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High penetration of wind power plants may have an adverse impact on power systems' stability by reducing the inertia, and problems like frequency stability could appear due to total inertia in the system being reduced, making the power system more vulnerable to disturbances. However, most recent grid codes include an emulation inertia requirement for wind power plants, because modern wind turbines are capable of providing virtual inertia through power electronic converter controls to improve frequency stability issues. Because of this, it is necessary that the inertia estimation analyze and quantify the impact of the inertia reduction in power systems. In this paper, an implementation of a methodology for the inertia estimation of wind power plants is presented. It is evaluated through synchrophasor measurements obtained from a Real-Time Digital Simulator (RTDS) implementation, using industrial Phasor Measurement Units (PMUs). This methodology is based on the swing equation. Furthermore, a comparison of the results obtained between two professional tools RSCAD and DIgSILENT PowerFactory is performed, in order to evaluate the accuracy and the robustness of the methodology. This methodology is applied for the inertia estimation of an equivalent of the southeast zone of the Mexican power system, where there is a large-scale penetration of wind power plants. The results demonstrate that this methodology can be applied in real power systems using PMUs. [ABSTRACT FROM AUTHOR]

It is well known that a low level of electrolytes in batteries produces a malfunction or even failure and irreversible damage. There are several kinds of sensors to detect the electrolyte level. Some of them are non-invasive, such as optical sensors of level, while some others are invasive; but both require one sensor per battery. This paper proposes a different approach to detect the low electrolyte level, which neither requires invasive sensors nor one sensor for each battery. The approach is based on the estimation of the internal resistance of an equivalent electrical circuit (EEC) model of the battery. To establish the detection criterion of the low level of electrolytes, a statistical analysis is proposed. To demonstrate the feasibility of this approach to be considered a valid method, multiple experiments were performed. The experiments consisted of determining how the internal resistance is affected at eight different levels of electrolyte at different aging levels of vented lead–acid (VLA) batteries. The results have demonstrated the feasibility of this approach. Hence, this approach has the potential to be used for the reducing of sensors and avoiding invasive methods to determine the low level of electrolytes. [ABSTRACT FROM AUTHOR]

This paper deals with a battery energy storage system (BESS) in only one of its multiple operating modes, that is when the BESS is charging the battery bank and with the focus on the control scheme design for the BESS input stage, which is a three-phase LCL-filter PWM rectifier. The rectifier's main requirements comprise output voltage regulation, power factor control, and low input current harmonic distortion, even in the presence of input voltage variations. Typically, these objectives are modeled by using a dq model with its corresponding two-loop controller architecture, including an outer voltage loop and a current internal loop. This paper outlines an alternative approach to tackle the problem by using not only an input–output map linearization controller, with the aim of a single-loop current control, but also by avoiding the dq modeling. In this case, the voltage is indirectly controlled by computing the current references based on the converter power balance. The mathematical model of the three-phase LCL-filter PWM rectifier is defined based on the delta connection of the filter, which accomplishes the requirements of a 100 kW BESS module. Extensive simulation results are included to confirm the performance of the proposed closed-loop control in practical applications. [ABSTRACT FROM AUTHOR]

The growing penetration of generation systems based on renewable energy in electric power systems is undeniable. These generation systems have many benefits, but also many challenges from the technical point of view. One of the biggest problems in the case of solar photovoltaic (PV) and wind energy is the intermittency of the raw material, thus hybrid generation systems that contain both sources are being used to complement electric power generation. To analyze the problems of this type of hybrid generation systems, it is necessary to develop models and test systems that allows to study their dynamic behavior. Reported in this paper is the implementation of a full hybrid PV–wind generation system model in a real-time digital simulation platform, and the development of the electronic converter controls. These controllers were implemented in digital devices (Arduino Due) and connected to the simulation platform to test their performance in real-time. In addition, the procedure followed for the development and implementation of the controllers is presented. The proposed test system can be used in renewable energy integration studies and the development of new control strategies. [ABSTRACT FROM AUTHOR]

This paper presents a control scheme of a wide-area controlled static VAr compensator (WAC-SVC) and its real-time implementation in a hardware-in-the-loop (HIL) simulation scheme with three control objectives: (1) to increase the critical clearing time, (2) to damp the power oscillations, and (3) to minimize the maximum line current. The proposed control scheme considers a correction strategy to compensate the delays up to 200 ms. In addition to this, a generator tripping scheme based on synchrophasor measurements to determine the proximity to the loss of synchronism is proposed. A delay compensation algorithm based on polynomial approximations is also developed. The proposed WAC-SVC is experimentally validated using a Real-Time Digital Simulator platform (RTDS), industrial communication protocols, a commercial device for PMU-based control implementations, and digital relays with PMU capability. The real-time simulation results confirm its effectiveness and feasibility in real industrial applications. Furthermore, practical guidelines to implement this kind of control schemes are provided. [ABSTRACT FROM AUTHOR]