Jorge Luis Agüero

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.

STATCOM modeling for mitigation of voltage fluctuations caused by electric arc furnaces

Voltage fluctuations caused by rapid industrial load changes have been a major concern for both power companies and customers in the area of power quality. The fast response of the static compensator (STATCOM) makes it an efficient solution for improving power quality in distribution systems. This paper describes a model for a PWM-based STATCOM used in a distribution system for mitigation of voltage fluctuations produced by an electric arc furnace (EAF). The analyzed system is modeled using MATLAB/Simulink power system blockset (PSB), including a complete STATCOM model with its power circuits and its control system. The complete model is validated by field test. Static and dynamic performance of STATCOM is evaluated and voltage fluctuation mitigation studies are performed and discussed. The voltage fluctuation mitigation is obtained by measurements and according to international standards

Grid frequency control. Secondary frequency control tuning taking into account distributed primary frequency control

A new method developed and applied to tune Secondary Control Loop (SCL) for grid frequency control is presented.

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

Synchronous Compensators: Models Verified by Tests of Automatic Voltage Regulator, Reactive Power Control, and Voltage Joint Control

This paper presents models verified by tests of the excitation control systems (ECSs) of six large synchronous compensators (SCs) rated +125/-120 MVAr. These equipments for grid voltage control are placed in the substation Ezeiza of 500 kV belonging to the Interconnected Argentine System (SADI in Spanish). The substation Ezeiza is located in the SADI load center. Each SC has an ECS integrated by an automatic voltage regulator (AVR) with several limiters and a reactive power control (RPC). ECSs are governed by a single voltage joint control (VJC) to control the voltage at a 500-kV bus bar. The ECS is UNITROL F from ABB and, the VJC is implemented in a programmable logic controller (PLC). The AVR, RPC, and VJC models are presented. These models were predefined with information furnished by the manufacturer. Then, these models were validated by tests. Test records and their simulations with the proposed model are also presented. Described models have been incorporated to the database of dynamic models used for stability studies in the SADI

Interaction between AVR reactive power control and high power ac-dc Converter Control as possible cause of instability

Two oscillatory episodes took place in the Argentinean power system at 22:20 and 22:50, June 7th, 2008. The first one started when a 40 MVAr capacitors bank was disconnected and the second one started when a 500 kV line was disconnected. Both oscillatory episodes produced great variation of active and reactive power in several 330 kV and 500 kV power system nodes. At first sight, these oscillations seemed inter-area electromechanical oscillations, but carried out studies suggest that this oscillatory behavior could be a consequence of interaction between Reactive Power Control of generators and the ac-dc Converter Control of high power loads.

Field testing and model validation of motor-generators

In this paper, the field tests conducted by the IITREE-LAT to verify the performance of motor-generators are presented. These machines are used as distributed energy resources (DER) in oil fields and different cities across Argentina. On the basis of these tests, the models regarding generator, power-speed control system and voltage control system are presented.

Synchronous Compensators. Models Verified by Tests of: Automatic Voltage Regulator, Reactive Power Control and Voltage Joint Control

This paper presents models verified by tests of the Excitation Control Systems (ECSs) of six large Synchronous Compensators (SCs) rated + 125/-120 MVAr. These equipments for grid voltage control are placed in the substation Ezeiza of 500 kV belonging to the Interconnected Argentine System (SADI in Spanish). The substation Ezeiza is located in the SADI load center. Each SC has an ECS integrated by an Automatic Voltage Regulator (AVR) with several limiters and a Reactive Power Control (RPC). ECSs are governed by a single Voltage Joint Control (VJC) to control the voltage at 500 kV bus bar. The ECS is UNITROL F from ABB and the VJC is implemented in a programmable logic controller (PLC). The AVR, RPC and VJC models are presented. These models were predefined with information furnished by manufacturer. Then, these models were validated by tests. Test records and their simulations with proposed model are also presented. Described models have been incorporated to the Data Base of Dynamic Models used for stability studies in the SADI.