Method for measuring degree of stability of generator and power transmission line, and electrical grid control system

A stability controlling system of a transformer substation grid, comprising:

• an electrical acquisition device;
• a monitoring device;
• a load regulating device, configured to regulate a load of an electric transmission line;
• and
• a high-speed communication network, configured to communicate a stability measuring and controlling system of the transformer substation grid with a wide area measurement system of a wide area power grid,
• wherein the electrical acquisition device and the monitoring device are configured to determine a dynamic reactive power reserve target value, a capacitive dynamic reactive power reserve target value, an inductive dynamic reactive power reserve target value, a capacitive stability, an inductive stability and a stability of the electric transmission line by:
• S31:
• collecting electrical quantities, and setting an alarm PQ curve of the electric transmission line;
• S32:
• calculating a dynamic reactive power reserve, an inductive dynamic reactive power reserve and a capacitive dynamic reactive power reserve of the electric transmission line;
• S33:
• calculating the dynamic reactive power reserve target value, the inductive dynamic reactive power reserve target value and the capacitive dynamic reactive power reserve target value of the electric transmission line;
• S34:
• calculating the capacitive stability, the inductive stability and the stability of the electric transmission line;
• and
• providing the dynamic reactive power reserve target value, the inductive dynamic reactive power reserve target value and the capacitive dynamic reactive power reserve target value of the electric transmission line, and the capacitive stability, the inductive stability and the stability of the electric transmission line to a transformer substation grid for improving a stability of the transformer substation grid,
• wherein in S33, the dynamic reactive power reserve target value, the inductive dynamic reactive power reserve target value and the capacitive dynamic reactive power reserve target value of the electric transmission line are calculated by:
• calculating a segment length between a left intersection point of a horizontal line passing through a coordinated PQ point of the electric transmission line and the alarm PQ curve of the electric transmission line and a right intersection point of the horizontal line passing through the coordinated PQ point of the electric transmission line and the alarm PQ curve of the electric transmission line as the dynamic reactive power reserve target value of the electric transmission line;
• calculating a segment length between the left intersection point of the horizontal line passing through the coordinated PQ point of the electric transmission line and the alarm PQ curve of the electric transmission line and the coordinated PQ point of the electric transmission line as the capacitive dynamic reactive power reserve target value of the electric transmission line;
• and
• calculating a segment length between the right intersection point of the horizontal line passing through the coordinated PQ point of the electric transmission line and the alarm PQ curve of the electric transmission line and the coordinated PQ point of the electric transmission line as the inductive dynamic reactive power reserve target value of the electric transmission line, and
• wherein in S34, the capacitive stability, the inductive stability and the stability of the electric transmission line are calculated by:
• calculating a percentage of the capacitive dynamic reactive power reserve of the electric transmission line accounting for the dynamic reactive power reserve target value of the electric transmission line as the capacitive stability of the electric transmission line;
• calculating a percentage of the inductive dynamic reactive power reserve of the electric transmission line accounting for the dynamic reactive power reserve target value of the electric transmission line as the inductive stability of the electric transmission line;
• and
• calculating a percentage of the dynamic reactive power reserve of the electric transmission line accounting for the dynamic reactive power reserve target value of the electric transmission line as the stability of the electric transmission line.

A stability controlling system of a wide area power grid, comprising:

• at least one of a stability controlling system of a power plant grid and a stability controlling system of a transformer substation grid;
• a wide area measurement system of the wide area power grid;
• and
• a high-speed communication network, configured to communicate with at least one of the stability controlling system of the power plant grid and the stability controlling system of the transformer substation grid,
• wherein the wide area measurement system of the wide area power grid is configured to calculate a stability of the wide area power grid using a stability measuring method for a wide area power grid by determining a capacitive stability, an inductive stability and a stability of the wide area power grid based on a capacitive stability, an inductive stability and a stability of the power plant and a capacitive stability, an inductive stability and a stability of the transformer substation, and providing a risk early warning for the wide area power grid based on the capacitive stability, the inductive stability and the stability of the wide area power grid, and transmit total power target values of the power plant grid or the transformer substation grid and a regulating instruction of the wide area power grid to the stability controlling system of the power plant grid or the stability controlling system of the transformer substation grid through the high-speed communication network after the regulating instruction is determined, wherein the capacitive stability, the inductive stability and the stability of the wide area power grid are determined by:
• determining a minimum of the capacitive stabilities of the power plant and the transformer substation in the wide area power grid as the capacitive stability of the wide area power grid;
• determining a minimum of the inductive stabilities of the power plant and the transformer substation in the wide area power grid as the inductive stability of the wide area power grid;
• and
• determining a sum of the capacitive stability of the wide area power grid and the inductive stability of the wide area power grid as the stability of the wide area power grid,
• the wide area measurement system of the wide area power grid determines the regulating instruction of the wide area power grid by:
• S211:
• giving a minimum stability of the wide area power grid;
• regulating the stability of the wide area power grid when the stability of the wide area power grid is less than the given minimum stability of the wide area power grid;
• and
• transmitting the regulating instruction to a power plant or a transformer substation with a minimum stability in the wide area power grid to increase the stability of the power plant or the transformer substation, and stopping regulation when the stability of the wide area power grid is greater than or equal to the given minimum stability.