Jg Han Slootweg

Impact of electrification of residential heating on loading of distribution networks

For network planning and analysis, future residential loads are mostly modelled based on historical data combined with an estimated load increase. However, new technologies arise which change the current residential loads substantially. One of these changes is the electrification of residential heating by (large-scale) application of micro combined heat and power (micro-CHP) and heat pumps. There is not much known about the actual impact of micro-CHPs and heat pumps because the amount of applications is still small. In this paper measurements are analysed and models are presented to estimate the (aggregated) peak and day profiles for one or more of these appliances. It is shown that the modelled profiles are a good representation of the generation and load profiles of micro-CHPs and heat pumps. The profiles can be used for network planning and impact studies of residential heating on the electricity distribution networks.

Smart Grids Put into Practice: Technological and Regulatory Aspects

The transition towards a more sustainable energy supply system causes changes in the supply and demand of energy and requires more flexible and efficient operation of the electricity distribution grids. It calls for smart grids with embedded intelligent control to incorporate electricity storage and controllable loads. This will ensure cost-effective development of an efficient and reliable electricity system that allows the large-scale integration of distributed generation. A holistic approach is needed to realise these smart grids. The different issues which need to be addressed to make smart grids a successful reality are covered in this article. First, the most important issues from a technological viewpoint are identified. However, adapting the grids to future developments goes far beyond simply developing and implementing technologies. Changes in technological systems affect the institutional design applied in those systems. An integral view of technical, institutional, economic and social aspects is needed to realise steps towards putting smart grids into practice. This article highlights the needed changes towards smart grids from the technological perspective of a Dutch distribution system operator (DSO) and elaborates on the implications of these changes for the regulation for this sector.

Load shifting potential of the washing machine and tumble dryer

Various smart grid pilots are being initiated worldwide to explore the flexibility in electricity demand of households. The potential flexibility of appliances can be unlocked using either manual or (semi-)automated demand response. In the Dutch smart grid pilot Your Energy Moment the effect of demand response is studied. The participating households are equipped with a smart washing machine or smart tumble dryer. These appliances can be used to manually respond to the dynamic tariff applied in the pilot, or cycles can be programmed to automatically respond to price fluctuations. Based on the pilot results, the total load shift of the washing machine and tumble dryer is quantified. Subsequently, the effect of the program function is studied, focusing on the use of this function and on the flexible hours provided for the schedule horizon. The results show that the load of the smart appliances is shifted in time. This load shift is a consequence of both manual and semi-automated load shift. The latter, semi-automated load shift related to the use of the program function, is however limited. Both the measured manual and semi-automated load shift did not change over time, indicating a structural change in behavior.

Demand side management of electric boilers

In this paper a control strategy for demand side management of electric storage water heaters is presented. The proposed algorithm reduces load variations, during any given optimization period, taken into account the base load. The algorithm uses the energy consumption model of the water heater as an input. The strategy can be applied to optimize present control strategies based on the existing ripple control technology, in order to improve the performance of the power system.

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.

Evaluating impact of new technologies on low voltage grids using probabilistic data enriched scenarios

In this paper a scenario-based method for long term load forecasting is proposed that incorporates the uncertainty and diversity in adoption of future developments in the evaluation and planning process of low voltage grids and that is able to account for local differences in expected loading. The approach incorporates the influence of local parameters in the scenarios using logistic regression based on data gathered from different sources. The method can be used to assess the resilience of low voltage grids under various different scenarios and assists grid planners in making informed investment decisions under uncertainty. It is designed such that it is open for addition of extra parameters and data to increase its robustness against a changing environment.

Incorporating the smart grid concept in network planning practices

Ongoing developments in the electricity system are changing the requirements for planning and design of distribution networks. Based on field research at several Dutch distribution network operators a conceptual planning process is defined and current practices in distribution network planning in the Netherlands are investigated. Currently mainly traditional deterministic approaches are applied, but the increased focus on efficiency and optimal utilisation of existing grids leads to the exploration of more detailed methods. So far, the uncertainties in costs and benefits and the absence of clear legislation hinder the incorporation of smart grid technologies in routine network planning.

Investigation of failures of low voltage grid components

Distribution System Operators (DSOs) in the Netherlands are generally more focused on Medium Voltage (MV) grids than on Low Voltage (LV) grids as higher voltage levels contribute more to the SAIDI. However increasing interruption times, increasing costs and the energy transition on LV level encourage the DSOs to focus on LV grids as well. A first step is the investigation of failures in LV grid components. In this paper a literature review on this topic is presented and the outcomes are discussed. It is concluded that the method of modelling of ageing components on MV level cannot be applied to LV level because of the absence of temperature-related and electric stresses in LV components. In addition the possibilities for diagnostics are limited due to attenuation of electric signals. Although statistical methods are currently used for condition assessment of distribution grids, the LV level remains partly unspoilt terrain. However there remain some challenges related to data availability and quality. The use of statistical methods is investigated in further research in order to be able to perform condition assessment on LV level.

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.

Distribution automation at Enexis: a case study

This chapter will describe in detail the DA concept developed by Enexis, and will explain which steps have been taken. The main lessons learned will be presented. Afterwards the preparation of the large-scale roll-out and the impact of DA on the organisation of the DSO will be described. Finally the findings after automation of more than 1000 substations will be given.