- AG C4.1: Strategic Directions
- AG C4.2: Institutional Liaison
- AG C4.3: Tutorials and Conferences
- JWG A1/C4.52 Wind generators and frequency-active power control of power systems
- JWG A2/C4.309 Electrical Transient Interaction between Transformers and the Power System
- JWG A2/C4.52 High-frequency transformer and reactor models for network studies
- JWG A3/B5/C4.37 System conditions for and probability of Out-of-Phase
- JWG B4/B1/C4.73 Surge and extended overvoltage testing of HVDC Cable Systems
- JWG B5/C4.61 Impact of Low Inertia Network on Protection and Control
- JWG C1/C4.36 Review of Large City & Metropolitan Area power system development trends taking into account new generation, grid and information technologies
- JWG C2/C4.37 Recommendations for Systematic Framework Design of Power System Stability Control
- JWG C4.24/CIRED Power Quality and EMC Issues Associated with Future Electricity Networks
- JWG C4.31/CIRED EMC between Communication Circuits and Power Systems
- JWG C4.40/CIRED Revisions to IEC Technical Reports 61000-3-6, 61000-3-7, 61000-3-13, and 61000-3-14
- JWG C4.42/CIRED Continuous assessment of low-order harmonic emissions from customer installations
- JWG C4/B4.38 Network Modelling for Harmonic Studies
- JWG C4/B4/C1.604 Influence of Embedded HVDC Transmission on System Security and AC Network Performance
- JWG C4/B5.41 Challenges with series compensation application in power systems when overcompensating lines
- JWG C4/C6.29 Power Quality Aspects of Solar Power
- JWG C4/C6.35/CIRED Modelling and dynamic performance of inverter based generation in power system transmission and distribution studies
- WG C4.111 Review of LV and MV Compatibility Levels for Voltage Fluctuation
- WG C4.112 Power Quality Monitoring in Flexible Power Networks
- WG C4.206 Protection of the High Voltage Power Network Control Electronics Against Intentional Electromagnetic Interference (IEMI)
- WG C4.207 EMC with communication circuits, low voltage systems and metallic structures
- WG C4.208 EMC in HV Substations and Generating Stations
- WG C4.23 Guide to Procedures for Estimating the Lightning Performance of Transmission Lines
- WG C4.25 Issues related to ELF Electromagnetic Field exposure and transient contact currents
- WG C4.26 Evaluation of Lightning Shielding Analysis Methods for EHV and UHV DC and AC Transmission-lines
- WG C4.27 Benchmarking of Power Quality Performance in Transmission Systems
- WG C4.28 Extrapolation of measured values of power frequency magnetic fields in the vicinity of power links
- WG C4.30 EMC in Wind Generation Systems
- WG C4.303 Pollution and Environmental Influence on Electrical Performance
- WG C4.305 Practices in Insulation Coordination of Modern Electric Power Systems Aimed at the Reduction of the Insulation Level
- WG C4.306 Insulation Coordination of UHV AC systems
- WG C4.307 Resonance and Ferroresonance in Power Networks and Transformer Energization Studies
- WG C4.32 Understanding of the Geomagnetic Storm Environment for High Voltage Power Grids
- WG C4.33 Impact of Soil-Parameter Frequency Dependence on the Response of Grounding Electrodes and on the Lightning Performance of Electrical Systems
- WG C4.34 Application of Phasor Measurement Units for monitoring power system
- WG C4.36 Winter Lightning – Parameters and Engineering Consequences for Wind Turbines
- WG C4.37 Electromagnetic Computation Methods for Lightning Surge Studies with Emphasis on the FDTD Method
- WG C4.39 Effectiveness of line surge arresters for lightning protection of overhead transmission lines
- WG C4.407 Lightning Parameters for Engineering Applications
- WG C4.408 Lightning Protection of Low-Voltage Networks
- WG C4.409 Lightning Protection of Wind Turbine Blades
- WG C4.410 Lightning Striking Characteristics to Very High Structures
- WG C4.43 Lightning problems and lightning risk management for nuclear power plants
- WG C4.44 EMC for Large Photovoltaic Systems
- WG C4.45 Measuring techniques and characteristics of fast and very fast transient overvoltages in substations and converter stations
- WG C4.46 Evaluation of Temporary Overvoltages in Power Systems due to Low Order Harmonic Resonances
- WG C4.47 Power System Resilience (PSR WG)
- WG C4.48 Overvoltage Withstand Characteristics of Power System Equipment 35-1200 kV
- WG C4.49 Multi-frequency stability of converter-based modern power systems
- WG C4.50 Evaluation of Transient Performance of Grounding Systems in Substations and Its Impact on Primary and Secondary Systems
- WG C4.501 Numerical Electromagnetic Analysis and Its Application to Surge Phenomena
- WG C4.502 Power system technical performance issues related to the application of long HVAC cables
- WG C4.503 Numerical techniques for the computation of power systems, from steady-state to switching transients
- WG C4.603 Analytical Techniques and Tools for Power Balancing Assessments
- WG C4.605 Modelling and aggregation of loads in flexible power networks
JWG C4/C6.35/CIRED Modelling and dynamic performance of inverter based generation in power system transmission and distribution studies
Background:
In recent years there has been much effort on the development of models for renewable generation sources (RES), primarily associated with wind generation1. However, further work is needed and some attention is now starting to be devoted to photovoltaic (PV) systems. Very little validation work has been done for the PV models up to this point. Thus, in general there is still a lack of validated and generally accepted dynamic electrical simulation models particularly for PV, for use in large system dynamic studies. Current trends towards integration of an increasing range of generation technologies widely differing in size and number poses serious concerns in the industry on how to represent these new technologies in power system network simulations. In fact, not only is there a lack of validated dynamic computer models of individual generating technologies, such as photovoltaics, fuel cells, micro turbines and other inverter based sources, but also there is no agreed methodology on how to represent or aggregate the enormous generation in large system dynamic studies, focusing on both local (distribution level) and widespread (transmission level) disturbances. Furthermore, as the penetration of such inverter based generation technologies increases, various aspects of the power system stability and dynamic performance may change. For example in the extreme where for certain island systems there is the potential for the system to have nearly 100% penetration of inverter based generation, in certain future scenarios, a phenomena such as rotor angle stability is no longer relevant. Also protection systems are heavily impacted by high penetration of inverter based generators. The abovementioned increased penetration of distributed energy resources (DER) also makes system operation more challenging than in the past, both for transmission system operators (TSOs) and distribution system operators (DSOs). Already in some areas the fulfillment of the consumers’ need is mostly achieved by generation which is connected directly to the distribution system; in the near future, this may become the norm. From a technological viewpoint, as already mentioned, most of these new generators use power electronic converters to interface to the grid, with completely different dynamic characteristics compared to the classical synchronous generators. TSOs routinely run dynamic time-domain simulations to assess the stability of the system. Models which are currently used to represent distribution systems are only based on a limited amount of information, generally related to the HV network, taking into account the lower voltage level contribution through the power exchange which has been historically measured at the HV-MV boundary or through the installed transformation power in any given substation. DSOs have a representation of their networks and have details about connected users and producers to some extent; however, this data is generally not suitable for dynamic simulations for either the distribution or transmission systems or, at least, has not been used for that purpose in the past, due to there being too high a level of detail. From the point of view of DSOs dynamic simulations may also now be necessary to focused on assessment of protection system behavior, distribution network automation operation, uncontrolled islanding of part of distribution systems sustained by DER, voltage issues, etc. Time-domain domain simulations may be needed for this purpose but, in order to run them, extremely accurate models of loads and generators, based on the features of real components, must be available. Being able to define detailed models for time domain simulations and, starting from these, simplified and reduced models would support the need of DSOs for representation of dynamic behavior of individual distribution systems (or parts of it), including embedded generation and load in a schematic and conventional way with acceptable adherence to the reality, as well as TSOs needs of managing a more complicated system than they were used to, also increasing the awareness of DSOs and single network users about the impact of distribution network design and of the dissemination of resources and consumption.
Scope:
Based on the aforementioned background, the aim of this WG is to address the following issues: 1. Provide critical overview of existing RES dynamic electrical simulation models and modeling methodologies, focusing primarily on photovoltaics and some other inverter-based sources, and their relevant parameters for both distribution and transmission system studies. Generation technologies for which adequate dynamic electrical simulation models are presently missing or not completely appropriate for the expected purposes will be identified. Reference will be made, and coordination done, with existing groups such as the IEC and WECC groups in an effort to briefly summarize, with reference, such working already in process to avoid duplication of effort. Suggestion will be made on improvements to the models and modeling methods as appropriate. 2. Develop a set of recommendations and step-by-step procedures for RES dynamic electrical simulation model development and validation for different types of large system dynamic studies (mainly small and large disturbance studies). 3. Provide recommendations on developing equivalent dynamic electrical simulation models of clusters of same and different types of RES technologies. 4. Provide an overview of potential new system performance issues that may arise as a result of very large penetration of inverter based generation (and load) technologies. Also, note that the models for distributed generation will be aggregated models as seen at the MV-LV and HV-MV transformations and should try to take into account: − extension, configuration and composition (bare conductors, cables, etc.) of the LV and MV networks; − contribution of embedded generation (type of plants, installed capacity, built-in protective relays, regulation capabilities and settings, etc.); − automated operation and/or protection systems such as load-shedding functionalities, self-healing characteristics, etc. − islanded operation on MV network. The characterization of loads is also important in these activities, but much of this work has already been done and soon to be completed by the WG C4.605 Modelling and aggregation of loads in flexible power networks. Therefore, any additional work done in this regard should be minimal and with reference primarily to the WG C4.605 work. The above scope is perhaps too large for a single Technical Brochure (CIGRE TBs are to be generally kept to around 100 pages). Therefore, the co-conveners will at the outset of the work identify the breakdown of the work into two subgroups which will each be responsible for one of the two Technical Brochures. The two documents should be complementary and the groups should work together to ensure consistency and to merge the experiences of transmission and distribution experts.
Deliverables:
A summary paper that will be published in Electra as well as two (2) detailed Technical Brochures to be published by CIGRE.
Co-Convenor: Koji Yamashita (Japan), Herwig Renner (Austria)