Startup method of idle load long line

Abstract

Disclosed is an unloaded long transmission line startup method, belonging to the electricity transmission and distribution technical field and used to solve the problem of quick starting up of the unloaded long transmission line during black startup. The invention adopts the technical scheme: directly connecting an inverter AC side of a high-voltage DC transmission of a networking voltage source current changer with the unloaded line transmission to be started up through a circuit breaker, firstly closing the circuit breaker when start-up, then charging the inverter AC side of the high-voltage DC transmission of the voltage source current changer, controlling the unloaded transmission line voltage through a modulation degree m by the inverter, allowing the effective value of the unloaded transmission line voltage to be recovered according to an appointed curve. The method is capable of effectively eliminating power frequency overvoltage and overvoltage when closing the brake, and capable of improving black startup speed and shortening blackout time.

Description

technical field [0001] The invention relates to a method for quickly starting a long no-load line during the black start process of a power grid, and belongs to the technical field of power transmission and distribution. Background technique [0002] With the continuous increase of cross-regional interconnection of power systems, the scale of power grids is getting larger and larger, and the mutual influence between subsystems is becoming more and more intense. Partial failures of subsystems may cause large-scale power outages due to incorrect actions of protection or automatic devices. Although the possibility of such a serious accident is very small, once it happens, the loss will be huge and the consequences will be unimaginable. Therefore, how to ensure the rapid and effective restoration of system operation after a blackout has always been a problem that the power industry pays close attention to and urgently needs to be solved. [0003] The recovery of the power grid...

AI Technical Summary

Problems solved by technology

At present, during the black start process, gas turbines or hydraulic turbines with low power requirements are generally used to charge the long unloaded line without load. The disadvantage of this method of starting the long unloaded line is that it will generate Operating overvoltage, and when the starting power supply is charging the no-load long line, power frequency overvoltage will be generated due to the line capacitance effect

In order to ensure the safety of the power grid, the closing overvoltage of the no-load line and the ferromagnetic resonance of the no-load transformer must be verified by strict calculations and experiments, otherwise it may cause extremely serious consequences

The existence of these problems greatly limits the operation speed of the black start scheme, greatly prolonging the power outage time of the load

Images