Search Results (9)

This paper introduces an advanced control method for a Shunt Active Power Filter (SAPF), engineered specifically for the compensation of non-active current and power management in DC-powered systems. Non-active current components frequently arise in practical DC systems due to power electronics and dynamic loads. Their presence leads to increased current draw from the source, higher losses, and accelerated deterioration of DC energy providers, such as fuel cells and batteries. The proposed SAPF control strategy is based on the concept of an equivalent conductance signal, which dynamically reflects the load’s active power consumption and the SAPF’s internal losses. A key feature of this method is the derivation of the conductance signal primarily from the DC-link capacitor voltage, effectively eliminating the need for additional current or power sensors and thereby simplifying the control hardware and software. This methodology enables efficient buffering of energy flow through user-defined time constants, significantly reducing both the average value and the variability range of the current required to transmit the demanded power (as measured by the RMS parameter and standard deviation of the source current, respectively). As a result, the degradation process of energy sources can be mitigated. Furthermore, the conductance signal’s ability to assume negative values allows for effective management of generative loads, enabling power flow back into the system or directing it to specific loads. The flexibility of tuning the SAPF’s functionality—by adjusting the time constant and imposing limits on the conductance signal’s variation range—is demonstrated in the presented results. Simulation examples, including the potential for direct energy exchange with the DC-link capacitor without affecting the upstream source, validate the effectiveness and versatility of the proposed control method in improving power quality and extending the lifespan of DC energy storage systems. Full article

Modern electrical systems are required to provide increasing standards of power quality, so converters in microgrids need to cooperate to accomplish the requirements efficiently in terms of costs and energy. Currently, power quality compensators (PQCs) are deployed individually, with no capacity to support distant nodes. Motivated by this, this paper proposes a consensus-based scheme, augmented by the conservative power theory (CPT), for controlling clusters of PQCs aiming to improve the imbalance, harmonics and the power factor at multiple nodes of a grid-tied AC microgrid. The CPT calculates the current components that need to be compensated at the point of common coupling (PCC) and local nodes; then, compensations are implemented by using each grid-following converter’s remaining volt-ampere capacity, converting them in PQCs and improving the system’s efficiency. The proposal yields the non-active power balancing among PQCs compounding a cluster. Constraints of cumulative non-active contribution and maximum disposable power are included in each controller. Also, grid-support components are calculated locally based on shared information from the PCC. Extensive simulations show a seamless compensation (even with time delays) of unbalanced and harmonics current (below 20% each) at selected buses, with control convergences of 0.5–1.5 [s] within clusters and 1.0–3.0 [s] for multi-cluster cooperation. Full article

Copper ore is a non-renewable resource with lower ore grades, which means that the extraction of more rock material is required to produce the same amount of copper, implying a greater consumption of materials, reagents, water, and energy. Since there is a greater amount of copper sulfide present in nature, concentration using the bubble flotation method will generate a greater number of tailings. This article discusses the environmental issues resulting from tailings dams and how multi-criteria decision analysis can help prioritize those sites in order to promote circular economy measures to compensate for and reduce the impacts of this type of waste generated by the copper mining industry. This work aims to contribute to this purpose by taking information from abandoned and non-active tailings, which are currently present as a result of the lack of regulations in times prior to environmental obligations and because they are metallurgical waste from old operations that had metal recovery rates that were much lower than the current rates. We propose a model based on the multi-criteria Promethee method to prioritize the tailings dams according to the commercial value of the existing materials in the deposits. A case study with an application of the model to 103 dams in the mining region of Coquimbo in northern Chile is shown. Full article

This paper presents a simple yet efficient control method for active power filters that can be used to improve power quality. Applying this method can open the way towards limiting the hardware and computational expenditure, which are needed for control of the active filter, while maintaining its required performance. The method is based on the indirect approach of obtaining reference signals combined with the closed-loop current control technique. Monitoring of changes of energy stored in reactance elements of the active filter is the base for obtaining reference signals for compensation. The active filter can perform classical compensation and, additionally, can perform some extra functionality for managing of active power in the system. In particular, it can stabilize the supplying source power, enable energy exchange between loads connected on DC and AC sides of the active filter, and—in a case of generating loads—enable their energy storage and redistribution amongst consuming loads. The presented method can be useful for voltage-source as current-source inverter based active filters, and for DC systems as well as for AC single- or three-phase ones. Full article

This paper presents a new framework based on geometric algebra (GA) to solve and analyse three-phase balanced electrical circuits under sinusoidal and non-sinusoidal conditions. The proposed approach is an exploratory application of the geometric algebra power theory (GAPoT) to multiple-phase systems. A definition of geometric apparent power for three-phase systems, that complies with the energy conservation principle, is also introduced. Power calculations are performed in a multi-dimensional Euclidean space where cross effects between voltage and current harmonics are taken into consideration. By using the proposed framework, the current can be easily geometrically decomposed into active- and non-active components for current compensation purposes. The paper includes detailed examples in which electrical circuits are solved and the results are analysed. This work is a first step towards a more advanced polyphase proposal that can be applied to systems under real operation conditions, where unbalance and asymmetry is considered. Full article

The paper deals with the determination and compensation of non-active torques of parallel HEV using an auxiliary electrical PMSM or IM motor. The non-active oscillating torque generating by the ICE engine was estimated, and consequently, the compensating torque component of the current was determined. Based on real measured data, the four regimes of operation have been investigated: compensating non-active torques, parallel operation, regenerating for PMSM, and both parallel operations, together with compensation. Using of p-q theory, the power of fundamental harmonic is presented by average values P_AV, Q_AV of total power waveforms p(t), and q(t). Worked-out simulation results are used for sizing and dimensioning of PMSM machine, VSI inverter, and traction accumulator-battery. Circuit simulator Matlab/Simulink was used for all simulation experiments. Full article

This paper proposes a new control method for a Unified Power Quality Conditioner (UPQC). This method is based on the load equivalent conductance approach, originally proposed by Fryze. It can be useful not only for compensation for nonactive current and for improving voltage quality, but it also allows one to perform some unconventional functions. This control method can be performed by extending the orthodox notion of ‘static’ load equivalent conductance into a time-variable signal. It may be used to characterize energy changes in the whole UPQC-and-load circuitry. The UPQC can regulate energy flow between all sources and loads being under compensation. They may be located as well for UPQC’s AC-side as DC-side. System works properly even if they switch their activity to work either as loads or generators. The UPQC can operate also as a buffer, which can store/share the in-load generated energy amongst other loads, or it can transmit this energy to the source. Therefore, in addition to performing the UPQC’s conventional compensation tasks, it can also serve as a local energy distribution center. Full article

This paper is focused on an adaptive controller for the direct current (DC) voltage in three-phase three-wire shunt active power filters systems. Although the controller structure of the proportional-integral (PI) type is determined off-line and does not change, the prescribed DC voltage and the controller parameters are calculated in an adaptation block, depending on the non-active power to be compensated. The adaptive control is based on the design expressions for the DC circuit of the shunt active power filter found by the authors, based on the detailed analysis of its operation, during the active filtering. The performances of the proposed adaptive control and its advantages compared to the classical control (where the prescribed DC voltage and the controller parameters are constant) were first determined on the virtual model of a laboratory setup. Then, the adaptive control was implemented on the dSPACE 1103 control board, which allowed the experimental determinations that prove and support the results obtained on the virtual model. Full article

New-generation power networks, such as microgrids, are being affected by the proliferation of nonlinear electronic systems, resulting in harmonic disturbances both in voltage and current that affect the symmetry of the system. This paper presents a method based on the application of geometric algebra (GA) to the resolution of power flow in nonsinusoidal single-phase electrical systems for the correct determination of its components to achieve passive compensation of true quadrature current. It is demonstrated that traditional techniques based on the concepts of Budeanu, Fryze or IEEE1459 fail to determine the interaction between voltage and current and therefore, are not suitable for being used as a basis for the compensation of nonactive power components. An example is included that demonstrates the superiority of GA method and is compared to previous work where GA approaches and traditional methods have also been used. Full article