Method for measuring electric power value in an hvdc system

1. A method for measuring an electric power value in a high voltage DC system having an electric power conversion station, the method comprising the steps of:

receiving a current value and a voltage value, which are measured from a sensor group installed in a position of the electric power conversion station, wherein the position comprises a location selected from the group consisting of an electric power receiving side transformer part, an electric power transmission side transformer part, an electric power receiving side converter part, an electric power transmission side converter part, and a DC electric power transmission part, and combinations thereof, wherein the sensor group comprises:

a current sensor that measures the current value; and

a voltage sensor that measures the voltage value;

identifying a line impedance of the position where the sensor group is installed;

calculating a first electric power value of the electric power conversion station by using the current value and the voltage value;

calculating a second electric power value of the electric power conversion station by using the current value and the line impedance;

calculating a third electric power value of the electric power conversion station by using the voltage value and the line impedance;

comparing the first electric power value, the second electric power value and the third electric power value with one another;

identifying a measured value with a smaller measuring error between a measuring error of the voltage value and a measuring error of the current value; and

determining any one of the second and third electric power values as an actual electric power value of the electric power conversion station based on the comparing step,

wherein the step of determining any one of the second and third electric power values as the actual electric power value comprises:

determining that the second electric power value calculated based on the current value and the line impedance is the actual electric power value of the electric power conversion station if it is identified that the measuring error of the voltage value is greater than the measuring error of the current value; and

determining that the third electric power value calculated based on the voltage value and the line impedance is the actual electric power value of the electric power conversion station if it is identified that the measuring error of the current value is greater than the measuring error of the voltage value,

wherein the step of identifying the measured value with the smaller measuring error comprises:

identifying that the measuring error of the current value is greater than the measuring error of the voltage value if the third electric power value is similar to the first electric power value, and the second electric power value is dissimilar to the first electric power value and the third electric power value; and

identifying the measuring error of the voltage value is greater than the measuring error of the current value if the second electric power value is similar to the first electric power value, and the third electric power value is dissimilar to the first electric power value and the second electric power value.

2. The method according to claim 1 , wherein the line impedance comprises an impedance of a line connecting the current sensor with the voltage sensor.

3. The method according to claim 1 , further comprises a step of determining whether an operating condition of the electric power conversion station is an electric power transmission operating condition or an electric power receiving operating condition,

wherein the step of identifying the line impedance of the position where the sensor group is installed comprises a step of identifying the line impedance corresponding to the operating condition.

4. The method according to claim 1 , further comprising a step of outputting a signal requesting a change of a sensor that has measured a measured value with a greater measuring error.