Patent Application
20220271620
The invention is framed in the electrical sector, more specifically in the sector of powering circuits specially designed to supply the electrical energy consumed by centrifugal pumps, driven by alternating-current (AC) motors.
Any water pump can be powered from a photovoltaic generator. A first approximation to its classification distinguishes between those powered with direct current (DC) and those powered with alternating current (AC).
DC powered pumps are of positive displacement (membrane, piston, eccentric helical screw . . . ) and cover small applications, less than 500 m4/day and their market is linked to recreation (boats, caravans, secondary dwellings . . . ) where operating times are usually limited to a few hours a day, a few days a year, which means low reliability requirements. Conversely, the market for the supply to towns, industrial and agricultural applications is covered with centrifugal pumps driven by alternating current (AC) powered induction motors.
The centrifugal pump is currently the most widely used machine for pumping liquids in general. Centrifugal pumps are always rotary and transform the mechanical energy of an impeller into kinetic or pressure energy of an incompressible fluid. These centrifugal pumps have a multitude of applications in industry as they are suitable for almost any use. The most common are those made with a single impeller, covering capacities up to 500 m3/h and manometric heads up to 100 m, with electric motors of standardised speed.
These pumps are powered directly from the network or through variable frequency drives, which allow them to be controlled (ramp starting and stopping, detection of anomalous situations . . . ). A variable frequency drive (VFD) or adjustable frequency drive (AFD) is a system for controlling the rotational speed of an (AC) alternating-current motor by controlling the power frequency supplied to the motor.
Standard frequency drives are designed to be powered from the conventional mains and incorporate an AC/DC converter and use an output to generate the wave with which they ultimately control the motors. To power these drives with photovoltaic generators, they must be connected directly to their internal DC bus, ensuring that the operating voltage of the photovoltaic generator is greater than √{square root over (2)} 230V=325V (monophasic) or 3√{square root over (2)} ·400V=540V (triphasic). Therefore, to reach these voltages, about 9 modules (3.015 kWp and 15.3 m2) are required for a monophasic motor and 15 modules (5.025 kWp and 25.5 m2) for a triphasic motor.
In summary, photovoltaic systems for pumps currently have two problems: On the one hand, they are only used in direct current (DC) installations, of small size and little use for a few hours and of low volume; on the other hand, they require a high photovoltaic power involving a large photovoltaic generator surface, and a variable speed device (expensive equipment).
Document CN 208478886 U discloses a high and low voltage power distribution cabinet including a body with a heat dissipation window; a lower dust collection device, a front door, and a solar panel mounted on the top of the cabinet body and a connection between the power distribution cabinet body and the solar panel. It also comprises a lightning rod, a battery placed under the solar panel, a lower wheel and a dust collection device.
Document CN 208835541 U provides an outdoor switch cabinet, which has a solar panel and can display video content, such as advertisements, by configuring a liquid crystal display, increasing the ornamental property of the switch cabinet and improving economic efficiency, and can receive 4G signals by establishing a 4G portable point that converts 4G data traffic to Wi-Fi signal for use by nearby persons.
Utility model CN 204668784 discloses an outdoor garden high-low voltage power distribution cabinet of solar energy power supply cooling, with a solar photovoltaic panel, an inverter 20, and a storage battery 18.
The circuit for powering centrifugal pumps object of this invention is of the type described in the preamble of claim 1 and comprises a power panel of the pump connected to an alternating current distribution network, and to said pump through a power line provided with a timer that regulates the operating time of the pump.
According to the invention this power circuit comprises at least one solar module of photovoltaic panels and a solar micro-inverter connected in parallel to the alternating current bus of the pump and which converts the direct current generated by the solar module into alternating current, said inverter performing the injection of alternating current to the pump power line, with the same values of voltage, frequency and phase-angle deviation as the current coming from the distribution network, when the timer activates the operation of the pump.
When the timer allows the passage of current from the distribution network to the pump, the micro-inverter synchronises with the electrical network, working in parallel to the network and reducing the alternating current consumption of the distribution network by the pump, depending on the irradiance received by the solar panels to which said micro-inverter is connected.
With the aforementioned characteristics, the operating principle of the power circuit of the invention is as follows:
When the pump is activated:
When the pump is deactivated:
In order to complement the description that is being carried out and with the purpose of facilitating the understanding of the characteristics of the invention, the present description is accompanied by a set of drawings wherein, by way of a non-limiting example, the following has been represented:
In
This power circuit comprises: a power panel (2) of the pump, which is connected to an alternating-current distribution network (3) and to the said pump (1) by means of a power line (4) provided with a timer (5) that regulates the operating time of the pump (1); a solar module comprising photovoltaic panels (6) and a solar micro-inverter (7) connected in parallel to the alternating-current bus of the pump (1), and which converts the direct current generated by the solar module into alternating current.
As mentioned above, when the micro-inverter detects voltage in the power line (4), due to the activation of the pump (1) by the timer (5), the micro-inverter (7) detects voltage in the power line, checks that the values of voltage, frequency, and phase-angle deviation are within the accepted values, connects to the network synchronising with it and injects current under the same frequency and voltage conditions; thereby reducing the current consumption from the network by the pump.
The number of photovoltaic panels (6) and the power of the micro-inverter (7) are based on the power of the pump (1), the power of the micro-inverter (7) being always slightly lower than that of the pump (1). For example, with a 750 W and 600 W power pump in the inverter a 670 Wp solar generator is required or, with a 1,000 W power pump and a 1,000 W inverter also a 1,100 Wp solar generator is required.
The impact on consumption is directly related to irradiance in the area depending on the season, for a pump such as the one in the first example mentioned above, with continuous operation of 12 hours between 7:00 a.m. and 06:00 p.m. in Valencia, a saving of 52% has been quantified.
Advantages of the system compared to the solutions currently used:
Once the nature of the invention as well as an example of preferred embodiment have been sufficiently described, it is stated for all pertinent purposes that the materials, form, size and arrangement of the elements described are susceptible to changes, provided these do not involve an alteration of the essential features of the invention which are claimed below.
| Number | Date | Country | Kind |
|---|---|---|---|
| P201930691 | Jul 2019 | ES | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/ES2020/070469 | 7/20/2020 | WO |
