Friederich Kupzog

Load recognition for automated demand response in microgrids

Microgrids are well-suited for electrification of remote off-grid areas. This paper sketches the concept of a plug-and-play microgrid with a minimum of configuration effort needed for setup. When the load of such an off-grid microgrid grows over the generation capacity and energy storage is not sufficient, demand has to be reduced to prevent a blackout. In order to decide which loads are inessential and can be shedded, automated load recognition on the basis of measured power consumption profiles is needed. Two promising approaches from the area of speech recognition, Dynamic Time Warping and Hidden Markov Models, are compared for this application. It is found that a key feature to achieve good recognition efficiency is a careful selection of the features extracted from the measured power data.

Microgrid automation - a self-configuring approach

The balance of supply and demand in a microgrid is traditionally maintained by exploiting the reserves on generation side, which is capital intensive. However, approaches of on-line energy management including peak-load reduction and control energy provision by the demand side can support to reduce the demand during the situation of energy imbalance. This article discusses a new approach of modeling an intelligent and self-configurable microgrid system using automated demand side management, i.e. automated load management. In this system, microgrid central controller (MGCC) can communicate with the loads and directs them to isolate from the grid in real-time to reduce overall demand load on the system especially during peak-load hours. For this purpose, each load is coupled with a control node to become an intelligent load. Control node is a simple controlling circuitry, consisting of a communication node, power measuring device and a switch that can isolate the load from the grid under the management of central controller. MGCC takes decisions on the basis of control algorithms, which are implemented in it. Proposed system increases the reliability of consistent energy supply and considerably reduces the installation and maintenance costs of a microgrid.

DG DemoNet-Concept - A new Algorithm for active Distribution Grid Operation facilitating high DG penetration

While distributed generation (DG) from renewable energy resources is seen as key element of future energy supply, current electricity grids are not designed to integrate a steadily increasing share of distributed generators. The hierarchical network topology was designed for unidirectional power flows and passive operation. In order to avoid excessively expensive grid reinforcements, new solutions for active grid operation will be necessary. This paper introduces a set of innovative technical measures that allow a higher DG penetration within the grid. A new control algorithm for coordinated voltage control in an active distribution grid featuring these measures is proposed. Simulation results for an application of the algorithm in an actual Austrian distribution grid segment are presented.

Self-controlled Exploitation of Energy Cost saving Potentials by Implementing Distributed Demand Side Management

Facing the shortage of energy resources and rising energy costs, it is crucial to increase the efficiency of energy usage. Daily consumption peaks in electrical power grids result in the necessity to maintain overcapacities that are only temporarily used. Although already deregulated, todays power markets still lack incentive for large consumer groups to avoid peak consumption. This paper discusses a distributed and integrated load management infrastructure based on a self-controlled load shifting strategy which aims to reduce peak consumption. Essential for its effective and flexible operation is the proposed communication infrastructure, which will enable a flow of information in addition to the flow of energy in national and international power grids. This low-cost and maintenance-free infrastructure will carry real-time pricing information and allow load management appliances to communicate with each other. As a result, the consumer can take part in the energy business and profit from shifting part of the daily load to off-peak hours.

A closer Look on Load Management

The rising share of energy generation of renewable energies leads to a more volatile energy generation. Large conventional generation capacities have to be kept in the system in order to smooth out the generation patterns of distributed generators. The controllability of electricity generation is on decrease. To improve adaptability of power systems due to these new challenges, the concept of load management gains in importance. This paper provides a closer look on the potential of specific consumption processes for load management measures. It proposes a new solution to enhance the idea of the interruptible load for demand side management relying on the particular properties of inert thermal processes. A general taxonomy is given, whereas two different options for inert thermal processes are discussed and compared in detail.

Modeling domestic housing loads for demand response

Increasing electricity demand and upcoming shortages of resources, make on-line energy management like peak-load reduction and control energy provision by the demand side of the electric power system a valuable method for keeping the grid stable and efficient. For developing the next generation if these methods, a simulation environment for studying demand response (DR) algorithms with large-scale and detailed grid simulations is currently developed. An important part of this is an accurate but computationally inexpensive dynamic model for domestic housing and small business loads. This paper presents the design of this model and the deduction of the model parameters. As a determining factor for domestic loads, the power consumption of heating, ventilation and air conditioning (HVAC) systems has been identified. The model is partly based on earlier proposals that simulate the state changes of thermostatically controlled processes, but the complexity is further reduced to an absolute minimum. The result can be used as one of the basic building blocks required to set up a comprehensive simulation of power consumption in electric power grids under DR conditions.

IT-enabled integration of renewables: a concept for the smart power grid

The wide utilisation of information and communication technologies is hoped to enable a more efficient and sustainable operation of electric power grids. This paper analyses the benefits of smart power grids for the integration of renewable energy resources into the existing grid infrastructure. Therefore, the concept of a smart power grid is analysed, and it is shown that it covers more than for example, time-of-use energy tariffs. Further, the communication technologies used for smart grids are discussed, and the challenge of interoperability between the smart grid itself and its active contributors such as functional buildings is shown. A significant share of electrical energy demand is and will be constituted by large functional buildings that are mostly equipped with automation systems and therefore enable a relatively simple IT integration into smart grids. This large potential of thermal storages and flexible consumption processes might be a future key to match demand and supply under the presence of a high share of fluctuating generation from renewables.

Rapid control prototyping platform for networked smart grid systems

With the progress of the smart grid development and the prototyping of active control solutions supporting grid operation in the presence of a large amount of distributed generators, a design methodology for networked smart grid systems is required. This paper proposes an approach for fast system simulation and emulation-supported prototyping. A distinct tool, the Simulation Message Bus, accompanies the development of distributed controllers for power distribution grids from concept to field application. With this, the idea of an integrated development tool chain as it is known e.g. in the semiconductor or car industry is brought to the energy domain.

Loose coupling architecture for co-simulation of heterogeneous components

Co-simulation of different domains is the method of choice if specialised tools exist for each domain and no monolithic solution is available. Motivated by the need for simulation and emulation of networked smart grid systems with interlinked controller, communication and power hardware components, this paper proposes a solution for loose coupling of heterogeneous components (i.e. continuous and time-triggered subsystems). The focus is on a lightweight message bus, allowing multiple simulators to exchange the same messages like in the real system. The architecture allows fast configuration and easy switching between emulated and real-world components. The solution is applied and verified in the context of a Smart Grid application. Photovoltaic inverters in a distribution grid are coordinated with a central onload tap change transformer in order to keep the grid voltages within the limits set by operation rules.

Active grid integration of distributed generation utilizing existing infrastructure more efficiently - an Austrian case study

This paper presents the technical and economical results for an Austrian case study for grid integration of distributed generation (DG). The current state of the grid segment is shown and its inability to host higher than present amounts of DG is discussed. Consequently, technical solutions to overcome this problem without reinforcing the grid are presented. Different strategies of active voltage control are studied on the basis of extensive simulations using the DIgSILENT PowerFactoryreg software. Detailed economic analyses for different grid segments as well as producer-driven strategies (e.g. local or coordinated voltage control) for voltage control are performed. These approaches are furthermore compared to conventional grid reinforcement measures, showing that investments in new smart grid technologies may even lead to lower overall cost for society.