Online Monitoring and Early Warning of Subsynchronous Oscillation Using Levenberg–Marquardt and Backpropagation Algorithm Combined with Sensitivity Analysis and Principal Component Analysis
Table 1
Main factors and their influencing degrees.
Influence factor
Influence degree
Description
Degree of series compensation
★★★
One of the critical factors to determine whether SSO occurs in a system
Grid line impedance
★★★
Affect the SSO characteristics by affecting the degree of series compensation
Natural frequency of torsional vibration mode of shafting
★★★
The risk increases when it is close to complementary to the electrical resonance frequency
Control system parameters of DFIG
★★★
The current loop proportional coefficient significantly impacts the subsynchronous resonance damping
Electrical parameters of DFIG
★★
It affects the equivalent series compensation of the system
Mechanical damping of unit shafting
★★
It affects all aspects of SSO
Unit combination mode
★★
The number and type of grid-connected units affect the external equivalent series compensation of the torsional mode of the unit
Grid operation mode
★★
It affects the equivalent series compensation of the system
Electrical parameters of synchronous
★★
The subtransient impedance more significantly impacts the global equivalent capability
Synchronous machine control system and its parameters
★
The speed regulation or excitation control system may have a feedback control effect on the subsynchronous signal
Control system parameters of HVDC
★
The current gain and time constant of the control system have a certain influence on the subsynchronous resonance damping