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 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: The disclosure relates to phasor-based monitoring, protection and control applications in electric power systems supervised and/or managed by a Supervisory Control And Data Acquisition/Energy Management System (SCADA/EMS). In order to enable the applications without incurring heavy infrastructural investments, a phasor measurement facility is integrated into a Remote Terminal Unit (RTU) that is part of the SCADA/EMS system and comprises Input/Output (I/O) interfaces hard-wired to a substation of an electric power system. By taking advantage of the fact that RTUs as indispensable building blocks for any SCADA/EMS are part of every substation of the power system, no extra housing, cabling and EMC shielding for the additional functionality needs to be provided.

Abstract: A method, device and computer program product for the prediction of the stability of an electric power network, where the method is executed after a fault or contingency has occurred, and comprises the steps of (a) during a time interval in which the network is in a transient condition, determining for at least one load connected to the electric power network, at least one parameter describing an estimated steady state behavior of the load, (b) executing a load flow calculation for the electric power network using the least one parameter describing the estimated steady state behavior the at least one load, (c) determining, if the load flow calculation indicates stability has a solution, that a future stability of the electrical power network exists, or, if the load flow calculation indicates instability does not have a solution, that a future stability of the electrical power network does not exist.

Abstract: For the control of an electric power transmission network, where local protection functions are implemented by a plurality of local protection devices (3,3a,3b,3b?,3c) located at a plurality of locations throughout the network, the following steps are executed measuring phasor data for voltages and currents at a plurality of locations (A,B) of the network, transmitting said phasor data to a central processing device (2), emulating, in the central processing device (2), protection functions that are implemented in the local protection devices (3,3a,3b,3b?,3c), and executing, in accordance with a given redundancy strategy, control commands that are issued redundantly by the local protection devices (3,3a,3b,3b?,3c) and by the central processing device (2). In a preferred variant of the invention, values of predetermined parameters that are used in the protection function, in particular protection threshold values, are adapted to measured values.

Abstract: A method is disclosed for the identification of weak and/or strong nodes of an electric power transmission system. Electric parameters characterizing nodes and branches of an electric power transmission system are subject to computational treatment to obtain equations of power flow in all nodes of the system at assumed 100 percent system load value. Using earth as the reference point, nodal impedance values are computed for all nodes, and used to construct a P-Q curve which presents the functional relation between the system's reactive and active load. The nodal coefficient of voltage stability is determined as the relative distance between the base load point of that node and the critical point on the P-Q curve situated most closely to the base point. The coefficient is compared with a threshold value considered to be a safe margin to maintain voltage stability for a given node.

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: The subject of the invention is a method of identification of weak and/or strong branches of an electric power transmission system. In the inventive method electrical parameters characterizing the nodes and branches of an electric power transmission system are subjected to computational treatment in order to obtain equations of power flow in all nodes of the system at assumed 100 percent system load value. Then an electric model of a branch is assumed and a curve P-Q is constructed which shows the functional relation between active and reactive load in the system. For the assumed branch model a branch voltage stability coefficient is determined. Then the analysed system is overloaded by increasing the total system load up to 120% base load and the branch voltage stability coefficient is determined again. The numerical values of the appropriately determined coefficients are compared with threshold values considered to be a safe margin for the maintenance of voltage stability for the given branch.

Abstract: The inventive method assesses the stability of an electric power transmission network, where said network comprises a plurality of substations, buses and lines, and a system protection center (8). It comprises the steps of 1. measuring phasor data (9) for voltages and currents at a plurality of locations of the network, 2. transmitting said phasor data (9) to said system protection center (8), 3. transmitting information (5) regarding the state of switches of at least one substation to the system protection center (8), and 4. the system protection center (8) determining at least one stability margin value of the transmission network. In this way, detailed real-time information about the state of the network is collected at a system level of the network, allowing a corresponding global analysis of the information. In a preferred embodiment of the invention, the system protection center determines one or more control commands (6), based on the phasor data (9) and on the state of switches.

Abstract: For the control of an electric power transmission network, where local protection functions are implemented by a plurality of local protection devices (3,3a,3b,3b′,3c) located at a plurality of locations throughout the network, the following steps are executed

Abstract: In a method and system for assessing the stability of an electric power transmission network, where at least one pair of measurements including a first and a second measurement point (P1,P2), each measurement point comprising a voltage and a current phasor, is processed and where a Thévenin impedance (Zt) and a present stability margin (dS(k)) value are computed, a validity indicator (v) is computed which depends on whether there is a difference between the first and second measurement points and whether there is a difference between corresponding estimated first and second load impedances (Za). From all validity indicators (v) associated with all of the at least one pair of measurements a quality indicator (q) is computed that is associated with the Thévenin impedance value (Zt) and with the present stability margin (dS(k)). The invention allows to continuously compute and output a present stability margin (dS(k)) value and to provide a measure (q) of its quality.

Abstract: The subject of the invention is a method of identification of weak and/or strong branches of an electric power transmission system.

Abstract: The subject of the invention is a method for the identification of weak and/or strong nodes of an electric power transmission system.

Abstract: A method, device and computer program product for the prediction of the stability of an electric power network, where the method is executed after a fault or contingency has occurred, and comprises the steps of (a) during a time interval in which the network is in a transient condition, determining for at least one load connected to the electric power network, at least one parameter describing an estimated steady state behavior of the load,(b) executing a load flow calculation for the electric power network using the least one parameter describing the estimated steady state behavior the at least one load, (c) determining, if the load flow calculation indicates stability has a solution, that a future stability of the electrical power network exists, or, if the load flow calculation indicates instability does not have a solution, that a future stability of the electrical power network does not exist.

Abstract: In a method and devices for assessing the stability of an electric power network, for each of a plurality of measurement locations with associated voltage and current measurements, a normalized power margin value dSn is computed, which is defined as a result of dividing an associated power margin value by an associated maximum allowable power flow. In a preferred embodiment of the invention, the normalised power margin value dSn is computed from an apparent load impedance Za and a Thévenin impedance Zt, that are perceived from the measurement location, as 1 dSn = ( Za - Zt Za + Zt ) 2 .

Abstract: In a method and a system for maintenance planning for a technical device, a status value is in each case used to characterize a state of a technical unit. A state of a higher-level unit which has a number of subunits each having associated status values is characterized by a common status value, which is calculated as a weighted sum of the status values of the number of subunits. The common status value is used for planning maintenance tasks on the device.

Abstract: In a method and system for assessing the stability of an electric power transmission network, where at least one pair of measurements comprising a first and a second measurement point (P1,P2), each measurement point comprising a voltage and a current phasor, is processed and where a Thévenin impedance (Zt) and a present stability margin (dS(k)) value are computed, a validity indicator (v) is computed which depends on whether there is a difference between the first and second measurement points and whether there is a difference between corresponding estimated first and second load impedances (Za). From all validity indicators (v) associated with all of the at least one pair of measurements a quality indicator (q) is computed that is associated with the Thévenin impedance value (Zt) and with the present stability margin (dS(k)). The invention allows to continuously compute and output a present stability margin (dS(k)) value and to provide a measure (q) of its quality.

Abstract: The inventive method assesses the stability of an electric power transmission network, where said network comprises a plurality of substations, buses and lines, and a system protection center (8).

Abstract: In a busbar protection method and a corresponding device, the maximum values of the currents in the outgoers are determined. The maximum values Ikmax of the current characteristics are extended by a certain hold time th. Subsequently, these current characteristics are processed further vectorially. With the aid of these current characteristics Ik changed in such a way, a fault signal is calculated by means of a protection algorithm, preferably the current comparison method with current stabilization or the phase comparison algorithm. It can be uniquely determined on the basis of the extension of the maximum according to the invention whether an external fault or an internal one is concerned. The advantage of the method and of the device according to the invention resides, in particular, in that the localization of the fault is possible in a reliable fashion even in the case of strong saturation of the current transformers. Above all, false tripping can be reliably avoided even in the case of external faults.