High-voltage frequency converter hot standby mutual switching grid-connected system

Abstract

The utility model relates to the technical field of power electronics, in particular to a hot standby interswitching grid-connected system of a high-voltage frequency converter, which comprises a plurality of compressor frequency conversion branches, a plurality of power frequency branches, a hot standby frequency conversion branch, a control unit and a central control system. The parallel circuits are arranged between the bus and the corresponding compressors, the wire inlet ends of the parallel circuits are connected with the bus through on-off switches, and the output ends of one group of parallel circuits are connected with one compressor; the wire inlet end of one hot standby frequency conversion branch is connected with a bus through another on-off switch, and the output end of the hot standby frequency conversion branch is connected to different compressors through different circuit breakers; a fault detection sensor, a data transmission module, a synchronous detection module and a frequency regulation module are arranged in the frequency converter of each branch, and the control unit is connected to a central control system; according to the utility model, stable switching, speed regulation, grid connection and operation of the compressor unit are realized.

Description

Technical Field

[0001] This utility model relates to the field of power electronics technology, and in particular to a high-voltage frequency converter hot standby and grid connection system. Background Technology

[0002] In modern industrial systems, compressor units, as core power equipment, are widely used in key fields such as petrochemicals, metallurgy, and power. In the petrochemical industry, they are responsible for the transportation and refining of oil and gas, as well as the compression of gases in chemical reactions. In the metallurgical industry, they assist in the gas supply during high-temperature smelting and rolling processes. In power generation, they undertake important tasks such as air compression and gas processing, playing an irreplaceable role in ensuring the continuity and stability of industrial production processes.

[0003] However, traditional variable frequency drive systems for compressor units have significant drawbacks. As a critical control node in the entire system, a single inverter's failure can easily trigger a complete unit shutdown. This not only leads to production interruptions, preventing the achievement of expected production output and missing optimal market supply opportunities, resulting in potential sales profit losses, but also prolongs the production cycle, increases manpower and material consumption, and even poses the risk of delivery delays and defaults. Furthermore, restarting the equipment consumes a large amount of electricity, increasing operating costs, and subsequent troubleshooting, parts replacement, and equipment debugging also require substantial financial and human resources investment.

[0004] With the advent of Industry 4.0, concepts such as intelligent manufacturing and automated production have gained widespread acceptance, and various industries are placing increasingly stringent demands on production reliability. Against this backdrop, developing a technical solution that ensures the continuous and stable operation of compressor units in the event of inverter failure has become a critical issue urgently needing to be addressed in the industrial sector. This is not only related to improving enterprise production efficiency but also to the survival and development of enterprises. While some hot standby solutions exist on the market, they generally suffer from long switchover times, poor compatibility, and an inability to accurately adapt to various failure scenarios, making it difficult to meet the ever-increasing high reliability requirements of modern industry. Summary of the Invention

[0005] This invention provides a high-voltage frequency converter hot standby switching grid connection system, which solves the problem of compressor unit shutdown when a single frequency converter fails, achieves high-reliability operation of the compressor unit, ensures the continuity of the production process, reduces economic losses caused by production interruption, and improves the system's adaptability to different types of frequency converter equipment failures and grid connection conditions. Each circuit can be connected to the grid independently. If the frequency converter of the corresponding compressor fails, the hot standby frequency converter can be used immediately for grid connection, reducing equipment restart energy consumption and fault maintenance costs, and extending equipment service life.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A high-voltage inverter hot standby switching grid-connected system includes multiple compressor inverter branches, multiple power frequency branches, one hot standby inverter branch, a control unit, and a central control system. One compressor inverter branch and one power frequency branch are connected in parallel to form a parallel circuit. The parallel circuit is located between a busbar and a corresponding compressor. The input terminal of the parallel circuit is connected to the busbar via an on / off switch, and the output terminal of one set of parallel circuits is connected to one compressor. The input terminal of one hot standby inverter branch is connected to the busbar via another on / off switch, and its output terminal is connected to different compressors via different circuit breakers.

[0008] Each inverter in the compressor inverter branch and the hot standby inverter branch is equipped with a fault detection sensor, a data transmission module, a synchronization detection module, and a frequency adjustment module. The signal line of the fault detection sensor is connected to the input terminal of the control unit. The signal lines of the data transmission module and the synchronization detection module are connected to the input and output terminals of the control unit. The input terminal of the frequency adjustment module is connected to the output terminal of the control unit. The output terminal of the frequency adjustment module is connected to the compressor. The control unit is connected to the central control system.

[0009] Furthermore, the compressor frequency conversion branch includes a power frequency circuit breaker, a main frequency converter, a main reactor, a reactor short-circuit circuit breaker, and an outgoing circuit breaker. The power frequency circuit breaker, the main frequency converter, and the outgoing circuit breaker are connected in series, and a parallel circuit of the main reactor and the reactor short-circuit circuit breaker is connected in series between the frequency converter and the outgoing circuit breaker.

[0010] Furthermore, the power frequency branch includes a power frequency circuit breaker, the output of which is connected to the compressor input.

[0011] Furthermore, the hot standby frequency converter branch includes an incoming circuit breaker, a hot standby frequency converter, a tap changer, and a reactor bypass circuit breaker. The output terminal of the incoming circuit breaker is connected in series to the hot standby frequency converter. The entire winding of the tap changer is connected in parallel to a reactor bypass circuit breaker, and a portion of the winding of the tap changer is connected in parallel to another reactor bypass circuit breaker. The output terminal of the hot standby frequency converter is connected to the common terminal of the tap changer and the two reactor bypass circuit breakers. The entire winding output terminal of the tap changer is connected to different compressors through different outgoing circuit breakers, and a portion of the winding output terminal of the tap changer is connected to another different compressor through different outgoing circuit breakers.

[0012] Furthermore, it also includes a reactor bypass cabinet, in which the two reactor bypass circuit breakers of the hot standby frequency converter branch are installed.

[0013] Furthermore, the grid connection of the variable frequency branch and the power frequency branch includes the grid connection of the compressor variable frequency branch and the corresponding power frequency branch, and the grid connection of the hot standby variable frequency branch and the corresponding power frequency branch.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1) Improve production continuity: Effectively avoid compressor unit shutdowns caused by single inverter failures, ensuring uninterrupted production processes. Actual testing has shown that applying this solution significantly reduces economic losses caused by production interruptions.

[0016] 2) Reduce operating costs: Reduce energy consumption during equipment restarts and maintenance costs, and extend equipment lifespan. Optimize switching processes and equipment operation control to improve the company's economic efficiency.

[0017] 3) Enhanced system adaptability: Diverse coping strategies are provided for different types of inverter equipment failures and grid connection conditions. Each circuit can be connected to the grid independently. If the inverter of the corresponding compressor fails, a hot standby inverter can be used immediately for grid connection. A standby one-to-one grid connection system cannot perform grid connection logic if the inverter outgoing line fails. For a standby one-to-N grid connection, if two inverters fail simultaneously, or if more than two motors require speed regulation, the system cannot meet the requirements. This invention can meet the speed regulation operation of all loads, and when multiple inverters of the corresponding loads fail, it meets the conditions for using a hot standby inverter for independent grid connection. It meets the needs of complex industrial production environments, and the system can operate stably in various complex failure and grid connection scenarios. Attached Figure Description

[0018] Figure 1 This is a system structure diagram of multiple compressor frequency conversion branches, multiple power frequency branches and one hot standby frequency conversion branch as described in the embodiment of this utility model. Detailed Implementation

[0019] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings:

[0020] This utility model discloses a high-voltage frequency converter hot standby switching grid-connected system, comprising multiple compressor frequency converter branches, multiple power frequency branches, one hot standby frequency converter branch, a control unit, and a central control system. One compressor frequency converter branch and one power frequency branch are connected in parallel to form a parallel circuit. The parallel circuit is located between the bus and the corresponding compressor. The input terminal of the parallel circuit is connected to the bus via an on / off switch, and the output terminal of one set of parallel circuits is connected to one compressor. The input terminal of one hot standby frequency converter branch is connected to the bus via another on / off switch, and its output terminal is connected to different compressors via different circuit breakers.

[0021] Each inverter in the compressor inverter branch and the hot standby inverter branch is equipped with a fault detection sensor, a data transmission module, a synchronization detection module and a frequency adjustment module. The signal line of the fault detection sensor is connected to the input terminal of the control unit. The signal lines of the data transmission module and the synchronization detection module are connected to the input and output terminals of the control unit. The input terminal of the frequency adjustment module is connected to the output terminal of the control unit. The output terminal of the frequency adjustment module is connected to the compressor. The control unit is connected to the central control system.

[0022] The fault monitoring sensor is used to detect inverter fault signals;

[0023] The data transmission module is used for transmitting power frequency and frequency conversion data with the control unit;

[0024] The synchronous detection module is used to detect the frequency, voltage, phase sequence, phase and phase shift angle parameters of the power grid to ensure parameter matching when the frequency converter branch is connected to the power frequency branch. The connection between the frequency converter branch and the power frequency branch includes the connection between the compressor frequency converter branch and the corresponding power frequency branch, and the connection between the hot standby frequency converter branch and the corresponding power frequency branch.

[0025] The frequency adjustment module is used to adjust the compressor output frequency.

[0026] See Figure 1 The compressor unit includes an MRC compressor, an ammonia synthesis compressor, a primary booster compressor, a secondary booster compressor, an ammonia compressor, and a nitrogen compressor. Taking the MRC compressor unit as an example, the 10KV busbar connects a compressor frequency converter branch and a power frequency branch in parallel via a switch. The output of the parallel circuit is connected to the MRC compressor. The compressor frequency converter branch includes a power frequency circuit breaker QF11, a main frequency converter, a main reactor DK1, a reactor short-circuit circuit breaker DF41, and an outgoing circuit breaker QF21. The main circuit inverter QF11, the main circuit frequency converter, and the outgoing circuit breaker QF21 are connected in series. A parallel circuit between the main circuit reactor DK1 and the reactor short-circuit circuit breaker DF41 is connected in series between the frequency converter and the outgoing circuit breaker QF21. The power frequency branch is connected to the outgoing terminal of the power frequency circuit breaker QF31 to the MRC compressor. The wiring branches of the ammonia synthesis compressor, the primary booster compressor, the secondary booster compressor, the ammonia compressor, and the nitrogen compressor are similar to the MRC wiring branches, except that different circuit breakers, reactors, and frequency converters are selected according to the compressor power and voltage.

[0027] The hot standby frequency converter branch includes an incoming circuit breaker QF1, a hot standby frequency converter, a tap changer DK0, and reactor bypass circuit breakers QF2 and QF3. The output terminal of the incoming circuit breaker QF1 is connected in series to the hot standby frequency converter. The entire winding of the tap changer DK0 is connected in parallel to the reactor bypass circuit breaker QF2. The output terminals of the reactor bypass circuit breaker QF2 are connected to the 21.5MW MRC compressor and the 12.6MW... The ammonia synthesis compressor, the 11.5MW primary booster compressor, and the 9.8MW secondary booster compressor are connected in parallel with a reactor bypass circuit breaker QF3 via a portion of the winding of the tap reactor DK0. The output terminal of the reactor bypass circuit breaker QF3 is connected to the 3.8MW ammonia compressor and the 2.25MW nitrogen compressor via output circuit breakers QF55 and QF56, respectively. The output terminal of the hot standby frequency converter is connected to the common terminal of the tap reactor and the two reactor bypass circuit breakers QF2 and QF3.

[0028] Among them, the two reactor bypass circuit breakers QF2 and QF3 of the hot standby frequency converter branch are installed in the reactor bypass cabinet.

[0029] Working principle: The hot standby inverter is always ready to take over from the faulty inverter; multiple circuit breakers are used to control the opening and closing of the circuit, realizing the connection and isolation of equipment; the reactor bypass cabinet optimizes current transmission and ensures system stability; the control unit is the core of the system, coordinating the work of each module; high-precision fault detection sensors can quickly and accurately detect inverter faults; the data transmission module is responsible for transmitting operating parameters; the synchronization detection module ensures that parameters such as phase are matched during grid connection; the frequency adjustment module precisely adjusts the frequency; all modules work together to achieve accurate monitoring and control of the compressor unit's operating status.

[0030] The working process includes: (1) Fault switching to standby unit: Taking the MRC compressor unit as an example, the hot standby frequency converter branch is always in standby ready state, and the status of the MRC compressor unit is monitored in real time. When the MRC compressor unit frequency converter detects the fault through the high-precision fault detection sensor and issues an instruction, the MRC compressor unit outgoing circuit breaker QF21 quickly trips to disconnect the faulty unit from the system and prevent the fault from expanding. At the same time, the standby frequency converter obtains the MRC compressor unit frequency converter operation parameters through the data transmission module and completes the switching. The reactor bypass cabinet QF2 closes and QF3 opens to provide a path for the standby frequency converter to connect. Subsequently, the standby frequency converter closes the corresponding MRC compressor unit QF51 and starts output. Through precise frequency and voltage control, the MRC compressor unit output is stopped and the frequency is increased to the original operating frequency condition to ensure that the MRC compressor unit is stably driven by the hot standby frequency converter.

[0031] (2) Standby inverter switches the unit to power frequency operation: As mentioned above, taking the MRC compressor unit as an example, when the MRC compressor unit is driven by the hot standby inverter, after the owner completes the process adjustment, the grid connection enable command is issued through the central control system. QF2 and QF3 in the reactor bypass cabinet are tripped under the control unit, creating conditions for grid connection. After receiving the control command, the hot standby inverter quickly increases the frequency to 50Hz according to the preset frequency increase program through the built-in frequency adjustment module. The synchronous detection module monitors the grid frequency, voltage, phase sequence, phase and phase shift angle and other parameters in real time to ensure that the grid connection is accurately executed after the grid connection conditions are met. After the corresponding QF31 of the MRC compressor unit is closed, the hot standby inverter stops running, and the corresponding QF51 of the MRC compressor unit is tripped. The MRC compressor unit enters the power frequency operation condition, and the hot standby inverter returns to the ready state to provide hot standby support for other units. Among them, the frequency adjustment module effectively improves the success rate and stability of grid connection.

[0032] (3) Seamless switchback from power frequency operation to original variable frequency operation: As mentioned above, taking the MRC compressor unit as an example, after the original variable frequency fault of the MRC compressor unit is repaired, it reaches the ready state after charging and comprehensive testing and initialization of internal circuits and components; after the user issues the start command of the MRC unit, the system monitors the operating conditions of the MRC unit in real time. When it detects that it is in power frequency operation, it judges the timing of the switchback based on real-time operating data and preset switchback conditions, and triggers the switchback process; the MRC compressor unit QF41 is opened, the output is started and it runs to 50Hz. The original variable frequency ensures that the output frequency is synchronized with the power grid through the frequency tracking algorithm. After meeting the grid disconnection conditions, it issues the grid disconnection command; subsequently, the MRC compressor unit QF21 is closed, QF31 is opened, and QF41 is closed. The control unit controls the operation of each circuit breaker through precise timing control to complete the seamless switchback. The MRC compressor unit returns to the original variable frequency drive operation. The control unit comprehensively analyzes multiple operating parameters and can accurately judge the timing of the switchback in a short time, ensuring a smooth and undisturbed switchback process.

[0033] When QF2 is closed and QF3 is open, it is suitable for the hot standby inverter switching operation of four water-cooled inverter devices, namely MRC compressor, ammonia synthesis compressor, primary booster compressor and secondary booster compressor, which fail simultaneously. The system dynamically adjusts the output parameters of the hot standby inverter through the control unit according to the fault type of the water-cooled inverter device and the real-time operating status of the system, so as to realize the rapid access and stable operation of the hot standby inverter, ensuring that the critical production process is not affected. It can automatically adjust the output voltage, current and other parameters according to the fault type to ensure that the hot standby inverter can also operate stably under complex fault conditions.

[0034] When QF3 is closed and QF2 is open, it is suitable for the hot standby inverter switching operation when two air-cooled inverter devices, namely the ammonia compressor and the nitrogen compressor, fail. Based on the characteristics and fault modes of air-cooled inverter devices, the system compares the data of the inverter circuit and the power frequency circuit by detecting parameters such as the frequency, voltage, phase sequence, phase and phase shift angle of the power grid, and accurately adjusts the hot standby inverter output to meet the diverse needs under different fault scenarios and ensure the stable operation of the unit. The frequency regulation and voltage are optimized for the heat dissipation characteristics and common faults of air-cooled inverter devices.

[0035] When QF3 and QF2 are tripped, it is applicable to any one of the six generating units in grid-connected operation. During grid connection, the system ensures the safe and stable connection of the generating unit to the grid through reasonable switch configuration and precise synchronous control. In terms of grid connection control, by detecting parameters such as the frequency, voltage, phase sequence, phase and phase shift angle of the grid, the data of the frequency converter circuit and the power frequency circuit are compared, which effectively reduces the grid connection impact.

[0036] The working principle and process of other compressor unit circuits are the same as those of MRC compressor units.

[0037] The above embodiments are implemented based on the technical solution of this utility model, providing detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the above embodiments. Unless otherwise specified, the methods used in the above embodiments are conventional methods.

Claims

1. A high-voltage frequency converter hot standby and grid-connected system, characterized in that, It includes multiple compressor inverter branches, multiple power frequency branches, one hot standby inverter branch, a control unit, and a central control system. The compressor inverter branch and the power frequency branch are connected in parallel to form a parallel circuit. The parallel circuit is set between the bus and the corresponding compressor. The input terminal of the parallel circuit is connected to the bus through an on / off switch, and the output terminal of one set of parallel circuits is connected to one compressor. The input terminal of the hot standby inverter branch is connected to the bus through another on / off switch, and the output terminal is connected to different compressors through different circuit breakers. Each inverter in the compressor inverter branch and the hot standby inverter branch is equipped with a fault detection sensor, a data transmission module, a synchronization detection module, and a frequency adjustment module. The signal line of the fault detection sensor is connected to the input terminal of the control unit. The signal lines of the data transmission module and the synchronization detection module are connected to the input and output terminals of the control unit. The input terminal of the frequency adjustment module is connected to the output terminal of the control unit. The output terminal of the frequency adjustment module is connected to the compressor. The control unit is connected to the central control system.

2. The high-voltage frequency converter hot standby and grid-connected system according to claim 1, characterized in that, The compressor frequency conversion branch includes a power frequency circuit breaker, a main frequency converter, a main reactor, a reactor short-circuit circuit breaker, and an outgoing circuit breaker. The power frequency circuit breaker, the main frequency converter, and the outgoing circuit breaker are connected in series, and a parallel circuit of the main reactor and the reactor short-circuit circuit breaker is connected in series between the frequency converter and the outgoing circuit breaker.

3. A high-voltage frequency converter hot standby and grid-connected system according to claim 1, characterized in that, The power frequency branch includes a power frequency circuit breaker, the output of which is connected to the compressor input.

4. A high-voltage frequency converter hot standby and grid-connected system according to claim 1, characterized in that, The hot standby frequency converter branch includes an incoming circuit breaker, a hot standby frequency converter, a tap changer, and a reactor bypass circuit breaker. The output terminal of the incoming circuit breaker is connected in series to the hot standby frequency converter. The entire winding of the tap changer is connected in parallel to a reactor bypass circuit breaker, and a portion of the winding of the tap changer is connected in parallel to another reactor bypass circuit breaker. The output terminal of the hot standby frequency converter is connected to the common terminal of the tap changer and the two reactor bypass circuit breakers. The entire winding output terminal of the tap changer is connected to different compressors through different outgoing circuit breakers, and a portion of the winding output terminal of the tap changer is connected to another different compressor through different outgoing circuit breakers.

5. A high-voltage frequency converter hot standby and grid-connected system according to claim 4, characterized in that, It also includes a reactor bypass cabinet, in which the two reactor bypass circuit breakers of the hot standby frequency converter branch are installed.

6. A high-voltage frequency converter hot standby and grid-connected system according to claim 1, characterized in that, The grid connection of the variable frequency branch and the power frequency branch includes the grid connection of the compressor variable frequency branch and the corresponding power frequency branch, and the grid connection of the hot standby variable frequency branch and the corresponding power frequency branch.

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