Study on the curative HVDC congestion management of the German TSOs

Abstract:
In order to reduce costly preventive measures, curative system management could enable higher utilization of the existing extra-high and high-voltage grid. This paper presents the state of the art for integrating curative grid operation for the German transmission system operator from a network planning perspective. The effects of the curative use of hvdc are shown using various objective functions. In today's power system operations, (n-1) security takes a preventive approach to maintaining system security. The system is operated in such a way that no outage event leads to an overload of the transmission network. To avoid n-1 violations, preventive redispatch, for example, is used in operational planning, resulting in increasing congestion removal costs. With the introduction of power flow-controlled resources such as high-voltage direct current (HVDC), where the power flow is not set automatically, as in the three-phase grid based on impedance ratios but is specified by default values for the control or regulation of the converter stations. These power flow control options can be used to increase the security and efficiency of transmission system operation. New degrees of freedom are opened for grid operation management and ensuring system security.The use of curative congestion management measures is an innovative approach to more efficient help and higher utilization of the existing transport capacities of the power grids. "Curative system management" is understood as reactive network congestion management, which solves network congestion only after it has occurred following a fault event. This is seen as having a high potential for reducing congestion management costs. The German TSO TransnetBW is pursuing the goal of testing curative grid operation management and integrating it into grid operations. This results in the necessity to integrate the new procedure into the existing congestion management process as well as to adapt the existing optimization function to the new curative concept. The proposed paper is organized as follows: Section I. gives the state of the art today network option, a short future development is given, focus is on the key processes and the relevant modules, this is categorized in grid planning, operational planning as well as real time grid operation. Based on this, a brief introduction of the main aspects of corrective operation management is given in Section II. Then, in Section III., the typical optimization functions are compared using a numerical case study. Accordingly, the results are discussed in Section IV.