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Panel Session
03 Aug 2020
The mechanism of the occurrence and development of AC power grid cascading failures includes key technologies such as overload identification, distance protection oscillation blocking, cascading failure evolution mechanism, wide-area system control, active partition control and others. These technologies have significantly increased the safe operation level of the AC grid.
However, in recent years, large-capacity power electronic devices have been widely used in power systems, involving various aspects such as power generation, transmission, power conversion, and power consumption. For example, the renewable energy sources such as wind power and photovoltaic on the power supply side are developing rapidly. The High-Voltage Direct Current (HVDC) transmission lines and flexible DC/AC transmission lines are responsible for more and more power transmission. The power electronic load such as inverter based air conditioners is getting higher and higher. The existing power grid presents a complex AC-DC hybrid state, which is significantly different from the traditional AC grid operating characteristics.
The coupling mechanism of AC/DC system is very complex, the system is continuous, discrete and interlaced with logic variables, the system state variables are coupled in a wide area, the dynamic time constants of each component are very different, many kinds of constraints restrict each other, different control variables interact with each other, and the control objectives have the possibility of coupling and conflict. For example, the semi-control characteristics of the thyristor device lead to the inevitable AC line failure in the AC-DC hybrid power grid, which will cause severe commutation failure of the HVDC converter station, continuous commutation failure or even multiple DC commutation failure. As a result, the converter station is blocked, which in turn causes a large-capacity power flow shift, which may induce system oscillation and cascading transmission failures.
However, in recent years, large-capacity power electronic devices have been widely used in power systems, involving various aspects such as power generation, transmission, power conversion, and power consumption. For example, the renewable energy sources such as wind power and photovoltaic on the power supply side are developing rapidly. The High-Voltage Direct Current (HVDC) transmission lines and flexible DC/AC transmission lines are responsible for more and more power transmission. The power electronic load such as inverter based air conditioners is getting higher and higher. The existing power grid presents a complex AC-DC hybrid state, which is significantly different from the traditional AC grid operating characteristics.
The coupling mechanism of AC/DC system is very complex, the system is continuous, discrete and interlaced with logic variables, the system state variables are coupled in a wide area, the dynamic time constants of each component are very different, many kinds of constraints restrict each other, different control variables interact with each other, and the control objectives have the possibility of coupling and conflict. For example, the semi-control characteristics of the thyristor device lead to the inevitable AC line failure in the AC-DC hybrid power grid, which will cause severe commutation failure of the HVDC converter station, continuous commutation failure or even multiple DC commutation failure. As a result, the converter station is blocked, which in turn causes a large-capacity power flow shift, which may induce system oscillation and cascading transmission failures.
Chairs:
Xinzhou Dong, Brian Johnson
Primary Committee:
Power System Relaying & Control (PSRC)
