Energy control method of alternating current and direct current hybrid micro-grid system

Abstract

The invention discloses an AC / DC hybrid micro-grid system energy control method, which comprises the following steps: S1, obtaining one-year meteorological data, and calculating the hour average output power of a wind power AC generator set and a photovoltaic DC generator set based on the one-year meteorological data; s2, calculating an hour source load power difference value based on the hour average output power of the wind power alternating current generator set and the photovoltaic direct current generator set; and S3, performing energy control based on the hour source load power difference. According to the invention, the energy control method of the AC-DC hybrid micro-grid system can be realized.

Description

Technical Field

[0001] The present invention relates to the field of AC-DC hybrid microgrid systems and energy control, and particularly to an energy control method for an AC-DC hybrid microgrid system. Background Art

[0002] An AC-DC hybrid microgrid contains various distributed power sources, such as solar photovoltaic, wind power generation, fuel cells, and energy storage devices, etc. The output power thereof has intermittency and volatility. If fluctuations occur, they will cause instability of the system frequency and voltage, resulting in equipment damage and user power outages. Summary of the Invention

[0003] The purpose of the present invention is to provide an energy control method for an AC-DC hybrid microgrid system, aiming to solve the energy control of the AC-DC hybrid microgrid system.

[0004] The present invention also provides an energy control method for an AC-DC hybrid microgrid system, including:

[0005] S1. Obtain annual meteorological data, and calculate the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set based on the annual meteorological data;

[0006] S2. Calculate the hourly source-load power difference based on the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set;

[0007] S3. Perform energy control based on the hourly source-load power difference.

[0008] By adopting the embodiment of the present invention, through energy management, the fluctuations of the output power are smoothed, the stability of the system frequency and voltage is ensured, and equipment damage and user power outages are prevented.

[0009] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it is implemented in accordance with the content of the description. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following specifically illustrates the specific embodiments of the present invention. Brief Description of the Drawings

[0010] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0011] Figure 1 It is a schematic diagram of an AC-DC hybrid microgrid system according to an embodiment of the present invention;

[0012] Figure 2 It is a schematic diagram of an AC-DC hybrid microgrid system in the prior art. Specific implementation manners

[0013] Hereinafter, the technical solutions of the present invention will be described clearly and completely in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0014] Method embodiments

[0015] According to an embodiment of the present invention, there is provided an energy control method for an AC-DC hybrid microgrid system. Figure 1 It is a schematic diagram of an energy control method for an AC-DC hybrid microgrid system according to an embodiment of the present invention, as Figure 1 shown, and specifically includes:

[0016] S1. Obtain annual meteorological data, and calculate the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set based on the annual meteorological data;

[0017] The total power generation of the wind power system can be expressed as:

[0018] W W = P W × C W × Δt;

[0019] In the formula: W w is the sum of the electric energy generated by the wind turbine per hour, kW·h; C w is the capacity of the wind turbine, kW.

[0020] The overall output power of the photovoltaic power generation system can be expressed as:

[0021] W pv = P pv × C pv × Δt;

[0022] In the formula: W pv is the sum of the electric energy generated by the photovoltaic unit per hour, kW·h; C pv is the capacity of the photovoltaic unit, kW.

[0023] Combined with the annual meteorological data, calculate the total electric energy generated by the wind power system and the photovoltaic power generation system, and divide the total electric energy by 8760 hours to obtain the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set.

[0024] S2. Calculate the hourly source-load power difference based on the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set;

[0025] The hourly average output power of the wind power AC generator set and the photovoltaic DC generator set minus the AC-DC load demand on the user side gives the hourly source-load power difference;

[0026] The total load of the hybrid microgrid system includes energy storage charging and AC-DC loads on the user side.

[0027] S3. Perform energy control based on the hourly source-load power difference.

[0028] In the embodiment of the present invention, energy control is performed every hour based on the hourly source-load power difference;

[0029] The energy control is based on an existing microgrid system, Figure 2 which is a schematic diagram of an AC-DC hybrid microgrid system in the prior art, as Figure 2 shown, and specifically includes:

[0030] AC bus, DC bus, AC load, wind power AC generator set, DC subnet, and photovoltaic DC generator set;

[0031] The DC subnet includes: DC load and energy storage system;

[0032] The energy storage system includes: hydrogen energy storage system and battery energy storage system;

[0033] The hydrogen energy storage system includes: electrolyzer, hydrogen storage tank, and fuel cell. The electrolyzer is connected to the hydrogen storage tank, the hydrogen storage tank is connected to the fuel cell, and the electrolyzer and the fuel cell are respectively connected to the DC bus;

[0034] The photovoltaic DC generator set, transformer, and battery energy storage system are connected to the DC bus, and the wind power AC generator set is connected to the AC bus.

[0035] The total load of the hybrid microgrid system includes: energy storage load and AC-DC loads on the user side;

[0036] The system further includes: a bidirectional AC-DC converter, which is used to input the excess power on the AC side into the DC subnet when the output power of the wind power AC generator set is greater than the AC load demand power, and input the power of the DC subnet into the AC subnet to supplement the AC side power difference when the output power of the wind power AC generator set is less than the AC load demand power on the user side.

[0037] In the embodiment of the present invention, the energy storage system is distributed on the DC bus of the AC-DC hybrid microgrid. Energy is transferred between the AC side and the DC side through a commutation device. After the electric energy generated by the distributed power sources on both the AC and DC sides meets the AC-DC load demands on both sides, the energy storage device is then started. By judging the relationship between the electric energy generated by the distributed power sources and the AC-DC loads on the user side, the operation strategy of the energy storage system is determined.

[0038] The distributed power sources include: photovoltaic DC generating sets, wind power AC generating sets, hydrogen energy storage systems, and battery energy storage systems.

[0039] In the embodiment of the present invention, the conditions required for executing the strategy are as follows:

[0040] When it is judged that the hourly source-load power difference is greater than zero, it is judged whether the maximum hourly charging power of the battery is greater than the hourly source-load power difference. If so, control strategy one is executed. If not, it is judged whether the sum of the maximum hourly charging power of the battery and the maximum hourly charging power of the electrolytic cell is greater than the hourly source-load power difference. If so, strategy three is executed. If not, control strategy two is executed;

[0041] When it is judged that the hourly source-load power difference is less than zero, the absolute value of the hourly source-load power difference is calculated. It is judged whether the maximum hourly discharging power of the battery is greater than the absolute value of the hourly source-load power difference. If so, control strategy four is executed. If not, it is judged whether the sum of the maximum hourly discharging power of the battery and the maximum hourly discharging power of the fuel cell is greater than the absolute value of the source-load power difference. If so, control strategy six is executed. If not, control strategy five is executed.

[0042] In the embodiment of the present invention, the specific content of the strategy is as follows:

[0043] Specifically, strategy one includes: after the output powers of the photovoltaic DC generating set and the wind power AC generating set meet the AC-DC loads on the user side, the remaining energy is supplied to the battery for charging.

[0044] Specifically, strategy two includes: after the output powers of the photovoltaic DC generating set and the wind power AC generating set meet the AC-DC load demands on the user side, the remaining energy is supplied to the battery and the electrolytic cell. The electrolytic cell converts the energy into hydrogen for storage. After the energy storage system reaches the maximum state of charge constraint during charging, the excess power is calculated and denoted as P tep .

[0045] Specifically, strategy three includes: after the output powers of the photovoltaic DC generating set and the wind power AC generating set meet the AC-DC loads on the user side, the remaining energy is supplied to the battery. After the battery reaches the maximum state of charge constraint, the excess electric energy is provided to the electrolytic cell.

[0046] Specifically, strategy four includes: when the AC-DC load deficit is not met by the wind power AC generating set and the photovoltaic DC generating set, the battery provides energy to the AC-DC load.

[0047] Strategy five specifically includes: the battery and fuel cell operate at maximum power to supply power to the AC-DC hybrid microgrid system. The constraint conditions are the state of charge and equivalent state of charge constraint conditions. When the total load demand of the hybrid microgrid system is not met, the deficit power P is calculated. sp .

[0048] When the energy storage battery and fuel cell discharge, there are state of charge and equivalent state of charge constraint conditions, and the SOC cannot exceed a certain range.

[0049] When the energy storage battery and fuel cell discharge, there are state of charge and equivalent state of charge constraint conditions, and the SOC cannot exceed a certain range.

[0050] Strategy six specifically includes: when the battery supplies power to the load of the distributed power source in the system at maximum power, if the demand is not met and the state of charge constraint during discharge is reached, the fuel cell will supplement the remaining insufficient power.

[0051] The beneficial effects are as follows:

[0052] For the established microgrid system model, an energy control decision is established to respond to the energy changes among the source, storage, and load. Through energy management, the fluctuation of the output power is smoothed, the system frequency and voltage stability are ensured, and equipment damage and user power outages are prevented.

[0053] The embodiment of the present invention is a system embodiment corresponding to the above method embodiment. The specific operations of each module can be understood with reference to the description of the method embodiment and will not be elaborated here.

[0054] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the technical solutions of the embodiments of the present invention deviate from the scope of this solution.

Claims

1. An energy control method for an AC-DC hybrid microgrid system, characterized in that, Including: S1. Obtain one-year meteorological data, and calculate the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set based on the one-year meteorological data; S2. Calculate the hourly source-load power difference based on the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set; S3. Perform energy control based on the hourly source-load power difference.

2. The method according to claim 1, wherein The specific content of S2 includes: The hourly source-load power difference is obtained by subtracting the AC / DC load on the user side from the hourly average output power of the wind power AC generator set and the photovoltaic DC generator set.

3. The method according to claim 1, wherein Including: The specific content of S3 includes: When it is judged that the hourly source-load power difference is greater than zero, judge whether the maximum hourly charging power of the battery is greater than the hourly source-load power difference. If so, execute Control Strategy 1. If not, judge whether the sum of the maximum hourly charging power of the battery and the maximum hourly charging power of the electrolytic cell is greater than the hourly source-load power difference. If so, execute Strategy 3. If not, execute Control Strategy 2; When it is judged that the hourly source-load power difference is less than zero, calculate the absolute value of the hourly source-load power difference, and judge whether the maximum hourly discharging power of the battery is greater than the absolute value of the hourly source-load power difference. If so, execute Control Strategy 4. If not, judge whether the sum of the maximum hourly discharging power of the battery and the maximum hourly discharging power of the fuel cell is greater than the absolute value of the source-load power difference. If so, execute Control Strategy 6. If not, execute Control Strategy 5.

4. The method according to claim 3, wherein The specific content of Strategy 1 includes: After the output of the photovoltaic DC generator set and the wind power AC generator set meets the AC / DC load on the user side, the remaining energy is supplied to the battery for charging.

5. The method according to claim 3, characterized in that The specific content of Strategy 2 includes: After the output of the photovoltaic DC generator set and the wind power AC generator set meets the demand of the AC / DC load on the user side, the remaining energy is supplied to the battery and the electrolytic cell. The electrolytic cell converts the energy into hydrogen for storage. After the energy storage system reaches the maximum state of charge constraint during charging, calculate the excess power.

6. The method according to claim 3, wherein The specific content of Strategy 3 includes: After the output of the photovoltaic DC generator set and the wind power AC generator set meets the AC / DC load on the user side, the remaining energy is supplied to the battery. After the battery reaches the maximum state of charge constraint, the excess electric energy is provided to the electrolytic cell.

7. The method according to claim 3, characterized in that, The specific content of Strategy 4 includes: When the wind power AC generator set and the photovoltaic DC generator set do not meet the load deficit, the battery provides energy to the AC / DC load.

8. The method according to claim 3, characterized in that, The specific content of Strategy 5 includes: The battery and the fuel cell operate at the maximum power to supply power to the AC / DC hybrid microgrid system. The constraint conditions are the state of charge and the equivalent state of charge constraint conditions. When the total load demand of the hybrid microgrid system is not met, calculate the deficit power.

9. The method according to claim 3, wherein The specific content of Strategy 6 includes: When the battery supplies power to the loads of the photovoltaic DC generator set and the wind power AC generator set in the system at the maximum power, if the demand is not met and the state of charge constraint during discharging is reached, the fuel cell will supplement the remaining insufficient power.

10. The method according to claim 9, wherein The total load of the hybrid microgrid system includes: the energy storage load and the AC / DC load on the user side.

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