WO2009087257A1

WO2009087257A1 - Safety system for defocusing and detecting the position of solar trackers

Info

Publication number: WO2009087257A1
Application number: PCT/ES2009/000008
Authority: WO
Inventors: Unai Romero Vergel
Original assignee: Hydra-Power, S.L.
Priority date: 2008-01-10
Filing date: 2009-01-09
Publication date: 2009-07-16
Also published as: AR070139A1

Abstract

The invention relates to a safety system for defocusing and detecting the position of solar trackers. The system is suitable for use in solar trackers that are actuated using one or more oil-hydrualic actuators (1) for the purposes of defocusing and/or solar tracking using one or more oil-hydraulic actuators. The system includes an accumulator (3) associated with a pressure switch, whereby the accumulator (3) is connected to an electrically powered valve (8) which is closed when the solar tracker is in the normal operating position, but which opens in the event of a power failure, by means of which the fluid flows from the accumulator (3) to the chamber (11) of the actuators or hydraulic cylinders (1 and 2), thereby generating the reverse movement of the actuator(s) (1 and 2) and, consequently, the defocusing of the solar tracker in order to prevent faults or damage occurring in pre-determined elements of the facility as a result of overheating.

Description

SECURITY SYSTEM FOR THE FOCUS AND DETECTION OF THE

POSITION OF SOLAR FOLLOWERS

OBJECT OF THE INVENTION

The present invention relates to an oil-hydraulic safety system for defocusing or returning to the safety position of solar trackers, a system that has been conceived and realized to avoid breakdowns or possible deterioration of a solar tracker and that could be caused by environmental causes or due to overheating in case of lack of power supply. The object of the invention is to achieve a blur of a solar tracker so that it varies its orientation with respect to the sun, so that the solar rays do not directly affect the corresponding panels or photovoltaic panels of the installation, or return the solar tracker to position of security either by accumulating more solar energy or by environmental causes such as high winds, rain, hail, etc. in cases of lack of electricity supply. The blur or return to the safety position is done through the storage of oil-hydraulic energy, in an oil-hydraulic accumulator / s.

It is also the object of the invention to achieve a detection of the position of the corresponding hydraulic actuators or cylinders that are used to perform the solar tracking movements.

BACKGROUND OF THE INVENTION

The solar trackers can be of one or two axes, always aiming to obtain the maximum energy from the sun. Among the solar trackers of an axis can be mentioned the parabolic troughs, as well as the photovoltaic, etc., while among the two-axis solar trackers those of the heliostat type can be mentioned, tilting on their respective axes to follow the solar movement and take advantage to the maximum its location. Said solar trackers, in an emergency situation such as a failure of the electrical connection, a control failure, a failure of the pumping equipment, etc., as a result of being in constant solar tracking, focused on the sun, must be performed a blur maneuver to prevent further capture / reflection of energy, since there are elements in the equipment susceptible to overheating failures.

The defocusing / safety position maneuver must always be performed in the opposite direction to the soft tracking, blurring in each case the necessary degrees so as not to cause damage to the installed materials.

Specifically, the solar trackers of two sun-oriented axes are made by an oil-hydraulic system guided by an electronic control control, so that once the tracker is oriented, the sun's rays affect heliostat elements and are reflected for concentration in a tower equipped with tubes / receivers through which a fluid that heats and circulates is sent to the corresponding system for generating electricity.

In this sense, to make the blur in said type of followers, an electric power generator driven by a thermal motor or battery of electric accumulation is usually used, supplying electric fluid when the power supply failure to the installation occurs. In addition to being an expensive maintenance solution, failure to start the thermal motor or electrical wiring to the follower can occur, including failures in the charging of the batteries, in the storage of said energy and in the control elements of the load

As for the solar trackers of an axis, the orientation to the sun is also carried out based on an oil-hydraulic system guided by an electronic control, so that once the tracker is oriented, the captured solar rays are reflected and concentrated on a tube, through which a fluid circulates that is heated and sent to the electric power generation system, as in the two-axis solar trackers referred to previously.

On the other hand, it should be said that the actuators that are used to carry out precisely the solar tracking are previously double-cylinder systems, that is to say formed by two double-acting hydraulic cylinders, so that the continuous operation of those cylinders establishes the monitoring solar of the equipment from the sunrise to the concealment, in order to get the maximum use of the solar rays so that they perpendicularly affect the solar panels and thus obtain the maximum performance of the installation.

The function of the monitoring means is to allow the maximum capture of. solar radiation for its transformation into electrical energy, therefore it is usual to provide these systems with electronic means to determine their position at all times. The drawback of this type of systems is that when using electronic means, they must be constantly connected to a source of electrical energy, so that in case of cuts or breakdowns in the supplying electric fluid, the system obviously does not fulfill its function, having to install electric accumulators.

DESCRIPTION OF THE INVENTION The security system for the defocusing of followers object of the invention, is precisely designed to solve the problems and inconveniences that may arise in traditional defocusing systems, that is, to minimize the risks of electrical failures, as well as eliminate the risks of start of the electric generator, having reduced the costs of the security system itself.

In this sense, the safety system in question, being of the oil-hydraulic type, has the particularity of incorporating oil-hydraulic energy storage accumulators, said accumulated energy being able to produce the blur, by means of the appropriate maneuver circuit, when there is a failure of the electrical energy that feeds the equipment or installation. In addition, the referred energy accumulators can perform other functions, such as the start-stop of the electric motor, so that it is not continuously starting and stopping.

As is evident, when blurring the position of the solar tracker is carried out, the sun's rays cease to concentrate on the absorber tube of the parabolic followers or concentrate / reflect on the two-axis followers, thereby eliminating the risk Failure due to overheating, both in terms of circulating fluid and other elements of the equipment or installation.

Equally remarkable is the fact that the blur of the follower occurs in the opposite direction to the solar tracking, avoiding that on the same day the sun's rays again affect the follower, or they return to concentrate in a position through which they have already passed .

Specifically, and as stated previously, the safety system is based on an oil-hydraulic circuit in which hydraulic valves are provided that, by means of a mechanical retention of the position, preserve the direction of circulation in which it was located. at the time of failure of the supply voltage, valves that combined with a valve that reverses the direction of fluid flow allow the system to recoil, regardless of the position or direction in which it is Find the solar tracker when the power failure occurs.

The oil-hydraulic accumulator or accumulators of the system are duly set at a pressure such that it is capable of moving the corresponding actuators, preferably constituted by the aforementioned oil-hydraulic cylinders, which conventionally move the follower a minimum of travel in the opposite direction to that of the solar tracking or a maximum in the case of returning the solar tracker to rest position. Said oil-hydraulic accumulator or accumulators are associated with a pressure switch that indicates the minimum pressure sufficient for the offset movement to be performed.

In short, the circuit corresponding to the system of the invention incorporates a supply valve for it or the actuators, and as a fundamental characteristic a second valve that is electrically activated and that in the normal operating position of the follower is closed, so that additional valve when there is a lack of electric current opens and the accumulator fluid is sent to the actuators or hydraulic actuators, passing through the control devices materialized in the respective valves that mechanically memorize the position and direction of the fluid, to the object of that the oil-hydraulic energy sent by the valve located in parallel with the valve or valves for feeding the actuators, is sent to the opposite chamber of said actuators, regulating their recoil and therefore the offset. On the other hand, a device that under conditions of absolute lack of power supply is capable of transmitting the situation twice as many cylinders or actuators, both for emergency situations and for the normal operation of the follower, is additionally provided. Said hydraulic device Determine the fluid inlet and outlet of each cylinder, to achieve the extension or contraction of the rod, as appropriate.

The device in question incorporates a cam or similar element that is mounted on the axis of rotation itself from the follower, which acts on a hydraulic control or switch that controls each of the actuator cylinders, determining the direction of circulation and therefore the direction of movement or displacement of the rods of said cylinders to carry out the intended solar tracking.

DESCRIPTION OF THE DRAWINGS

To complement the description that is going to be made next and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached to the present specification based on which the innovations and advantages of the system object of the invention. Figure 1.- Shows a representation corresponding to the block diagram of the hydraulic circuit in which the safety system of the invention is embodied.

Figure 2, - Shows a schematic view of the hydraulic cam device by means of which it is possible to detect the current position of the hydraulic actuators or cylinders.

DESCRIPTION OF THE PREFERRED EMBODIMENT As can be seen in figure 1, the safety system of the invention, intended to produce the offset of a solar tracker and whose operation is carried out by means of a pair of actuators or hydraulic cylinders 1 and 2, It comprises an oil-hydraulic accumulator / s 3 associated with a pressure switch 4.

The system includes a power equipment 5 as well as a control block 7 and a valve 6 incorporated in the control block 7 itself and intended for power supply. the directional valves that feed the actuators or hydraulic actuator cylinders 1 and 2, said valve 6 being connected to the power equipment 5.

Well, as a fundamental characteristic, the system incorporates a second valve 8, in parallel with the previous one connected to the oil-hydraulic accumulator 3, said valve 8 being normally closed and electrically activated 9.

In this way, in the event of a lack of electrical current or failure of electrical energy, the said valve 8 opens and in its connection with the oil-hydraulic accumulator 3 sends the hydraulic fluid of the latter to the hydraulic actuators or cylinders 1 and 2, prior passing through two control devices 10 constituted by two valves that have mechanically memorized the position and direction of the fluid, so that the hydraulic force or fluid sent by the valve 8 is applied to the chamber 11 of the actuators or cylinders 1 and 2, opposite to the chamber 12, being in this where the fluid is normally applied in a normal operating situation through the valve 6.

Therefore, the application of the fluid to the chamber 11 will cause the pistons 13 of the actuators or cylinders 1 and 2 to move in the opposite direction, achieving the recoil of them and therefore the retraction of the rods 14, thereby achieving the offset of the solar tracker that is actuated by said actuators or cylinders 1 and 2.

For its part, the oil-hydraulic accumulator 3, is properly set at a pressure such that it is capable of moving the pistons 13 of the actuators or cylinders 1 and 2 of the follower, a minimum travel in the opposite direction to the conventional forward displacement.

As for pressure switch 4, it is intended to indicate the minimum hydraulic pressure of accumulator 3, providing the oil-hydraulic energy necessary for produce the movement or blur that is intended, whether from blurring a few degrees so that solar energy is not captured, until returning the entire solar tracker to its rest / safety position. To achieve the detection of the position of the actuators or cylinders 1 and 2, as shown in Figure 2, and which are articulated to a triangular configuration piece 15, a hydraulic device based on a cam 16 is provided for each of the cylinders or actuators 1 and 2, cam 16 which is mounted on the axis of rotation 17 of the solar collector 18, in this case parabolic, so that when the rotation of that cam 17 occurs and under some steps 19 established on the periphery thereof, the incident will occur on a hydraulic control or switch 20, which in each case commands the respective distributor of the hydraulic cylinder or actuator 1 or 2, establishing the direction of fluid circulation and therefore the displacement in one direction or another of the rods 14 of these cylinders 1 and 2, varying the direction of rotation 21 and therefore the position of the solar collector 18.

Claims

1.- SAFETY SYSTEM FOR THE FOCUS AND DETECTION OF THE POSITION OF SOLAR FOLLOWERS, which is applicable in solar trackers whose operation is carried out by means of hydraulic actuators or cylinders (1 and 2), the movement of the follower being carried out through a valve ( 6) which sends the fluid to the respective chamber (12) of the actuators or cylinders (1 and 2) to move the piston (13) and corresponding rod (14) outwards, all associated with a power equipment (5 ) and a control block to which the valve itself (6) belongs, is characterized in that it incorporates a valve (8) in parallel with the valve (6), which is connected to an oil-hydraulic accumulator (3) associated with a pressure switch (4), and whose valve (8) is electrically powered and in the closed position in the normal operation of the system to produce solar tracking, so that in the event of a power failure said valve (8) opens and sends ia the accumulator fluid (3) to the actuators or cylinders (1 and 2), fluid that is applied to the chamber (11) of the actuators or cylinders (1 and 2) to produce the reverse displacement of the pistons (13) and therefore the retraction of the rod (14) of such actuators or cylinders (1 and 2), to produce the offset of the corresponding follower; having provided that between the valves (6 and 8) and the actuators themselves (1 and 2) are interleaved control devices (10) materialized by respective valves that memorize the position of the fluid direction, to establish the position inversion and send the fluid to the chamber (11) when the valve (8) enters into operation.

2.- SAFETY SYSTEM FOR THE FOCUS AND DETECTION OF THE POSITION OF SOLAR FOLLOWERS, according to claim 1, characterized in that it includes a device for detecting the position of the actuators or cylinders (1 and 2), constituted by a cam (16) mounted on the own axis (17) of the solar collector (18), cam (16) whose rotation produces the incidence, through steps (19) provided in the periphery of the same, on a control constituted by a hydraulic switch

(20) as a means that commands the cylinders or actuators (1 and

2), to determine the displacement in one or another direction of the rods (14) of these cylinders or actuators (1 and

2) and with it the correct solar tracking of the collector (18).