Denis Mende

Fraunhofer IEE & University of Kassel · Grid Planning and Grid Operation

Due to the increasing demand for transport of electrical energy, measures for power flow control, congestion management, and higher utilisation of the existing grid play a decisive role in the transformation of the power system. Hence, enormous efforts must be undertaken using measures of congestion management. Modelling and integration of correspo...

The increased integration of variable renewable energy sources into the power grid can, amongst others, lead to fluctuations in voltage, which may result in issues like harmonics, flicker, unbalanced loads, and power oscillations. These factors can negatively impact power quality and the ability to transfer power effectively. Therefore, effectively...

Die vorliegende Arbeit untersucht den Einfluss verschiedener Detailgrade auf die Ergebnisqualität von Netzstudien. Dabei werden die Herausforderungen der Netzplanung im Zusammenhang mit dem raschen Ausbau erneuerbarer Energien und der Elektrifizierung von Wärme- und Mobilitätssektoren angesprochen. Es wird eine zweistufige Methodik angewendet, die...

In several countries, PV capacity has exceeded the country's minimum load. Unlimited feed-in at all times is therefore becoming less and less possible. Curtailment is not a goal. It is a method for increasing the utilization of power grids without exceeding their physical limits. The ratio of annual energy yield to peak power is smaller for PV sy...

The planned massive increase of producers and consumers such as electric vehicles, heat pumps and photovoltaic systems in distribution grids will lead to new challenges in the electrical power system. These can include grid congestions at the low voltage level but also at higher voltage levels. Control strategies can enable the efficient use of fle...

State-of-the-art strategic grid planning processes are concerned with fulfilling the requirements of normal grid operation as well as performance under disturbances such as (n-1)-failures and selected exceptional contingencies. In order to ensure grid security, it becomes important to also consider events of low probability but the high impact in t...

Local reactive power control in distribution grids with a high penetration of distributed energy resources (DERs) will be essential in future power system operation. Appropriate control characteristic curves for DERs support stable and efficient distribution grid operation. However, the current practice is to configure local controllers collectivel...

The local reactive power control in distribution grids with a high penetration of distributed energy resources (DERs) is essential in future power system operation. Appropriate control characteristic curves for DERs support stable and efficient distribution grid operation. However, the current practice is to configure local controllers collectively...

This paper presents an approach for calculating optimized operating conditions in hybrid AC/DC systems while considering constraints on the small-signal dynamics. The implementation is based on a closed form power flow optimization considering the steady-state operating conditions and the damping of the eigenvalues calculated from a linearized syst...

Mit einem sicherheitsorientierten und koordinierten Flexibilitätsmanagement ist es möglich, dezentrale Anlagen an Systemführungsaufgaben über die Grenze von Verteil- und Übertragungsnetz hinweg zu beteiligen. In einem innovativen Netzbetrieb werden neben etablierten präventiven Maßnahmen künftig auch kurative Maßnahmen zum Einsatz kommen. Die in de...

This paper presents the development and consolidation of procedures for congestion management by market- and grid-related degrees of freedom. These methods are used in a time-step overlapping computational approach, which is necessitated by the newly implementation of pumped hydroelectric energy storage. The implemented application example is using...

Security, reliability and economic efficiency are three of the essential maxims for the operation of the electric power grid by the transmission system operators. The demand for transport of electrical energy resulting from generation located increasingly remote from consumption, combined with long-lasting expansion measures of the grid, leads to n...

The PV penetration in many countries is continuously growing and PV is becoming a major energy source in the future electricity grid worldwide. Therefore, PV systems and PV hybrids need to take over more and more system responsibility by providing ancillary services. Ancillary service “means a service necessary for the operation of a transmission o...

The PV penetration in many countries is continuously growing and PV is becoming a major energy source in the future electricity grid worldwide. Therefore, PV systems and PV hybrids need to take over more and more system responsibility by providing ancillary services. The report highlights the status and the potential of PV and PV hybrids as an anci...

Due to higher penetration of renewable energy sources, grid reinforcements, and the utilization of local voltage control strategies, a significant change in the reactive power behavior as well as an increased demand for additional reactive power flexibility in the German power system can be predicted. In this paper, an application-oriented reactive...

The so-called short-term voltage stability is typical of nonlinear problems arising in dynamic performance of electric power systems. This paper reports a simulation result on load margin for short-term voltage stability of the IEEE 9-bus system connected to a multi-terminal DC system based on voltage-source converter (VSC). The simulation shows th...

Requirements on electrical energy transmission and the work of system operators are changing due to the shift from centralized towards decentralized generation. This leads to an increased need of transport capacities in grids. In this paper, a robust method is presented to solve the resulting transmission expansion planning (TEP) problem using a no...

The last two decades have been witness of a transformation on how electrical energy is supplied. This paper presents an overview of the North Seas Offshore Network II project investigating the required advancements to enable an effective deployment of further 30 GW of offshore wind to be installed in the German North Sea exclusive economic zone acc...

The paper at hand describes the implementation, verification and application examples of an optimiza-tion approach for HVDC-systems from grid operations’ viewpoint. Due to the changing generation and consumer landscape, regulatory and socio-economic developments, and an ever-increasing number of new technical equipment the demand for flexibilities...

Serving a twofold purpose, integrated offshore grids can facilitate the connection of offshore wind generation with onshore networks as well as the interconnection of asynchronous market areas for power trade. With a growing amount of offshore wind generation being deployed in Northern Europe, the relevance of a North Seas Offshore Network (NSON) i...

Der zunehmende Anteil von Erzeugungsanlagen auf Basis von erneuerbaren Energien und Stromrichtertechnologie führt zu einer Verdrängung der konventionellen Erzeugungsstruktur mit Synchronmaschinen. Diese Änderungen in der Erzeugungs- aber auch in der Verbraucherlandschaft führen zu einer entscheidenden Veränderung des dynamischen Frequenz- / Wirklei...

The European power grid infrastructure faces various challenges due to the expansion of renewable energy sources (RES). To conduct investigations on interactions between power generation and the power grid, models for the power market as well as for the power grid are necessary. This paper describes the basic functionalities and working principles...

Der Beitrag stellt ein neu entwickeltes Verfahren zur effizienten Engpassbeseitigung durch Anpassung der Einspeisung beliebiger Erzeugungsanlagen vor. Der Schwerpunkt der Darstellung liegt auf der Prozesskette reichend von der Gesamtsystemmodellierung über die Ermittlung der Einflussfaktoren auf den Engpass bis hin zur Aufstellung und Lösung eines...

This contribution investigates the influence of SiC semiconductor devices for HVDC transmission technology on system level. Different SiC devices are recently in the focus of many scientific publications. However, for extra high power applications, the SiC-JFET exhibits promising properties. In order to assess the impact on system losses of such a...

The article at hand gives an overview of a developed method and tool to flexibly and efficiently remediate different kinds of congestion in the power grid. The presented approach consists of three main steps: Building the network model, identifying the technical factors influencing the congestion, formulating and solving an optimization problem to...

Frequency control in interconnected electrical power systems is nowadays realized using the networks’ conventional thermal power plants. With the ongoing changes in power systems worldwide the share of these conventional power plants is decreasing while renewable resources such as wind power and photovoltaics are increasing their share continuously...

The most obvious impact of the steadily increase of distributed generators on the network is the local overvoltage. PV-plants having local voltage regulation capabilities can mitigate overvoltage by absorbing reactive power. In this investigation the focus is laid on two relevant requirements for voltage regulation; “Q(V)-droop” and “PF(P)-droop”....

Kurzfassung Die stetig steigende Durchdringung der Energieversorgungsnetze mit dezentralen Energieeinspeisern macht eine Betei-ligung dieser an der Bereitstellung von Systemdienstleistungen unabdingbar. Eine Blindleistungsregelung zur statischen Spannungsstützung kann effektiv für eine Erhöhung der Netzaufnahmekapazität bzw. der Verfügbarkeit von E...

The constantly increasing penetration of distribution networks with local renewable resources makes it essential that such resources participate in the provision of grid management services. Reactive power control for static voltage support can effectively increase the grid's hosting capacity and the availability of power generation plants. As stud...

Because of the rapid increase of distributed generation, active voltage regulation becomes relevant for low voltage networks. In this paper, several power electronic voltage regulation approaches are presented and compared to each other through a Monte-Carlo-based network analysis. The focus of the investigation is on a series voltage regulator, fo...

In dieser Veröffentlichung wird eine umfassende Methode zur Ermittlung der Aufnahmekapazität von Niederspannungs-Verteilnetzen eingeführt. Zu diesem Zweck werden statistisch abgeleitete Referenznetze vorgestellt, die einen Großteil der vorhandenen Niederspannungsnetze abbilden. Die vorgestellte Methodik erlaubt die Angabe einer mittleren Aufnahmeka...

This paper introduces methods to determine the impact of a steadily increasing share of distributed generation on the electricity supply. For this purpose, two approaches to determine the possible amount of distributed generation in low-voltage distribution networks are introduced. The hosting capacity of a network is defined and reference networks...