N Niels Blaauwbroek

Local market framework for exploiting flexibility from the end users

This paper introduces a decentralized implicit interaction framework for trading flexibility available from proactive end users (prosumers) in an economically-efficient way. The proposed framework consists of two mechanisms: ahead planning via markets and real-time dispatching. The ahead, market-based planning includes two mechanisms, day-ahead and intra-day, which are operated by a local flexibility market operator. Each local market seeks to adjust the energy programs before they will be forwarded to the wholesale energy market such that, if accepted, the programs will result in no congestion issues in the distribution grid. The real-time dispatching consists of a set of control actions that are determined and implemented by the DSO to resolve a network congestion issue, should the market-based planning fail. The second part of the paper focuses on establishing a strategy for the DSO to procure the flexibility it needs from the above-mentioned day-ahead and intra-day markets, as well as through real-time dispatching, at the lowest possible cost. To this end, a hierarchical, bi-level optimization problem is proposed, which is mathematically proven to yield the optimal bidding strategy (including prices and volumes) for the DSO.

Data acquisition and processing for power hardware-in-the loop simulations of LV distribution feeders

The expected development of grid monitoring applications and control functionalities in low voltage distribution networks calls for advanced simulation tools for performance assessment of these applications. Power hardware-in-the-loop simulations form a cost effective approach to accurately capture the (dynamic) system behaviour. This paper describes the development of a data acquisition and processing system that enables power hardware-in-the-loop simulation of a real physical feeder within a larger simulated three-phase low voltage network simulated in real-time. With the aid of the data acquisition and processing system, the performance of newly developed monitoring and control applications can be assessed and evaluated in terms of accuracy, speed and effectiveness. To this extend, the paper shows how the data acquisition and processing system is implemented and discusses the possibilities that it creates for verifying newly developed applications for distribution grid automation.

Applying demand side management using a generalised three phase grid supportive approach

Demand side management is often seen as a promising tool for distribution network operators to mitigate network operation limit violations. Many demand side management applications have been proposed, each with their own objectives and methodology. Quite often, these demand side management applications do not have a direct interface with the network monitoring applications of the network operator, and therefore are not always capable of resolving operation limit violations effectively. Besides, for network operators it can be difficult to deal with the various types of demand side management applications run by different aggregators or energy suppliers. Therefore, this paper proposes a generalised three phase grid supportive demand side management approach for distribution networks, establishing a new interface between the monitoring and network analysis tools of the network operator and the demand side management application. Using the network sensitivity, independently of what objective de demand side management application pursues, the demand side management application will be able to resolve network operation limit violations as specified by the network operator. A case study based on fair power sharing shows the applicability of the proposed approach for mitigating over and under voltages as well as over currents simultaneously, followed by recommendations for future work and conclusions.

Conceptual framework and simulation platform for reliable distribution grid monitoring and control with market interaction

In order to maintain reliability and reduce uncertainties in the operation of the distribution network caused by a large penetration of distributed generation and energy intensive appliances, monitoring capabilities of distribution networks need to be improved for the deployment of proper control actions. This paper proposes a conceptual framework for securing network operation by enhanced monitoring and control applications by taking market aspect into account. A simulation platform is proposed for the performance assessment of the monitoring and control applications, which will reveal how their accuracy is affected by the reliability of the measurement equipment and the communication system, as well as the interaction with the energy markets.

Multi-agent scheme to handle flexible loads on low voltage distribution grids

The large scale integration of electric vehicles and distributed energy resources on low voltage grids might cause serious problems related to, for instance, under/over voltages and line overloading. In order to cope with these problems, this paper presents a multi agent system (MAS) developed to dynamically schedule flexible loads on low voltage grids, preventing operation limit violations. Since different geographical positions of the loads in the grid will cause a different impact on the grid, load flow calculations are used to indicate operation limit violations. The application uses a decentralized algorithm which ensures similar chances of being scheduled to the customer loads using a priority scheme. A case study is carried out on a 70-bus feeder where electric vehicle loads are scheduled to prevent under voltages, showing the applicability of the approach.

Branch current state estimation of three phase distribution networks suitable for paralellization

The evolution of distribution networks from passive to active distribution systems puts new requirements on the monitoring and control capabilities of these systems. The development of state estimation algorithms to gain insight in the actual system state of a distribution network has resulted in a wide range of distributed and decentralized algorithms that make use of parallel computing to deal with scalability and improve computational efficiency. From these state estimation algorithms, the branch current based state estimation has been proven suitable for distribution networks in terms of computational performance and convergence, but suffer from the fact that nodal voltage calculations are required within each iteration of the state estimation algorithm. This is usually accomplished using a forward sweep from the slack node, but this method is not suitable for parallelization. Therefore, this work proposes to replace the forward sweep with a Newton-Raphson optimization for calculating the nodal voltages, which is suitable for parallelization. The applicability of using Newton-Raphson for calculating nodal voltages within the state estimation is proven using numerical results, which clears the way for future work to implement the Newton-Raphson method within state estimation in a parallelized approach.