Flywheel energy storage UPS system and method using split transformer

Abstract

The invention relates to a flywheel energy storage UPS system and method using a split transformer, and the system comprises a standby generator set which is disposed at a power supply end and is connected in parallel with a commercial power supply end, and when the commercial power is abnormal, the standby generator set can serve as a power supply to supply power to a load; one end of the switch control assembly is connected with the commercial power and the standby generator set, the other end of the switch control assembly is connected with a load, and the commercial power, the standby generator set and the load can be connected or disconnected; the output end of the flywheel energy storage device is connected to a power supply line between the switch control assembly and the load and can serve as a power source to supply power to the load. The number of the flywheel energy storage devices is more than two, and the more than two flywheel energy storage devices are connected to a power supply line through the split transformer. Compared with a traditional on-line low-voltage UPS system, the on-line low-voltage UPS system has the advantages that by using the backup flywheel energy storage device and the split transformer, the operation efficiency is as high as 99%, and the system loss is greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of physical energy storage technology, and in particular to a flywheel energy storage UPS system and method using a split transformer. Background Art

[0002] The flywheel dynamic UPS system is mainly composed of diesel generator sets, static switches / fast switches (HSS, High Speed ​​Switch), reactors, bidirectional converters, flywheel energy storage systems, distribution systems and control systems. The general flywheel dynamic UPS system has a major defect, that is, as the capacity of the flywheel unit increases and the grid voltage level increases, the corresponding PCS performance requirements are also higher. Most of the flywheel energy storage systems on the market are low-voltage flywheel energy storage systems. During the grid connection process, a single flywheel is connected to a transformer, which is very costly. Especially for large-scale cluster applications, this connection method will increase the cost even more. Summary of the invention

[0003] In view of this, the present application proposes a flywheel energy storage UPS system using a split transformer to solve the problems embodied in the above-mentioned background technology.

[0004] According to one aspect of the present application, there is provided a flywheel energy storage UPS system using a split transformer, characterized in that a backup generator set, a switch control assembly, a flywheel energy storage device and a split transformer;

[0005] The standby generator set is arranged at the power supply end and connected in parallel with the mains power supply end. When the mains power is abnormal, the standby generator set can be used as a power source to supply power to the load;

[0006] One end of the switch control component is connected to the mains and the standby generator set, and the other end is connected to the load, and can connect or disconnect the mains, the standby generator set and the load;

[0007] The output end of the flywheel energy storage device is connected to the power supply line between the switch control component and the load, and can be used as a power source to supply power to the load; and

[0008] There are more than two flywheel energy storage devices, and the more than two flywheel energy storage devices are connected to the power supply line through one split transformer.

[0009] As an optional implementation scheme of the present application, optionally, the switch control component is composed of a first switch, a static switch and an inductor, the left end of the first switch is connected to the AC power and the standby generator set, and the right end of the inductor is connected to the load.

[0010] As an optional implementation scheme of the present application, optionally, the flywheel energy storage device includes a flywheel device, a machine-side converter, a grid-side converter and a second switch connected in sequence, and the output end of the grid-side converter is connected to the power supply line between the switch control component and the load.

[0011] As an optional implementation scheme of the present application, optionally, the left end of the split transformer is connected to a flywheel energy storage device, and the right end is connected to a power supply line.

[0012] As an optional implementation scheme of the present application, optionally, the standby generator set is a diesel generator set, and the diesel generator set is arranged in parallel with the mains power supply end at the power supply end, and when the mains power is abnormal, the diesel generator set supplies power to the load.

[0013] According to the second aspect of the present application, a control method for a flywheel energy storage UPS system is provided, characterized in that the system power supply control is performed using the system of claims 1-5, including:

[0014] Real-time monitoring of the city power supply;

[0015] When the mains power supply is detected to be abnormal, the flywheel energy storage device is used to assist in powering the load to ensure that the load voltage is stable.

[0016] As an optional implementation scheme of the present application, optionally, when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, including:

[0017] When the mains power outage is detected, the flywheel energy storage UPS system sends a start command to the standby engine group, waits for its power supply voltage to be normal and the flywheel energy storage device is in phase with the standby engine group, and then connects to the standby engine group;

[0018] When it is detected that the mains power is restored, the flywheel energy storage device is connected to the mains power after the phase is synchronized with the mains power side.

[0019] As an optional implementation scheme of the present application, optionally, when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, and further includes:

[0020] When a temporary drop in the city voltage is detected, the flywheel energy storage UPS system supports the load voltage in a very short time;

[0021] When it is detected that the mains voltage has temporarily dropped and recovered, the flywheel energy storage UPS system quickly synchronizes with the mains phase and restores the mains power supply.

[0022] As an optional implementation scheme of the present application, optionally, when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, and further includes:

[0023] When the mains power supply is abnormal, the static switch is immediately turned off and the power supply mode is switched from PQ mode to VF mode;

[0024] When the AC power supply is abnormal, the abnormal situation is determined based on the recovery of the grid-side voltage 10ms to 20ms later.

[0025] As an optional implementation scheme of the present application, optionally, when there is no abnormality in the real-time monitoring of the mains power supply, the flywheel energy storage UPS system will adjust the flywheel output and compensate for the load harmonics according to the output voltage value of the voltage detection point increased on the load side.

[0026] Beneficial effects of this application:

[0027] The present invention adopts a flywheel physical energy storage method, which is more environmentally friendly, safer and more reliable than traditional chemical battery energy storage. Compared with the general flywheel energy storage UPS system, it uses a split transformer to connect multiple flywheel systems, which makes the cost of this system lower in the process of large-scale cluster applications. The energy storage device of this system is backup type, and compared with the traditional online low-voltage UPS system, the operating efficiency is as high as 99%, which greatly reduces the system loss. The response time of this system to complete "event detection + switching + compensation" can reach ≤10ms. The reactor in this system can effectively suppress short-circuit current and prevent the power supply circuit breaker from tripping before the load side circuit breaker. Under normal mains power supply mode, the flywheel energy storage device in this system is in standby state, which will not reduce the load voltage quality, and can also compensate for load harmonics to ensure the stability of load side voltage. The topology of this system can be applied to a variety of voltages, including 0.4kV / 0.69kV low-voltage systems and 6kV / 10kV / 20kV medium-voltage systems. Compared with other UPS systems, it has a wider range of uses and can be used on the load side as well as the grid side. Based on the topology of this system, the system can be modularized and has a large parallel capacity. A single system can reach 2MW, and each 2MW can be connected in parallel. Currently, the medium-voltage system can reach 16MW.

[0028] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the present application and, together with the description, serve to explain the principles of the present application.

[0030] Figure 1 A system topology diagram of a flywheel energy storage UPS system using a split transformer according to an embodiment of the present application is shown;

[0031] Figure 2 A flow chart showing a control method of a flywheel energy storage UPS system according to an embodiment of the present application; DETAILED DESCRIPTION

[0032] Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0033] Among them, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application or simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] In addition, in order to better illustrate the present application, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0037] Example 1

[0038] Figure 1 The system topology diagram of the flywheel energy storage UPS system using a split transformer according to the first embodiment of the present application is shown. Figure 1As shown, the system topology is characterized by a backup generator set, a switch control assembly, a flywheel energy storage device and a split transformer;

[0039] The standby generator set is arranged at the power supply end and connected in parallel with the mains power supply end. When the mains power is abnormal, the standby generator set can be used as a power source to supply power to the load;

[0040] In this embodiment, the standby generator set can be a diesel engine set, which is arranged at the power supply end in parallel with the power grid supplied by the AC power supply, and an ATS (Automatic Transfer Switch) automatic transfer switch is used to realize power switching when the AC power is abnormal. When the AC power is cut off, the standby generator set replaces the AC power to supply power to the load.

[0041] One end of the switch control component is connected to the mains and the standby generator set, and the other end is connected to the load, and can connect or disconnect the mains, the standby generator set and the load;

[0042] In this embodiment, the left end of the switch control component is connected to the mains power and the backup generator set, and the right end is connected to the load. When the mains power is stably supplied, the switch control component connects the mains power and the load, and the mains power supplies power to the load. When the mains power is abnormal, the switch control component will cut off the connection with the mains power and connect the backup generator set, and use the backup generator set to power the load until the mains power supply resumes normal.

[0043] The output end of the flywheel energy storage device is connected to the power supply line between the switch control component and the load, and can be used as a power source to supply power to the load; and

[0044] There are more than two flywheel energy storage devices, and the more than two flywheel energy storage devices are connected to the power supply line through one split transformer.

[0045] In this embodiment, the output end of the flywheel energy storage device is connected to the right end of the switch control assembly and the left end of the load, and the flywheel energy storage device can be used as a backup power supply to supply power to the load. There are more than two flywheel energy storage devices, and up to eight flywheel energy storage devices can be connected in parallel to one split transformer, and connected to the power supply circuit through the split transformer.

[0046] As an optional implementation scheme of the present application, optionally, the switch control component is composed of a first switch, a static switch and an inductor, the left end of the first switch is connected to the AC power and the standby generator set, and the right end of the inductor is connected to the load.

[0047] In this embodiment, the switch control assembly is used to connect or disconnect the mains power and the standby generator set with the load. The reactor of the switch control assembly can effectively suppress the short-circuit current and prevent the power supply side circuit breaker from tripping before the load side circuit breaker. The left end of the first switch of the switch control assembly is connected to the mains power and the standby generator set, and the right end of the reactor is connected to the load, so as to realize the connection between the power supply side and the load side.

[0048] As an optional implementation scheme of the present application, optionally, the flywheel energy storage device includes a flywheel device, a machine-side converter, a grid-side converter and a second switch connected in sequence, and the output end of the grid-side converter is connected to the power supply line between the switch control component and the load.

[0049] In this embodiment, the number of the flywheel energy storage devices of the flywheel energy storage UPS system is at most eight and at least two, and each of the flywheel energy storage devices includes a flywheel device, a machine-side converter, a grid-side converter and a second switch connected in sequence, the machine-side converter in the flywheel energy storage device is responsible for converting the rotational motion of the flywheel into electrical energy and storing it, the grid-side converter is used to convert electrical energy into AC electrical energy, and the output end of the grid-side converter is connected to the power supply line between the switch control component and the load, thereby realizing the connection with the mains and the load.

[0050] As an optional implementation scheme of the present application, optionally, the left end of the split transformer is connected to a flywheel energy storage device, and the right end is connected to a power supply line.

[0051] In this embodiment, the split transformer is a special type of transformer having two or more independent windings, each of which can output electrical energy independently. The left end of the split transformer is connected to a plurality of the flywheel energy storage devices, and the right end is connected to the line between the switch control assembly position and the load position, which can realize efficient conversion and matching of electrical energy of the flywheel energy storage UPS system, improve energy conversion efficiency, and protect the safe and stable operation of the flywheel energy storage UPS system.

[0052] As an optional implementation scheme of the present application, optionally, the standby generator set is a diesel generator set, and the diesel generator set is arranged in parallel with the mains power supply end at the power supply end, and when the mains power is abnormal, the diesel generator set supplies power to the load.

[0053] In this embodiment, the standby generator set is a diesel generator set, which serves as a backup power source. An ATS (Automatic Transfer Switch) automatic transfer switch is connected to the right side of the diesel generator set, which is connected in parallel with the mains power supply and the ATS on its right side. When the mains power is cut off, it is used to quickly cut off the mains power supply and connect the diesel generator set to power the load.

[0054] Example 2

[0055] Figure 2 FIG. 1 is a flow chart showing a control method of a flywheel energy storage UPS system according to Embodiment 2 of the present application. Figure 2 As shown, the flow chart includes:

[0056] S100, real-time monitoring of the city power supply;

[0057] In this embodiment, the control method of the flywheel energy storage UPS system will monitor the mains power supply in real time. Once the mains power supply is abnormal, the control method of the flywheel energy storage UPS system will respond quickly to the abnormal situation.

[0058] S200: When the mains power supply is detected to be abnormal, the flywheel energy storage device is used to assist in powering the load to ensure a stable load voltage.

[0059] In this embodiment, when the control method of the flywheel energy storage UPS system detects that the mains power supply is abnormal, the static switch will be immediately turned off and switched to the VF (voltage and frequency mode) constant frequency mode, and the flywheel energy storage device will be used to assist in powering the load to ensure the stability of the load voltage.

[0060] As an optional implementation scheme of the present application, optionally, when the AC power supply abnormality is monitored, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, including: when the AC power outage is monitored, the flywheel energy storage UPS system sends a start command to the standby engine group, waits for its power supply voltage to be normal and the flywheel energy storage device is phase-synchronized with the standby engine group side, and then connects to the standby engine group; when the AC power is monitored to be restored, the flywheel energy storage device is phase-synchronized with the AC power side and then connected to the AC power.

[0061] In this implementation scheme, after the flywheel energy storage UPS system detects a power outage in the city power supply, the flywheel energy storage UPS system will immediately send a start command to the standby generator set, and at the same time, the ATS (automatic switching switch) will switch to the standby generator set side. When the voltage on the grid side (standby generator set side) is detected to be normal, the flywheel energy storage device will achieve phase synchronization with the grid side. After the synchronization is completed, the static switch will be triggered to close, and the standby generator set will be connected to achieve uninterrupted switching from the city power supply to the standby generator set. When the city power supply is restored, the flywheel energy storage UPS system will also immediately turn off the static switch, switch to VF mode, and switch the ATS to the city power side. After completing the synchronization with the city power supply, the static switch will be triggered to close, and the city power will be connected to complete the uninterrupted switching from the standby generator set to the city power supply, thereby ensuring the stability of the load-side power supply.

[0062] As an optional implementation scheme of the present application, optionally, when an abnormality in the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure a stable load voltage, and also includes: when a temporary drop in the mains voltage is detected, the flywheel energy storage UPS system supports the load voltage in a very short time; when the mains voltage is detected to be restored after a temporary drop, the flywheel energy storage UPS system quickly synchronizes with the mains phase and restores the mains power supply.

[0063] In this embodiment, the voltage sag is also called voltage drop, voltage sag, voltage sag and power shake in China, which refers to the sudden drop of the effective value of voltage and then quickly returns to normal. The IEEE standard defines voltage sag as: a sudden drop in the effective value of voltage, lasting from half a cycle to 1 minute, measured in percentage of residual voltage. According to authoritative data from EPRI (Electrical Research Institute of the United States), more than 92% of power quality events are voltage sags and swells, and other power quality events account for less than 8%, which is the most common power quality problem in the industrial field. The flywheel energy storage UPS system can achieve that when a voltage sag occurs, the flywheel energy storage device supports the load voltage within 10ms, and when the sag is restored, it quickly synchronizes with the mains phase and restores the mains power supply, ensuring that the load will not be affected by the voltage sag. When the mains power is cut off, the flywheel energy storage UPS system will immediately turn off the static switch and switch to the VF (voltage and frequency mode) constant frequency mode. After 10ms to 20ms, it will be determined whether the grid-side voltage of the mains power has recovered. If it has recovered, it will be determined as a voltage sag. The flywheel energy storage UPS system will quickly achieve phase synchronization with the power grid, trigger the static switch to close, and connect to the mains power.

[0064] As an optional implementation scheme of the present application, optionally, when the AC power supply is monitored to be abnormal, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, and also includes: when the AC power supply is abnormal, the static switch is immediately turned off, and the power supply mode is switched from the PQ (power and quality mode) mode to the VF (voltage and frequency mode) constant frequency mode; when the AC power supply is abnormal, the abnormal situation is determined according to the recovery of the grid-side voltage 10ms to 20ms after the AC power supply is abnormal.

[0065] In this embodiment, when the mains power is cut off, the flywheel energy storage UPS system will react immediately to protect the load from being affected. When the mains power is cut off, the flywheel energy storage UPS system immediately turns off the static switch, and the working mode is switched from PQ mode to VF (voltage and frequency mode) constant frequency mode. According to the actual needs of the load, the output voltage and frequency are adjusted to ensure that the load can work normally. And after the mains power supply is abnormal for 10ms to 20ms, it is determined whether the market power outage is true based on whether the grid-side voltage is restored. The flywheel energy storage UPS system continuously monitors the grid-side voltage of the mains power supply 10ms to 20ms after the mains power outage occurs, and determines whether the grid-side voltage of the mains power supply is restored. If the grid-side voltage of the mains power supply is restored, it is immediately determined that this situation is a voltage sag and is handled according to the voltage sag. If the grid-side voltage has not been restored for a long time, it will be determined that this situation is a mains power outage and handled.

[0066] As an optional implementation scheme of the present application, optionally, when there is no abnormality in the real-time monitoring of the mains power supply, the flywheel energy storage UPS system will adjust the flywheel output and compensate for the load harmonics according to the output voltage value of the voltage detection point increased on the load side.

[0067] In this embodiment, when the flywheel energy storage UPS system is stably powered by city electricity or diesel generator, the flywheel energy storage UPS system is adjusted to PQ mode to work. First, one or more voltage detection points need to be set on the load side, and these detection points can monitor the voltage conditions on the load side in real time. When voltage fluctuations or instability are detected, the flywheel energy storage UPS system will immediately respond according to the output voltage value. Next, by adjusting the output of the flywheel, that is, the rate at which the flywheel energy storage system releases or absorbs energy, the voltage can be accurately regulated. At the same time, in order to further improve the stability of the voltage, it is also necessary to compensate for the harmonics generated by the load to ensure the stability and control of the voltage on the load side.

[0068] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A flywheel energy storage UPS system using a split transformer, characterized in that: Standby generator sets, switch control components, flywheel energy storage devices and split transformers; The standby generator set is arranged at the power supply end and connected in parallel with the mains power supply end. When the mains power is abnormal, the standby generator set can be used as a power source to supply power to the load; One end of the switch control component is connected to the mains and the standby generator set, and the other end is connected to the load, and can connect or disconnect the mains, the standby generator set and the load; The output end of the flywheel energy storage device is connected to the power supply line between the switch control component and the load, and can be used as a power source to supply power to the load; and There are more than two flywheel energy storage devices, and the more than two flywheel energy storage devices are connected to the power supply line through one split transformer.

2. The flywheel energy storage UPS system using a split transformer as claimed in claim 1, characterized in that: The switch control assembly consists of a first switch, a static switch and a reactor. The left end of the first switch is connected to the mains and the standby generator set, and the right end of the reactor is connected to the load.

3. The flywheel energy storage UPS system using a split transformer as claimed in claim 1, characterized in that: The flywheel energy storage device comprises a flywheel device, a machine-side converter, a grid-side converter and a second switch which are connected in sequence, and the output end of the grid-side converter is connected to the power supply line between the switch control component and the load.

4. The flywheel energy storage UPS system using a split transformer as claimed in claim 1, characterized in that: The left end of the split transformer is connected to the flywheel energy storage device, and the right end is connected to the power supply line.

5. The flywheel energy storage UPS system using a split transformer as claimed in claim 1, characterized in that: The standby generator set is a diesel generator set, which is arranged in parallel with the mains power supply end at the power supply end, and when the mains power is abnormal, the diesel generator set supplies power to the load.

6. A control method for a flywheel energy storage UPS system, characterized in that: Using the system of claims 1-5 to control system power supply, comprising: Real-time monitoring of the city power supply; When the mains power supply is detected to be abnormal, the flywheel energy storage device is used to assist in powering the load to ensure that the load voltage is stable.

7. The control method of the flywheel energy storage UPS system according to claim 6, wherein when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, comprising: When the mains power outage is detected, the flywheel energy storage UPS system sends a start command to the standby engine group, waits for its power supply voltage to be normal and the flywheel energy storage device is in phase with the standby engine group, and then connects to the standby engine group; When it is detected that the mains power is restored, the flywheel energy storage device is connected to the mains power after the phase is synchronized with the mains power side.

8. The control method of the flywheel energy storage UPS system according to claim 6, wherein when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, comprising: When a temporary drop in the city voltage is detected, the flywheel energy storage UPS system supports the load voltage in a very short time; When it is detected that the mains voltage has temporarily dropped and recovered, the flywheel energy storage UPS system quickly synchronizes with the mains phase and restores the mains power supply.

9. The control method of the flywheel energy storage UPS system according to claim 6, wherein when the abnormality of the mains power supply is detected, the flywheel energy storage device is used to assist in powering the load to ensure the stability of the load voltage, and further comprises: When the mains power supply is abnormal, the static switch is immediately turned off and the power supply mode is switched from PQ mode to VF mode; When the AC power supply is abnormal, the abnormal situation is determined based on the recovery of the grid-side voltage 10ms to 20ms later.

10. The control method of a flywheel energy storage UPS system as claimed in claim 6, wherein when there is no abnormality in the real-time monitoring of the mains power supply, the flywheel energy storage UPS system adjusts the flywheel output and compensates for the load harmonics according to the output voltage value of the voltage detection point added on the load side.

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