The high-voltage generator set of the backup power station of the data center usually adopts the parallel mode, and the parallel high-voltage generator system should generally be equipped with the following systems:
1. Parallel system
The parallel system of the high-voltage unit is divided into a parallel control system and a parallel switch system according to the principle of high and low pressure separation (the parallel control system is a low-voltage system, and the parallel switch system is a high-voltage system).
A. Parallel control system: 1 main control cabinet + N parallel sub-control cabinets (each generator set is equipped with 1 parallel sub-control cabinet)
The main control cabinet controls the parallel operation of all generator sets and is equipped with a display screen to display the parallel control status of each generator set. The sub-control cabinet monitors the voltage of the busbar and the generator set and compares it, adjusts the voltage and speed of the generator set to achieve the purpose of synchronizing the generator set with the busbar. After synchronization, it sends a closing command to the parallel circuit breaker and the circuit breaker closes. Complete the parallel function. Usually equipped with various instruments to monitor the electrical parameters of the generator set and busbar.
B. Parallel switch cabinet:
Each generator set is equipped with a parallel switch cabinet. When the parallel control system determines that the generator set is synchronized with the busbar, it will issue a closing command, and the parallel circuit breaker will be closed to complete the parallel function. Usually 10KV or above parallel switchgear needs to be equipped with differential protection function to protect the power source-diesel generator set.
C, PT cabinet:
Each parallel busbar is equipped with a PT cabinet. The PT cabinet is used to sense the voltage of the parallel busbar and provide it to the parallel sub-control cabinet. Parallel sub-control cabinets must have busbar voltage samples to complete the parallel function.
2. DC power system
In order to ensure the reliability of operation, the electric operating mechanism of the high-voltage circuit breaker usually adopts a DC power supply, and the DC power supply cabinet is to provide the electric operation power supply for the high-voltage circuit breaker. Its voltage and capacity are designed according to the requirements of high-voltage circuit breakers. The voltage is usually 110VDC, 220VDC and 24VDC.
3. Connect
In order to avoid the adverse effects caused by the ground fault of the generator set and the power distribution system, the high-voltage generator set is usually designed with a grounding protection system. The grounding system usually adopts medium-linear and low-resistance grounding. There are two types of grounding systems in existing applications: centralized grounding systems and decentralized grounding systems.
A. Centralized grounding system: each generator set is equipped with a high-voltage contactor, and a grounding system is equipped with a grounding resistance grounding method. The control system realizes the purpose of allowing only one unit to be grounded per busbar by controlling the high-voltage contactor of each generator set. At the same time, the grounding resistor is equipped with a current transformer to measure the ground current, and a ground fault relay is used to set a ground fault signal when the ground current exceeds the set value;
B. Distributed grounding system: Each generator set is equipped with a grounding resistance cabinet, and each grounding resistance cabinet is equipped with a high-voltage contactor, a current transformer and a ground fault relay. And use the control system to control the high-voltage contactor in the grounding system to achieve the purpose of allowing only one grounding resistance to be grounded. So as to realize the correct function of grounding protection.
In summary, the parallel high-voltage generator set system needs to be equipped with the following equipment:
A. Parallel control system: One main control cabinet and one parallel sub-control cabinet for each unit;
B. Parallel switch cabinet: each unit is equipped with one parallel switch cabinet;
C. PT cabinet: one parallel system is equipped with one PT cabinet;
D. DC power supply cabinet: its capacity, voltage and quantity are designed according to the high-voltage circuit breakers in the system;
E. Grounding resistance cabinet: centralized grounding resistance cabinet and independent grounding resistance cabinet;
F. Feeder cabinet: Connect the output power of the generator set with the load to realize the power distribution function.
Post time: Aug-12-2021