Abstract: The present disclosure is concerned with the reduction of an operational security margin of a power system without jeopardizing the safety of the power system or incurring heavy investments. According to the disclosure, a check for basic accuracy or correctness of a conventional State Estimation (SE) procedure allows to increase a level of confidence in the results of the procedure. To this end, an accuracy of the estimated states is verified by comparing the latter with the results (y, y?) of independent phasor measurements performed at selected locations of the power system. Unless a discrepancy is reported by this comparison, the results of the SE can be assumed to be sufficiently accurate, and any conservative or additional security margin intended to compensate for SE uncertainty can be relaxed. Hence, established trustworthiness in the estimated states allows increasing the transmitted power where the estimated states do indicate such a possibility, i.e.

Abstract: The present disclosure relates to monitoring of electromechanical oscillations in electric power systems, and their identification by an adaptive algorithm based on a repeatedly measured and evaluated signal. In order for an estimation of parameters of a model of the power system to reasonably converge, proper initialization of the recursive calculation is required, including the definition of tuning parameters constraining the model and the calculation. Initialization for a second signal to be exploited can then be simplified by copying the set of tuning parameters tuned previously for a different signal. A conditioning gain multiplying the second signal establishes compatibility between the different signals, and a signal pre-filter in turn discards contributions beyond a frequency band comprising typical electromagnetic oscillations.

Abstract: A relationship between a temperature TI of a power line or power transmission conductor, an electrical quantity of the power line such as a current I or power flow P through the power line, as well as meteorological quantities or ambient conditions of the power line such as wind speed W, wind direction, humidity, solar radiation S and ambient temperature Ta, is established in the form of a thermal model of the power line. Values of the aforementioned quantities or variables are continuously measured, and the collected values of the quantities are evaluated in order to update model parameters of the thermal model during operation of the power line. In one example, an average temperature representative of the entire line is determined via two Phasor Measurement Units (PMU) 11, 11? providing synchronized phasor values from two ends of the power line. An ohmic resistance of the power line is computed from the phasor values, from which in turn the average line temperature can be derived.

Abstract: The present disclosure relates to monitoring of electromechanical oscillations in electric power systems, and their identification by an adaptive algorithm based on a repeatedly measured and evaluated signal. In order for an estimation of parameters of a model of the power system to reasonably converge, proper initialization of the recursive calculation is required, including the definition of tuning parameters constraining the model and the calculation. Initialization for a second signal to be exploited can then be simplified by copying the set of tuning parameters tuned previously for a different signal. A conditioning gain multiplying the second signal establishes compatibility between the different signals, and a signal pre-filter in turn discards contributions beyond a frequency band comprising typical electromagnetic oscillations.

Abstract: The present disclosure is concerned with the reduction of an operational security margin of a power system without jeopardizing the safety of the power system or incurring heavy investments. According to the disclosure, a check for basic accuracy or correctness of a conventional State Estimation (SE) procedure allows to increase a level of confidence in the results of the procedure. To this end, an accuracy of the estimated states is verified by comparing the latter with the results (y, y?) of independent phasor measurements performed at selected locations of the power system. Unless a discrepancy is reported by this comparison, the results of the SE can be assumed to be sufficiently accurate, and any conservative or additional security margin intended to compensate for SE uncertainty can be relaxed. Hence, established trustworthiness in the estimated states allows increasing the transmitted power where the estimated states do indicate such a possibility, i.e.

Abstract: The present invention is concerned with a method for real-time emergency control of power transmission networks, based on a modification of the model predictive control (MPC) approach. Following the detection of a contingency at time tc only one nominal trajectory xnom is approximated, together with its corresponding trajectory sensitivities for evaluating the effect of various key parameters or potential control actions. An optimum input control is finally identified via the solution of a cost function including e.g. a punishment for excessive load shedding. The process is started only if the nominal trajectory does not remain within acceptable trajectory limits.

Abstract: A method for determining an equivalent impedance of a transmission section of an electrical network, includes representing the transmission section as having at least two interfaces with other sections of the network. For each interface, a voltage phasor and a current phasor flowing through the interface are determined from simultaneously made measurements at the interfaces. From the phasors, the equivalent impedance is calculated. The required simultaneousness of the phasor measurements is achieved by means of Phasor Measurement Units (PMUs) that are synchronized via the Global Positioning System (GPS).

Abstract: A relationship between a temperature Tl of a power line or power transmission conductor 10, an electrical quantity of the power line such as a current l or power flow P through the power line, as well as meteorological quantities or ambient conditions of the power line such as wind speed W, wind direction, humidity, solar radiation S and ambient temperature Ta, is established in the form of a thermal model of the power line. Values of the aforementioned quantities or variables are continuously measured, and the collected values of the quantities are evaluated in order to update model parameters of the thermal model during operation of the power line. In an exemplary embodiment, an average temperature representative of the entire line is determined via two phasor measurement units (PMU) 11, 11? providing synchronized phasor values from two ends of the power line. An ohmic resistance of the power line can be computed from the phasor values, from which in turn the average line temperature can be derived.

Abstract: In a method, computer program and system for determining an operational limit of a power transmission line, time-stamped current phasor information and voltage phasor information for a first end and a second end of the line are determined, an ohmic resistance of the line is computed from the phasor information, and an average line temperature is computed from the ohmic resistance. This allows to determine the average line temperature without dedicated temperature sensors. The average line temperature represents the actual average temperature and is largely independent of assumptions regarding line parameters.

Abstract: In a method, computer program and system for estimating a state of an electric power transmission network, time-stamped phasor measurements are made by phasor measurement units (1) located at a first set of locations (11,12) throughout the network, and a plurality of voltage and/or current phasors at a second set of locations is estimated, where the locations of the first (11,12) and second sets of locations are distant from one another, and a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units is inferred from the phasor measurements and the estimated phasors. In a preferred variant of the invention, the network elements are transmission lines (L1 . . . L8), switchgear, under load tap changing transformers, compensation devices (13) or FACTS devices, and the status information describes whether a network element (L4,L5,13) is electrically connected to or disconnected from the network.

Abstract: In a method, computer program and system for determining an operational limit of a power transmission line, time-stamped current phasor information and voltage phasor information for a first end and a second end of the line are determined, an ohmic resistance of the line is computed from the phasor information, and an average line temperature is computed from the ohmic resistance. This allows to determine the average line temperature without dedicated temperature sensors. The average line temperature represents the actual average temperature and is largely independent of assumptions regarding line parameters.

Abstract: The present invention is concerned with a method for real-time emergency control of power transmission networks, based on a modification of the model predictive control (MPC) approach. Following the detection of a contingency at time tc only one nominal trajectory xnom is approximated, together with its corresponding trajectory sensitivities for evaluating the effect of various key parameters or potential control actions. An optimum input control is finally identified via the solution of a cost function including e.g. a punishment for excessive load shedding. The process is started only if the nominal trajectory does not remain within acceptable trajectory limits.

Abstract: In a method, computer program and apparatus for determining parameters of an equivalent circuit representing a transmission section of an electrical network, the transmission section (4) is representable as having at least two interfaces (5,6,7) with other sections (1,2,3) of the network, and the method comprises the steps of

Abstract: In a method, computer program and system for estimating a state of an electric power transmission network, time-stamped phasor measurements are made by phasor measurement units (1) located at a first set of locations (11,12) throughout the network, and a plurality of voltage and/or current phasors at a second set of locations is estimated, where the locations of the first (11,12) and second sets of locations are distant from one another, and a status of network elements (L4,L5,13) that are remotely located from the phasor measurement units is inferred from the phasor measurements and the estimated phasors.