Pieter Vingerhoets

LINEAR breakthrough project: Large-scale implementation of smart grid technologies in distribution grids

The LINEAR project (Local Intelligent Networks and Energy Active Regions) focuses on the introduction and implementation of innovative smart-grid technologies in the Flanders region, and aims at a breakthrough in the further development and deployment of these solutions. It consists of a research component and a large-scale residential pilot, both focusing on active demand-side management of domestic loads. This paper describes the unique approach, the main objectives and the current status of this project. Selected business cases and target applications are discussed in detail.

LV distribution network feeders in Belgium and power quality issues due to increasing PV penetration levels

In this paper, the impact of residential distributed energy resources (DER) on the power quality is investigated in four feeder types of the electrical LV distribution network in Flanders, Belgium. The investigated power quality issues are over-voltage, under-voltage and unbalance. The results of the simulations are discussed in detail. The paper leads to an estimation of the compliance to the power quality standard EN 50160, and a summary of issues in the distribution grids when increasing the amount of DER.

Demand response of a heterogeneous cluster of electric water heaters using batch reinforcement learning

A demand response aggregator, that manages a large cluster of heterogeneous flexibility carriers, faces a complex optimal control problem. Moreover, in most applications of demand response an exact description of the system dynamics and constraints is unavailable, and information comes mostly from observations of system trajectories. This paper presents a model-free approach for controlling a cluster of domestic electric water heaters. The objective is to schedule the cluster at minimum electricity cost by using the thermal storage of the water tanks. The control scheme applies a model-free batch reinforcement learning (batch RL) algorithm in combination with a market-based heuristic. The considered batch RL technique is tested in a stochastic setting, without prior information or model of the system dynamics of the cluster. The simulation results show that the batch RL technique is able to reduce the daily electricity cost within a reasonable learning period of 40-45 days, compared to a hysteresis controller.

Cluster Control of Heterogeneous Thermostatically Controlled Loads Using Tracer Devices

Managing the aggregated demand of large heterogeneous clusters of thermostatically controlled loads (TCLs) is considered a sequential decision-making problem under uncertainty. Recent research indicates that using reduced-order models in combination with a broadcasted control signal offers a viable solution to the tradeoff between computational feasibility, and accurately describing the steady-state and transient cluster response. In this paper, we propose a novel control strategy based on tracer devices, which we define as a limited amount of virtual TCLs that represent the entire cluster of heterogeneous TCLs. These second-order model devices are identified in a nonintrusive manner, and capture both steady-state and transient population dynamics, as well as cluster heterogeneity. Additionally, the dispatch mechanism is included in the optimization, further improving the tracking performance. The parameterizable number of tracer devices enables a covering of the tradeoff domain. Both approaches have been evaluated in two scenarios. In the first small-scale scenario, improvements in price and power deviations are evaluated when using increasing numbers of tracer devices and integrating the dispatch dynamics. Results from the second large-scale scenario show that root mean square dispatch errors can be reduced by more than 10% when integrating the dispatch mechanism in the resulting high-fidelity model.

Precision measurement of the electric quadrupole moment of 31Al and determination of the effective proton charge in the sd-shell

Abstract The electric quadrupole coupling constant of the 31 Al ground state is measured to be ν Q = | e Q V z z h | = 2196 ( 21 ) kHz using two different β -NMR (Nuclear Magnetic Resonance) techniques. For the first time, a direct comparison is made between the continuous rf technique and the adiabatic fast passage method. The obtained coupling constants of both methods are in excellent agreement with each other and a precise value for the quadrupole moment of 31 Al has been deduced: | Q ( Al 31 ) | = 134.0 ( 16 ) mb . Comparison of this value with large-scale shell-model calculations in the sd and sdpf valence spaces suggests that the 31 Al ground state is dominated by normal sd-shell configurations with a possible small contribution of intruder states. The obtained value for | Q ( Al 31 ) | and a compilation of measured quadrupole moments of odd- Z even- N isotopes in comparison with shell-model calculations shows that the proton effective charge e p = 1.1 e provides a much better description of the nuclear properties in the sd-shell than the adopted value e p = 1.3 e .

Distributed voltage control mechanism in low-voltage distribution grid field test

In this paper, we present a distributed voltage control mechanism that is being used in the large-scale field-test of the Linear project. The control system developed does not require a communication network between the different households. Only the locally measured household supply voltage is taken into account. The proposed control system is compatible with DSM infrastructure currently being developed, such as home gateways and smart meters. Moreover, the proposed control system can also be used as a fallback mechanism for other communication-based DSM control systems when communication fails or when the system has been compromised due to cyber security issues. Using Monte Carlo simulations on two accurately modeled field test grids and device models, the proposed approach and its various parameter set points are benchmarked against the optimal Dynamic Programming solution. Simulation results point out that on average the amount of over and under voltage occurrences can be lowered by more than 30 %.

Reducing overvoltage problems with active power curtailment —Simulation results

High penetration levels of photovoltaic systems on low voltage electricity nets tend to lead to overvoltage problems. Currently, in the residential sector of the Belgian Flanders region, the only way to reduce those problems is by means of completely halting the inverter. This paper investigates the power quality improvements of a fixed method of gradual active power curtailment in order to minimize overvoltage problems, as well as a basic economic impact on the end user. The method is simulated on 3 models of existing low voltage feeders located in the northern region of Belgium. Results show that overvoltage problems are nullified and unbalance is improved.

Double-layered control methodology combining price objective and grid constraints

A major challenge consists of considering all stakeholders of the future Smart Grid, each with their specific and possibly opposing objectives. A distribution network operator aims at guaranteeing power quality criteria while consumers aspire lowering their power consumption bill. This fundamental issue currently delays the transition from small-scale research projects to a large-scale all-encompassing smart distribution grid. This paper describes a double-layered control methodology using the available flexibility of the majority of discrete smart appliances currently in use. The effect of striving for the objectives separately as well as in combination is examined. The results show that the targeted objective(s) strongly influence(s) the performance in terms of cost effectiveness as well as number of voltage issues.

Standalone LV distribution network voltage control mechanism

This paper describes a voltage stabilizing control mechanism using the available flexibility of smart devices within one household. The flexibility of all types of smart appliances is used, especially smart on/off devices. The main advantage of the developed control system is that it does not require a communication network between the different households, only locally available measurements, such as the household supply voltage, are taken into account. The control system will be rolled out in a real life pilot test. Simulation results point out that the amount of over and under voltage occurrences on average are lowered with 35%.

Development of a laboratory platform for distributed grid management applications

This paper describes practical experiences in the design and implementation of a laboratory platform for developing and evaluating distributed grid management applications. The applications considered here are focused primarily on the implementation of control mechanisms for demand response of a heterogeneous portfolio of loads and distributed energy resources connected at low voltage levels. Lessons learned from the development of interfaces to various devices for integration into complex multi-host distributed control system architectures are described. Additionally, the authors provide reflections on practical aspects of building such systems and propose a set of requirements for the development of larger pilot tests.