Converter control method, device and power supply system

Abstract

The present invention discloses a converter control method, device and power supply system. The converter is connected to a power grid and a DC bus, and the method includes: calculating a current loop set value according to a set power and a power grid voltage; determining the positive and negative of the current loop set value; controlling the converter to perform rectification or inversion according to the positive and negative of the current loop set value, and controlling the converter to take power from the power grid according to the set power or feed the power to the grid according to the set power according to the current loop set value. The present invention can effectively control the grid-side converter to perform rectification or inversion, and the grid-side converter can take power from the power grid according to the set power or feed the power to the grid according to the set power, thereby realizing the constant power control of the grid-side converter, avoiding impact on the power grid, and solving the problem that the control method of the grid-side converter in the prior art is easy to cause impact on the power grid, thereby ensuring the stable operation of the entire system.

Description

Technical Field

[0001] The present invention relates to the field of energy control technology, and in particular to a converter control method, device and power supply system. Background Art

[0002] As energy issues become increasingly severe, traditional energy sources are becoming increasingly depleted. In addition, as people's living standards improve, electricity consumption has risen sharply, and the AC power grid needs to assume greater redundancy to respond to the demand on the load side. Electricity consumption is divided into peak and valley times. For example, at noon, electricity consumption will suddenly increase, and power stations need to generate more electricity. After the peak time of noon, power stations do not need to generate so much electricity, and transformers and other equipment must be designed according to the maximum power consumption. This situation will have a huge impact on the power grid, resulting in waste of power generation and waste of power equipment costs.

[0003] The power supply system includes power generation equipment (such as photovoltaic power generation, wind power generation, etc.), energy storage equipment, loads, energy dispatching equipment and power grid. At present, the DC bus voltage is stabilized by the grid-side converter. Figure 1 The dual-loop control of the voltage outer loop and the current inner loop shown in the figure generally uses a PI controller to control the DC bus voltage. Specifically, the voltage loop collects the actual voltage of the DC bus, and the voltage loop calculates the current loop set value by comparing the actual voltage with the set voltage. The current loop controls the duty cycle of the IGBT by comparing the current loop set value with the actual current fed back, thereby controlling the AC / DC conversion of the grid-side converter by controlling the on and off of the IGBT. When stabilizing the DC bus voltage, if the actual voltage is greater than the set voltage, it means that energy flows to the bus capacitor, and it needs to be fed into the grid; if the actual voltage is less than the set voltage, it means that the power generation is insufficient and it is necessary to draw power from the grid. The entire system draws power from the grid. At this time, the switching in and out of a large number of loads is likely to cause an impact on the grid.

[0004] With regard to the problem that the control method of the grid-side converter in the prior art is likely to cause impact on the power grid, no effective solution has been proposed so far. Summary of the invention

[0005] The embodiments of the present invention provide a converter control method, device and power supply system to at least solve the problem in the prior art that the control method of the grid-side converter easily causes impact on the power grid.

[0006] To solve the above technical problems, an embodiment of the present invention provides a converter control method, wherein the converter is connected to a power grid and a DC bus, and the method includes: calculating a current loop set value based on a set power and a power grid voltage; determining the positive or negative sign of the current loop set value; controlling the converter to perform rectification or inversion based on the positive or negative sign of the current loop set value, and controlling the converter to draw power from the power grid according to the set power or to feed power to the grid according to the set power based on the current loop set value.

[0007] Optionally, calculate the current loop given value based on the set power and grid voltage, including: calculate P÷U÷I 0 , where P represents the set power, U represents the grid voltage, and I 0 Represents the per-unit value of current; the calculation result is used as the given value of the current loop.

[0008] Optionally, determining the positive or negative of the current loop given value includes: when the converter has a voltage loop, calculating a reference current loop given value through the voltage loop, and using the positive or negative of the reference current loop given value as the positive or negative of the current loop given value; when the converter does not have a voltage loop, determining the positive or negative of the current loop given value based on the generated power and the load power.

[0009] Optionally, the positive or negative value of the current loop given value is determined based on the generated power and the load power consumption, including: if the generated power is greater than the load power consumption, then the positive or negative value of the current loop given value is determined as a first result, wherein the first result corresponds to converter inversion; if the generated power is less than the load power consumption, then the positive or negative value of the current loop given value is determined as a second result, wherein the second result corresponds to converter rectification.

[0010] Optionally, after controlling the converter to draw power from the power grid according to the set power or to feed power to the grid according to the set power according to the current loop given value, it also includes: if the set power is less than the load power consumption, controlling the energy storage device to discharge; if the set power is greater than the load power consumption, charging the energy storage device or reducing the set power.

[0011] Optionally, the method further includes: stabilizing the DC bus voltage by an energy storage converter, wherein the energy storage converter is connected to the power generation equipment and the DC bus.

[0012] An embodiment of the present invention also provides a converter control device, wherein the converter is connected to a power grid and a DC bus, and the converter control device includes: a calculation module, used to calculate a current loop set value based on a set power and a power grid voltage; a determination module, used to determine the positive or negative sign of the current loop set value; and a control module, used to control the converter to perform rectification or inversion based on the positive or negative sign of the current loop set value, and control the converter to draw power from the power grid according to the set power or feed power to the grid according to the set power based on the current loop set value.

[0013] An embodiment of the present invention further provides a power supply system, comprising: the converter control device described in the embodiment of the present invention, the converter control device is communicatively connected with an energy storage device, a load and a converter, and the energy storage device and the load are both connected to a DC bus.

[0014] An embodiment of the present invention further provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the embodiment of the present invention when executing the computer program.

[0015] The embodiment of the present invention further provides a non-volatile computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the embodiment of the present invention are implemented.

[0016] By applying the technical solution of the present invention, a current loop set value is calculated according to the set power and the grid voltage, the positive and negative of the current loop set value are determined, and the converter is controlled to perform rectification or inversion according to the positive and negative of the current loop set value, and the converter is controlled to draw power from the grid according to the set power or feed the grid according to the set power according to the current loop set value, so that the grid-side converter is effectively controlled to perform rectification or inversion, and the grid-side converter can draw power from the grid according to the set power or feed the grid according to the set power, thereby realizing constant power limit control of the grid-side converter, avoiding impact on the grid, and solving the problem that the control method of the grid-side converter in the prior art is prone to impact on the grid, thereby ensuring stable operation of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of dual-loop control of a grid-side converter in the prior art;

[0018] Figure 2 is a schematic diagram of a power supply system provided by an embodiment of the present invention;

[0019] Figure 3 is a flow chart of a converter control method provided by an embodiment of the present invention;

[0020] Figure 4 Schematic diagram of constant power limit dual-loop control of a grid-side converter provided by an embodiment of the present invention;

[0021] Figure 5 It is a structural block diagram of a converter control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all 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.

[0023] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0025] like Figure 2 As shown, it is a schematic diagram of a power supply system, which includes: a power generation device 10, an energy storage device 20, a load 30, a power grid 40 and an energy dispatching device 50. The power generation device 10 can be a photovoltaic power generation device, a wind power generation device and the like. The power generation device 10 is connected to the DC bus through the energy storage converter 11, and the DC bus is connected to the power grid 40 through the grid-side converter 41. The energy storage device 20 and the load 30 are both connected to the DC bus (that is, the load 30 is a DC load). The energy dispatching device 50 is communicatively connected with the energy storage device 20, the load 30 and the grid-side converter 41.

[0026] The energy storage converter 11 may specifically be a boost circuit, which increases the generated voltage to a constant value.

[0027] The grid-side converter 41 is a bidirectional converter, which is used to perform AC-DC conversion, for example, converting the DC power generated by the power generation equipment 10 into AC power and transmitting it to the grid (or supplying AC load), or converting AC power into DC power. The grid-side converter 41 can be a dual-loop control of a voltage outer loop and a current inner loop, or a single-loop control of only a current loop.

[0028] The energy dispatching device 50 is user-oriented and is used to control the charging and discharging of the energy storage device 20 , control the switching of the load 30 , and control the grid-side converter 41 .

[0029] The function of bus capacitor C is power decoupling, that is, when the power of the previous stage is insufficient, the bus capacitor can provide part of the power, and when the power of the previous stage increases, the increased power can be temporarily stored in the bus capacitor. Bus capacitor C is equivalent to a buffer and will not cause a sudden change in the power of the next stage.

[0030] The embodiment of the present invention provides a method for controlling a converter, wherein the converter is connected to a power grid and a DC bus, that is, the grid-side converter 41 . The method for controlling the converter may be executed by an energy dispatching device 50 . Figure 3 is a flow chart of a converter control method provided by an embodiment of the present invention, such as Figure 3 As shown, the method comprises the following steps:

[0031] S301, calculating the current loop set value according to the set power and the grid voltage.

[0032] S302, determine whether the current loop given value is positive or negative.

[0033] S303, controlling the converter to perform rectification or inversion according to the positive and negative current loop given value, and controlling the converter to draw power from the grid according to the set power or to feed the grid according to the set power according to the current loop given value.

[0034] The set power is a target power calculated in advance according to the actual power consumption of the power supply system, and the value of the set power can be changed according to actual needs. For example, the set power is obtained according to the sum of the powers required by each load to be turned on.

[0035] The positive and negative values ​​of the current loop given value correspond to the rectification and inversion of the grid-side converter. For example, if the current loop given value is negative, the grid-side converter performs inversion, and if the current loop given value is positive, the grid-side converter performs rectification. Of course, rectification can also be performed when the current loop given value is negative, and inversion can be performed when the current loop given value is positive. The current loop in the converter can control the duty cycle of the switch tube (such as IGBT) through the above current loop given value, thereby realizing the constant power control of the converter.

[0036] This embodiment calculates the current loop set value according to the set power and the grid voltage, determines the positive and negative of the current loop set value, controls the converter to perform rectification or inversion according to the positive and negative of the current loop set value, and controls the converter to draw power from the grid according to the set power or feed the grid according to the set power according to the current loop set value, effectively controls the grid-side converter to perform rectification or inversion, and the grid-side converter can draw power from the grid according to the set power or feed the grid according to the set power, thereby realizing constant power limit control of the grid-side converter and avoiding impact on the grid. This solves the problem in the prior art that the control method of the grid-side converter is prone to impact on the grid, thereby ensuring stable operation of the entire system.

[0037] In an optional implementation, S301 calculates the current loop given value according to the set power and the grid voltage, including: calculating P÷U÷I 0 , where P represents the set power, U represents the grid voltage, and I 0 represents the per-unit value of the current; the calculation result is used as the current loop given value. The per-unit value of the current is preset. In this embodiment, the current loop given value is calculated according to the set power, so that the current loop can ensure that the grid-side converter draws power from the grid according to the set power or feeds the grid according to the set power based on the current loop given value.

[0038] S302 determines whether the current loop given value is positive or negative, including the following two situations:

[0039] (1) When the converter has a voltage loop, a reference current loop given value is calculated through the voltage loop, and the positive and negative signs of the reference current loop given value are used as the positive and negative signs of the current loop given value.

[0040] In this case, the grid-side converter adopts dual-loop control of the voltage outer loop and the current inner loop. The voltage loop calculates the current loop given value a (as a reference current loop given value, including two attributes of positive and negative and size) based on the actual voltage of the DC bus collected. The specific calculation process is the prior art and is not described in detail. The current loop given value b is calculated based on the set power and the grid voltage, and the positive and negative attributes of the current loop given value a are assigned to the current loop given value b. In other words, this embodiment only uses the positive and negative attributes of the current loop given value a calculated by the voltage loop, and does not use its size attribute.

[0041] (2) When the converter does not have a voltage loop, the positive or negative value of the current loop given value is determined according to the generated power and the load power.

[0042] In this case, the grid-side converter only has a current loop, which can only perform current control and cannot automatically identify whether to perform rectification or inversion. In the case of a single current loop, this embodiment can determine whether to perform rectification or inversion based on the generated power and the load power, so that the grid-side converter is in the correct working mode, solving the problem of being unable to automatically identify whether to perform rectification or inversion in the case of a single current loop.

[0043] Further, the positive and negative values ​​of the current loop given value are determined according to the power generation and the load power, including: if the power generation is greater than the load power, the positive and negative values ​​of the current loop given value are determined as a first result, wherein the first result corresponds to the converter inversion; if the power generation is less than the load power, the positive and negative values ​​of the current loop given value are determined as a second result, wherein the second result corresponds to the converter rectification. In this way, the grid-side converter can be placed in the correct working mode.

[0044] Taking into account that both the generated power and the load power may change during the operation of the power supply system, resulting in insufficient or excess set power, in an optional implementation, after controlling the converter to draw power from the grid or feed the grid according to the set power according to the current loop given value, it also includes: if the set power is less than the load power, controlling the energy storage device to discharge; if the set power is greater than the load power, charging the energy storage device or reducing the set power.

[0045] In this implementation, if the set power is not enough for the load, the shortfall is provided by the energy storage device. If there is a surplus of the set power, the energy storage device can be charged or the set power value can be reduced. In the entire power supply system, the energy storage device is always in a discharging state to stabilize the bus voltage. If the energy storage device is to be charged, it is necessary to use the high and low voltage differences to force charging, and the electric energy flows from high potential to low potential.

[0046] In this embodiment, the grid-side converter performs constant power control, and the DC bus voltage is stabilized by the energy storage converter, wherein the energy storage converter is connected to the power generation equipment and the DC bus, thereby ensuring stable operation of the system.

[0047] This embodiment uses energy storage as the center to regulate the energy of the entire system. The energy storage converter DC / DC connected to the user-side load stabilizes the DC bus voltage. Under the dispatch of the energy dispatching equipment, the grid-side converter AC / DC connected to the power grid is effectively controlled to perform rectification or inversion, and the grid-side converter AC / DC is used to draw power from the grid or feed power to the grid according to the set power, thereby avoiding impact on the grid and coordinating with the regulation of energy storage to maintain the stable operation of the entire system.

[0048] like Figure 4The figure shows a schematic diagram of the constant power dual-loop control of the grid-side converter. The voltage loop collects the actual voltage of the DC bus and calculates the current loop set value a based on the actual voltage of the DC bus. The energy dispatching equipment calculates the current loop set value b based on the set power and the grid voltage, and assigns the positive and negative values ​​of the current loop set value a to the current loop set value b. The current loop controls the duty cycle of the switch tube according to the positive and negative current loop set value b (i.e. +b or -b), so that the grid-side converter can correctly perform rectification or inversion and realize constant power control.

[0049] Based on the same inventive concept, an embodiment of the present invention further provides a converter control device, which can be used to implement the converter control method described in the above embodiment. The converter is connected to the power grid and the DC bus for AC-DC conversion. The converter control device can be implemented by software and / or hardware, and the converter control device can generally be integrated into the energy dispatching equipment of the power supply system.

[0050] Figure 5 is a structural block diagram of a converter control device provided by an embodiment of the present invention, such as Figure 5 As shown, the converter control device comprises:

[0051] A calculation module 51 is used to calculate a current loop given value according to a set power and a grid voltage;

[0052] A determination module 52, used to determine whether the current loop given value is positive or negative;

[0053] The control module 53 is used to control the converter to perform rectification or inversion according to the positive or negative value of the current loop given value, and to control the converter to draw power from the power grid according to the set power or feed power to the grid according to the set power according to the current loop given value.

[0054] Optionally, the calculation module 51 is specifically used to calculate P÷U÷I 0 , where P represents the set power, U represents the grid voltage, and I 0 Represents the per-unit value of current; the calculation result is used as the given value of the current loop.

[0055] Optionally, the determination module 52 includes:

[0056] A first determining unit is used for calculating a reference current loop given value through the voltage loop when the converter has a voltage loop, and taking the positive and negative signs of the reference current loop given value as the positive and negative signs of the current loop given value;

[0057] The second determining unit is used to determine the positive or negative of the current loop given value according to the generated power and the load power when the converter does not have a voltage loop.

[0058] Optionally, the second determination unit is specifically used to: if the generated power is greater than the load power consumption, determine the positive or negative value of the current loop given value as a first result, wherein the first result corresponds to the converter inversion; if the generated power is less than the load power consumption, determine the positive or negative value of the current loop given value as a second result, wherein the second result corresponds to the converter rectification.

[0059] Optionally, the above-mentioned converter control device also includes: an energy storage control module, which is used to control the converter to draw power from the power grid according to the set power or feed the power to the grid according to the set power after the control module 53 controls the converter according to the current loop given value. If the set power is less than the load power consumption, the energy storage device is controlled to discharge; if the set power is greater than the load power consumption, the energy storage device is charged or the set power is reduced.

[0060] Optionally, the DC bus voltage is stabilized by an energy storage converter, wherein the energy storage converter is connected to the power generation equipment and the DC bus.

[0061] The above converter control device can execute the converter control method provided by the embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method. For technical details not described in detail in this embodiment, please refer to the converter control method provided by the embodiment of the present invention.

[0062] An embodiment of the present invention further provides a power supply system, comprising: the converter control device described in the above embodiment, the converter control device is communicatively connected with an energy storage device, a load and a converter, and the energy storage device and the load are both connected to a DC bus.

[0063] An embodiment of the present invention further provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the above embodiment when executing the computer program.

[0064] An embodiment of the present invention further provides a non-volatile computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the above embodiment are implemented.

[0065] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0066] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling a converter, wherein the converter is connected to a power grid and a DC bus, characterized in that: The method comprises: Calculate the current loop given value according to the set power and the grid voltage, wherein P÷U÷I0 is calculated, and the calculation result is used as the current loop given value, where P represents the set power, U represents the grid voltage, and I0 represents the current per unit value; Determine whether the current loop given value is positive or negative; Controlling the converter to perform rectification or inversion according to the positive or negative value of the current loop given value, and controlling the converter to draw power from the power grid or feed power to the grid according to the set power according to the current loop given value; Determining whether the current loop given value is positive or negative includes: In the case where the converter has a voltage loop, a reference current loop given value is calculated through the voltage loop, and the positive and negative signs of the reference current loop given value are used as the positive and negative signs of the current loop given value; In the case where the converter does not have a voltage loop, the positive or negative value of the current loop given value is determined according to the generated power and the load power consumption. If the generated power is greater than the load power consumption, the positive or negative value of the current loop given value is determined as a first result, wherein the first result corresponds to converter inversion; if the generated power is less than the load power consumption, the positive or negative value of the current loop given value is determined as a second result, wherein the second result corresponds to converter rectification.

2. The method according to claim 1, characterized in that After controlling the converter to draw power from the power grid or feed power to the power grid according to the set power according to the current loop given value, the method further includes: If the set power is less than the load power, the energy storage device is controlled to discharge; If the set power is greater than the load power, the energy storage device is charged or the set power is reduced.

3. The method according to any one of claims 1 to 2, characterized in that Also includes: The DC bus voltage is stabilized by an energy storage converter, wherein the energy storage converter is connected to a power generation device and a DC bus.

4. A converter control device, wherein the converter is connected to a power grid and a DC bus, characterized in that: The converter control device comprises: A calculation module is used to calculate a current loop given value according to a set power and a grid voltage, wherein P÷U÷I0 is calculated, and the calculation result is used as the current loop given value, where P represents the set power, U represents the grid voltage, and I0 represents the current per unit value; A determination module, used to determine whether the current loop given value is positive or negative; A control module, used for controlling the converter to perform rectification or inversion according to the positive or negative value of the current loop given value, and controlling the converter to draw power from the power grid according to the set power or feed the power to the grid according to the set power according to the current loop given value; The determination module comprises: A first determining unit is used for calculating a reference current loop given value through the voltage loop when the converter has a voltage loop, and taking the positive and negative signs of the reference current loop given value as the positive and negative signs of the current loop given value; The second determination unit is used to determine the positive or negative value of the current loop given value according to the power generation power and the load power consumption when the converter does not have a voltage loop; if the power generation power is greater than the load power consumption, the positive or negative value of the current loop given value is determined as a first result, wherein the first result corresponds to converter inversion; if the power generation power is less than the load power consumption, the positive or negative value of the current loop given value is determined as a second result, wherein the second result corresponds to converter rectification.

5. A power supply system, characterized in that: include: The converter control device according to claim 4 is communicatively connected to an energy storage device, a load and a converter, and both the energy storage device and the load are connected to a DC bus.

6. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method according to any one of claims 1 to 3 when executing the computer program.

7. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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