Marcelo Pozo

Control of an island Micro-hydropower Plant with Self-excited AVR and combined ballast load frequency regulator

This project describes the design and construction of an Automatic Voltage Regulator (AVR) and an Electronic Load Controller (ELC) for the voltage and the frequency regulation in an island Micro-hydropower Plant (MHP). For the frequency control, the speed regulation by ballast load method has been used. To this approach, a combined binary-continuous load regulation was employed. The implemented AVR is totally self-excited by means of an energy transfer system which allows an isolated operation of the MHP. The entire system has been designed considering the current standard regulations of the Ecuadorian Agency of Electricity Control and Regulation (ARCONEL). The frequency and the voltage regulation were properly achieved through the implementation of digital PI controllers tuned based on mathematic models obtained from experimental data of frequency and voltage. The control of the system was validated by both, software simulations and field tests performed.

Active power control of a Virtual Power Plant

The present work develops the entire control system to achieve the active power regulation in a detailed model of a small-scale Virtual Power Plant (VPP). Firstly, the proposed VPP topology is exposed. A DC bus has been used for the integration of the different distributed generators and the storage system. Different DC-DC power converters schemes have been employed to fulfill this goal. Later, by means of an Energy Management System strategy who commands a three-leg three-phase inverter having a suitable modulation technique, the control of the demanded active power is performed. The results exhibit successful responses of the system for both, dynamic and steady state.

Battery energy storage system for a hybrid generation system grid connected using fuzzy controllers

This work presents a Battery Energy Storage System (BESS) incorporated to a hybrid generation system — grid connected (Solar Photovoltaic and Eolic) applied in a specific facility located in Quito — Ecuador. For controlling the state of charge and discharge of the battery bank, a supervisory controller based on peak shifting principle is used. A bidirectional converter controls the power flux from the battery into the DC bus and vice versa, whereas the inverter controls the amount of power injected into the AC bus. In order to manage the energy from the inverter, active and reactive (P-Q) control is applied. The control structure involves two cascade loops formed by an internal current control and a superimposed voltage control. Fuzzy logic combined with proportional-integral controllers is applied, ensuring thus, robustness to the system. In this document, the results for two main operating modes, charging and discharging batteries are presented and discussed.

Novel protection schema for a radial microgrid system

The improved use of renewable power generation and the coordinated connection with electrical networks and loads bring a new concept, the microgrids. In general, a microgrid can operate in both grid connected mode and islanding mode. Ensuring the continuity of protection in both operation modes is a great technical challenge. Dealing with different short circuit currents level depending on the operation mode as well as ensuring selectivity and sensitivity are the issues of the proposed protection scheme. The present work presents a microgrid protection scheme for a three bus-bar radial microgrid which includes energy storage and a static compensator (STATCOM). Protection strategy is based on the implementation of bi-directional overcurrent relays and includes over- and under-voltage and frequency relays as back-up protection. The main restriction is perhaps a limitation in normal working at 80% of the rated current of the converter-based generator, leaving the 20% remaining to overcurrent detection. In the other hand, an impedance measurement method is used to perform the islanding protection. Results show that the protection scheme detect effectively the islanding condition and also isolate three-phase faults applied in each bus-bar.

Sliding-Mode control on DC-DC converters of a virtual power plant

In this work, Sliding-Mode Control (SMC) is employed to control different DC-DC converters in a Photovoltaic-Wind-Battery based Virtual Power Plant (VPP). Firstly, the VPP scheme is detailed. Secondly, a DC-DC converter is employed on every Distributed Generator and Energy Storage System. Moreover, in order to integrate the output power of the DC-DC converters and for feeding a three-phase voltage source inverter synchronized to the distribution network, a DC bus is applied. Thus, the design of the proposed SMC controller is achieved by using space state small-signal average equations from the converters. Likewise, the system performance is analyzed on different scenarios and profiles. Finally, the results are exposed remarking proper dynamic and steady-state responses.

Improved particle swarm optimization based MPPT for PV systems under Partial Shading Conditions

In this work, an improved Particle Swarm Optimization (PSO) algorithm is employed to perform the Maximum Power Point Tracking (MPPT) of a 1.2 MW Photovoltaic farm under Partial Shading Conditions (PSC). High efficiency, low complexity and reduced tracking time are the main features achieved by integrating the ability to ensure a Global Maximum Power Point (GMPP) operation provided by PSO and the fast convergence of Perturb and Observe (P&O) algorithm. In addition, Sliding-Mode Control (SMC) is used on a cascade scheme on the DC-DC power converters in order to achieve a suitable energy conversion. Thus, the design of the SMC is achieved by using the space state representation of the power converters. Finally, photovoltaic system performance is analyzed for different solar radiation profiles. The obtained results show the proper dynamic and steady-state responses.