Grid-connected inverters
Grid-connected inverters play a crucial role in decentralised energy generation. They are the key element for integrating renewable energies into our electricity grids. As a central component of photovoltaic or wind energy systems, they form the interface for converting direct current (DC) into alternating current (AC) and feeding this into the public power grid. AIT is a pioneer in the research, development and testing of innovative functionalities of such grid-connected inverters, which make it possible for a high proportion of the electrical energy supply from renewable sources to be fed into the power grid in a decentralised manner.
DEVELOPMENT OF GRID-CONNECTED INVERTERS
AIT offers comprehensive services for the development of grid-connected inverters. These include licensable technologies, hardware and software development services, development platforms for controller design and a comprehensive laboratory infrastructure for development and acceptance tests on grid-connected inverters.
Grid forming / dynamic control of grid-connected inverters
The shift in the energy mix towards renewable energy sources and increased decentralisation pose a challenge to the stability of electricity grids. In order to minimise stability problems and make energy systems more robust, grid control strategies have been developed to mimic the behaviour of synchronous generators and also to improve the emulation of flywheel masses of renewable energy generation plants. The grid-forming inverter plays a crucial role in this, and our research focuses on the development, testing and validation of advanced grid-forming control strategies for the evolving power grids.
VALIDATION OF SPECIFIED FUNCTIONS
As a prerequisite for connection to public power grids, it is often necessary to check and confirm that these inverters fulfil the required standards, norms and specifications.
Validation covers various aspects:
- Technical specifications: The technical properties of the grid-connected inverter must fulfil the defined requirements. This includes aspects such as power factor, efficiency, voltage and frequency regulation and response to grid fluctuations.
- Grid connection regulations: Compliance with national and international grid connection regulations is crucial. The aim here is to ensure that the inverter is correctly synchronised with the public grid and does not cause any interference.
- Safety standards: Validation also involves checking safety standards. This concerns both the safe operation of the inverter and the protection of persons and property.
- EMC tests: Electromagnetic compatibility tests are important to ensure that the inverter does not generate any disruptive electromagnetic emissions and at the same time is robust against external influences.
- Stability and reliability: Validation includes tests on the stability and reliability of the grid-connected inverter under various operating conditions. This also includes long-term tests to ensure performance over time.
- Test standards: International testing standards such as IEC, UL or other relevant standards are included in the validation process. Cooperation with certification bodies and compliance with these standards facilitate validation.
Validation is an iterative process that takes place both during the development phase and during series production. It ensures that the grid-connected inverters meet the highest quality and performance standards and can be easily integrated into existing power grids.
GRID INTEROPERABILITY AND COMMUNICATION
In the area of grid interoperability, comprehensive testing is carried out to ensure that all components can interact seamlessly with each other. This includes end-to-end functionality testing from the communication interface to the power supply interface using SunSpec specifications. Integration tests with external third-party devices, such as sensors, PV systems and grid operator gateways, ensure that different systems work together seamlessly. In addition, controller hardware-in-the-loop (CHIL) tests are carried out on converter controllers to check their performance and adaptability.
Our range of services:
- Interoperability testing
- End-to-end functionality tests from the communication interface to the power supply interface
- Integration tests with external devices from third-party providers
- Controller hardware-in-the-loop (CHIL) tests
GRID CODE CONSULTING AND MODELLING
In the area of grid code consulting, the focus is on expertise in global grid connection requirements. Not only are the specific requirements of individual regions taken into account, but comprehensive advice is also offered on the globally applicable standards. The development and implementation of numerical simulation models in Matlab/Simulink/SimPowerSystems® and DIgSILENT Powerfactory® enables precise modelling and simulation of grid connections. Computer simulation-based investigations are carried out to optimise smart grid applications and prepare for future challenges.
Our range of services:
- Consultancy on global grid connection requirements
- Development and implementation of numerical simulation models in Matlab/Simulink/SimPowerSystems®/PLECS and DIgSILENT Powerfactory®
- Computer simulation-based analyses for smart grid applications
SOFTWARE DEVELOPMENT AND FIRMWARE DEVELOPMENT FOR INVERTERS
Application of current software standards and development methods
- Design of the high-level software architecture
- RTOS-compliant DSP/uC firmware and FPGA-HDL code
- Development of portable application software
Standards & legal framework for inverters - international & in the EU
Compliance with national and international grid connection regulations is of crucial importance for the integration of on-grid inverters into electricity grids. Various standards and legal requirements define the requirements for safe and efficient operation.
EN 50549-1/2/10 defines the requirements for generation systems that are connected in parallel to distribution grids. In Germany, VDE AR N 4105, VDE 0124-100, VDE AR N 4110, FGW TR3 and VDE 0126-1-1 are decisive for the grid connection regulations. Austria adheres to OVE R 25.
IEC 62116 is an international standard for power-connected photovoltaic inverters and specifies test procedures to prevent the formation of islands. International test standards, such as IEC, UL 1741 and IEEE 1547.1, are available through partnerships with global certification providers.
In addition to the connection standards, EMC tests, immunity tests, safety tests and fault analyses of relevant components of power conversion systems are crucial. These tests not only ensure conformity with legal requirements, but also the robustness and reliability of on-grid inverters in different operating scenarios.
Compliance with these standards and legal framework conditions is essential to ensure the safe and efficient integration of on-grid inverters into national and international power grids.
Checking compliance with national and international grid connection regulations
Our range of services:
- EN 50549-1/2/10
- VDE AR N 4105, VDE 0124-100 (Germany)
- VDE AR N 4110, FGW TR3 (Germany)
- VDE 0126-1-1 (Germany)
- OVE R 25 (Austria)
- IEC 62116
- International test standards (IEC, UL 1741, IEEE 1547.1 etc.) available through partnership with global certification providers.
- EMC tests, immunity tests, safety tests and fault analyses of relevant components of power conversion systems
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