Power quality requirements and responsibilities at the point of connection

In the present power delivery environment, electricity as a product has become more competitive than before. Modern electrical devices are complex in terms of their functionalities and are more sensitive to the quality of the supplied electricity. A disturbance in supply voltage can cause significant financial losses for an industrial customer. Moreover, there are increasing number of disputes in different countries of the world among the network operators, the customers and the device manufacturers regarding their individual responsibility concerning 'Power Quality' (PQ) problems and solutions. In addition, the existing standards on PQ give very limited information about responsibility sharing among the involved parties. PQ disturbances can be originated in the network as well as at the customer's premises and can propagate to other parts of the network. The PQ level in the network is also highly influenced by PQ emission behaviors of customer's devices and the network characteristics. During the last decades, PQ related complaints have increased largely. Inadequate PQ can lead to various technical and financial inconveniences to the customers and the network operators. This research aims to find out a socio-economically optimum solution to PQ problems. The main objectives of this thesis are defined as: "Analyze main PO problems and their consequences to various involved parties in the network. Next, define optimal PQ criteria at the customer's point of connection (POC) and finally specify responsibilities of the involved parties". The thesis is based on practical field measurements of PQ parameters in the network, on analyzing the developed network models by using computer simulations and laboratory experiments. The most important part of the work is the verification of simulation results with thepractical measurements. Further, the obtained results are compared with the values given in the available standards. Lastly optimal PQ parameters at a poc are defined for flicker, harmonics and voltage dips. A summary of the research work reported in this thesis is as follows: • Obtained a deeper insight in PQ problems around the world • Developed typical network models for computer simulations on different PQ phenomena (such as flicker, harmonics and voltage dips) and verified the results with field measured data • Gathered practical information on various technical and financial consequences of inadequate PQ for different parties namely: the network operators, the customers and the equipment manufacturers • Made an inventory on various existing (and developing) standards and technical documents on PQ around the world. Then, compared the limits given on various PQ parameters in those standards/documents and discussed their relevance and applicability in the future • A proposal is given about optimal PQ limits (for flicker, harmonics) at the low voltage (LV) customer's POC Also, the average and maximum values of voltage dips in the networks are estimated • Suitable planning level limit values for flicker, harmonics and voltage dips are proposed • PQ related responsibilities of the customers, network operators and device manufacturer at the customer's POC are defined The main conclusions and thesis contributions are: • It is found that a harmonization among the presently available PQ standards is required and a dedicated set of global standards is needed to get optimal PQ at the customer's POC Various limiting values on different PQ parameters (e.g. flicker emission and harmonic current emission limits for a customer) at a POC are proposed in this thesis. Also, the average and maximum numbers of voltage dips in the Dutch high voltage (HV) and medium voltage (MV) networks are estimated. • A new set of planning level values for flicker severities at different voltage levels of a network is proposed. For harmonics, a proposal is given to change the planning level values for 'triple n' harmonic voltages and new values are suggested for the MV and LV networks. Moreover, it was proposed that the 3rd harmonic summation coefficient value of the standard can be modified to a higher value as sufficient diversity is found in the system. Regarding voltage dips, the numbers of planning and compatibility levels are proposed for a MV network in the Netherlands. In this thesis, PQ responsibility sharing procedures are defined for a network operator, customer and a device manufacturer. Network impedance is identified as an important parameter in deciding flicker and harmonics at a POC The network operator should provide information on the approximate number of occurrence of voltage dips in a year at a customer's POC To maintain sufficient PQ level in the network, all the involved parties should follow certain rules and duties. It was concluded that PQ regulation can be successfully implemented in the electricity business when all the involved parties are aware of their respective responsibilities in the network

The History of the Development of the Rectenna

The history of the development of the rectenna is reviewed through its early conceptual developmental phases. Some selective aspects of the current solar power satellite rectenna development are examined

International White Book on DER Protection : Review and Testing Procedures

This white book provides an insight into the issues surrounding the impact of increasing levels of DER on the generator and network protection and the resulting necessary improvements in protection testing practices. Particular focus is placed on ever increasing inverter-interfaced DER installations and the challenges of utility network integration. This white book should also serve as a starting point for specifying DER protection testing requirements and procedures. A comprehensive review of international DER protection practices, standards and recommendations is presented. This is accompanied by the identifi cation of the main performance challenges related to these protection schemes under varied network operational conditions and the nature of DER generator and interface technologies. Emphasis is placed on the importance of dynamic testing that can only be delivered through laboratory-based platforms such as real-time simulators, integrated substation automation infrastructure and fl exible, inverter-equipped testing microgrids. To this end, the combination of fl exible network operation and new DER technologies underlines the importance of utilising the laboratory testing facilities available within the DERlab Network of Excellence. This not only informs the shaping of new protection testing and network integration practices by end users but also enables the process of de-risking new DER protection technologies. In order to support the issues discussed in the white paper, a comparative case study between UK and German DER protection and scheme testing practices is presented. This also highlights the level of complexity associated with standardisation and approval mechanisms adopted by different countries