Alfredo Pianeta Escudero

Bio: Alfredo Pianeta Escudero is an academic researcher from University of Brasília. The author has contributed to research in topics: Busbar & Emtp. The author has an hindex of 3, co-authored 5 publications receiving 40 citations.

A Wavelet-Based Busbar Differential Protection

Abstract: This paper presents a new wavelet-based busbar differential protection algorithm, named as 87BW function. The instantaneous current-based differential protection fundamentals are taken into account and the well-known 1-out-of-1 and 2-out-of-2 tripping logics are mapped into the wavelet domain. Operating and restraint wavelet coefficients energy of currents are computed, regarding station configuration and bus zones boundaries. Thereby, the proposed 87BW function can be properly used in both static and dynamic busbar configuration. Its performance was evaluated through EMTP-based simulations of faults in a 230 kV power substation with double bus single breaker configuration. The obtained results reveal it provides ultra-high-fast trip for internal and evolving external-to-internal faults, guaranteeing security for normal through-load and external faults as well, even in the case of early and severe current transformer saturation.

A Wavelet-Based Busbar Differential Protection

Abstract: This paper presents a new wavelet-based busbar differential protection algorithm, named as 87BW function. The instantaneous current-based differential protection fundamentals are taken into account and the well-known 1-out-of-1 and 2-out-of-2 tripping logics are mapped into the wavelet domain. Operating and restraint wavelet coefficients energy of currents are computed, regarding station configuration and bus zones boundaries. Thereby, the proposed 87BW function can be properly used in both static and dynamic busbar configuration. Its performance was evaluated through EMTP-based simulations of faults in a 230 kV power substation with double bus single breaker configuration. The obtained results reveal it provides ultra-high-fast trip for internal and evolving external-to-internal faults, guaranteeing security for normal through-load and external faults as well, even in the case of early and severe current transformer (CT) saturation.

Low-impedance busbar differential protection modeling and simulation using ATP/EMTP

Abstract: This work describes the modeling of busbar differential protection function by using the MODELS language available in the software Alternative Transients Program (ATP). This type of modeling includes data acquisition and signal conditioning modules for suitably implementing the commercially used 1-out-of-1 and 2-out-of-2 logics. This algorithm is based on instantaneous values of currents and considers an additional zone selection logic to keep up with the dynamic reconfiguration of flexible busbar arrangements. The results show that this type of modeling is a powerful tool for assessments of protection relays for any substation configuration in operational conditions, not readily available in actual records.

Discrete Fréchet distance algorithm based criterion of transformer differential protection with the immunity to saturation of current transformer

Abstract: The saturation of current transformers (CTs) has adverse impact on the reliability of the transformer differential protection. However, the overall phase information of currents are less affected by CT saturations. The Frechet distance algorithm, which is provided with the superiorities in the similarity identification, is utilized to acquire the phase information difference between the currents on both sides of the transformer. On this basis, the discrete Frechet distance algorithm based criterion of transformer differential protection is put forward. It can identify the differences of phase characteristics of currents on transformer both sides under various conditions including faults accompanied with CT saturations, transformer ultra-saturation and abnormal samplings. The effectiveness of the proposed criterion were validated respectively with simulation and experiment tests.

Instantaneous-Power-Based Busbar Numerical Differential Protection

Abstract: This paper presents a new method for busbar differential protection based on the instantaneous power concept. In order to do so, the instantaneous power per phase of each network element connected to the busbar is computed by using the instantaneous current values and a voltage memory action strategy. The performance of the proposed technique is compared to one of the traditional instantaneous-current-based differential protection algorithms, which is widely used by manufacturers of commercial relays. Both internal and external faults, as well as evolving external-to-internal faults, were simulated in a power substation with double-bus single-breaker configuration using the software ATPDraw. The obtained results reveal that the proposed algorithm is twice or more faster than the traditional instantaneous-current-based algorithm for most of the internal and evolving external-to-internal faults, while ensuring secure operation for external ones even when severe current transformer (CT) saturation takes place, through a new harmonic power restraint strategy. Also, since the proposed method provides faster fault detection time, the requirements for CT time to saturate may be alleviated, guaranteeing correct operation even in the case of early CT saturation.

A New Principle for Initial Traveling Wave Active Power Differential Busbar Protection

Abstract: To avoid the impact of the transient saturation of a current transformer, a fast busbar protection method based on the initial traveling wave integrated active power differential principle is proposed in this paper. The Peterson equivalent model is applied to analyze the initial traveling wave distribution characteristics of the internal and external faults of the busbar. The initial traveling wave active powers of each sampling point on each transmission line connected to the busbar are calculated with the implementation of an S-transform. By introducing the integrated active power actuating quantity and active power braking quantity, a protection criterion with a characteristic braking ratio is proposed. The theoretical analysis and experimental simulation results show that the protection performance is sensitive and reliable, with a quick response and simple criterion, and is essentially not susceptible to the impacts of the initial fault angle, fault type, and fault resistance.

Enhanced Generalized Alpha Plane for Numerical Differential Protection Applications

Abstract: This paper revisits the generalized alpha plane (GAP) formulation applied to differential protection of multi-terminal apparatus. The GAP formulation is improved by aiming for three main goals: 1) control over the internal fault settlement region (FSR); 2) enabling a simple operation characteristic instead of a restraint characteristic; and, 3) The adjustments are not dependent to the device type. For this purpose, the GAP formulation is redefined in terms of two settings, which transform the FSR into a circumference with a controllable center and radius. Thereby, a circular operation characteristic with an adjustable radius is enabled around the FSR, for to improve security. To validate and test the performance of the improved GAP, numerous computer simulations have been carried out using Alternative Transients Program on different multi-terminal equipment (i.e., busbars, transmission lines, and power transformers). Furthermore, massive data analysis is held as a means to highlight the GAP's sensibility. The obtained results demonstrate a well-stable pre-fault point, a consistent circular FSR, and the effectiveness of the improved GAP even under severe conditions.

DC busbar protection for HVDC substations incorporating power restoration control based on dyadic sub-band tree structures

Abstract: In this paper, a new direct current (dc) busbar protection for high voltage dc (HVdc) substations is proposed. The proposed scheme relies on the instantaneous current measurements obtained from the elements (lines and converters) connected to a dc busbar. Such current measurements are analyzed through dyadic sub-band tree structures that are used to extract the specific features, such as polarity, wavelet energy, and wavelet energy ratios. The performance of the scheme is assessed through the transient simulation using the verified PSCAD models. The simulation results revealed that the scheme can: 1) discriminate, effectively and within a very short period of time, between the internal and external faults; 2) detect pole-to-pole and pole-to-ground faults (both solid and highly resistive); 3) switch to healthy busbars (if available) to allow continuous operation; 4) re-energize the converter and restore the power to pre-fault conditions; and 5) remain stable during disturbances and external faults.