Dual Frequency Regulation in Pumping Mode in a Wind–Hydro Isolated System

Abstract

Frequency control is one of the most critical tasks in isolated power systems, especially in high renewable penetration scenarios. This paper presents a new hydropower pumped-storage dual control strategy that combines variable-speed-driven pumps and fixed-speed-driven pumps. A possible case for implementation of such a control scheme is described based on El Hierro Island’s power system. This isolated power system consists of a hybrid wind pumped-storage hydropower plant and diesel generators. The pumped-storage power plant is divided into a hydropower plant equipped with four Pelton turbines and a pump station equipped with both fixed- and variable-speed pumps. According to the proposed control scheme, frequency regulation will be provided by a dual controller: a continuous controller for the variable-speed pumps and a discrete controller for the fixed-speed pumps. The Pelton units, which operate as synchronous condensers, also supply the power system inertia. Therefore, diesel units may be disconnected, decreasing generation costs and greenhouse gas emissions. Owing to the combination of both controllers and the inertia of the Pelton units, an acceptable frequency regulation can be achieved. This technique has been validated through computer simulations.

Evaluation of the Operating Efficiency of a Hybrid Wind–Hydro Powerplant

“…The first one is increasing or decreasing, in a fast way, the non-wind generated power in cases of wind generation decreasing below the load [22,23]. The second is increasing or decreasing, also in a fast way, the pumping power demanded [24].…”

“…This process continues until all pumps are in operation at rated power, or the required power consumption is reached. Figure 9 shows the efficiency evolution of the pump station depending on the power required for frequency regulation [24]. (Table A7) drive the fixed speed pumps and 1600 kW motors (Table A4) As in the case of turbining, pump operation is only possible if there is enough water stored in the lower reservoir.…”

“…This process continues until all pumps are in operation at rated power, or the required power consumption is reached. Figure 9 shows the efficiency evolution of the pump station depending on the power required for frequency regulation [24]. could be obtained.…”

Data-Driven Control Techniques for Renewable Energy Conversion Systems: Wind Turbine and Hydroelectric Plants

“…The disturbance compensation problem is solved by finding the control input u that minimises the cost function of Equation (16):…”

“…On the other hand, an advanced control logic combining four control schemes that rely on adaptive, fuzzy and neural network regulators was investigated in [13]. Finally, regarding joint wind-hydro deployments, some more recent works analysed the problem of frequency control of isolated systems [16,17].…”