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Frederiksberg, Denmark

Hansen J.Z.,Danish Energy Association
IET Conference Publications | Year: 2013

In this paper is given an overall assessment of the condition of the medium voltage XLPE cable population in Denmark. The assessment is based on results from Danish failure statistics. It is concluded that there are no significant signs of an increasing failure rate for dry-cured XLPE cables after a service time of a least 30 years. It is also shown that a large part of the failures take place while the system is operated at elevated phase-to-earth voltage on sound phases due to an earth fault somewhere in the system. An analysis also shows that the systems often are operated with an earth fault in 30 minutes or more before the XLPE cable failure occurs, which is interesting when comparing to recommended test duration for power frequency testing of MV cables.

Biegel B.,University of Aalborg | Andersen P.,University of Aalborg | Stoustrup J.,University of Aalborg | Hansen L.H.,DONG Energy | Tackie D.V.,Danish Energy Association
Proceedings of the American Control Conference | Year: 2013

We present an architecture for an unbundled liberalized electricity market system where a virtual power plant (VPP) is able to control a number of distributed energy resources (DERs) directly through a two-way communication link. The aggregator who operates the VPP utilizes the accumulated flexibility of the DERs to participate in the electricity market on equal terms with conventional power plants. The focus of this paper is the interface between the DERs and the VPP: this interface must enable the aggregator to overview the total DER flexibility and remote control the DERs to provide a desired accumulated response. In this paper, we design such an information model based on the markets that the aggregator participates in and based on the flexibility characteristics of the remote controlled DERs. The information model is constructed in a modular manner making the interface suitable for a whole range of different DERs. The devised information model can serve as input to the international standardization efforts on DERs. © 2013 AACC American Automatic Control Council.

Biegel B.,University of Aalborg | Hansen L.H.,DONG Energy | Stoustrup J.,University of Aalborg | Andersen P.,University of Aalborg | Harbo S.,Danish Energy Association
Energy | Year: 2014

A transition from an oil and coal based energy system to a systems based on renewable and sustainable energy sources has begun in many countries throughout the developed world. As a pioneer, Denmark currently has a wind energy penetration of 30% in the electricity sector and an end goal of 100% renewables in all energy sectors by 2050. The main elements in this transition are an increase in the wind energy production and electrification of main energy sectors such as transport and heating. Activation of flexible consumption in the electricity markets is believed to be one of the means to compensate for the growth of fluctuating renewables and the decrease of conventional power plants providing system-stabilizing services. In this work, we examine the requirements for flexible consumption to be active in the spot market and the regulating power market in the Nordic system and estimate the costs of entering these markets; further, we briefly describe the debated and planned changes in the electricity market to better accommodate flexible consumers. Based on recent market data, we estimate the revenue that flexible consumers can generate by market entry depending on the capacity of the consumers. The results show that consumers should have an energy capacity in the magnitude of 20-70kWh to break-even in the spot market, while a capacity of 70-230kWh is required in the regulating power market under current regulations. Upon implementation of the debated and planned market changes, the break-even capacity will decrease significantly, possibly to an energy capacity as low as 1kWh. © 2013 Elsevier Ltd.

Biegel B.,University of Aalborg | Westenholz M.,Better Place | Hansen L.H.,DONG Energy | Stoustrup J.,University of Aalborg | And 2 more authors.
Energy | Year: 2014

Flexible consumption devices are often able to quickly adjust the power consumption making these devices very well suited as providers of fast ancillary services such as primary and secondary reserves. As these reserves are among the most well-paid ancillary services, it is an interesting idea to let an aggregator control a portfolio of flexible consumption devices and sell the accumulated flexibility in the primary and secondary reserve markets. However, two issues make it difficult for a portfolio of consumption devices to provide ancillary services: First, flexible consumption devices only have a limited energy capacity and are therefore not able to provide actual energy deliveries. Second, it is often difficult to make an accurate consumption baseline estimate for a portfolio of flexible consumption devices. These two issues do not fit the current regulations for providing ancillary services. In this work we present a simple method based on the existing ancillary service markets that resolves these issues via increased information and communication technology. The method allows an aggregator to continuously utilize the markets for slower ancillary service to ensure that its portfolio is not driven towards the energy limitations resolving both the baseline issue and the energy limitation issue. © 2014 Elsevier Ltd.

Harbo S.,Danish Energy Association | Biegel B.,University of Aalborg
2013 4th IEEE/PES Innovative Smart Grid Technologies Europe, ISGT Europe 2013 | Year: 2013

To substantiate and structure demand-side flexibility aggregation, a legally binding contract between aggregator and consumers is key. Flexibility contracts are the focus of this work. © 2013 IEEE.

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