Henrik W. Bindner

Testing of a Predictive Control Strategy for Balancing Renewable Sources in a Microgrid

This paper presents the design of a control strategy for the energy management of a grid-connected microgrid with local distributed energy resources as: 10-kW photovoltaic plant, 11-kW wind turbine, and 15-kW-190-kWh vanadium-based electric storage system. According to future regulations, the renewable energy producers will also have to provide a day-ahead hourly production plan. The overall idea is, by knowing the meteorological forecasts for the next 24 h, to dispatch the microgrid in order to be able to grant the scheduled hourly production by means of proper management of the storage system. The usage of the storage system is, however, minimized by the energy management strategy. The system design is validated by experimental testing carried out in SYSLAB, a distributed power system test facility at Riso Campus, Technical University of Denmark.

An overview of demand side management control schemes for buildings in smart grids

The increasing share of distributed energy resources and renewable energy in power systems results in a highly variable and less controllable energy production. Therefore, in order to ensure stability and to reduce the infrastructure and operation cost of the power grid, flexible and controllable demand is needed. The research area of demand side management is still very much in flux and several options are being presented which can all be used to manage loads in order to achieve a flexible and more responsive demand. These different control schemes are developed with different organization of the power sector in mind and thus can differ significantly in their architecture, their integration into the various markets, their integration into distribution network operation and several other aspects. This paper proposes a classification of load control policies for demand side management in smart buildings, based on external behavior: direct, indirect, transactional and autonomous control; internal operation: decision support system scope, control strategy, failure handling and architecture. This classification assists in providing an overview of the control schemes as well as different ways of representing a building.

A simple, robust & reliable wind diesel concept for remote power supply

The paper introduces a Wind Diesel concept suitable for remote communities, the ‘Simple, Robust & Reliable Concept’ developed at Riso. All components are standard components, the system is self regulating using the component controllers and there is no power electronics. The paper documents a performance in terms of fuel savings and power quality that makes the concept a commercially viable option for including wind power in remote power supply systems.

Scheduling of domestic water heater power demand for maximizing PV self-consumption using model predictive control

This paper presents a model predictive control (MPC) strategy for maximizing photo-voltaic (PV) self-consumption in a household context exploiting the flexible demand of an electric water heater. The predictive controller uses a water heater model and forecast of the hot water consumption in order to predict the future temperature of the water and it manages its state (on and off) according to the forecasted PV production, which are computed starting from forecast of the solar irradiance. Simulations for the proof of concept and for validating the proposed control strategy are proposed. Results of the control approach are compared with a traditional thermostatic controller using historical measurements of a 10 kW PV installation. Economic results based on the Italian self consumption tariffs are also reported. The model of the water heater complex is a mixed grey and white box and its parameters have been estimated using a real water heater device.

Utilization of Flexible Demand in a Virtual Power Plant Set-Up

High penetration levels from renewable energy sources in large-scale power systems demand a high degree of flexibility in the transmission and distribution system. This paper presents a method for utilization of flexible demand in the low-voltage distribution system using the thermal mass of a building to defer power consumption from electric space heating. The power consumption for heating is controlled by an operational virtual power plant, which is sending a set point for requested power consumption to the building management system. An optimization problem is formulated such that the discrete dispatch of power from ten electric space heaters is following the power set point given constraints on the indoor comfort that is defined by the users of the building. The controlling method has been implemented in an intelligent office building and used for demonstration of flexible demand in the low voltage network.

Simulation model developed for a small-scale PV system in distribution networks

This paper presents a PV panel simulation model using the single-diode four-parameter model based on data sheet values. The model was implemented first in MATLAB/Simulink, and the results have been compared with the data sheet values and characteristics of the PV panels in standard test conditions. Moreover to point out the strong dependency on ambient conditions and its influence on array operation and to validate simulation results with measured data a complex model has also been developed. A PV inverter model, using the same equations and parameters as in MATLAB/Simulink has also been developed and implemented in PowerFactory to study load flow, steady-state voltage stability and dynamic behavior of a distributed power system.

A flex-market design for flexibility services through DERs

The high penetration of distributed energy resources (DERs) will significantly challenge the power system operation due to their intermittent characteristic. In order to utilize the DERs as economically efficient as possible in the distribution grid, an Aggregator-based Flex-market is proposed in this paper. With the brand new notion of Flexibility Clearing House (FLECH), the proposed Flex-market has the ability to promote small scale DERs (up to 5MW) to participate in flexibility services trading. Accordingly, efforts to relieve the congestions in local grid areas, the contractual flexibility services of DERs are stipulated accommodating the various requirements of DSOs. The trading setups and processes are illustrated in details as well. Additionally, the demonstration diagram of Flex-market is also introduced in this paper. The diagram is utilized to test the feasibility and robustness of the market solutions.

Building a test platform for agents in power system control: Experience from SYSLAB

A tighter integration of information and communication technologies into power grids and a gradual decentralization of control are widely regarded as key responses to the transformation of power systems, even though many different approaches are investigated to achieve this. Lack of system-level simulation tools and the high risk of tests on a real-world power grid create a need for small, experimental grids on which new control concepts can be safely tested and demonstrated. In order to accommodate a wide range of possible control structures, the controller platform on such grids needs to be as flexible as possible. Software agents promise to be a programming paradigm in support of flexible, distributed applications. This paper describes their application in SYSLAB, an experimental facility for distributed power systems, and discusses experience gained in the implementation process.

Application of Network-Constrained Transactive Control to Electric Vehicle Charging for Secure Grid Operation

This paper develops a network-constrained transactive control method to integrate distributed energy resources (DERs) into a power distribution system with the purpose of optimizing the operational cost of DERs and power losses of the distribution network, as well as preventing grid problems including power transformer congestion and voltage violations. In this method, a price coordinator is introduced to facilitate the interaction between the distribution system operator and the aggregators in the smart grid. Electric vehicles are used to illustrate the proposed network-constrained transactive control method. Mathematical models are presented to describe the operation of the control method. Finally, simulations are presented to show the effectiveness of the proposed method. To guarantee its optimality, we also checked the numerical results obtained with the network-constrained transactive control method and compared them with the one solved by centralized control, and found a good performance of the proposed control method.

Evaluation of the performance of indirect control of many DSRs using hardware-in-the-loop simulations

Controlling the power consumption of many Demand Side Resources, DSRs, will be required in the future power system where a big share of the electric energy will be produced using stochastic renewable sources and the conventional power plants might not have the flexibility of providing all the regulating power. Indirect control of demand side resources is supposed to shift the electric power consumption of each single unit through broadcasting of a control signal; the flexibility in the aggregated power consumption can be used for supplying balancing power to the electric power system. Indirect control approach is convenient from communication point of view since the real-time data flow is only in one direction because the decision is computed locally according to user preferences. On the other hand, this approach results in an open loop control scheme, since it is assumed that no real-time power readings from the units can be performed. The aim of the paper is to discuss the performance of an emulated closed loop control using an estimator for predicting the aggregate power response and a regulator. By using these components it is possible to produce a control signal to broadcast to distributed demand side resources. A population of DSRs, buildings with electric space heating, is indeed simulated in a software simulation platform using an hardware in the loop approach, that allows to feedback the real heat dynamics of SYSLAB FlexHouse into the simulations for pretending more realistic result.