Industry4Redispatch Deliverable 10.3 – Guideline for TSO-DSO Interaction

Industry4Redispatch Industry4Redispatch (I4RD) Deliverable 10.3 1/12 Industry4Redispatch (I4RD) Deliverable 10.3 Guideline for TSO-DSO interaction AUTHORS Sawsan Henein [email protected] AIT Austrian Institute of Technology GmbH Helfried Brunner helfried.brun[email protected]t AIT Austrian Institute of Technology GmbH Simon Strehn [email protected] AIT Austrian Institute of Technology GmbH PROJECT MANAGEMENT AIT – Tara Esterl +43 664 8157 810 [email protected] Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 2/12 Document control information Title D10.3 Guideline for TSO-DSO interaction Dissemination Level CO Confidential, only for members of the consortium RE Restricted to a group specified by the consortium PP Restricted to other programme participants (NEFI) PU Public Status Draft WP Manager accepted Co-ordinator accepted Action requested to be revised / added to by Partners to be reviewed by applicable Partners for approval of the WP Manager (EB) for approval of the Project Coordinator Requested deadline for Action Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 3/12 TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................................................................................... 4 LIST OF ABBREVIATIONS .......................................................................................................................................................... 4 1. INTRODUCTION ............................................................................................................................................................... 5 1.1. BACKGROUND ..................................................................................................................................................................... 5 1.2. PURPOSE OF THE DOCUMENT ................................................................................................................................................. 5 1.3. RELATION TO OTHER PROJECT ACTIVITIES .................................................................................................................................. 5 1.4. STRUCTURE OF THE DOCUMENT .............................................................................................................................................. 6 2. STAKEHOLDER REQUIREMENTS ....................................................................................................................................... 6 3. TSO-DSO INTERACTION I4RD SOLUTION APPROACH ....................................................................................................... 7 4. KEY RESULTS AND CHALLENGES ....................................................................................................................................... 8 5. RECOMMENDATIONS FOR TSOS AND DSOS ..................................................................................................................... 9 6. CONCLUSION AND OUTLOOK ......................................................................................................................................... 10 7. REFERENCES .................................................................................................................................................................. 12 Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 4/12 LIST OF FIGURES Figure 1: Interaction and alignment with related work packages and tasks. .................................................................................. 6 Figure 2: Functionalities and data exchanges of the planned TSO-DSO interaction process. .......................................................... 7 LIST OF ABBREVIATIONS CGMES Common Grid Model Exchange Standard D Deliverable DS Distribution system DSO Distribution system operator FSPs Flexibility service providers OLTC On-load tap changer RD Redispatch RES Renewable energy resources SoMa Sonstige Marktregeln TSO Transmission system operator WP Work package Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 5/12 1. Introduction 1.1. Background The increased global concerns on climate change during the latest years leads the European Commission to an ambiguous goal of decarbonisation of energy systems while ensuring the safe and secure supply of energy Fehler! Verweisquelle konnte nicht gefunden werden.. To meet the requirement of this goal, a massive integration of distributed renewable energy sources (RES) is required. This increases the complexity of operational and planning activities of power systems and raises the need for effective cooperation between Transmission System Operators (TSOs) and Distribution System operators (DSOs). Concurrently, the volatile and non-dispatchable nature of variable RES create new challenges for the TSOs and DSOs who seek to secure enough flexibility resources to integrate them into the redispatch process, such as flexibility resources from industrial customers. One important aspect is the increase of the awareness of TSOs and DSOs that each flexibility activation affects the power exchanges with power flow on neighbouring networks and thus also their operating states. These actions need to be coordinated to maintain grid security, enhance network performance, and avoid violations of the operational network limits throughout the entire power system. The enhancement of the TSO-DSO cooperation requires a significant amount of high-quality data and information to be exchanged between TSOs and DSOs in an efficient and reliable procedure [1]. Flexibilities of distributed industries, usually connected at high and medium voltage distribution networks (110kV and 10/20/30kV in Austria), may be utilized to mitigate transmission network congestions, thus holding the potential to reduce redispatch costs. The activation of distributed flexibilities may cause violations of the operational distribution network constraints (asset loading and voltage limits) due to high coincidence. Therefore, a TSO-DSO interaction process is needed to provide the TSO with a day-ahead access to the most cost-effective flexibility bid combinations that maintain limit compliance at the distribution level [1]. To avoid negative interactions of the measures on other network levels or network areas, these measures must be coordinated horizontally and vertically between the grid operators. The design of network operator coordination mechanism, and the definition of requirements and challenges is therefore essential for the implementation of these measures. The I4RD project goal is to enable the integration of industrial and commercial customers supplied on the distribution level into the redispatch process at the transmission level, considering the grid constraints at the distribution level. 1.2. Purpose of the document A guideline for future TSO-DSO interaction for redispatch with flexibility from industry is drawn up through a qualitative analysis of the project results, taking into consideration all the requirements and experiences from different stakeholders especially DSOs and TSOs within the development and validation phase. In addition, experiences collected from current and previous projects are considered. 1.3. Relation to other project activities Figure 1 shows that project task 10.3, covered by this deliverable, builds on the results from WP5 (initial specification, simulation-based validation, process implementation, and detailed process specification phases). The detailed process specification and its pre-validation lay the foundation for cost-benefit-analysis from the DSO-perspective (WP7, see D7.1 [2]), for the scalability analysis (WP8), and for the proof-of-concept (WP9), and provide valuable insights for the development of these guidelines for the TSO-DSO interaction (WP10). Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 6/12 Figure 1: Interaction and alignment with related work packages and tasks. 1.4. Structure of the document Section 2 summarizes stakeholders’ requirements defined within the I4RD project. Section 3 gives insights into the developed interaction approach within I4RD project and related data exchange. Section 4 summarizes the key results and challenges. Section 5 elaborates the recommendations and guidelines for TSOs, and DSOs followed by conclusions and an outlook. 2. Stakeholder requirements Within the I4RD project, different European projects and initiatives have been reviewed to assess the existing TSODSO coordination mechanisms considering market-based and non-market-based schemes. From these projects, synergies to the I4RD project, lessons learned, and key success factors are identified (WP5, see D5.1 [3]). This served as foundation for the definition of the TSO-DSO interaction process for the Austrian Redispatch mechanism. In the course of the project, a continuous cooperation and knowledge exchange took place with working groups of the Association of the Austrian Electricity Industry (Österreichs Energie), working on the definition of TSO-DSO interaction processes to be implemented in the Austrian electricity market regulations. In addition, expert interviews were conducted within the project to gain an overview of the Austrian network operators’ requirements on the TSODSO interaction process. The identified basic requirements for the TSO-DSO interaction process are divided into four categories, i.e., fairness, practicability, accuracy, as well as scalability & replicability. Fairness comprises transparency, freedom from discrimination, and self-determination, which means that outsiders can easily understand and reproduce the coordinator’s decisions, all flexibility providers have an equal prospect to contribute to system operation, and each network operator maintains the operational responsibility for its own network. Practicability implies the use of simple, robust, and quick procedures that involve low data exchanges and avoid the exchange of sensitive and confidential data. Accuracy promotes optimal resource utilization and scalability and replicability allow for the seamless process integration of additional participants and system portions without deteriorating fairness, practicability, and accuracy. Fairness, practicability, and accuracy are conflicting requirements that must be traded off against each other. Especially, resource utilization, transparency, and privacy span a trilemma in which only two requirements can be maximized at the expense of the remaining one (WP5, see D5.1 [3]). After thorough consultations among the Austrian network operators, the project consortium concluded that a centralized, sensitivity-based bid set filtering method is the most appropriate to address Austrian stakeholder needs. The resulting core process flows reflect a balanced compromise aimed at achieving a suitable trade-off between fairness, practicality, and precision. Although simplified distribution system models reduce the accuracy of calculations, the resulting errors are considered minor considering existing modelling and forecasting uncertainties Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 7/12 as well as the limited amount of flexibility offers and capacity to be expected in short to medium term at medium voltage network level. These errors or DSOs limits violations can be avoided via the use of safety margins. Therefore, the consortium accepts these limitations in favour of promoting fairness and feasibility, which reflects the tendency of most of the European projects and initiatives which have been reviewed within the project. 3. TSO-DSO interaction I4RD Solution approach This section outlines the specification of the fundamental process flows for the TSO-DSO interaction, detailing the functions involved, their allocation among the relevant stakeholders, and the required interfaces. The process flows were developed in close collaboration with the corresponding working group from (Österreichs Energie), by addressing the requirements outlined in section 2 and the learnings from various European research projects and initiatives reviewed (WP5, see D5.1 [3]). The TSO-DSO interaction process involves three major functionalities that are executed by different parties: • calculation of the simplified Distribution System (DS) model • filtering of bid sets, and • selection of the final bid set. Local sensitivity analysis is used to derive the simplified DS model, which allows considering distribution network constraints (both voltage limits and asset loading). The DSO calculates this simplified representation of its own network and sends it to the filtering platform (see Figure 2). The platform uses optimization processes to identify meaningful bid combinations that avoid violations of the operational voltage and loading limits of branches. In the scope of the project, these bid sets are used by the network operators for RD at the transmission system level. They will also calculate the impact of the bid sets on the TSO-DSO intersections (WP5, see D5.2 [4]). Figure 22 shows the functionalities (orange fonts) and data exchanges (arrows) of the planned TSO-DSO interaction process (blue box). It shows the calculation procedure for the simplified DS model, the filtering processes, and the proposed data exchanges between different parties. Figure 2: Functionalities and data exchanges of the planned TSO-DSO interaction process. Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 8/12 The calculation of the simplified distribution system model includes initial calculation of the simplified DS model and its re-calculation after bid set selection (if redispatch at the distribution level is necessary). The DSO re-calculates the simplified DS model after receiving relevant bid sets from the platform and after selecting the most suitable bid set. This re-calculation is optional and happens only if the platform detects violations (or approaching limits) of the distribution network’s operational voltage or current limits based on the initially calculated baseline network state. In contrast to the initial calculation, the re-calculation is based on the modified industry schedules, which reflect the effects of the selected bids including the corresponding anticipatory and catch-up effects (WP3, see D3.3 [5]). The bid set filtering is the core task of the planned TSO/DSO interaction process. If redispatch is necessary the platform uses the simplified DS model to identify pareto optimal bid sets, i.e., sets with low cost and high power that do not cause any limit violations at the distribution level. These bid sets are then provided to the TSO. The TSO receives these bid sets and selects the most suitable one by solving an optimal power flow problem that respects the transmission constraints. Pareto optimal bid sets give the optimal solution of DSO level for any specific TSO redispatch demand and can therefore be used at the transmission level without violating distribution network constraints. The proposed data exchange between different parties is a vital part of the planned TSO-DSO interaction process. Sets of data must be transmitted between the participating project partners and the data exchanges must be facilitated within a suitable IT infrastructure. The main exchanges for this process are the DS capacities, i.e., the simplified DS model, the redispatch bids provided by the flexibility service providers, and the communication of the pareto optimal bid sets to the TSO. These bid-sets should be generated for every distribution grid area. The interaction process should bundle the bid sets in a data-exchange format which contain information about • the distribution grid area associated with the list of bid-sets • the respective price-volume curve of bids-sets ranging from the maximum power reduction up to the maximum infeed • the list of bids associated with each point in the price-volume curve Besides the consideration of grid capacity constraints, the TSO-DSO interaction also requires other data exchanges that are outside the scope of the project but should be listed, nonetheless. • Schedules of power generation and load are the basis for grid security analysis and capacity calculation. Any schedules required to perform the capacity calculation are exchanged within the existing framework for the exchange of schedules in accordance with Austrian electricity market rules (Sonstige Marktregeln - SoMa [6]). • Measurement data for ex-post validation will not yet be harmonized but exchanged manually after the demonstration was completed. 4. Key Results and Challenges Flexibilities of distributed industries, connected at the distribution networks, can be a useful tool to mitigate transmission system congestions, thus holding the potential to reduce redispatch costs. The activation of flexibilities on the distribution level may cause violations of the operational distribution network constraints (loading and voltage). Therefore, a TSO-DSO interaction process is needed to provide the TSO with a day-ahead access to the most cost-effective flexibility bid combinations that maintain limit compliance at the distribution level. This process shall be fair, practicable, accurate, scalable, and replicable. Confidentiality of the DSOs, transparency, and short calculation times are integral part of these requirements. The presented TSO-DSO interaction process improves fairness and practicability at the expense of accuracy by using the simplified DS model. It considers the constraints of distribution systems by transparent bid set filtering without requiring detailed distribution system information. Industry4Redispatch (I4RD) Industry4Redispatch (I4RD) Deliverable 10.3 9/12 The proposed sensitivity-based distribution system model allows calculating the states of network elements for a specific bid combination, while reducing calculation times (compared to full power flow simulations) and supporting confidentiality of DSOs and transparency to an acceptable degree. Its accuracy depends on the linearity of the distribution system and the bidden power. Within the project activities the proposed solution has proven its feasibility in the demonstration activities (WP8, see D8.1 [7]). This is true for flexibility resources located at the 110kV distribution system level, in particular. At this voltage level both accurate system models, even implemented in SCADA systems, and the provision forecasts at costumer level is already state of the art. Distribution systems contain several sources of non-linearity, including networkand control-related ones. Networkrelated non-linearities arise from branch resistances and spatial voltage magnitude and angle variations, thus increasing from the high to the low voltage level. Control related non-linearities are relevant when distributed energy resources are controlled to adapt their (active/reactive) power contributions depending on the distribution network state. This is one of the challenges to be tackled in the next decade, when more and more flexibility providers as well as flexibility capacities are going to be located at medium voltage level. As also proven by the industry (WP3, see D3.4 [8]) it is not expected to see high numbers and capacities of flexibility provision from small and medium size industry widely spread in Austrians medium voltage networks in short-term. The sensitivity-based model supports the precise detection of limit violating bid combinations in the analysed synthetic distribution system when accurate forecasts of the loading on the network are available, and bids have unity power factors, indicating almost linear relations between the network state (node voltages / branch loadings) and active power changes of flexibility providers is almost linear in the regarded system. However, the linearity of any real distribution system should be analysed prior to implementation and re-evaluated after network reinforcements/expansions and adjustments of the applied controls. 5. Recommendations for TSOs and DSOs A set of recommendations should be considered by TSOs and DSOs to be able to join the proposed redispatch process and facilitate the interaction between TSOs and DSOs. These contribute to the further enhancement of the interaction process on the long term. Forecasting: Forecasting procedures for industrial loads need to be established and introduced by the FSPs. They are already established at 100-kV-level and need to be extended to medium voltage level connected loads with increasing numbers and capacities of flexibility providing resources located there. At medium voltage level it needs to be a combination of forecasts provided by FSPs (both at individual customer level and aggregated starting from medium voltage level) as well as DSO forecasts for non-flexibility providing loads and generators including aggregation. Network, load and generation models: Respective grid models need to be made available and a procedure to collect and process the corresponding data needs to be established. At medium voltage level this will be simplified and aggregated modules. The requested degree of detail of the grid model is going to depend on the number and capacity of flexibility providing industry and existing grid capacity in the specific grid area. Capacity data must be transmitted for an entire business day. Depending on the resolution of congestion forecasting processes, capacity data can be calculated at different time resolutions. At the moment an hourly resolution is foreseen and a change towards 15minute intervals needs to be anticipated for the future, which is unlikely to happen any time soon even at transmission level. The future international procedures only foreseen 1h resolution. A data format for capacity exchange should consider that the interaction process may benefit from a transmission of bundled timeseries, describing the entire business day or a selected period thereof, instead of individual files. In case of I4RD, already used data format for capacity information which exists in the international TSO processes. Identification of constraints: Distribution system operators need to be aware of the most critical situations and actual constraints in their supply areas. The data format shall cover asset loading and voltage constraints. Additionally, the format should be able to represent general linear constraints by a DSO to account for any