Automatic-coordination network-forming type multi-time-scale mixed energy storage system and automatic-coordination network-forming type multi-time-scale mixed energy storage method

Abstract

The invention discloses an automatic coordination network construction type multi-time scale hybrid energy storage system and method, and belongs to the technical field of energy storage and new energy. In the system, a super capacitor is connected in parallel with a direct current bus of an inverter; the inverter adjusts the phase of the AC side output voltage according to the DC bus voltage; the first DC / DC converter regulates and generates an output current instruction of the short-time energy storage battery according to the DC bus voltage, and tracks the output current instruction of the short-time energy storage battery through a current inner loop PI controller; and the second DC / DC converter inputs the filtered DC bus voltage difference into the PI controller with amplitude limiting and saturation resistance to generate an output current instruction of the amplitude-limited long-time energy storage battery, and the output current instruction of the amplitude-limited long-time energy storage battery is tracked through the current inner loop PI controller. According to the invention, automatic coordination distribution output among energy storage systems with different time scales can be realized without depending on communication, and the response speed and reliability of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage and new energy technology, and specifically relates to an automatically coordinated grid-type multi-time scale hybrid energy storage system and method. Background Art

[0002] The increasingly severe energy and environmental crises facing the public have driven the vigorous development of renewable energy generation. Renewable energy output exhibits random fluctuations, posing a threat to power balance and voltage and frequency stability as renewable energy penetration increases. On a timescale of seconds, renewable energy generation systems lack inertia. As the proportion of renewable energy replacing synchronous generators increases, the grid's inertia decreases, leading to a decline in frequency stability. Therefore, the grid requires energy storage systems that can compensate for the inertia shortfall caused by renewable energy generation and increase the grid's equivalent inertia. On timescales of seconds to minutes, renewable energy generation systems struggle to provide stable frequency regulation power due to the unpredictable random fluctuations in input power. Therefore, the grid also requires energy storage power sources with timescales of seconds to minutes to provide primary frequency regulation power. On longer timescales, environmental factors such as prolonged cloudy days or no wind can also cause hourly grid power imbalances. Therefore, the grid also requires hourly long-duration energy storage power sources to compensate for chronic renewable energy shortages and maintain system frequency stability. How to achieve coordinated coordination among various energy storage sources operating at these different timescales is a key issue that must be addressed in new power systems. Currently, the only way to achieve automatic coordination of power sources with different timescales is through unified commands issued by a central controller or dispatching system via communication. However, this communication-dependent coordination method has low reliability, and a communication failure can easily lead to the loss of system coordination. Therefore, in summary, current energy storage systems require a central control system to distribute output commands to energy storage sources with different timescales via communication. The coordination and reliability of the various energy storage sources in the system need to be further improved. Summary of the Invention

[0003] The present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system and method, aiming to solve the problem in current energy storage systems that a central control unit needs to be used to distribute output instructions to energy storage power sources of different time scales through communication, and the coordination and reliability of the coordination between various energy storage power sources in the system need to be further improved.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system, comprising a supercapacitor, a short-term energy storage battery, a long-term energy storage battery, an inverter, a first DC / DC converter, and a second DC / DC converter; wherein: The supercapacitor is connected in parallel to the DC bus of the inverter; the short-term energy storage battery is connected to the DC bus of the inverter through a first DC / DC converter; and the long-term energy storage battery is connected to the DC bus of the inverter through a second DC / DC converter. The inverter is configured to adjust the phase of the AC side output voltage according to the DC bus voltage; the first DC / DC converter is configured to generate an output current instruction for the short-term energy storage battery according to the DC bus voltage regulation and limit it, and track the output current instruction of the short-term energy storage battery after limiting through a current inner-loop PI controller; the second DC / DC converter is configured to input the filtered DC bus voltage difference into a PI controller with limiting anti-saturation to generate an output current instruction for the long-term energy storage battery after limiting, and track the output current instruction of the long-term energy storage battery after limiting through the current inner-loop PI controller.

[0005] In some embodiments, the inverter adjusts the phase of the AC side output voltage according to the DC bus voltage, specifically using the following formula (1): (1); in, θ is the phase of the inverter AC side output voltage, is the rated value of the inverter DC bus voltage, is the DC bus voltage value, is the differential operator, is the integration coefficient.

[0006] In some embodiments, the short-term energy storage battery output current command generated by the first DC / DC converter is as follows: (2); in, is the current instruction, is the proportional coefficient of the current of the short-term energy storage battery and the DC bus voltage; The upper and lower limits of the current command are determined by the battery management system of the short-time energy storage battery according to the state of charge of the short-time energy storage battery.

[0007] In some embodiments, the second DC / DC converter performs a low-pass filter with a filtering time constant of minutes on the DC bus voltage difference, and inputs it into a PI controller with limiting anti-saturation to obtain the output current instruction of the long-term energy storage battery after limiting.

[0008] Furthermore, the output limit value of the PI controller with limiter anti-saturation is determined by the battery management system of the long-term energy storage battery according to the state of charge of the long-term energy storage battery.

[0009] Furthermore, when the output of the PI controller with limiting anti-saturation reaches the limit value, the PI controller enters the anti-saturation mechanism, and the integral operation of the PI controller stops until the output returns to the limit range and then resumes the integral operation.

[0010] In some embodiments, the output current command of the short-term energy storage battery is limited and then tracked by a current inner loop PI controller.

[0011] In some embodiments, the output current command of the limited long-term energy storage battery is tracked by a current inner loop PI controller.

[0012] In some embodiments, the output distribution of the supercapacitor, the short-term energy storage battery, and the long-term energy storage battery is achieved through automatic coordinated control of the DC bus voltage.

[0013] The present invention also provides an automatically coordinated network-type multi-time scale hybrid energy storage method, comprising the following steps: S1, adjust the phase of the AC side output voltage according to the DC bus voltage through the inverter; S2. Generate an output current command for the short-term energy storage battery according to the DC bus voltage through a first DC / DC converter and limit the output current command, and track the output current command of the short-term energy storage battery after the limit through a current inner loop PI controller; S3. Input the filtered DC bus voltage difference into a PI controller with limiting anti-saturation through a second DC / DC converter to generate a limited output current command of the long-term energy storage battery, and track the output current command of the long-term energy storage battery through a current inner loop PI controller.

[0014] Compared with the prior art, the present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system and method, which has the following beneficial effects: The present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system that can automatically achieve the power required for inertia support provided by supercapacitors, the power required for short-term frequency modulation and damping provided by short-term energy storage batteries, and the power that changes slowly over minutes or more provided by long-term energy storage batteries. The present invention can thus give full play to the rapid output capability of supercapacitors to ensure sufficient inertia support power, and ensure that the limited capacity of supercapacitors is fully used to provide the power required for inertia, thereby reducing the energy demand for supercapacitors when providing a specified inertia, thereby improving the economic efficiency of configuring supercapacitors. The primary frequency modulation power of longer time scales is automatically coordinated and provided in a time-sharing manner by short-term energy storage and long-term energy storage. As a result, long-term energy storage does not need to respond quickly, reducing the response speed requirements of long-term energy storage batteries, thereby reducing the cost of configuring long-term energy storage. The present invention can enable energy storage power sources of different time scales to achieve automatic coordinated output without the need for communication. Compared with the method of using a central controller or a dispatching system to distribute output instructions to energy storage power sources of different time scales through communication, the present invention can make the automatic coordinated operation of the energy storage system more stable and reliable, and has better practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 This is a schematic diagram of the architecture of an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system of the present invention; Figure 2 This is a schematic diagram of the coordinated control of DC voltage by the inverter, short-term energy storage and long-term energy storage controller in an automatically coordinated grid-type multi-time scale hybrid energy storage system of the present invention. DETAILED DESCRIPTION

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0020] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0021] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] How to develop a grid-type multi-time-scale hybrid energy storage system that automatically coordinates and allocates output without relying on communication to meet the current rapid development needs of new energy and energy storage systems.

[0024] like Figure 1 As shown, the present invention provides an automatically coordinated grid-type multi-time scale hybrid energy storage system, including a supercapacitor, a short-term energy storage battery, a long-term energy storage battery, an inverter, a first DC / DC converter, and a second DC / DC converter; wherein: The supercapacitor is connected in parallel to the DC bus of the inverter; the short-term energy storage battery is connected to the DC bus of the inverter through a first DC / DC converter; and the long-term energy storage battery is connected to the DC bus of the inverter through a second DC / DC converter. The inverter is configured to adjust the phase of the AC side output voltage according to the DC bus voltage; the first DC / DC converter is configured to generate an output current instruction for the short-term energy storage battery according to the DC bus voltage regulation and limit it, and track the output current instruction of the short-term energy storage battery after limiting through a current inner-loop PI controller; the second DC / DC converter is configured to input the filtered DC bus voltage difference into a PI controller with limiting anti-saturation to generate an output current instruction for the long-term energy storage battery after limiting, and track the output current instruction of the long-term energy storage battery after limiting through the current inner-loop PI controller.

[0025] In this invention's self-coordinating, grid-based, multi-timescale hybrid energy storage system, supercapacitors are directly connected in parallel to the DC bus, providing the fastest response and prioritizing the handling of high-frequency power fluctuations. Short-term energy storage is connected via a first Direct Current (DC) converter, which has the second fastest response and handles frequency modulation and power damping. Long-term energy storage is connected via a second DC / DC converter, which has the slowest response and provides long-term power balancing. This invention utilizes a layered physical structure to naturally prioritize the output of energy storage at different timescales, eliminating reliance on communication coordination. The inverter, first DC / DC converter, and second DC / DC converter all use the DC bus voltage as an input parameter to generate their own current commands. Automatic coordination is achieved through local voltage feedback, eliminating the need for a central controller or external communication, improving system reliability. The inverter directly regulates phase-stabilized voltage, short-term energy storage tracks the current command via a PI (Proportional Integral) controller, and long-term energy storage avoids integral saturation via an anti-saturation PI controller. Independent closed-loop control of each unit reduces system complexity and enhances dynamic response.

[0026] In some specific embodiments, the present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system. A formula is set for the inverter to adjust the phase of the AC-side output voltage based on the DC bus voltage. The inverter converts voltage deviations into phase adjustments through integral control, directly stabilizing the DC bus voltage and improving the system's inertia support capability. A formula is set for the output current command of the short-term energy storage battery generated by the first DC / DC converter. Through the short-term energy storage current command formula and the limiting mechanism, the limiting value is adjusted in real time by the battery management system to avoid overcharging or over-discharging, ensuring that the short-term energy storage responds to frequency modulation requirements within a safe state of charge range.

[0027] Furthermore, in the automatically coordinated grid-type multi-time-scale hybrid energy storage system of the present invention, the second DC / DC converter performs a low-pass filter with a filtering time constant of minutes on the DC bus voltage difference, and inputs it into a PI controller with limiting anti-saturation to obtain the output current instruction of the long-term energy storage battery after limiting. Preferably, the output limit value of the PI controller with limiting anti-saturation is determined by the battery management system of the long-term energy storage battery according to the charge state of the long-term energy storage battery. The present invention filters out high-frequency fluctuations through minute-level filtering to ensure that the long-term energy storage only responds to slow power demands and reduces its frequent action losses; the limiting and integral freezing mechanism avoids controller output saturation, maintains the stable output of the long-term energy storage, and extends the battery life.

[0028] Furthermore, in the present invention's automatically coordinated, grid-type, multi-time-scale hybrid energy storage system, the output current command of the short-term energy storage battery is limited and tracked by a current inner-loop PI controller. The output current command of the limited long-term energy storage battery is tracked by a current inner-loop PI controller. The output distribution of supercapacitors, short-term energy storage batteries, and long-term energy storage batteries is achieved through automatic coordinated control of the DC bus voltage. Furthermore, the present invention relies solely on local voltage signals to complete output distribution, avoiding coordination failures caused by communication delays or interruptions, and enhancing the reliability of the energy storage system.

[0029] The present invention also provides an automatically coordinated network-type multi-time scale hybrid energy storage method, comprising the following steps: S1, adjust the phase of the AC side output voltage according to the DC bus voltage through the inverter; S2. Generate an output current command for the short-term energy storage battery according to the DC bus voltage through a first DC / DC converter and limit the output current command, and track the output current command of the short-term energy storage battery after the limit through a current inner loop PI controller; S3. Input the filtered DC bus voltage difference into a PI controller with limiting anti-saturation through a second DC / DC converter to generate a limited output current command of the long-term energy storage battery, and track the output current command of the long-term energy storage battery through a current inner loop PI controller.

[0030] The following is a further detailed description of an automatically coordinated grid-type multi-time-scale hybrid energy storage system and method of the present invention through specific embodiments.

[0031] like Figure 1As shown, the automatically coordinated grid-type multi-time-scale hybrid energy storage system of the present invention includes three time-scale energy storage power sources: supercapacitors, short-term energy storage batteries, and long-term energy storage batteries. These three energy storage power sources are connected to the power grid through an inverter, wherein the supercapacitor is connected in parallel to the DC bus of the inverter, the short-term energy storage battery is connected to the DC bus of the inverter through a first DC / DC converter, and the long-term energy storage battery is connected to the DC bus of the inverter through a second DC / DC converter. Through the automatic coordinated control of the DC bus voltage by the inverter, the first DC / DC converter, and the second DC / DC converter, the present invention can realize the automatic distribution of output of the three energy storage power sources with different time scales without the need for communication.

[0032] like Figure 2 As shown, preferably, in the automatic coordinated grid-type multi-time scale hybrid energy storage system of the present invention, the inverter, the first DC / DC converter and the second DC / DC converter are arranged according to Figure 2 The DC bus voltage is automatically coordinated and controlled in this way.

[0033] First, the inverter directly adjusts the phase of its AC side output voltage according to the DC bus voltage, specifically using the following formula (1): (1); in, θ is the phase of the inverter AC side output voltage, is the rated value of the inverter DC bus voltage, is the DC bus voltage value, is the differential operator, is the integration coefficient.

[0034] At the same time, the first DC / DC converter connected to the short-term energy storage battery adjusts the output current instruction of the short-term energy storage battery according to the DC bus voltage according to the following formula (2): (2); in, is the current instruction, is the proportional coefficient of the current of the short-term energy storage battery and the DC bus voltage; Current command After the limit, the current command after the limit is obtained; among them, the upper limit value of the limit and lower limit The battery management system of the short-term energy storage battery is used to calculate the state of charge of the short-term energy storage battery. Then, the current inner loop PI controller is used to calculate the state of charge of the short-term energy storage battery. ; Make the output current of the short-term energy storage battery Track the current command after the limit.

[0035] Then, the second DC / DC converter connected to the long-term energy storage battery converts the DC bus voltage difference through the filter time constant T Low-pass filter at the minute level Then, it is sent to the PI controller with limiting anti-saturation To control, the PI controller outputs the upper limit value of the limit and lower limit The battery management system of the long-term energy storage battery is given according to the state of charge of the long-term energy storage battery. Once the output of the PI controller reaches the limit value, the PI controller enters the anti-saturation mechanism and the integral control no longer operates until the output of the PI controller changes to the limit value range and then the integral operation is restarted. The final output of the PI controller with limiter anti-saturation is the output current instruction of the long-term energy storage battery Then, the current inner loop PI controller is used to make the output current of the long-term energy storage battery Track the current command.

[0036] In summary, the present invention provides an automatically coordinated, grid-type, multi-time-scale hybrid energy storage system and method, which realizes automatic coordination of multi-time-scale energy storage through hierarchical access and local closed-loop control; and improves the reliability and stability of the energy storage system by optimizing the dynamic response of short-term energy storage, the stability of long-term energy storage, and communication-free collaboration.

[0037] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the specification and described above. Any equivalent changes, modifications and evolutions made by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. An automatically coordinated grid-type multi-time scale hybrid energy storage system, characterized in that: The system comprises a supercapacitor, a short-term energy storage battery, a long-term energy storage battery, an inverter, a first DC / DC converter, and a second DC / DC converter; wherein: The supercapacitor is connected in parallel to the DC bus of the inverter; the short-term energy storage battery is connected to the DC bus of the inverter through a first DC / DC converter; the long-term energy storage battery is connected to the DC bus of the inverter through a second DC / DC converter; The inverter is configured to adjust the phase of the AC side output voltage according to the DC bus voltage; the first DC / DC converter is configured to generate an output current command for the short-term energy storage battery according to the DC bus voltage regulation and limit the output current command of the short-term energy storage battery after the limit is tracked by a current inner-loop PI controller; the second DC / DC converter is configured to input the filtered DC bus voltage difference into a PI controller with limiter anti-saturation to generate an output current command for the long-term energy storage battery after the limit is generated, and the output current command for the long-term energy storage battery after the limit is tracked by the current inner-loop PI controller.

2. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1 is characterized in that: The inverter adjusts the phase of the AC side output voltage according to the DC bus voltage, specifically using the following formula (1): （1）； in, θ is the phase of the inverter AC side output voltage, is the rated value of the inverter DC bus voltage, is the DC bus voltage value, is the differential operator, is the integration coefficient.

3. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1 is characterized in that: The short-term energy storage battery output current command generated by the first DC / DC converter is as follows: （2）； in, Output current instruction for short-term energy storage battery, is the proportional coefficient of the current of the short-term energy storage battery and the DC bus voltage; The upper and lower limits of the current command are determined by the battery management system of the short-time energy storage battery according to the state of charge of the short-time energy storage battery.

4. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1, characterized in that: The second DC / DC converter performs low-pass filtering with a filtering time constant of minute level on the DC bus voltage difference, and inputs the filtering into a PI controller with amplitude limiting and anti-saturation to obtain the output current instruction of the long-term energy storage battery after amplitude limiting.

5. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 4 is characterized in that: The output limit value of the PI controller with limiter anti-saturation is determined by the battery management system of the long-term energy storage battery according to the state of charge of the long-term energy storage battery.

6. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 4, characterized in that: When the output of the PI controller with limiting anti-saturation reaches the limiting value, the PI controller enters the anti-saturation mechanism, and the integral operation of the PI controller stops until the output returns to within the limiting range and then the integral operation is resumed.

7. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1, characterized in that: The output current instruction of the short-time energy storage battery is tracked by a current inner loop PI controller after being limited.

8. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1, characterized in that: The output current instruction of the long-term energy storage battery after the limit is tracked by the current inner loop PI controller.

9. The self-coordinated grid-type multi-time-scale hybrid energy storage system according to claim 1, characterized in that: The output distribution of the supercapacitor, the short-term energy storage battery and the long-term energy storage battery is achieved through automatic coordinated control of the DC bus voltage.

10. An automatically coordinated network-type multi-time scale hybrid energy storage method, characterized in that: The method is carried out based on the automatically coordinated grid-type multi-time-scale hybrid energy storage system according to any one of claims 1 to 9, and the method comprises the following steps: S1, adjust the phase of the AC side output voltage according to the DC bus voltage through the inverter; S2. Generate an output current command for the short-term energy storage battery according to the DC bus voltage through a first DC / DC converter and limit the output current command, and track the output current command of the short-term energy storage battery after the limit through a current inner loop PI controller; S3. Input the filtered DC bus voltage difference into a PI controller with amplitude limiting and anti-saturation through a second DC / DC converter to generate an output current command of the long-term energy storage battery after amplitude limiting, and track the output current command of the long-term energy storage battery through a current inner loop PI controller.

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