Flywheel array uninterruptible power supply control method

Abstract

The invention discloses a flywheel array uninterruptible power supply control method, and relates to the technical field of energy storage, the flywheel array uninterruptible power supply control method comprises the following steps: 1, uninterruptible power supply working principle, the main function of the online uninterruptible power supply (UPS) is to ensure that a connected device can still obtain a stable and high-quality power supply when the mains supply is abnormal, and the working process of the UPS is as follows: the UPS firstly receives alternating current from the mains supply, and the quality of the alternating current is generally low due to the interference or fluctuation of a power grid; alternating currents are firstly purified through a distillation filter in the UPS to remove clutters and noise in the currents, the filtered alternating currents are converted into direct currents, the adopted DSP control system can achieve high control precision while the requirement for the model precision is low, and therefore the requirement for the computer processing capacity is effectively reduced, and the reliability of the system is improved. And the cost investment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage, and in particular to a flywheel array uninterruptible power supply control method. Background Art

[0002] The world is facing a severe energy crisis. With the rapid increase in the global population, traditional energy resources are becoming increasingly scarce. The damage and pollution to the environment during their mining and use have reached a worrying level, and this damage is often irreversible. According to IDC data analysis, the cost of electricity has risen to become the biggest challenge facing data center operators. In particular, the power consumption of equipment such as UPS (uninterruptible power supply system) and air conditioners far exceeds the power consumption of the server itself. In addition, traditional acid lead batteries are not environmentally friendly and have potential fire and explosion hazards. In order to cope with these problems, intelligent green UPS systems equipped with efficient and environmentally friendly equipment have become the core of data center energy conservation and emission reduction strategies. Traditional battery power systems require continuous air conditioning cooling, operate 24 hours a day, and consume a lot of energy. In contrast, UPS systems based on flywheel energy storage do not require air conditioning cooling, which greatly reduces operating costs. This system not only takes up less space and has low maintenance costs, but also does not require frequent battery replacement and has a service life of up to 20 years. Due to its high safety, good economic benefits and environmental protection characteristics, UPS technology based on flywheel energy storage is gradually becoming the first choice for data centers and is expected to be more widely used in the future.

[0003] Uninterruptible Power Supply System (UPS) is a storage power supply device that can provide electric energy continuously, stably and uninterruptedly. It has a wide range of applications. It is a power electronic device that can provide continuous, stable and uninterrupted power supply and is used in many fields.

[0004] At present, pulse width modulation based on the area equivalent principle is often used to control the power supply, but high-frequency regulated switching devices will cause battery interference, and the life of the switch also greatly limits the practicality of this control method. Fuzzy control is also a common power supply control method on the market. Its performance is highly dependent on the quality of fuzzy sets and fuzzy rules. Fuzzy rules must be carefully planned and optimized to achieve the desired goals; delay control is simple to implement and low in cost, but its accuracy is low. In UPS equipment, the slow response and accuracy of the delay strategy are difficult to meet the requirements. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a flywheel array uninterruptible power supply control method that can solve the problems of the background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a flywheel array uninterruptible power supply control method, comprising the following steps:

[0007] Step 1: Working principle of uninterruptible power supply. The main function of online uninterruptible power supply (UPS) is to ensure that the connected devices can still obtain stable and high-quality power supply when the mains power supply is abnormal. The working process of UPS is as follows: UPS first receives AC power from the mains. Usually, the power quality may be low due to grid interference or fluctuations. This AC power is first purified by the distillation filter inside the UPS to remove clutter and noise in the current. The filtered AC power is converted into DC power;

[0008] Step 2: System design, including TMS320F2812 device introduction, system hardware design, DSP software setting, reference sinusoidal signal generation and synchronization, output voltage RMS adjustment, master-slave-free adaptive parallel control strategy, and experimental results.

[0009] Preferably, the second step: TMS320F2812 device introduction, TMS320F2812 DSP is a 32-bit high-performance digital signal processor with a maximum processing frequency of 150MHz. This processor is praised for its fast processing capability, high accuracy and numerous built-in functions. It has two built-in event management modules (EVA and EVB) and an analog-to-digital conversion (ADC) module.

[0010] Preferably, the second step: system hardware design, connecting the TMS320F2812 DSP controller to the UPS system. Usually, the UPS system adopts a bridge transformer circuit, through the sinusoidal pulse width modulation (SPWM), the principle of which is to compare the feedback voltage with the reference sinusoidal wave voltage, and generate a switch control signal to control the on and off of each bridge arm IGBT, so that the output voltage waveform is close to the given voltage waveform.

[0011] Preferably, the second step: DSP software setting, the system's software control process, improves the control effect by adding interrupt processing, and the main program will continuously process interrupt tasks during execution.

[0012] Preferably, the second step: generation and synchronization of reference sine wave signal, the generation of reference sine wave signal usually adopts the table lookup timing generation technology, this method generates sine wave signal at a frequency of 50Hz, divides a complete cycle into 192 equal parts, calculates and records the sine value of each point, and saves it in a data structure called reference sine table. The system reads a data point from the table every 1 / 192 cycle and performs necessary processing. Since DSP only supports unipolar input of 0 to 5V, the generated reference sine table is also unipolar. When the power grid is operating normally, the inverter will work synchronously with the power grid. If the power grid is abnormal, the built-in timer of DSP will generate a reference frequency of 50Hz, guide the inverter to operate according to this frequency, effectively alleviate the impact on the load that may be caused during the switching process from the mains to the inverter, and ensure the stability and safety of the UPS system.

[0013] Preferably, the second step: output voltage effective value adjustment, adding an output voltage effective value adjustment link can ensure that the inverter outputs a voltage within an acceptable fluctuation range when the load or mains power is unstable. The specific implementation method is: take 1 / 192 mains power cycle as the sampling period, sample the output voltage of the inverter, and convert the sampled voltage into a voltage of 0 to 5V and input it into the A / D conversion channel of the DSP. After analog-to-digital conversion, read the conversion value and calculate its square sum, and add it to the square sum of the previous data point to calculate the effective value of the output voltage.

[0014] Preferably, the second step: a master-slave-free adaptive parallel control strategy, the master-slave-free adaptive parallel control is intended to achieve coordinated control and performance optimization between multiple flywheel energy storage devices when the flywheel energy storage array generates electricity, and to achieve adaptive control through information sharing and mutual cooperation between the flywheel energy storage devices to ensure stable power output of the UPS system.

[0015] Preferably, the second step: non-master-slave adaptive parallel control strategy, including non-master-slave parallel framework and adaptive control strategy, the non-master-slave parallel grid-connected battery energy storage system introduced in this paper, in which multiple energy storage devices (UB1, UB2, ..., UBn) are combined in parallel through the conversion link to form a large-capacity system, and finally connected to the power grid, all the conversion units in the system are consistent in power and control circuit design, according to the specific working mode, the control unit of each converter will adjust the corresponding operating state, so that the entire energy storage system can be in grid-connected operation or as an emergency power supply and other different states of stable operation; adaptive control is a technology that can automatically adjust the system control parameters according to changes in the external environment, aiming to enable the control system to adapt to changes in the outside world and maintain the optimal state on a certain performance indicator. By combining traditional PI control with adaptive control to form adaptive PI control, the dynamic performance of the system is significantly improved. The system in this paper adopts a dual closed-loop PI controller of current and voltage as the core, and adjusts its parameters by adding an adaptive mechanism in front of the PI controller, so as to achieve more precise control.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The flywheel array uninterruptible power supply control method adopts a DSP control system that can achieve higher control accuracy while requiring lower model accuracy, thereby effectively reducing the demand for computer processing power and reducing cost investment.

[0018] (2) The flywheel array uninterruptible power supply control method adopts a master-slave parallel-free design architecture to enhance the overall reliability of the system. Even if a single flywheel unit fails, it will not affect the normal operation of the entire UPS system.

[0019] (3) The flywheel array uninterruptible power supply control method, the adaptive control can automatically adjust the gain setting of the regulator according to the changes in the working environment and operating conditions by real-time monitoring and analysis of system status indicators, thereby ensuring that the system operates according to the established performance standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0021] Figure 1 This is a structural block diagram of the uninterruptible power supply of the present invention;

[0022] Figure 2 This is the inverter system control diagram of the present invention;

[0023] Figure 3 This is a connection diagram between DPS and UPS of the present invention;

[0024] Figure 4 This is a flow chart of DSP controlling UPS uninterruptible power supply of the present invention;

[0025] Figure 5 The energy storage system of the present invention has no master-slave parallel framework;

[0026] Figure 6 This is the adaptive control block diagram of the present invention;

[0027] Figure 7 This is a gain adaptive structure diagram of the present invention;

[0028] Figure 8 This is a model diagram of the flywheel energy storage system of the present invention;

[0029] Fig. 9 It is the phase current waveform diagram of the system of the present invention;

[0030] Fig.10 This is a waveform diagram of the system output under step disturbance of the present invention. DETAILED DESCRIPTION

[0031] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0032] See also Figure 1-10 The present invention provides a technical solution: a flywheel array uninterruptible power supply control method, comprising the following steps:

[0033] Step 1: How does an uninterruptible power supply work?

[0034] The main function of an online uninterruptible power supply (UPS) is to ensure that connected devices can still obtain stable and high-quality power when the mains power supply is abnormal. The working process of UPS is as follows: UPS first receives AC power from the mains, which is usually of low quality due to grid interference or fluctuations. This AC power is first purified by the distillation filter inside the UPS to remove clutter and noise in the current. The filtered AC power is converted into DC power. This step is usually completed by a rectifier, which converts the AC power into DC power for the next step of processing. The DC power is then fed into the inverter. In the inverter, the DC power is converted into higher-quality sinusoidal AC power using sinusoidal pulse width modulation (SPWM) technology. This technology ensures that the output AC power has high purity and stability, which is suitable for sensitive equipment. When the mains power is normally supplied, the UPS not only provides power conversion, but also charges the internal battery or other energy storage devices to ensure that there is enough reserve power available when the mains power is interrupted. Once the mains power supply is interrupted or there is a problem, the energy storage system in the UPS immediately intervenes to provide the necessary DC power to the inverter to maintain the operation of the inverter. In this way, the inverter can continue to provide uninterrupted, stable sine wave AC power to the external load. During the whole process, the UPS ensures that all connected devices such as computer systems, medical equipment or other critical equipment will not be interrupted due to power problems, thereby protecting these devices from damage caused by power problems.

[0035] Step 2: System Design

[0036] 1. TMS320F2812 device introduction

[0037] The TMS320F2812 DSP is a 32-bit high-performance digital signal processor with a maximum processing frequency of 150MHz. This processor is praised for its fast processing power, high accuracy and numerous built-in functions. It has two built-in event management modules (EVA and EVB) and an analog-to-digital conversion (ADC) module. In these event management modules, two general-purpose timers that are widely used for event time control and sampling are usually included, and the timing comparison functions of these timers can be independently controlled by specific preset targets. In addition, its ADC module has a 12-bit resolution and provides 16 analog input channels, which can be set as two independent 8-channel modules. It is particularly noteworthy that the TMS320F2812 is also equipped with 12 pulse width modulation (PWM) channels, which can generate control waveforms for UPS uninterruptible power supplies, demonstrating its excellent ability as a core control unit.

[0038] 2. System hardware design

[0039] Connect the TMS320F2812 DSP controller to the UPS system. Usually the UPS system uses a bridge transformer circuit. The circuit diagram is as follows: Figure 2 As shown. Through the sinusoidal pulse width modulation (SPWM), the principle is to compare the feedback voltage with the reference sinusoidal voltage, generate a switch control signal to control the on and off of each bridge arm IGBT, so that the output voltage waveform is close to the given voltage waveform.

[0040] System hardware connection Figure 3 As shown in the figure, the 2812DSP samples the output filtered voltage VO and current IO through two ADC channels (ADC2 / 13 and ADC4 / 15). At the same time, the initial voltage and current are sampled through the ADC3 / 14 channel. By comparing the deviations of these sampled values, the system uses the PID control algorithm to adjust and generate switching signals. These signals control the inverter through the driver to make the output voltage waveform as close to the preset voltage waveform as possible. In addition, the figure also shows the process of 2812DSP sampling the rectified DC voltage and battery power. When the AC input fails, the system will switch to battery power to provide a stable DC power supply for the inverter and ensure the stability of the AC output.

[0041] 2. DSP software settings

[0042] The system's software control process is as follows Figure 4 As shown in the figure, the control effect is improved by adding interrupt processing. The main program will continuously process interrupt tasks during execution.

[0043] 3. Generation and synchronization of reference sinusoidal signals

[0044] The table lookup timing generation technology is usually used to generate the reference sine wave signal. This method generates a sine wave signal at a frequency of 50Hz, divides a complete cycle into 192 equal parts, calculates and records the sine value of each point, and saves it in a data structure called a reference sine table. The system reads a data point from the table every 1 / 192 cycle and performs necessary processing. Since the DSP only supports unipolar inputs of 0 to 5V, the generated reference sine table is also unipolar. When the power grid is operating normally, the inverter will work synchronously with the power grid. If the power grid is abnormal, the built-in timer of the DSP will generate a reference frequency of 50Hz, guiding the inverter to operate at this frequency, effectively alleviating the impact on the load that may be caused during the switching process from the mains to the inverter, and ensuring the stability and safety of the UPS system.

[0045] 4. Output voltage effective value adjustment

[0046] Adding the output voltage effective value adjustment link can ensure that the inverter outputs a voltage within an acceptable fluctuation range when the load or mains power is unstable. The specific implementation method is: take 1 / 192 mains power cycle as the sampling period, sample the inverter output voltage, and convert the sampled voltage into a voltage of 0~5V and input it into the DSP's A / D conversion channel. After analog-to-digital conversion, read the conversion value and calculate its square sum, and add it to the square sum of the previous data point to calculate the effective value of the output voltage. That is:

[0047]

[0048] Where U i is the final output voltage sampling value of the inverter, and U is the effective value of the output voltage.

[0049] 5. No master-slave adaptive parallel control strategy

[0050] The master-slave-free adaptive parallel control is designed to achieve coordinated control and performance optimization between multiple flywheel energy storage devices when the flywheel energy storage array generates electricity. Adaptive control is achieved through information sharing and mutual cooperation between flywheel energy storage devices to ensure stable power output of the UPS system.

[0051] 6.1 No master-slave parallel framework

[0052] The master-slave-free parallel grid-connected battery energy storage system introduced in this article is as follows Figure 5 In this system, multiple energy storage devices (UB1, UB2, ..., UBn) are combined in parallel through the conversion link to form a large-capacity system, which is finally connected to the power grid. All the conversion units in the system are consistent in power and control circuit design. According to the specific working mode, the control unit of each converter will adjust the corresponding operating state, so that the entire energy storage system can work stably in different states such as grid-connected operation or as an emergency power supply.

[0053] 6.2 Adaptive Control Strategy

[0054] Adaptive control is a technology that can automatically adjust system control parameters according to changes in the external environment. It aims to enable the control system to adapt to changes in the outside world and maintain the optimal state of a certain performance indicator. By combining traditional PI control with adaptive control to form adaptive PI control, the dynamic performance of the system is significantly improved. The system in this article uses a dual closed-loop PI controller of current and voltage as the core, and adjusts its parameters by adding an adaptive mechanism in front of the PI controller to achieve more precise control. The connection block diagram of the system is shown in Figure 6 middle.

[0055] The system adopts variable gain control in adaptive control system, and the control structure is as follows Figure 7 shown.

[0056] 6. Experimental results

[0057] According to the control strategy proposed above, with the TMS320F2812 DSP controller, the QFFL600 / 300 flywheel energy storage unit is selected, which has good power characteristics, fast dynamic response, discharge depth of up to 75%, efficiency of more than 85%, and operating life is not limited by the number of charge and discharge times. A simulation experimental platform is built, and the simulation model on the Simulink software is as follows: Figure 8 shown.

[0058] Fig. 9 Represents the output phase current waveform of the overall system. The experimental results show that the output current waveform is a sine wave.

[0059] After 2s and 5s of simulation, the system is switched from no-load operation to load operation. The results are as follows: Fig.10 As shown, the system has good anti-interference ability.

[0060] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A flywheel array uninterruptible power supply control method, characterized in that: The following steps are involved: Step 1: Working principle of uninterruptible power supply. The main function of online uninterruptible power supply (UPS) is to ensure that the connected devices can still obtain stable and high-quality power supply when the mains power supply is abnormal. The working process of UPS is as follows: UPS first receives AC power from the mains. Usually, the power quality may be low due to grid interference or fluctuations. This AC power is first purified by the distillation filter inside the UPS to remove clutter and noise in the current. The filtered AC power is converted into DC power; Step 2: System design, including TMS320F2812 device introduction, system hardware design, DSP software setting, reference sinusoidal signal generation and synchronization, output voltage RMS adjustment, master-slave-free adaptive parallel control strategy, and experimental results.

2. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: TMS320F2812 device introduction, TMS320F2812 DSP is a 32-bit high-performance digital signal processor with a maximum processing frequency of 150MHz. This processor is praised for its fast processing capability, high accuracy and numerous built-in functions. It has two built-in event management modules (EVA and EVB) and an analog-to-digital conversion (ADC) module.

3. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: system hardware design, connects the TMS320F2812 DSP controller to the UPS system. Usually the UPS system adopts a bridge transformer circuit, through the sinusoidal pulse width modulation (SPWM), the principle of which is to compare the feedback voltage with the reference sinusoidal wave voltage, generate a switch control signal to control the on and off of each bridge arm IGBT, so that the output voltage waveform is close to the given voltage waveform.

4. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: DSP software setting, the system's software control process, improves the control effect by adding interrupt processing. The main program will continuously process interrupt tasks during execution.

5. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: generation and synchronization of reference sine wave signals. The generation of reference sine wave signals usually adopts the table lookup timing generation technology. This method generates sine wave signals at a frequency of 50Hz, divides a complete cycle into 192 equal parts, calculates and records the sine value of each point, and saves it in a data structure called a reference sine table. The system reads a data point from the table every 1 / 192 cycle and performs necessary processing. Since the DSP only supports unipolar inputs of 0 to 5V, the generated reference sine table is also unipolar. When the power grid is operating normally, the inverter will work synchronously with the power grid. If the power grid is abnormal, the built-in timer of the DSP will generate a reference frequency of 50Hz, guiding the inverter to operate at this frequency, effectively alleviating the impact on the load that may be caused during the switching process from the mains to the inverter, and ensuring the stability and safety of the UPS system.

6. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: output voltage effective value adjustment, adding the output voltage effective value adjustment link can ensure that the inverter outputs a voltage within an acceptable fluctuation range when the load or mains power is unstable. The specific implementation method is: take 1 / 192 mains power cycle as the sampling period, sample the output voltage of the inverter, and convert the sampled voltage into a voltage of 0~5V and input it into the A / D conversion channel of the DSP. After analog-to-digital conversion, read the conversion value and calculate its square sum, and add it to the square sum of the previous data point to calculate the effective value of the output voltage.

7. A flywheel array uninterruptible power supply control method according to claim 1, characterized in that: The second step: master-slave-free adaptive parallel control strategy. The master-slave-free adaptive parallel control aims to achieve coordinated control and performance optimization among multiple flywheel energy storage devices when the flywheel energy storage array generates electricity. Adaptive control is achieved through information sharing and mutual cooperation among flywheel energy storage devices to ensure stable power output of the UPS system.

8. A flywheel array uninterruptible power supply control method according to claim 7, characterized in that: The second step: non-master-slave adaptive parallel control strategy, including non-master-slave parallel framework and adaptive control strategy, this article introduces a non-master-slave parallel grid-connected battery energy storage system, in which multiple energy storage devices (UB1, UB2, ..., UBn) are combined in parallel through the conversion link to form a large-capacity system, and finally connected to the power grid. All the conversion units in the system are consistent in power and control circuit design. According to the specific working mode, the control unit of each converter will adjust the corresponding operating state, so that the entire energy storage system can work stably in different states such as grid-connected operation or as an emergency power supply; Adaptive control is a technology that can automatically adjust system control parameters according to changes in the external environment. It aims to enable the control system to adapt to changes in the outside world and maintain the optimal state of a certain performance indicator. By combining traditional PI control with adaptive control to form adaptive PI control, the dynamic performance of the system is significantly improved. The system in this article uses a dual closed-loop PI controller of current and voltage as the core, and adjusts its parameters by adding an adaptive mechanism in front of the PI controller to achieve more precise control.

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