. A power control method for a power supply system, characterized in that: The method is applicable to at least one detection control unit in a power supply system, wherein the power supply system further comprises N distributed power sources, wherein the N distributed power sources are connected in parallel or in series to a power grid, where N is an integer greater than 1; the method comprises: When it is detected that the power supply system oscillates beyond a preset threshold range, based on the impedance of each distributed power supply in the N distributed power supplies to the grid connection point of the power supply system, the power compensation control ratio of each distributed power supply is obtained, the power compensation control ratio is the ratio of the power output of each distributed power supply to the total power output of the power supply system, the power compensation control ratio includes an active power compensation control ratio and a reactive power compensation control ratio, the active power compensation control ratio is the ratio of the active power output of each distributed power supply to the total active power output of the power supply system, the reactive power compensation control ratio is the ratio of the reactive power output of each distributed power supply to the total reactive power output of the power supply system, including: when the impedance of the distributed power supply to the grid connection point of the power supply system is L1, the active power compensation control ratio is ε 1p(k) , the reactive power compensation control ratio is ε 1q(k) When the impedance of the distributed power supply to the grid point of the power supply system is L2, the active power compensation control ratio is ε 2p(k) , the reactive power compensation control ratio is ε 2q(k) ; When L1 is greater than L2, ε 1p(k) Less than ε 2p(k) , ε 1q(k) Greater than ε 2q(k) ; Based on the power compensation control ratio, the power output ratio of each distributed power source is controlled.

11. The method according to claim 10, characterized in that When the impedance from a first distributed power source among the N distributed power sources to the grid connection point is greater than a first threshold value, controlling the active power output by the first distributed power source to be less than a first preset power; or When the impedance from the first distributed power source to the grid connection point is less than or equal to the first threshold value, the active power output by the first distributed power source is controlled to be greater than or equal to the first preset power.

12. The method according to claim 10, characterized in that When the impedance from a second distributed power source among the N distributed power sources to the grid connection point is greater than a second threshold value, controlling the reactive power output by the second distributed power source to be greater than a second preset power; or When the impedance from the second distributed power source to the grid connection point is less than or equal to the second threshold value, the reactive power output by the second distributed power source is controlled to be less than or equal to the second preset power.

13. The method according to claim 10, characterized in that When it is detected that the power supply system oscillates beyond the preset threshold range, controlling the sum of the active powers output by the N distributed power sources to be equal to the total active power output by the power supply system before the power supply system oscillates beyond the preset threshold range; Furthermore, the sum of the reactive powers output by the N distributed power sources is controlled to be equal to the total reactive power output by the power supply system before the power supply system oscillates beyond the preset threshold range.

14. The method according to any one of claims 10 to 13, characterized in that: When it is detected that the power supply system oscillates beyond a preset threshold range, each distributed power source is numbered in ascending order based on the impedance from each distributed power source to the grid connection point, and based on the number of each distributed power source and N, the active power compensation control ratio of each distributed power source is obtained, and the active power output of each distributed power source is controlled based on the active power compensation control ratio.

15. The method according to claim 14, characterized in that The active power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies p(k) satisfy: The active power P output by the distributed power supply numbered k among the N distributed power supplies ref(k) satisfy: P ref(k) =P all ε p(k) +(SOC ave -SOC k )G pi_soc Wherein, k is an integer greater than or equal to 1 and less than or equal to N, The K p_p is the first proportional coefficient, the K p_i is the first integral coefficient, s is the Laplace operator, and P all is the total active power output by the power supply system, the SOC ave is the average value of the state of charge SOC of the N distributed power sources, the SOC k is the SOC of the distributed power supply numbered k, the G pi_soc is the transfer function.

16. The method according to any one of claims 10 to 13, characterized in that When it is detected that the power supply system oscillates beyond a preset threshold range, each distributed power source is numbered based on the impedance from each distributed power source to the grid connection point in ascending order, and based on the number of each distributed power source and N, the reactive power compensation control ratio of each distributed power source is obtained, and the reactive power output of each distributed power source is controlled based on the reactive power compensation control ratio.

17. The method according to claim 16, characterized in that The reactive power compensation control ratio ε of the distributed power supply numbered k among the N distributed power supplies q(k) satisfy: The reactive power Q output by the distributed power supply numbered k among the N distributed power supplies ref(k) satisfy: Q ref(k) =Q all ε q(k) ; Wherein, k is an integer greater than or equal to 1 and less than or equal to N, The K q_p is the second proportional coefficient, the K q_i is the second integral coefficient, s is the Laplace operator, and Q all is the total reactive power output by the power supply system.

18. The method according to any one of claims 10 to 13, characterized in that: Collecting the current and voltage of the grid connection point of the power supply system, and obtaining the effective value of the oscillation component of the voltage, the effective value of the oscillation component of the current, and the effective value of the oscillation component of the system frequency based on the voltage and current of the grid connection point; When the effective value of the oscillating component of the voltage is greater than the third threshold value, the effective value of the oscillating component of the current is greater than the fourth threshold value and / or the effective value of the oscillating component of the system frequency is greater than the fifth threshold value, it is determined that the oscillation of the power supply system exceeds the preset threshold range.

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