Parallel operation UPS system control method

Abstract

The invention discloses a parallel operation UPS system control method, and relates to the technical field of UPS power supplies, the parallel operation UPS system comprises a common battery pack, an AC / DC converter, a DC / DC converter and a DC / AC converter, in the system, at least two UPSs are connected with each other and are jointly connected to the same battery pack through the DC / DC converter; the parallel operation system can realize two main working modes: a backup mode and a capacity mode. According to the parallel operation UPS system control method, the output voltage, frequency and phase of each UPS module are accurately controlled, high synchronization among the UPS modules is ensured, the output current of each UPS module is accurately controlled, uniform distribution of loads is achieved, redundant communication links, a reliable communication protocol and an error detection mechanism are adopted, and the reliability of the system is improved. Accurate transmission and effective execution of the control instruction can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of UPS power supply, and in particular to a parallel UPS system control method. Background Art

[0002] UPS (Uninterruptible Power System) is a system device that connects an energy storage unit (such as a battery pack) to a host and converts direct current into municipal electricity through the host's inverter. It is mainly used to provide stable and uninterrupted power supply to loads such as a single computer, a computer network system or other power equipment. Therefore, how to improve the reliability of UPS has become an urgent problem to be solved in this field.

[0003] The existing technology has the following problems:

[0004] 1. It is difficult to keep the output voltage, frequency, phase, etc. of each UPS highly consistent, which is prone to circulating current. Circulating current will not only increase the energy loss of the system, but also may damage the UPS equipment. If the output characteristics of each UPS are different, the loads they bear will also be different, which will not only reduce the overall efficiency of the system, but also may accelerate the damage of the overloaded UPS and shorten its service life.

[0005] 2. In a parallel system, if the loads of each UPS are unevenly distributed, some UPS may be overloaded while others may be lightly loaded or unloaded. The overloaded UPS may be subjected to greater thermal and mechanical stress, which will accelerate its aging process, shorten its service life, and reduce the efficiency of the entire system.

[0006] 3. In the parallel UPS (uninterruptible power supply) system, communication failure is also a common and critical problem. When the communication interface or communication line is damaged or the communication module or circuit board inside the UPS fails, it may cause communication failure, which may easily cause the system to be unable to respond to failures or abnormal situations in time, reducing the stability and reliability of the system. Summary of the invention

[0007] The present invention provides a parallel UPS system control method to solve the problems raised in the above background technology.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A parallel UPS system control method includes a shared battery pack, an AC / DC converter, a DC / DC converter and a DC / AC converter. The system includes at least two UPSs, which are connected to each other and to the same battery pack through a DC / DC converter. The parallel system can realize two main working modes: a backup mode and a capacity mode. In the backup mode, when a main UPS fails or shuts down, the standby UPS will automatically take over the load to ensure reliable power supply to the load. In the capacity mode, when the load exceeds the capacity of a single UPS device, multiple UPS devices will jointly provide a stable power supply for the load. The parallel UPS system control method includes synchronization technology, current sharing technology, master-slave control and 3C type parallel control.

[0010] Preferably, the first UPS also includes a first DC-DC converter having one side connected to the connection point of the first rectifier and the first inverter; the second UPS also includes a second DC-DC converter having one side connected to the connection point of the second rectifier and the second inverter; the other sides of the first DC-DC converter and the second DC-DC converter are connected to each other and are also commonly connected to the common battery pack; in the normal working mode, the AC power input is output through the AC / D converter and the DC / AC converter to provide a stable and clean 50Hz sinusoidal power supply for the load and the charger charges the battery pack; in the battery pack power supply mode, when the AC power is extremely bad or there is a power outage, the battery pack is used for power supply to provide a stable and clean 50Hz sinusoidal power supply for the load; the power supply time depends on the UPS power battery capacity and the load size.

[0011] Preferably, when the main UPS fails or shuts down, the normal UPS will continue to obtain energy from the mains and convert it into direct current through its AC / DC converter for use by the load; the battery pack is converted from a discharge state to a charge state, and the rectifier of the normal UPS provides a charging voltage for the battery pack; when the faulty UPS is restarted, the normal UPS will gradually reduce its output power to transfer part of the load to the faulty UPS; the battery pack is converted from a charge state to a discharge state, and can provide additional power to meet the load demand.

[0012] Preferably, the synchronization technology can ensure that the output voltage and current of each UPS inverter module remain synchronized in phase and frequency; the parallel unit detects the frequency and phase of the mains power and sends a synchronization pulse to each UPS inverter; when there is no mains power, the crystal oscillator can generate a synchronization pulse, and the phase-locked loop control of each inverter unit ensures the synchronization of the output voltage of each unit; the current balancing technology disperses the control right to each inverter module, and obtains the compensation signal control strategy of each frequency and voltage by integrating the current and frequency signals of each module, so as to realize true redundant parallel connection; the master-slave control implements the parallel control unit on each module, and selects a UPS module as the master and other units as slaves through the working mode selection switch; the 3C parallel control adds the output current feedback signal of the first inverter to the control loop of the second inverter, and connects them in sequence to form a ring structure.

[0013] Preferably, when the AC power voltage exceeds the first range of the preset voltage and the local inverter is in normal working condition, it continues to supply power in inverter mode while monitoring the AC power voltage and the inverter output voltage; the parallel UPS switches to battery mode and is powered by a battery pack to protect equipment and loads from being affected by AC power abnormalities.

[0014] Preferably, when the AC power voltage does not exceed the first range of preset voltages and the output side voltage of the local inverter exceeds the second range of preset voltages, the local UPS can continue to obtain power from the AC power to provide a stable power supply for the load; the UPS system will control the AC power to pre-charge the battery pack, adjust the output voltage and frequency, and ensure a smooth transition of the load.

[0015] Preferably, if the local AC power voltage exceeds a preset first voltage range and the output side voltage of the local inverter does not exceed a preset second voltage range and the first fault signal sent by the parallel UPS is not received and the second fault signal sent by the parallel UPS is received, the parallel UPS will immediately switch to bypass mode and directly supply power to the load from the AC power to avoid the impact of the inverter failure on the load; if the AC power is also unreliable or there are other risks, the UPS may switch to battery power supply mode.

[0016] Preferably, the steps of the parallel UPS system control method are as follows:

[0017] S1: System planning and preparation: Determine the required UPS model, capacity and number of parallel units based on factors such as load power demand and reliability requirements, and ensure that all selected UPS equipment models, capacities, input and output parameters are the same or compatible so that they can run in parallel;

[0018] S2: Single-machine debugging: Check and connect the UPS input line, output line, battery line, etc. according to the user manual or quick installation guide of the UPS device, turn on the UPS device one by one, and perform self-test to ensure that each UPS is normal when running alone. Set the output voltage, frequency and other parameters of each UPS as needed to ensure that the parameters are consistent;

[0019] S3: Parallel cable connection: Select a suitable parallel cable according to the requirements of the UPS equipment, ensure the quality and reliability of the parallel cable, connect one end of the parallel cable to the parallel interface of one UPS, and the other end to the parallel interface of another UPS to form a loop, and ensure that the parallel cable is firmly connected without looseness.

[0020] S4: Parallel settings: Open the setting interface of the UPS device, which may be through the LCD interface, WEB interface or other methods, find the parallel setting option, set the parallel mode to "parallel", and set the output voltage, frequency and other parameters after paralleling according to actual needs;

[0021] S5: Inverter startup and test: Turn on the output switch of each UPS in turn to start the UPS to output power. Observe the UPS display screen to ensure that the output voltage, frequency and other parameters after parallel operation are normal. Connect the load equipment to the UPS output socket after parallel operation to ensure that the power of the load equipment does not exceed the total capacity of all UPS equipment. Perform a load test to check the stability and reliability of the parallel system. The overload and underload capacity of the parallel system can be tested by increasing or decreasing the number of load equipment.

[0022] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0023] 1. The present invention provides a parallel UPS system control method. The synchronization technology ensures a high degree of synchronization between the UPS modules by accurately controlling the output voltage, frequency and phase of each UPS module. This can significantly reduce the circulation phenomenon, reduce the energy loss of the system, and protect the equipment from damage. Moreover, the synchronization technology is combined with the load distribution algorithm to monitor the load of each UPS module in real time and dynamically adjust it as needed. By accurately controlling the load distribution, the load balance between the modules is ensured, thereby improving the overall efficiency and reliability of the system.

[0024] 2. The present invention provides a parallel UPS system control method. The current balancing technology realizes uniform load distribution by accurately controlling the output current of each UPS module. It can dynamically adjust the load ratio of each module according to the actual load of the system to ensure that each module operates within its rated load range, thereby improving the overall efficiency and reliability of the system. In addition, the current balancing technology has fault detection and isolation functions, which can timely detect and isolate faulty modules to prevent the spread of faults from affecting the entire system. This further improves the reliability and availability of the parallel UPS system.

[0025] 3. The present invention provides a parallel UPS system control method. The 3C parallel control emphasizes the reliability and stability design of the communication system. By adopting redundant communication links, reliable communication protocols and error detection mechanisms, the accurate transmission and effective execution of control instructions can be ensured. Even in the event of failure of some communication links, the system can maintain normal operation, thereby improving the fault tolerance and reliability of the system. In addition, the 3C parallel control is usually combined with an intelligent monitoring system to monitor the operating status and performance parameters of each UPS in real time. Through data analysis and early warning functions, potential problems and failures can be discovered in time, and corresponding maintenance measures can be taken. This helps to reduce the difficulty of maintenance and monitoring and improve the maintainability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural diagram of a parallel UPS system of the present invention;

[0027] Figure 2 A signal flow diagram of a parallel UPS system control method of the present invention;

[0028] Figure 3 A signal flow diagram of a parallel UPS system control method of the present invention;

[0029] Figure 4 The figure is a flow chart of the parallel UPS system control method of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0031] like Figure 1As shown, a parallel UPS system control method includes a shared battery pack, an AC / DC converter, a DC / DC converter and a DC / AC converter, at least two UPS in the system, the two UPS are connected to each other and connected to the same battery pack through a DC / DC converter; the parallel system can realize two main working modes: backup mode and capacity mode; in the backup mode, when the main UPS fails or shuts down, the standby UPS will automatically take over the load to ensure reliable power supply to the load; in the capacity mode, when the load exceeds the capacity of a single UPS device, multiple UPS devices will jointly provide stable power supply for the load; the parallel UPS system control method includes synchronization technology, current sharing technology, master-slave control and 3C parallel control.

[0032] Backup mode means connecting multiple UPS devices together through a specific parallel controller, with one UPS device acting as the main UPS responsible for supplying power to the load, and the remaining UPS devices acting as backup UPS in standby mode. When the main UPS fails or shuts down, the backup UPS will automatically take over the load to maintain reliable power supply to the load.

[0033] Capacity mode means that when the load exceeds the capacity of a single UPS device, multiple UPS devices are operated in parallel through the parallel controller to jointly provide stable power for the load. At this time, all UPS devices are in working state and share the load.

[0034] Among them, the first UPS also includes a first DC-DC converter with one side connected to the connection point of the first rectifier and the first inverter; the second UPS also includes a second DC-DC converter with one side connected to the connection point of the second rectifier and the second inverter; the other sides of the first DC-DC converter and the second DC-DC converter are connected to each other and are also connected to a common battery pack; in normal working mode, the AC power input is output through the AC / D converter and the DC / AC converter to provide a stable and clean 50Hz sinusoidal power supply for the load and the charger charges the battery pack; in the battery pack power supply mode, when the AC power is extremely bad or there is a power outage, the battery pack will be used for power supply to provide a stable and clean 50Hz sinusoidal power supply for the load; the power supply time depends on the UPS power battery capacity and the load size.

[0035] refer to Figure 1 The parallel UPS system control method is applied to a target UPS in a parallel UPS system. The parallel UPS system includes a target UPS and a parallel UPS. The target UPS and the parallel UPS are connected to the same battery pack and the target UPS and the parallel UPS are in communication connection.

[0036] Among them, when the main UPS fails or shuts down, the normal UPS will continue to obtain energy from the mains and convert it into DC power for the load through its AC / DC converter; the battery pack is converted from a discharge state to a charge state, and the rectifier of the normal UPS will provide a charging voltage for the battery pack; when the faulty UPS restarts, the normal UPS will gradually reduce its output power to transfer part of the load to the faulty UPS; the battery pack is converted from a charge state to a discharge state, which can provide additional power to meet the load requirements.

[0037] refer to Figure 2 and Figure 3 When the main UPS fails or shuts down, the normal UPS will continue to obtain energy from the mains, so that the battery pack will be converted from a discharge state to a charge state. When the faulty UPS restarts, the normal UPS will gradually reduce its output power, so that the battery pack will be converted from a charge state to a discharge state.

[0038] Among them, the synchronization technology can ensure that the output voltage and current of each UPS inverter module are synchronized in phase and frequency; the parallel unit detects the frequency and phase of the AC power and sends a synchronization pulse to each UPS inverter; when there is no AC power, the crystal oscillator can generate a synchronization pulse, and the phase-locked loop control of each inverter unit can ensure the synchronization of the output voltage of each unit; the current balancing technology disperses the control right to each inverter module, and obtains the compensation signal control strategy of each frequency and voltage by integrating the current and frequency signals of each module to achieve true redundant parallel connection; the master-slave control puts the parallel control unit on each module, and selects a UPS module as the master and the other units as slaves through the working mode selection switch; the 3C parallel control adds the output current feedback signal of the first inverter to the control loop of the second inverter, and connects them in sequence to form a ring structure.

[0039] Synchronization technology refers to the use of specific methods or equipment to keep the amplitude, frequency and phase of the output voltage of multiple UPS devices consistent when they are running in parallel. Current balancing technology refers to the use of specific control strategies in a parallel UPS system to evenly distribute current among various UPS devices when sharing the load, thereby avoiding overload of a single device. 3C parallel control is a special parallel control method. The output current feedback signals of each inverter are connected in sequence into a ring structure, forming a parallel relationship in terms of power output.

[0040] Among them, when the AC power voltage exceeds the first range of the preset voltage and the local inverter is in normal working condition, it continues to supply power in inverter mode, and monitors the AC power voltage and inverter output voltage at the same time; the parallel UPS switches to battery mode and is powered by the battery pack to protect the equipment and load from the abnormality of the AC power.

[0041] Although the mains voltage is abnormal, the UPS will continue to supply power in inverter mode because the local inverter is in normal working condition. This means that the load will be powered by the alternating current (AC) generated by the inverter instead of directly by the mains.

[0042] Among them, when the AC power voltage does not exceed the first range of preset voltages and the output side voltage of the local inverter exceeds the preset second voltage range, the local UPS can continue to obtain power from the AC power to provide a stable power supply for the load; the UPS system will control the AC power to pre-charge the battery pack, adjust the output voltage and frequency, and ensure a smooth transition of the load.

[0043] Although the output voltage of the inverter is abnormal, the mains voltage is normal. Therefore, the UPS system will continue to draw power from the mains in order to maintain continuous power supply to the load.

[0044] Among them, if the local AC power voltage exceeds the preset first voltage range and the output side voltage of the local inverter does not exceed the preset second voltage range and the first fault signal sent by the parallel UPS is not received, and the second fault signal sent by the parallel UPS is received, the parallel UPS will immediately switch to bypass mode and directly supply power to the load from the AC power to avoid the impact of inverter failure on the load; if the AC power is also unreliable or there are other risks, the UPS may switch to battery power supply mode.

[0045] Although the AC voltage is out of range, the inverter output is stable. To avoid the impact of potential inverter failure on the load, the parallel UPS will immediately switch to bypass mode. In bypass mode, the parallel UPS directly obtains power from the AC to power the load, bypassing the inverter.

[0046] The steps of the parallel UPS system control method are as follows:

[0047] S1: System planning and preparation: Determine the required UPS model, capacity and number of parallel units based on factors such as load power demand and reliability requirements, and ensure that all selected UPS equipment models, capacities, input and output parameters are the same or compatible so that they can run in parallel.

[0048] S2: Single-machine debugging: Check and connect the UPS input line, output line, battery line, etc. according to the user manual or quick installation guide of the UPS device, turn on the UPS devices one by one, and perform self-test to ensure that each UPS is normal when running alone. Set the output voltage, frequency and other parameters of each UPS as needed to ensure that the parameters are consistent.

[0049] S3: Parallel cable connection: Select a suitable parallel cable according to the requirements of the UPS equipment, ensure the quality and reliability of the parallel cable, connect one end of the parallel cable to the parallel interface of one UPS, and the other end to the parallel interface of another UPS to form a loop, and ensure that the parallel cable is firmly connected without looseness.

[0050] S4: Parallel settings: Open the setting interface of the UPS device, which may be through the LCD interface, WEB interface or other methods, find the parallel setting option, set the parallel mode to "Parallel", and set the output voltage, frequency and other parameters after parallel operation according to actual needs.

[0051] S5: Inverter startup and test: Turn on the output switch of each UPS in turn to start the UPS to output power. Observe the UPS display screen to ensure that the output voltage, frequency and other parameters after parallel operation are normal. Connect the load equipment to the UPS output socket after parallel operation to ensure that the power of the load equipment does not exceed the total capacity of all UPS equipment. Perform a load test to check the stability and reliability of the parallel system. The overload and underload capacity of the parallel system can be tested by increasing or decreasing the number of load equipment.

[0052] refer to Figure 3 , as the specific steps of the parallel UPS system control method.

[0053] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for controlling a parallel UPS system, comprising a common battery pack, an AC / DC converter, a DC / DC converter and a DC / AC converter, characterized in that: The system includes at least two UPS, which are interconnected and connected to the same battery pack through a DC / DC converter; the parallel system can realize two main working modes: backup mode and capacity mode; in the backup mode, when the main UPS fails or shuts down, the standby UPS will automatically take over the load to ensure reliable power supply to the load; in the capacity mode, when the load exceeds the capacity of a single UPS device, multiple UPS devices will jointly provide stable power supply for the load; the parallel UPS system control method includes synchronization technology, current sharing technology, master-slave control and 3C parallel control.

2. A parallel UPS system control method according to claim 1, characterized in that: The first UPS further includes a first DC-DC converter having one side connected to a connection point between the first rectifier and the first inverter; the second UPS further includes a second DC-DC converter having one side connected to a connection point between the second rectifier and the second inverter; The other sides of the first DC-DC converter and the second DC-DC converter are connected to each other and are also connected to the common battery pack; in normal working mode, the AC power input is output through the AC / D converter and the DC / AC converter to provide a stable and clean 50Hz sinusoidal power supply for the load and the charger charges the battery pack; in the battery pack power supply mode, when the AC power is extremely bad or there is a power outage, the battery pack will be used to supply power to provide a stable and clean 50Hz sinusoidal power supply for the load; the power supply time depends on the UPS power supply battery capacity and the load size.

3. A parallel UPS system control method according to claim 1, characterized in that: When the main UPS fails or shuts down, the normal UPS will continue to obtain energy from the mains and convert it into direct current through its AC / DC converter for use by the load; the battery pack is converted from a discharge state to a charge state, and the rectifier of the normal UPS provides a charging voltage for the battery pack; when the faulty UPS is restarted, the normal UPS will gradually reduce its output power to transfer part of the load to the faulty UPS; the battery pack is converted from a charge state to a discharge state, and can provide additional power to meet the load demand.

4. A parallel UPS system control method according to claim 1, characterized in that: The synchronization technology can ensure that the output voltage and current of each UPS inverter module are synchronized in phase and frequency; the parallel unit detects the frequency and phase of the mains power and sends a synchronization pulse to each UPS inverter; when there is no mains power, the crystal oscillator can generate a synchronization pulse, and the phase-locked loop control of each inverter unit can ensure the synchronization of the output voltage of each unit; the current balancing technology disperses the control right to each inverter module, and obtains the compensation signal control strategy of each frequency and voltage by integrating the current and frequency signals of each module, so as to realize true redundant parallel connection; the master-slave control implements the parallel control unit on each module, and selects a UPS module as the master and other units as slaves through the working mode selection switch; the 3C parallel control adds the output current feedback signal of the first inverter to the control loop of the second inverter, and connects them in sequence to form a ring structure.

5. The parallel UPS system control method according to claim 1, characterized in that: When the AC power voltage exceeds the first range of the preset voltage and the local inverter is in normal working condition, it continues to supply power in inverter mode while monitoring the AC power voltage and the inverter output voltage; the parallel UPS switches to battery mode and is powered by the battery pack to protect the equipment and load from the influence of AC power abnormality.

6. A parallel UPS system control method according to claim 1, characterized in that: When the AC power voltage does not exceed the first range of preset voltages and the output side voltage of the local inverter exceeds the second range of preset voltages, the local UPS can continue to obtain power from the AC power to provide a stable power supply for the load; the UPS system will control the AC power to pre-charge the battery pack, adjust the output voltage and frequency, and ensure a smooth load transition.

7. The parallel UPS system control method according to claim 1, characterized in that: If the local AC power voltage exceeds the preset first voltage range and the output side voltage of the local inverter does not exceed the preset second voltage range and the first fault signal sent by the parallel UPS is not received and the second fault signal sent by the parallel UPS is received, the parallel UPS will immediately switch to bypass mode and directly supply power to the load from the AC power to avoid the impact of inverter failure on the load; if the AC power is also unreliable or there are other risks, the UPS may switch to battery power supply mode.

8. The parallel UPS system control method according to claim 1, characterized in that: The steps of the parallel UPS system control method are as follows: S1: System planning and preparation: Determine the required UPS model, capacity and number of parallel units based on factors such as load power demand and reliability requirements, and ensure that all selected UPS equipment models, capacities, input and output parameters are the same or compatible so that they can run in parallel; S2: Single-machine debugging: Check and connect the UPS input line, output line, battery line, etc. according to the user manual or quick installation guide of the UPS device, turn on the UPS device one by one, and perform self-test to ensure that each UPS is normal when running alone. Set the output voltage, frequency and other parameters of each UPS as needed to ensure that the parameters are consistent; S3: Parallel cable connection: Select a suitable parallel cable according to the requirements of the UPS equipment, ensure the quality and reliability of the parallel cable, connect one end of the parallel cable to the parallel interface of one UPS, and the other end to the parallel interface of another UPS to form a loop, and ensure that the parallel cable is firmly connected without looseness; S4: Parallel settings: Open the setting interface of the UPS device, which may be through the LCD interface, WEB interface or other methods, find the parallel setting option, set the parallel mode to "parallel", and set the output voltage, frequency and other parameters after paralleling according to actual needs; S5: Inverter startup and test: Turn on the output switch of each UPS in turn to start the UPS to output power; observe the UPS display screen to ensure that the output voltage, frequency and other parameters after parallel operation are normal, connect the load equipment to the UPS output socket after parallel operation, ensure that the power of the load equipment does not exceed the total capacity of all UPS equipment, perform load test, and check the stability and reliability of the parallel system; the overload and underload capacity of the parallel system can be tested by increasing or decreasing the number of load devices.

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