HV Underground Cables Magnetic Field Mitigation Measures

The non stopping growth of urban centers and increasing demand for electrical energy causes more high voltage lines and underground cables installed in cities. As a direct consequence, the generation of Magnetic Fields (MF) is increased due to the new power lines and cables. Magnetic Fields have raised concerns in the population for years by its association with possible health effects. Before building new facilities it is necessary to assess whether these would meet the requirements of the regulations. Thus it is necessary to have tools that quantify the MF values emitted by the planned facilities. In the laying of cables, two zones are identified. The first one is where the phases are regularly laid close to each other. The other area is where the joints are made. In this area is where the distances between phases are higher. In the latter, the magnetic field values are higher due to the increase of the separation.Trabajo C3-203. 46ª CIGRÉ SESSION (International Council on Large Electric Systems).Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctrico

Use of magnetic field calculation tools to design MV/LV substations

Medium Voltage (MV) to Low Voltage (LV) Substations are one of the last links in the distribution process of Electric Power. Associated with these is the generation of magnetic field. These have generated great concern in the population due to its possible link to health effects in humans, so it is necessary to know what are the levels generated by existing and new facilities, considering different constructive topologies. To achieve the objective, magnetic field calculations are performed using 3D simulation tools, allowing to reproduce the layout of ground level substations, knowing the magnetic field values for different loading conditions and considering balanced and unbalanced load conditions, with current in neutral conductors. In 2013 measurement campaigns of Magnetic Field on substations were performed, also loads were surveyed. The results of the calculation of magnetic field generated by ground level substations, considering different topologies used in Argentina are presented in this paper. In order to validate the results, comparisons between measured and calculated values are performed. Generated levels are studied for different cases. Obtained magnetic fields values are compared with limits of Argentinean regulation and recommended references values by international organizations such as ICNIRP (International Commission on Non-Ionizing Radiation Protection) and IEEE (Institute of Electrical and Electronics Engineers).Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Influence of the representation of the distribution transformer core configuration on voltages developed during unbalanced operations

The object of this paper is to emphasize the importance of the representation of the core configuration when seeking transients developed in a distribution transformer under an unbalanced situation. Digital time-domain simulations are performed with the Alternative Transients Program (ATP) for the case of a distribution three-phase transformer using the following two core configuration representations available in the ATP: three-legged core form and fivelegged core. Severe overvoltages and high saturated currents would not be evidenced if the wrong core configuration representation was used during simulations.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Experience in the design of external protection systems against lightning

This paper describes the experience acquired during the revision and determination of external lightning protection systems in some refinery plants, in Argentina. With this purpose a program, developed by IITREE, based on the Monte Carlo statistical technique, was used, among other things, to determine in a period of time the frequency of lightning flashes to structures. International and American standards were used as reference.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Experience in the design of external protection systems against lightning

This paper describes the experience acquired during the revision and determination of external lightning protection systems in some refinery plants, in Argentina. With this purpose a program, developed by IITREE, based on the Monte Carlo statistical technique, was used, among other things, to determine in a period of time the frequency of lightning flashes to structures. International and American standards were used as reference.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Reactive an harmonics compensation in a medium voltage distribution nertwork with active filters

This paper presents the design of a shunt active filter to compensate reactive power and harmonics in the medium voltage level of a power distribution system. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The alternative of shunt active filter compensation connected to the 13.8 kV level is analyzed. Two alternatives are proposed, the first one considers full compensation with the active filter while the second one uses the existing capacitor bank and builds the complementary compensation with the active filter. In the last case, the capacitor bank is modified to make a 5th harmonic filter to avoid system resonances. Both proposals show very good performance.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

HV Underground Cables Magnetic Field Mitigation Measures

The non stopping growth of urban centers and increasing demand for electrical energy causes more high voltage lines and underground cables installed in cities. As a direct consequence, the generation of Magnetic Fields (MF) is increased due to the new power lines and cables. Magnetic Fields have raised concerns in the population for years by its association with possible health effects. Before building new facilities it is necessary to assess whether these would meet the requirements of the regulations. Thus it is necessary to have tools that quantify the MF values emitted by the planned facilities. In the laying of cables, two zones are identified. The first one is where the phases are regularly laid close to each other. The other area is where the joints are made. In this area is where the distances between phases are higher. In the latter, the magnetic field values are higher due to the increase of the separation.Trabajo C3-203. 46ª CIGRÉ SESSION (International Council on Large Electric Systems).Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctrico

Active and hybrid filters in medium voltage distribution power systems

This paper presents the design of different topologies of active power filters to compensate reactive power and harmonics in the medium voltage level of a distribution power system. One pure active filter and two hybrid topologies, are implemented. A pure active compensation is obtained with a Shunt Active Power Filter (SAPF). The shunt combination of SAPF and passive filter, form one of the hybrid topologies implemented, named Shunt Hybrid Active Power Filter (SHAPF). The other hybrid topology, called Hybrid Shunt Active Power Filter (HSAPF), connects the active filter in series with two shunt passive filters. The control algorithm are implemented with the d-q theory measuring the system current to compensate the load, setting a feedback control loop, rather than a simple feedforward compensation. Simulation for different load demands and distortions are performed. Finally a comparative evaluation of the different filters is carried out.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Load characterization in medium voltage of an electric distribution utility related to active filters

The behavior of the actual load of an electric energy distribution utility by means of voltage and current measurements is analyzed in this paper. Steady and transient states are taken into account. The main attention is fixed in points where present shunt compensation is installed. Results of field measurements and the connection and disconnection of capacitor banks are shown. Studies for future compensation are detailed and the possible advantages of active filter incorporation are analyzed in order to replace or complement the existing compensation. The minimal requirements are established in order to consider the design of the active filters and their compatibility with the existing installations.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE

Hybrid power filter to enhance power quality in a medium-voltage distribution network

This paper deals with the problem of reactive power and harmonics in a standard medium-voltage (MV) distribution network. It proposes a simple and inexpensive solution to enhance power quality when a particular connection to the high-voltage transmission network is required. It presents the design of a hybrid active filter topology connected to the MV level of a power distribution system. Its main task is to regulate a 132-kV voltage level. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The topology of a shunt hybrid active filter is analyzed. It is built with the series connection of a passive filter and a low-rated active filter. The proposed filter is directly connected to a 13.8-kV level with no need of a step-down transformer. The possibility of different levels of reactive power compensation is implemented. The proposal shows very good performance for different load demands.Instituto de Investigaciones Tecnológicas para Redes y Equipos Eléctricos (IITREE