Jfg Sjef Cobben

Theft detection and smart metering practices and expectations in the Netherlands

This paper provides insight into the illegal use or abstraction of electricity in the Netherlands. The importance and the economic aspects of theft detection are presented and the current practices and experiences are discussed. The paper also proposes a novel methodology for automated detection of illegal utilization of electricity in the future distribution networks equipped with smart metering infrastructure. The necessary data requirements for smart meters and distribution substations are defined, in order to unlock this feature in distribution network. The paper also proposes the measures, which should be undertaken by the smart metering standards.

An analysis of diversity factors applied to harmonic emission limits for energy saving lamps

An experimental investigation of diversity factors for CFLs (compact fluorescent lamps) in combination with LED (light emitting diode) lamps is presented in this paper. Diversity factors were calculated for different configurations of lamps connected to the same feeder in one phase. It was found that the presence of LED lamps with a high apparent power input can lead to considerable damping of harmonics. If the number of CFLs is much greater, this effect was found as very low. Harmonic emission limits for lamps were also analyzed. A conclusion has been made that with a sufficient variety of energy saving lamps phasing out of incandescent lamps should not significantly impact the resultant harmonic distortion.

Smart MV/LV transformer for future grids

An increasing amount of distributed generation in the future grid will be connected at the customers point of connection. The generation within the low voltage grid will affect the power quality of customers connected to this grid. Hence, the concept of a Smart MV/LV transformer as a part of the Smart MV/LV substation is discussed in this paper. The main aims are to support the accommodation of distributed generation among the LV grid and to ensure that the voltage levels will comply with the power quality standards for all customers connected to that grid.

Harmonic current pollution in a low voltage network

Modern household customers use many power electronic based devices for their daily usage. Those devices emit harmonic current pollutions and eventually increase harmonic voltage distortion level in the network. In the future network, the background harmonic pollution in the MV and upstream networks could increase with the integration of more distributed generations. Thus, the harmonic related problem will increase in the network and therefore should be considered seriously. With the distorted supply voltage, most of the devices produce even more harmonic current pollutions. In this paper, three typical households are modeled with their various connected devices. Each device is tested in the laboratory to find out its harmonic current emission spectrum for different grid voltage conditions. Also, harmonic current spectrums are measured in the laboratory at each of the three house models terminal. Further, harmonic simulation is done on a typical low voltage network in which several household customers are connected and the above measured harmonic spectrums of households are used in the analysis. Harmonic current emission levels at different points of the network are calculated. Those values are compared with the laboratory measurements and also with the available standard limits. This analysis gives an overview of harmonic current emission level at different installations of a low voltage network.

Smart transformer for mitigation of voltage fluctuations in MV networks

This paper describes the application of the smart medium to low voltage transformer to increase the flexibility of distribution networks, support the accommodation of distributed generation and to attenuate the voltage fluctuations originating from medium voltage network. The theoretical framework is set and three possible control strategies are investigated and their performance to mitigate voltage fluctuations is compared. The most suitable control strategy is chosen on basis of performance and suitability for practical implementation. In addition, a new application of voltage control in low voltage network is proposed.

Analysis of power quality performance of the dutch medium and low voltage grids

Modern installations have become sensitive to power quality (PQ) related problems because more sophisticated devices with non-linear operating characteristics are often used there. On the contrary, most of these devices produce emissions that could decrease the PQ level of the network. It is becoming an increasing problem for the network operators to maintain good voltage quality because of the interactions of customerpsilas loads with the grid. It is anticipated that the networkpsilas physical characteristics (e.g. short circuit power, grid impedance) can influence the PQ performance (harmonic distortion, flicker severity) in the distribution grid. In this paper, a typical modern medium and low voltage Dutch grid is described that is modelled in the analysis tool dasiaPower Factorypsila. The network is simulated to analyze grid impedance and short circuit powers at different parts of the network. Furthermore, the importance of grid impedance is analyzed in relation to PQ aspects at the customerpsilas point of connection.

Optimization of State-Estimator-Based Operation Framework Including Measurement Placement for Medium Voltage Distribution Grid

To provide a guideline for grid operators to manage medium voltage distribution grids, this paper presents a probabilistic approach for measurement placement optimization and a state-estimator-based operation framework. The Monte Carlo method is used to optimize the measurement placement with minimum measured points, which support the observability of state estimator and satisfy the requirements for operation activities. The proposed framework covers several important factors from practical situations, including cost allocation of measurement systems, unavailability of measurement data, and small voltage deviation across medium voltage (MV) grids. Finally, a case study on a typical European distribution grid demonstrates the feasibility of the framework.

Aiding Power System Support by Means of Voltage Control With Intelligent Distribution Substation

AC power systems have to continuously balance generation and consumption in order to maintain a stable system frequency. The mismatches between the electricity generated and consumed have to be compensated by means of ancillary services, usually provided by conventional power plants. However, the recent developments in power distribution and automation will allow some of those services to be provided by distribution networks. Therefore, in this paper voltage control, at distribution substations, is used in connection with demand response (DR) for aiding system support in the Netherlands. The available capacity, which could be accessible by applying active voltage control, is evaluated and quantified as a function of supplied load over time. The DR capacity is estimated and the implications on power system imbalances are demonstrated in a case study for the Netherlands. In addition, the impact on the network losses is addressed and evaluated.

Assessment of the impacts of voltage dips for a MV customer

Voltage dips problems often cause large financial losses to sensitive industrial and commercial customers. Worldwide many industrial customers, connected to the high and medium voltage networks, often complain about voltage dips to their network operators. A voltage dip problem becomes critical in case of the incompatibility between the power supply and the immunity of the connected devices at customers installation. Improving the networks supply performance to reduce voltage dips would lead to huge amount of investment; whereas a process outage at a customers installation often involves significant amount of financial losses. Therefore, an optimized solution is to be found out based on the networks yearly dip statistics and the sensitivity of the customers installations to restrict this problem. In this paper, an industrial customer connected to a typical MV network is considered. The annual voltage dip frequency of the Dutch network is estimated and its impact on the considered customer is analyzed. Further, a methodology is proposed to define responsibilities of the different parties involved to minimize voltage dip problems.

Assessment of demand response possibilities by means of voltage control with intelligent MV/LV distribution substation

Demand response is considered as one of the possibilities, which should help to keep our power systems in balance of generation and production. To keep the system balanced will become more difficult, when large shares of electricity are generated from intermitted renewable resources. The availability and response speed of demand response are going to be the crucial factors enabling the integration into the future power system as a reliable option. Therefore, taking into account those factors, the possible demand response by the means of local voltage control is proposed in this paper. The constraints and the availability of the proposed new demand response tool are addressed in this paper and are underpinned with results from a field test experiment with experimental MV/LV substation allowing local implementation of voltage control.