Francisco Blazquez

• Universidad Politécnica de Madrid

Non-toroidal-shaped primary pass-through protection current transformers (CTs) are used to measure high currents. Their design provides them with a big airgap that allow the passing of several cables per phase though them, which is the main advantage versus toroidal types, as the number of CTs required to measure the whole phase current is drastica...

Non-toroidal shape primary pass through protection current transformers (CTs) are used to measure high currents. Their design provides them with a big airgap that allow passing several cables per phase though them, which is the main advantage versus toroidal types, as the number of CTs required to measure the whole phase current is drastically redu...

Spanish Patent: Sistema y método de localización de excentricidades en máquinas eléctricas rotativas basados en la medida de flujo disperso (13), (14), (15) de la máquina rotativa a monitorizar mediante al menos cuatro sensores (8) de flujo disperso opuestos geométricamente e instalados en el exterior de dicha máquina rotativa, permitiendo detectar...

There are several techniques for current measurement. Most of them are capable of measuring both alternating and direct current (AC/DC) components. However, they have severe drawbacks for rotating applications (large size, sensitivity to external fields, and low signal amplitude). In addition to these weaknesses, measured signals should be transmit...

The growing adoption of electric vehicles has recently attracted increasing attention of scientists and brought about pioneering research studies from various fields. Safety concerns particularly those regarding ground faults detection and protection, have extensively been addressed. Ground faults occur quite frequently in electric vehicles and the...

Nowadays, non-toroidal shape primary pass-through current transformers are commonly used for large current machines with several cables per phase. As these transformers exhibit no radial symmetry, it is not clear if they can be tested using the indirect test described in the IEC 61869 standard. In order to answer this question, two non-toroidal sha...

This paper presents the design of a permanent magnet synchronous generator with outer rotor for wind power application. The proposed model incorporates a control system for the injected active power and also to avoid permanent magnet demagnetization. In addition, it considers a high-frequency harmonics filter to mitigate wave distortions at the loa...

Currently, heating and cooling systems used for achieving thermal comfort in commercial buildings represent a significant energy consumption. Traditionally, power supply installations of these Heating, Ventilation and Air Conditioning Systems (HVAC) present low efficiency. In these installations the power is supplied from the substation to the HVAC...

Diagnosis is a main concern in power systems with generators driven by internal combustion engines, especially by low and medium speed diesel engines. The purpose of this paper is to develop a new diagnostic method that avoids generator operation in dangerous torque imbalance conditions. Torque in internal combustion engines has a periodic oscillat...

Synchronous generators with brushless excitation have the disadvantage that the field winding is not accessible for the de-excitation of the generator. This means that, despite the proper operation of the protection system, the large deexcitation time constant may produce severe damage in the event of an internal short circuit. This paper describes...

The study of electric power systems within the field of Electrical Engineering is usually approached by computer simulation because any actual test is quite complex to be implemented, especially with renewable energies. Having the aim to improve student learning about this topic, a new subject called “Devising an Electric Power System” was organize...

In this paper, the influence of the rotor capacitance in the detection and location of a ground-fault in the excitation circuit of a 106 MVA static excitation synchronous generator by a new on-line method is presented. In this generator, numerous rotor ground-fault trips took place always about an hour after the synchronization to the power system....

Frequency Response Analysis is a well-known technique for the diagnosis of power transformers. Currently, this technique is under research for its application in rotary electrical machines. This paper presents significant results on the application of Frequency Response Analysis to fault detection in field winding of synchronous machines with stati...

Permanent magnet synchronous motors PMSM are widely used in industry due to their higher torque and higher power to volume ratio. Moreover they have a better dynamic performance compared to the motors with electromagnetic excitation. Despite its robustness electrical, mechanical and magnetic faults has been described. It has led to the development...

Locating stator-winding ground faults accurately is a very difficult task, especially in high-impedance grounded generators. Through the conventional measurements of power plants, obtaining the precise location of these defects in on-line operating conditions is not possible, because the fault resistance is unknown. This paper presents a general al...

Synchronous machines with brushless excitation have the disadvantage that the field winding is not accessible for the de-excitation of the machine. This means that, despite the proper operation of the protection system, the slow deexcitation time constant may produce severe damage in the event of an internal short circuit. A high-speed de-excitatio...

This paper presents a synchronous machine model designed to simulate internal ground faults along the stator windings. The purpose of this model is to help to set the 100 % stator ground fault protection based on the measurement of the third harmonic in the grounding resistor. The setting of the above protection is not easy, as the third harmonic i...

Thermal power plants have traditionally operated at rated power as base load, but nowadays they operate at partial loads because of the new situation of the electricity market. These plants have raised their auxiliary services consumption because, in most of the cases, the auxiliaries were not designed to efficiently operate at partial loads. This...

This paper presents a new algorithm for detecting ground faults in rotor windings. This location method is suitable for synchronous generators with static excitation, whose excitation field winding is fed by controlled rectifiers through an excitation transformer. This new algorithm is an improvement of an online ground-fault location method presen...

In this paper, a novel excitation-system ground-fault location method is described and tested in a 106 MVA synchronous machine. In this unit, numerous rotor ground-fault trips took place always about an hour after the synchronization to the network. However, when the field winding insulation was checked after the trips, there was no failure. The da...

This paper presents a new algorithm for estimating the ground-fault resistance value in rotor windings. This new algorithm is an improvement of an on-line ground-fault location method presented previously. This location method is suitable for synchronous generators with static excitation, whose excitation field winding is fed by controlled rectifie...

Las maquinas sincronas con excitacion indirecta sin escobillas (tipo brushless) presentan el problema de que no es posible acceder al devanado de campo para desexcitar la maquina. Esto provoca que, a pesar de la operacion correcta del sistema de protecciones, la lenta constante de tiempo de desexcitacion pueda producir graves danos en el caso de un...

In weak grids, an important problem with voltage stability and protections coordination of power plants exists. This problem appears because all the generation groups are connected to the same bus bar. As a result, if a fault occurs in any of the generation groups, or in the bus bar that connect them, the system voltage will have large oscillations...

Existen numerosos procesos industriales en que se ven involucradas sustancias inflamables, susceptibles de provocar una explosión. Debido a las dramáticas consecuencias, tanto personales como materiales, que conllevan los accidentes en este tipo de entornos, es de vital importancia mantener unas estrictas medidas de seguridad en estas áreas de trab...

In this paper, the applicability of the FRA technique is discussed as a method for detecting inter-turn faults in stator windings. Firstly, this method is tested in an individual medium-voltage stator coil with satisfactory results. Secondly, the tests are extended to a medium-voltage induction motor stator winding, in which inter-turn faults are p...

Electrical Protection systems and Automatic Voltage Regulators (AVR) are essential components of actual power plants. Its installation and setting is performed during the commissioning, and it needs extensive experience since any failure in this process or in the setting, may entails some risk not only for the generator of the power plant, but also...

This paper presents a high performance system of regulation and stabilization of luminous flux for public street lighting installations. Its purpose is to reduce the luminous flux of the luminaries efficiently by reducing their voltage supply, resulting in the improvement of energy efficiency in the installation. The system is basically composed of...

This study presents a novel high-speed de-excitation system for brushless synchronous machines, where the de-excitation time constant can reach values of several seconds. In these conditions, despite the proper operation of the protection system, the slow de-excitation time constant may produce severe damage in the event of an internal short circui...

The increasing penetration of wind energy into power systems has pushed grid operators to set new requirements for this kind of generating plants in order to keep acceptable and reliable operation of the system. In addition to the low voltage ride through capability, wind farms are required to participate in voltage support, stability enhancement a...

It is known that for some years it has been developed a technique based on the sweep frequency response analysis (SFRA) for the diagnosis of power transformer windings[1]-[6]. Since the first works to nowadays many developments and improvements have been made. The relevance of this method has resulted in the creation of new standards for applying t...

Student competitions are commonly used as part of engineering education curricula. This paper describes ‘Race with the Wind’, an international student competition to design and build wind generators, and presents an analysis of how the competition contributes to the acquisition of general competences within the Electrical Engineering curriculum at...

Among the existing renewable sources, wind energy is reaching production rates that are becoming important on the worldwide energy scene. Since the control of these wind generators is a very technical discipline, practical teaching methodologies are of special relevance. Paradoxically, in the past, the training of engineers specializing in this are...

Among the existing renewable sources, wind energy is reaching production rates that are becoming important on the worldwide energy scene. Since the control of these wind generators is a very technical discipline, practical teaching methodologies are of special relevance. Paradoxically, in the past, the training of engineers specializing in this are...

Frequency response analysis (FRA) is a very common test for the diagnosis of power transformers. This paper presents some relevant results on the application of FRA to the diagnosis of rotating machines. First, a reference rotor position for obtaining the reference FRA response of a rotating machine is proposed. Then, FRA with the proposed rotor po...

This paper presents a novel on-line rotor ground fault location method for synchronous machines, which, combined with rotor ground fault protection, can detect and locate faults in the rotor. This method is suitable for synchronous machines with static excitation systems, whose excitation field winding is fed by rectifiers through an excitation tra...

This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adaptin...

The increasing penetration of wind energy in power systems has forced operators worldwide to develop new grid codes to integrate this form of generation. One important aspect of the problem is the low-voltage ride-through capability of wind generators. This paper describes a solution for wind farms with squirrel-cage asynchronous generators based o...

Power quality is a main concern in power systems with generators driven by internal combustion engines, especially by low- and medium-speed diesel engines. The torque in internal combustion engines, which is the superposition of the torques from each cylinder, has periodic oscillations. These torque oscillations, once the generator is connected to...

This paper presents a novel ground-fault-detection technique for synchronous machines. This technique is suitable for synchronous machines with static excitation systems, whose excitation field winding is fed by rectifiers through an excitation transformer. The main contribution of this new technique is that it can detect and discriminate both ac-...

This paper presents a high-efficiency voltage regulator, which combines robustness, low costs and easy maintenance without power electronics components. These characteristics make it suitable for rural networks, where investments and operational cost in power quality improvement are limited. The regulator consists of a multiwinding reduced-power tr...

In this paper the basic lines of a complete teaching methodology that has been developed to adapt the electric machines learning process to the European Higher Education Area (EHEA) are presented. New teaching materials that are specific to Electric Machines have been created (textbooks, self-learning e-books, guidelines for achieving teamwork rese...

The large increase in wind generation could improve the final development of wind systems with brushless doubly-fed induction machines (BDFIM) as an alternative to the doubly-fed asynchronous machines. For this reason, a detailed study of several aspects of the BDFIM design, as well as of its rotor configuration, is absolutely essential. In this pa...

In this paper, the development of a physical platform and the description of a specific methodology to be employed for experimental teaching in wind energy electrical generation in the `Electrical Generation with Renewable Energy Sources' course, within the Electrical Engineering educational program at the Universidad Politecnica de Madrid, is pres...

An optimal design of a salient poles permanent magnets synchronous motor is presented. Firstly, a multivariable optimization process is performed by geometric programming method in order to minimize the total cost of the motor. Then a finite element method is used to evaluate recursively the motor torque. This methodology is applied to the optimal...

In this paper, a physical model for a distributed generation (DG) system with power quality improvement capability is presented. The generating system consists of a 5 kW PEM fuel cell, a natural gas reformer, hydrogen storage bottles and a bank of ultra-capacitors. Additional power quality functions are implemented with a vector-controlled electron...

This paper presents a dynamic model for variable speed wind energy conversion systems, equipped with a variable pitch wind turbine, a synchronous electrical generator, and a full power converter, specially developed for its use in power system stability studies involving large networks, with a high number of buses and a high level of wind generatio...

In this article we present the design and development of a control board that uses of two floating point digital signal processors to control a double converter inside a small wind turbine induction generator. The algorithms programmed on the processors have the ability to perform a vector control over the transient torque on the generator, control...

This paper presents the justification of the need of voltage sag generating equipment for the test and possible certification of the wind generators response to such disturbances. It also includes an overview of the equipment currently used with similar objectives.

Wind generation peculiarities introduce new uncertainty factors in the operation of electric power systems. This paper tries to clarify this situation, remarking the main effects involved, reviewing the current state of wind generation technologies, and analyzing the solu-tions that can be applied. It is shown how the capabilities of most current t...

The planning and operation of the electric power supply system should be affected by large penetration of wind power systems connected to it. This paper begins with a discussion about the main technical issues that can appear in networks with high level of penetration of wind systems, and shows how the variable speed wind generators could be a usef...

IEC 60034-1 Ed 10.2 1999-08 -states in Section 12-Electromagnetic Compatibility (EMC) the limits for the conducted disturbance on AC supply terminals of asynchronous machines with slip-rings. CISPR standards describe the radio disturbance apparatus and methods for measurement of conducted disturbances, but this equipment seems not to be suitable fo...