Dynamic voltage stability thanks to new control concepts
In particular, the ability of rural low-voltage grids to absorb decentralised electricity generation is currently largely limited by the need to maintain the permissible voltages according to DIN EN 50160. The thermal load limits for operating equipment can only be solved by the use of storage systems, down-regulation or by expanding the grid. In contrast, further technical options are available for voltage limit violations. These are already being tested in individual pilot projects and the first products are already available on the market. However, the technical and economic criteria used are still largely unclear.
During the course of the LISA research project (Guidelines for integrating voltage-stabilising applications), the interaction between the different voltage-maintaining measures will be analysed for the various grid situations and the resulting strategies integrated in a joint control concept as well as in guidelines for applying and using the different measures. The control concept shall also reliably coordinate previously autonomous voltage regulators at the different grid levels, optimise the non-stationary system behaviour and ensure stable voltage regulation. A plan to build and deploy hybrid communication networks enables the selection and installation of a communications infrastructure appropriate for the regulation. To verify the results, laboratory tests are planned for selected system configurations using real system components, since it is only in this manner that the actual interaction can be verified beyond doubt. Finally, the system components shall be implemented in actual grids belonging to the Pfalzwerke utility company and their behaviour theoretically predicted with the help of the guidelines shall be verified in practical tests.
Guidelines for making sensible use of the technical possibilities
Based on the findings resulting from the systematic investigation of the various concepts and their possible applications, corresponding recommendations for using the options shall be derived in the form of guidelines. These guidelines are intended to enable practitioners at the network operators to find technically and economically optimal solutions, without high analytical expenditure, for their specific circumstances. At the same time, the project is also intended to provide the manufacturers of the equipment and control systems with information for further development. This particularly concerns the control concepts for coordinated voltage regulation across the grid levels. In addition, it is also intended to develop a plan for hybrid communications networks to connect the different mechanisms for stabilising the voltage in the distribution grid, which will then be incorporated into the guidelines. The individual aspects will then be verified in a practical test in the grid belonging to Pfalzwerke Netz AG.
During the course of the project, the interaction between the different voltage stabilising measures for the various grid situations will be analysed and the resulting strategies integrated in a joint control concept as well as in the described guidelines. A hybrid communications infrastructure has not yet been tested in the combination forms. Exciting is the question as to what happens if the communication between the equipment fails?
Important findings on route to a smart grid
The findings for solving the voltage stability problems represent an important step in integrating renewable energy into the electricity grids and thus transforming the current energy supply into a smart grid.
The main innovation of the approach is the development of guidelines with recommendations for the coordinated use of voltage-stabilising measures in low-voltage grids. A systematic analysis is therefore being carried out for the first time which will assess existing individual technical measures for stabilising the voltage according to their performance capability in different network topologies.
The control concept will be able to coordinate different, already partially tested technical methods for stabilising the voltage within the same low-voltage grid and to harmonise them so that optimum grid control is ensured. For the first time it will be possible to use the respectively most appropriate mechanism for regulating the voltage at different points in the grid without the regulation "conflicting" with other controllers. Possible stability risks will be identified in dynamic simulations and included as framework conditions for designing the guidelines. This therefore offers the highly promising prospect of being able to reduce the total expenditure required to regulate the voltage in distribution grids.
In addition, concepts for developing hybrid communications infrastructures are being developed for the first time that reflect the different requirements for controlling the various methods for ensuring voltage stability. The resulting insights for developing hybrid communication networks will be integrated in the guidelines and also verified in the corresponding field structures.
The sub-projects in the joint project
Economic and technical analysis of the technical alternatives using real and artificial grids based on system simulations
Design of the system consisting of primary technical equipment as well as measurement, control and communications devices
Component and system tests in the testing facility
Field trials in actual grids
The tasks of the project partners at a glance
Pfalzwerke - Project management; coordinating the collaboration between the project partners; communications and measurement technology; defining the measurement campaign, system security, communicative connection of a backend system, recommendations for the communicative development of the grid; technical economic evaluation
Pfalzwerke Netz AG - Defining user scenarios, load flow analysis of real grids, stability analysis of the control concept, implementation and testing phase, recommendations for the communicative development of the grid; laboratory and field testing; technical economic evaluation
A. Eberle GmbH & Ca. KG - Analysing communications requirements and technical options; defining the measurement campaign, system security, laboratory and field testing; technical economic evaluation
IDS GmbH - System concept, laboratory and field testing; technical economic evaluation
Power Plus Communications AG - Communications and information technology infrastructure; analysis of the communication requirements, recommendations for the communicative development of the distribution grids; laboratory and field testing; technical economic evaluation
TU Kaiserslautern - Reviewing state of scientific knowledge, defining scenarios, analysing technical options, system simulations, field testing, comparative assessments
Forschungsgemeinschaft für Elektrische Anlagen und Stromwirtschaft - Reviewing state of scientific knowledge, defining scenarios, analysing technical options, system simulations, field testing, comparative assessments
The preliminary findings are expected at the end of 2015.
09/2014 - 02/2017
67061 Ludwigshafen am Rhein, Germany