Christian A. Hans

Christian A. Hans
Technische Universität Berlin | TUB · Department of Energy and Automation Technology

Dr.-Ing.

About

20
Publications
4,381
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
303
Citations
Citations since 2016
15 Research Items
294 Citations
20162017201820192020202120220204060
20162017201820192020202120220204060
20162017201820192020202120220204060
20162017201820192020202120220204060
Introduction
My research focuses on control concepts for microgrids. Here I am especially interested in control schemes for electric grids with high renewable share, model predictive control, time-series based forecasting and energy management.
Additional affiliations
October 2011 - November 2015
Younicos AG
Position
  • Engineer
Education
December 2012 - March 2021
Technische Universität Berlin
Field of study
  • Operation control of islanded microgrids
September 2009 - June 2010
Universidad Politécnica de Madrid
Field of study
  • Industrical Engineering & Telecommunication Engineering
October 2005 - September 2011
RWTH Aachen University
Field of study
  • Electrical Engineering

Publications

Publications (20)
Article
Full-text available
In this paper, we present a risk-averse model predictive control (MPC) scheme for the operation of islanded microgrids with very high share of renewable energy sources. The proposed scheme mitigates the effect of errors in the determination of the probability distribution of renewable infeed and load. This allows to use less complex and less accura...
Preprint
Full-text available
In this paper, we propose a model predictive control based operation strategy that allows for power exchange between interconnected microgrids (MGs). Particularly, the proposed conditional cooperation approach ensures that each MG in the network benefits from power exchange with others. This is realised by including a condition which is based on th...
Book
Full-text available
Islanded microgrids (MGs) are small electric power networks that have no connection to a larger grid. They typically comprise storage units, renewable and conventional generators as well as loads. The central question of this work is: How to operate islanded MGs with high renewable share, i.e., how to control the energy of the storage units, and ho...
Preprint
Full-text available
In this paper, an approach for active power control of individual wind turbines is presented. State-of-the-art controllers typically employ separate control loops for torque and pitch control. In contrast, we use a multivariable control approach. In detail, active power control is achieved by using reference trajectories for generator speed, genera...
Preprint
Full-text available
In this paper we present a stochastic scenario-based model predictive control (MPC) approach for the operation of islanded microgrids with high share of renewable energy sources. We require that the stored energy remains within given bounds with a certain probability using risk-based constraints as convex approximations of chance constraints. We sh...
Preprint
Full-text available
In this paper, we propose a minimax model pre-dictive control (MPC)-based energy management system that is robust with respect to uncertainties in renewable infeed and load. The MPC formulation includes a model of low-level droop control with saturation at the power and energy limits of the units. Robust MPC-based energy management systems tend to...
Preprint
Full-text available
This paper compares different forecasting methods and models to predict average values of solar irradiance with a sampling time of 15 min over a prediction horizon of up to 3 h. The methods considered only require historic solar irradiance values, the current time and geographical location, i.e., no exogenous inputs are used. Nearest neighbor regre...
Article
Full-text available
In this work, we propose a hierarchical distributed model predictive control strategy to operate interconnected microgrids (MGs) with the goal of increasing the overall infeed of renewable energy sources. In particular, we investigate how renewable infeed of MGs can be increased by using a transmission network allowing the exchange of energy. To ob...
Preprint
Full-text available
In this paper, we propose a model predictive control based two-stage energy management system that aims at increasing the renewable infeed in interconnected microgrids (MGs). In particular, the proposed approach ensures that each MG in the network benefits from power exchange. In the first stage, the optimal islanded operational cost of each MG is...
Preprint
Full-text available
In this paper we present a risk-averse model pre-dictive control (MPC) scheme for the operation of islanded microgrids with very high share of renewable energy sources. The proposed scheme mitigates the effect of errors in the determination of the probability distribution of renewable infeed and load. This allows to use less complex and less accura...
Presentation
Full-text available
Microgrids (MGs) gather a combination of generation units, loads and energy storage elements into a system that can be controlled locally. For such MGs, we propose a hierarchical distributed model predictive control (MPC) strategy to operate them in an interconnected way with the goal of increasing the overall infeed of renewable energy sources. In...
Conference Paper
Full-text available
Secondary frequency control, i.e., the task of restoring the network frequency to its nominal value following a disturbance, is an important control objective in microgrids. In the present paper, we compare distributed secondary control strategies with regard to their behaviour under the explicit consideration of clock drifts. In particular we show...
Article
Clock drift in digital controllers is of great relevance in many applications. Since almost all real clocks exhibit drifts, this applies in particular to networks composed of several individual units, each of which being operated with its individual clock. In the present work, we demonstrate via extensive experiments on a microgrid in the megawatt-...
Conference Paper
microgrids (MGs) are a promising solution to global energy challenges. Robust and reliable operation while maximizing infeed from renewable sources and reducing the use of thermal generation are important objectives in the control of MGs. In this paper, two model predictive control strategies are applied to operate a grid-connected MG in the presen...
Conference Paper
Full-text available
Clock drift in digital controllers is of great relevance in many applications. Since almost all real clocks exhibit drifts, this applies in particular to networks composed of several individual units, each of which being operated with its individual clock. In the present work, we investigate the effect of clock drifts in inverter-based microgrids....
Conference Paper
Full-text available
We address an optimal control problem for a microgrid in islanded operation with bounded uncertain load and renewable infeed. While model predictive control (MPC) with worst-case cost evaluation is often employed to obtain robust optimal control laws in the presence of bounded disturbances, it suffers from an inherent conservativeness. To counterac...
Conference Paper
This paper deals with the optimal tracking control of a spark ignited combustion engine. The overall controller consists of an (a priori given) feed-forward part that steers the system close to the desired trajectory and an optimal adaptive predictive controller for the tracking error dynamics. The latter is based on estimating a linear model along...
Conference Paper
Full-text available
Due to the steady growth of decentralised distributed generation, the operational management of small, local electricity networks (microgrids) is becoming an increasing challenge to meet: How to provide an operational control for microgrids with a high share of renewable energy sources (RES) that is robust to perturbations? In this paper we address...

Network

Cited By

Projects

Projects (4)
Project
Many wind farms are operated to a considerable extent in so-called power tracking mode in order to meet requirements of power system operators. In this mode, wind energy converters do not feed in the uncertain weather-dependent maximum possible power, but are operated with reduced power. Within this research project, existing degrees of freedom in the design of wind energy converters and wind farm controllers shall be exploited in order to achieve a better operation of the overall wind farm in power tracking mode.
Project
This field of research concerns the lower control layers in power systems. These are low-level plant control, primary and secondary control. In future power systems, many rotating generators, e.g., coal power plants, will be replaced by inverter-interfaced renewable sources. Unfortunately, not all ancillary services, such as frequency control or a desired short circuit behavior, can be satisfactorily provided by these renewable sources. Therefore, the use of storage units which provide ancillary services has been advocated. Our research in this field focuses on some of these ancillary services.
Project
One approach to handle the operation of complex future energy systems with a large share of small-scale renewable energy sources is to partition of the overall grid into smaller microgrids. To the outside world, each microgrids appears as a single entity that can provide or consume power. Allowing power exchange between these entities typically increase the overall system performance. In detail, an interconnection allows to benefit from effects like smoothing by geographical dispersion of renewable generators which can lead to a significant increase of renewable infeed. The central question of my research in this area is: How to enable optimal trading among a network of interconnected microgrids while preserving each microgrids’ autonomy?