Mario César Beroqui

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.

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.

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

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.