María Beatriz Barbieri

Hybrid Active Filter for Reactive and Harmonics Compensation in a Distribution Network

The problem of reactive power and harmonics in the medium voltage level of a power distribution system is considered in this paper. Reconfiguration of the power delivery network imposes new constraints in a distribution substation so that the reactive compensation should be increased. The alternative of a shunt hybrid active filter connected to the 13.8-kV level to enhance the power quality is analyzed in this paper. This proposal uses the existing capacitor bank to build a hybrid filter in which the complementary compensation is performed by the active filter. The performance of the hybrid filter is evaluated with extensive simulations considering reactive power, harmonics, and unbalance compensation. It shows very good behavior in steady-state and transient conditions.

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.

Comparison of active filters topologies 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. Simulation for different load demands and distortions are performed. Finally a comparative evaluation of the different filters is carried out.

Hydraulic transients in hydropower plant impact on power system dynamic stability

Futaleufu hydropower plant has 4 Francis turbines rated 118 MW and it is connected to the power system by 2times330 kV lines. Studies carried out in the past did not predict the instable operation of Futaleufu after a 330 kV line fault, when some Futaleufu turbines are automatically disconnected as a consequence of the faulted line tripping. Load rejection caused by disconnected turbines generate large transients in the remaining turbines due to hydraulic coupling through the common conduits. Then, to improve related models and, therefore, to improve studies results of such a line fault it was necessary to make several tests in Futaleufu power plant. Finally, these models were used to conduct studies to design a new automatism, like the gate partial closing of the remaining turbines, to obtain a dynamically stable operation of Futaleufu after the disconnection by fault of a line of 330 kilovolts.

Reactive and Harmonics Compensation in a Medium Voltage Distribution Network 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.

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

Compensation with Hybrid Active Power Filter in an Industrial Plant

This paper presents the application of a hybrid active power filter for reactive and harmonic compensation at the level of Medium Voltage (MV) of an electrical network of an industrial plant. It is considered as control algorithm, the application of the d-q theory and performing the current measuring in the system, establishing a feedback control loop (feedback). It is analyzed a hybrid topology called Shunt Hybrid Active Power Filter SHAPF. This proposal uses an existing capacitor bank, transformed into a passive filter, and connected in series with the Active Filter to build a hybrid filter in which the compensation supplement is made by the active filter. We analyze different scenarios of operation. The topology has very good performance under steady state and transient.

Transients Due to Multiple Prestrike Phenomenon when Energizing Capacitor Banks with a Vacuum Circuit-Breaker

The phenomenon of multiple pre-strikes of the arc was observed in field measurements of the energization of a single 4.8 MVAR, 13.2 kV capacitor bank. This paper presents field measurements records and the results of the computer simulation of the transients when energizing the capacitor bank, carried out in order to calculate the over-voltages generated in remote points. A method to avoid the phenomenon is proposed

Consequence of an unbalanced supplying condition on a distribution transformer

Most of the time transformers work under balanced supplying conditions. However, after some fault conditions or anomalous switching operations, zero sequence component in excitation may be expectable. Transformers behavior under zero sequence excitation may be very different from usual behavior and might become dangerous. Some simulations are performed with the Alternative Transients Program (ATP), representing a three-legged core type three-phase transformer with a model available in the ATP library. Results show overvoltages and high saturated currents on the unloaded transformer. The proper use of the three-legged core type transformer model, shows evidence of the influence of the characteristics of zero sequence transformer on the development of such overvoltages and high transformer currents. Besides, regardless of load conditions, important homopolar currents are observed flowing to ground from the transformer high voltage neutral. The resultant homopolar fluxes could cause heating and damage in a three-legged core type transformer.

Filtro activo adaptado a diferentes configuraciones operativas de una planta industrial

In this paper the analysis of a Hybrid Active Power Filter for reactive and harmonic compensation in an industrial plant is presented. This proposal uses existing capacitor banks, which are transformed into passive filters which together with an active part form an adaptive and economic compensation system.