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Sinopak
I. Block Diagram of the MV UPS Solution
The overall architecture of the MV UPS system is realized using an impedance-isolated static converter.
As shown in the above figure, the power circuit of the whole device is composed of a bypass high-voltage circuit breaker, a grid-connected high-voltage circuit breakers, a load-side high-voltage circuit breaker, and a high-voltage side reactor, a step-up transformer, a bidirectional current converter, and a storage battery pack.
Notes:
1. In the MV UPS system, different step-up transformers are configured to match power distribution at different high voltages;
2. Bidirectional current converter, AC690V, and DC1,000-1,500V;
II. Introduction to MV UPS Operation Modes and the Switching Process
1. Bypass operation: When a serious fault occurs in the MV UPS system, the system will switch to the bypass mode in order to ensure the reliability of load power supply. In this mode, the system closes the bypass circuit breaker actively, and disconnects the grid-connected and load circuit breakers, so that the grid supplies power to the load alone; (This is very unlikely due to redundant architecture design.)
2. Start/stop process: Before the UPS system enters steady-state operation from the shutdown state, the PCS and the grid side are synchronized, and then the grid-connected and load circuit breakers are closed to intervene in the load. After the system stabilizes, the bypass circuit breaker will be disconnected, and the system will enter the stable operation mode.
3. Stable regulation mode: The bypass circuit breaker is opened, and the grid-connected and load circuit breakers are closed. When one or more power quality events such as voltage sag, sudden rise or drop, harmonic wave, flicker or fluctuation occur in the power grid, the PCS will respond flexibly to ensure that the voltage at the load end meets the load demand, and ensure safe and reliable power supply to the load.
4. Off-grid mode: When a serious fault occurs in the power grid that exceeds the system's regulation capacity or may cause serious damage to the load and inverter, the system will switch to off-grid operation. At this point, the system bypass switch is disconnected, the grid-connected circuit breaker of each UPS unit is disconnected, the load circuit breaker is closed, and the PCS unit supplies power to the load alone.
Introduction to the Bypass Operation Mode
The bypass operation mode allows the load to be supplied with power directly by the power grid through the bypass circuit breaker in the static impedance isolator; only when a serious fault occurs in the MV UPS system will the system switch to bypass operation to ensure the reliability of load power supply.
Switching among operation modes can achieve the 0ms power-off switching of the load.
ØSwitching from steady state operation to bypass operation: First adjust the synchronization between the system load end and the power grid, and then close the system bypass circuit breaker. When the PCS output voltage drops to around 0 quickly (shutdown), the grid-connected and load circuit breakers are disconnected sequentially.
ØSwitching from bypass operation to steady-state operation: First adjust the synchronization between the system output and the power grid, and then close the grid-connected and load circuit breakers concurrently. After stable operation is achieved, the bypass circuit breaker will be disconnected, and the system will enter steady-state operation mode.
Addressing challenges of AIDC through the MV UPS + CBM power architecture advocated by Sinopak
I. Block Diagram of the MV UPS Solution
The overall architecture of the MV UPS system is realized using an impedance-isolated static converter.
As shown in the above figure, the power circuit of the whole device is composed of a bypass high-voltage circuit breaker, a grid-connected high-voltage circuit breakers, a load-side high-voltage circuit breaker, and a high-voltage side reactor, a step-up transformer, a bidirectional current converter, and a storage battery pack.
Notes:
1. In the MV UPS system, different step-up transformers are configured to match power distribution at different high voltages;
2. Bidirectional current converter, AC690V, and DC1,000-1,500V;
II. Introduction to MV UPS Operation Modes and the Switching Process
1. Bypass operation: When a serious fault occurs in the MV UPS system, the system will switch to the bypass mode in order to ensure the reliability of load power supply. In this mode, the system closes the bypass circuit breaker actively, and disconnects the grid-connected and load circuit breakers, so that the grid supplies power to the load alone; (This is very unlikely due to redundant architecture design.)
2. Start/stop process: Before the UPS system enters steady-state operation from the shutdown state, the PCS and the grid side are synchronized, and then the grid-connected and load circuit breakers are closed to intervene in the load. After the system stabilizes, the bypass circuit breaker will be disconnected, and the system will enter the stable operation mode.
3. Stable regulation mode: The bypass circuit breaker is opened, and the grid-connected and load circuit breakers are closed. When one or more power quality events such as voltage sag, sudden rise or drop, harmonic wave, flicker or fluctuation occur in the power grid, the PCS will respond flexibly to ensure that the voltage at the load end meets the load demand, and ensure safe and reliable power supply to the load.
4. Off-grid mode: When a serious fault occurs in the power grid that exceeds the system's regulation capacity or may cause serious damage to the load and inverter, the system will switch to off-grid operation. At this point, the system bypass switch is disconnected, the grid-connected circuit breaker of each UPS unit is disconnected, the load circuit breaker is closed, and the PCS unit supplies power to the load alone.
Introduction to the Bypass Operation Mode
The bypass operation mode allows the load to be supplied with power directly by the power grid through the bypass circuit breaker in the static impedance isolator; only when a serious fault occurs in the MV UPS system will the system switch to bypass operation to ensure the reliability of load power supply.
Switching among operation modes can achieve the 0ms power-off switching of the load.
ØSwitching from steady state operation to bypass operation: First adjust the synchronization between the system load end and the power grid, and then close the system bypass circuit breaker. When the PCS output voltage drops to around 0 quickly (shutdown), the grid-connected and load circuit breakers are disconnected sequentially.
ØSwitching from bypass operation to steady-state operation: First adjust the synchronization between the system output and the power grid, and then close the grid-connected and load circuit breakers concurrently. After stable operation is achieved, the bypass circuit breaker will be disconnected, and the system will enter steady-state operation mode.
Addressing challenges of AIDC through the MV UPS + CBM power architecture advocated by Sinopak
