ES2393095B1 - AUTONOMOUS SOLAR CONCENTRATOR WITH ELECTRICAL STORAGE THROUGH A CONDENSER AND ITS OPERATING METHOD. - Google Patents

Abstract

Autonomous solar concentrator characterized by having an electrical energy storage through a condenser (4). This solar concentrator has a mirrored surface (2) that moves on one or more axes by means of a drive made up of electrical elements (8) that consume the electricity provided by an autonomous energy system made up of one or more photovoltaic panels (9) which charge a capacitor (4) which performs the function of electrical storage. A local control (5) performs the operation of the solar concentrator and energy-saving management by disconnecting consumption at night and in periods of stored low voltage. Said local control (5) communicates through a radio modem (11) and receives the information from a wind switch (10) to protect the concentrator from the action of dangerous winds.

Description

AUTONOMOUS SOLAR CONCENTRATOR WITH ELECTRICAL STORAGE

BY CONDENSER AND ITS METHOD OF OPERATION

Technical sector of the invention

5

The present invention relates to a novel solar concentrator designed under the

use of very high electrical capacity capacitors in order to eliminate the

traditional electrical storage using a charger and batteries. This invention

It can be used in future concentrating solar thermal plants that use

single or multi-axis solar concentrators such as heliostats, collectors

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parabolic cylindrical or discs.

Background of the Invention

Since the early years of the 1980s, various types of

initiatives for the development of electricity production plants using technologies

concentrating solar power plants, initiatives whose purpose has been to demonstrate the

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technical feasibility in the production of electricity by employing

solar concentrators such as heliostats and parabolic trough collectors

(CCPs).

Currently, a large number of plants are in the project and advanced construction

solar thermal plants in Spain that use solar concentrators and it is expected that these

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initiatives mean the rebound and leadership of Spanish companies in these

technologies.

The solar thermal energy map installed in Spain is currently distributed in

as follows: PS10 (11 MW}, PS 20 (20 MW), ANDASOL 1 (50 MW),

PUERTOLLANO (50 MW}, PUERTO ERRADO (1, 4 MW), LA RISCA (50 MW),

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ANDASOL 2 (50 MW}, SOLNOVA 1 (50 MW), EXTRESOL 1 (50 MW}, SOLNOVA 3

(50 MW) and LA FLORIDA (50 MW).

The concentrating solar power plants PS10 and PS20 from the company Abengoa and

GemaSolar of the company Torresol Energy are currently the first initiatives

commercial using conventional heliostat fields.

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From the commercial experience obtained in these plants, other initiatives will be born that

will very possibly promote a market that will need sensors, discs or

Increasingly reliable and lower cost heliostats.

With this panorama it is to be expected that in a short period of time, this technology

demand autonomous solar concentrators and especially autonomous heliostats

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due to the greater possibilities that these concentrators have to reduce

sensitively the costs of installing the solar fields of future plants

solar thermal. That is why in the future we will refer to this type of

concentrators without limiting their use to other types such as sensors

parabolic cylindrical or discs.

5

Autonomous heliostat is a type of solar concentrator that has been patented by

CIEMAT in 1999 (ES 215503181) and, until now, has used a

electrical storage consisting of charger and batteries.

The clearest referent for the use of autonomous heliostats is in the current

PCHA heliostat field located in the Almería Solar Platform. These

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Heliostats, in operation since 2004, constitute the first field of

Known autonomous heliostats and they all employ electrical storage

Composed of a charger and a battery.

These autonomous heliostats are solar concentrators arranged in areas

cleared in the open air with high solar radiation and extreme temperatures in summer and

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winter, which hinders optimal battery operation, shortens

their half-life is significant, thus increasing maintenance costs of this type

heliostats.

The electric battery is also an element that has a high environmental cost and

requires additional collection and recycling.

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For these reasons and in an attempt to solve these problems, the hub

autonomous solar of the invention employs a new storage system

electric, which replaces the traditional system consisting of charger and battery.

Description of the invention:

The main objective of the invention is the incorporation of a new system of

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Electric storage that replaces the traditional battery and electric charger in

solar concentrators.

This new electrical storage system is based on the use of ultra

capacitors

By using ultra-capacitors (English term ultracapacitors) you can

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get:

• The elimination of the battery and its associated problems such as:

o Being little respectful with the environment with high cost of recycling.

o Extreme working conditions in heliostat fields (high

temperature, humidity, ...) shorten the life of the batteries

increasing the maintenance costs of the plant. Them and

translates into a decrease in savings achieved through

application of the concept "autonomous heliostat" described in patent

P9901275.

• Elimination of charge regulator

5

One of the important features of a standalone hub is the bass

energy consumption required for its operation, and the fact that this

consumption occurs in coincidence with the electrical production performed by a

photovoltaic panel. This allows the accumulated energy needs to be minimized and

enables the use of other devices, different from those traditionally used,

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such as electric capacitors.

The autonomous concentrator of the invention, powered by a

autonomous power consisting of a photovoltaic panel and a capacitor

enables the elimination of the charge regulator and the battery achieving a

coincidence between panel production and concentrator consumption, in addition to

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not generate gases, be more immune to adverse weather conditions and

guarantee a much longer life than a battery. Although it is a better solution, continue

having some drawbacks and advantages:

• They are very expensive (3 to 6 times the price of the battery) although an

downward price trend at a rate of 20% per year and is to be expected from

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According to the increasing demand of these elements in the market, which

in the medium term, they can be compared in price to the batteries.

• Less energy storage (1 0-20 times less than the battery) so

it is necessary to supply this deficit by increasing the power of the photovoltaic panel and

decrease the consumption of the hub through local monitoring controls

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more efficient solar. It is also necessary for this to establish procedures for

savings, security and emergency as well as operational strategies and

specific functional.

• The occupied volume is greater than the batteries for the same capacity of

storage.

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The use of only capacitors is possible for the following reasons:

1) Due to the simultaneity between energy production and consumption. In

favorable solar radiation conditions, the panel is capable of providing in just a few

few hours (2-3) the daily energy required by the concentrator. So that

exceptionally, and on very cloudy days, the hub may run out

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supply. This circumstance can almost be avoided through operational strategies and

functional.

2) Under normal conditions, the capacitor will provide energy during the

raising and lowering the concentrator at the first and last hour of the day, as well as

energy required to safely bring the

5

concentrator due to low radiation or high wind speed.

3) Under normal solar tracking conditions the condenser will be fully

charged only buffering production changes of the photovoltaic panel

due to fluctuations in radiation caused by the passage of clouds.

4) In cloudy sky conditions, the diffuse radiation captured by the panel

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photovoltaic can charge the capacitor and even guarantee consumption

minimum necessary of the hub to stay operational and communicated with the

control room (no axis movement).

5) Although they are more expensive than batteries, they have a much longer life (at least 5

times)

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6) During inoperative periods due to maintenance work, low radiation

(cloudy days) or at night, the hub will automatically stay

disconnected from the condenser to the object to reduce unnecessary consumption. The control

The local autonomous hub will be specially designed for the management of

these consumptions and for the connection / disconnection of the same by means of a

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light (the photovoltaic panel itself and others), the knowledge of the voltage in the

condenser and time clocks.

On days of bad solar radiation conditions the condenser recovers

quickly in the presence of gaps and, unless light conditions are

very lousy and elongate over time, the capacitor is normally maintained

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with a load greater than 90% and the photovoltaic panel is capable, in most

cases, to keep the small consumption of electronics as well as low

Consumptions of performing solar monitoring tasks (motors running

pulsing).

Only significant condenser discharge occurs during rise

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or lowering the hub early or late in the day when the

hub movement are kept running continuously

during a certain time.

The condenser must be dimensioned taking into account this phase of consumption of the

concentrator assuming as a good value of energy stored in the

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condenser, the one necessary to lower the concentrator at least twice to the last

time of day from the solar tracking position to the down position or rest. Capacitor sizing can be minimized by accepting the following premises:

5 • The concentrator is raised a certain time after sunrise when the solar radiation exceeds 300W / m2 and / or it is lowered a certain time before sunset when the solar radiation falls below 300W / m2. These radiation conditions are usually insufficient for maintaining the thermal conditions of the usual solar receivers. In any case, this threshold of

1 Or solar radiation will depend on the thermal conditions of the solar receiver.

• Maximum wind speed conditions are extreme and only the elevation axis is acted to arrange the mirrored surface in a safe position, by the shortest route and in the shortest possible time.

• Consumptions are switched off at night or in periods of very low solar radiation (very cloudy days). A system of time control and / or surveillance of

Light will allow the connection / disconnection of the consumptions of the hub. One of the characteristics of these elements is the low self-discharge of the condenser, which ensures that, once the consumption is disconnected during the night period, the energy stored in the last hours of the previous day is in

20 large measure available to start operation first thing in the day. With these starting bases, a preferential application has been made and own operational and functional strategies have been established.

Brief description of the drawings

To complement the description made, and in order to help better

In order to understand the characteristics of the invention, a detailed description of a preferred embodiment will be made, based on a set of drawings that accompany this specification and where, for merely illustrative and non-limiting purposes, it has been represented the following: Figure 1 shows a view of a self-contained heliostat with electrical storage

30 by means of a condenser Figure 2 shows a block diagram of the local control of the autonomous heliostat thus conceived. Figure 3 shows a block diagram of the monitoring device. In the figures described the numerical references correspond to the following parts

35 and elements:

one.

Hollow pedestal

2.

Mirrored surface of autonomous heliostat

3.

Pedestal window

Four.

Electric capacitor

5.

Local control

6.

Head, or reducing mechanism

7.

Angular reader and lift axis limit switches (EL) 7 'Angular reader and azimuth axis limit switches (AZ)

8.

Electric drives or motors

9.

1O photovoltaic panel. Wind breaker

eleven.

Radio-modem

12.

Non-return diode

13.

Control board

14.

Motor control cards

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Real-time clock with battery

16.

Monitoring device

17.

Electric or electronic switch

18.

Ce / ce converter

19.

Field console

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Local command

twenty-one.

Ports of entry

22.

Microcontroller

2. 3.

RAM on the control board 13

24.

ROM of control board 13

25.

Departure ports

Description of a preferred application

For a better understanding of the invention, a preferred embodiment of the autonomous solar concentrator with electrical storage by means of a condenser, in which a heliostat has been chosen as the type concentrator, will be described in detail and based on the drawings. 1, the autonomous heliostat with electrical storage by means of a condenser consists of a mobile structure in two axes composed of a hollow pedestal (1), a head or reducing mechanism (6), a torsion tube and lattices that fix and support the structure to one mirror surface (2) of 40 meters

squares that moves following the sun.

The mirrored surface (2) is made up of two petals with a central opening that

gives the heliostat greater mobility on the lifting axis allowing an angle

of movement on this axis greater than 180 °.

5

In the head (6), angular position readers are arranged on both axes as well

as limit switches (7 and 7 ') that limit their angle of movement and

two motors (8}, which drive the head (6). On the motors (8), and solidary to the

head (6), a photovoltaic panel (9) is arranged and a

wind (1 O) and a radio modem (11).

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This arrangement allows movement on the azimuth axis of the photovoltaic panel (9)

this being installed with a fixed inclination of approximately 40 °.

The pedestal (1) has a window (3) made to allow the mounting of the

condemners (4) and the local control cabinet (5) inside it. The

window has a lid fixed by two handles.

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The DC motors (8) of 12Vdc and 70 watts of power drive the

mechanism by an autonomous power system consisting of a panel

photovoltaic (9) of 12Vdc and 55Wp and the capacitor (4) of 325F.

This arrangement of the local control (5) and the capacitors (4) provides ventilation

and natural cooling as well as additional protection for electronics and

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electrical elements. This is due to the upward air flow that originates

inside the pedestal (1) since it is open at its bottom and top.

This is an important factor to consider in facilities located in areas

arid semi-desert where the climatic conditions are very adverse.

Local control (5) of the autonomous heliostat powered by capacitors

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(4) is an electronic device that controls the operation of the heliostat and

manages its energy conditions, ensuring the safety and integrity of the equipment.

This local control (5) will have specific operational and functional strategies

to guarantee operation and safety avoiding situations of lack of

energy in adverse light and wind conditions.

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To guarantee this, the condenser (4) will maintain a charge level that guarantees

at all times the folding of the mirrored surface (2) under adverse conditions

light and wind.

In order to optimize and correctly size the power supply system of the

heliostat, a preferential, non-limiting application has been made, in which

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equipped with an existing heliostat on the Almería Solar Platform, with sensors

sufficient for the measurement of actual consumption under different operating conditions. Likewise, this heliostat has been equipped with a capacitor (4) in order to study its behavior in real work cycles. The condenser (4) of the heliostat has been made by arranging eight 2.7V and 2600F capacitors each. The capacitor (4) thus formed has a maximum voltage of 21.6 V with a total capacity of 325 farad. The eight capacitors have been connected in series by means of compensating plates and the whole assembly has been mounted on a polystyrene support arranged inside a basket, inside the pedestal (1) of the heliostat. The condenser (4) thus formed has replaced traditional photovoltaic power elements such as charge regulator and electric battery. This capacitor (4) is installed in parallel with the photovoltaic panel (9) and a diode

(12) will avoid downloading it at night. The load is also connected in parallel with the capacitor (4) by means of an electrical or electronic switch (17) that allows the connection / disconnection of the electrical consumption of the heliostat and the local control (5) of the heliostat. The local control (5) of the heliostat, managed by microcontroller (22), will decide the disconnection of the electrical consumptions aided by a monitoring device (16). The monitoring device 16 has been expressly designed for this preferred application. Very low consumption, powered directly from the photovoltaic panel (9), from the capacitor (4) or by means of a small cell or independent battery, it will be responsible for managing energy savings by informing the local control (5) of the conditions of capacitor charge (4). A small relay, connected in parallel with the photovoltaic panel, detects that the light conditions are sufficient first thing in the day and the voltage generated by the photovoltaic panel is sufficient to activate it. This relay will also be responsible for disconnecting the load at night. The local control (5) will decide the total disconnection of consumption when:

•

The monitoring device (16) detects a low voltage in the panel (9) or in the capacitor (4) and the heliostat is in the folding or folding position or in order of end of operation

•

Night time or absence of light detected by the photovoltaic panel (9). The automatic connection of consumptions is made under conditions of: -time control. Presence of light. -operating voltage of the capacitor (4).

The time control is carried out by a real-time clock (15) maintained with a small battery or its own battery arranged in the local control plate (13) of the heliostat and will be the one that, together with the monitoring device (16), actuates the electrical switch

or electronic (17) to connect the load electrically feeding the local control (5)

5 first thing in the day when the condenser (4) has the ideal charging conditions to guarantee the operation of the heliostat. In order for the flip-flop (SR, in figure 3) of the surveillance circuit (16) to tilt and activate the switch (17), it will be necessary for both conditions to be met: that there be light by activating the monitoring circuit relay (16) and the clock (15) wakes up on time

1 Or set before disconnection. Once the switch (17) is activated, a direct current to DC / DC converter (18) will generate the 5V Vcc voltage to supply the local control components (5). The rest of the components such as the engine controls (14), the field console (19) and the radio modem (11) will be

15 fed to the voltage of the capacitor Ve. In addition to including the clock (15), the local control board (13) incorporates a microcontroller (22) in charge of managing the operation of the heliostat. The microcontroller (22) is communicated with the outside through input ports

(21) and output ports (25) and uses RAM (23) and ROM (24) type memories to

20 their tasks. It also has a local control (20) to allow the movement of the motors (8) of the heliostat by means of the local action of switches located outside the local control panel (5). The microcontroller (22) will perform the functions of:

• Calculation of the corrected solar vector 25 • Reading of the angular position and precise positioning of axes

•

Solar tracking tasks

•

Operational and energy saving strategies

•

Communications management

•

Self-diagnosis and self-protection

30 In accordance with strategies for energy management and saving, under normal conditions, the heliostat disconnects the nightly consumptions and the condenser (4) will have enough charge during sunrise to start routine operation. During the rise of the heliostat early in the day and during the descent of the heliostat at sunset, the heliostat consumes much of the daily energy. Also, during

35 these periods of time, solar radiation is low, so the contribution of the panel

photovoltaic (9) is minimal and it is necessary to resort to the energy accumulated in the

condenser (4).

That is why the condenser (4) must be dimensioned to guarantee the

power supply in these periods.

5

During the rest of the time the heliostat will be monitoring the sun and the

Consumption will be very small since the motors (8) work in a pulsating way.

In these conditions the photovoltaic panel (9) will quickly charge the capacitor (4)

even in adverse light conditions such as the passage of clouds or strong

mist.

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During heliostat operation and under optimal light conditions, it is usual for the

capacitor (4) is always charged since the photovoltaic panel (9) is

dimensioned to provide enough energy to take over the consumption of the

heliostat in solar tracking operation.

This energy storage guarantees the reduction of the heliostat in any

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moment and in any circumstance as well as makes it possible to assume the consumption of the

control board (13) managed by microcontroller (22) and radio-modem (11)

to keep equipment operational and in service while waiting for conditions

operational and light are restored.

The heliostat is equipped with a wind switch (1 O) that informs the control

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local (5) when wind speed and direction conditions are dangerous for

the heliostat. Upon detection of an emergency, local control of the heliostat

will decide to maneuver the lift shaft to get, by the shortest path

possible to position the mirrored surface (2) in the most suitable safe position

guarantee its integrity.

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These conclusions have been obtained from actual operating data collected

of this preferred application.

The tests and trials carried out in this preferred application show

various functional and operational strategies in order to save and manage more

efficient energy accumulated in the capacitor. These are:

30

1.-At night the heliostat is in the down position with the photovoltaic panel

facing south, and the electrical consumptions are disconnected from the capacitor already

that the switch (17) is open. A diode prevents discharge of the capacitor to

through the photovoltaic panel at night allowing the capacitor to conserve,

during the night period, the energy left over from the previous day.

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2.-With the first rays of light, even before dawn, the relay of the circuit

surveillance (16) has been activated since the voltage generated by the photovoltaic panel, in

open circuit due to load disconnection, quickly rises to reach

the relay activation threshold. One of the logic gate inputs (ANO, in

figure 3) of the monitoring circuit (16) is therefore activated and the other input

5

awaits the awakening time set on the clock (15) on the

control (13). This clock (15) was programmed by the microcontroller (22) previously

before the disconnection of the previous day. In this first phase of dawn, the

solar radiation will be low but enough to start with a slow charge of the

capacitor (moment that occurs when the voltage of the photovoltaic panel is

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approximately 0.3V higher than that of the capacitor)

3At the time set on the clock, a flip flop (SR,

in figure 3) of the monitoring circuit (16) and the switch (17) and the

local control (5) of the heliostat will be connected to the condenser (4) being powered

electrically.

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4.The local control (5) will decide, depending on the loading conditions of the

capacitor (4), send heliostat east for solar tracking only

on the azimuth axis to achieve greater collection of photovoltaic energy and

more energetic and faster charging of the condenser in the first minutes of the day before

start with routine operation.

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5.-From the central control, and in order to achieve a greater accumulation of

power before starting the rise of the heliostat, it will wait to send the order

rise when the radiation conditions are the minimum established for the

start of operation. These conditions will depend on the type and characteristics of the

solar receiver and are usually about 300w / m2 of direct solar radiation.

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6.-In these conditions the local control will receive the order of rise in which it must

consume much of the accumulated energy but will have the help of the panel

photovoltaic which will take care of a sensible percentage of consumption.

7.-In operating light conditions (above 300w / m2) the heliostat will rise by

your security corridor until you are in focus tracking throughout the day.

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8.-Once the heliostat has reached its position of solar tracking to focus, the

Electricity consumption drops substantially as the motors (8) remain working

pulsating way. Under these conditions the condenser (4) recovers quickly and

stays charged above 90% throughout the solar day even with

adverse weather conditions (low radiation, strong fog, passing clouds ...)

35

mission of the condenser (4) during this phase of operation, will be to dampen

daylight variations causing small discharges that quickly recover when light conditions are restored. 9.-When the light conditions do not allow the operation of the solar receiver or when it is at the end of the day near sunset, the condenser (4) of the heliostat

5 has enough charge to lower the heliostat. The descent order will be received from the central control and the heliostat, still assisted by the radiation captured by the photovoltaic panel (9), will perform its knockdown maneuver, leaving the heliostat, at the end of it, with the photovoltaic panel (9) facing the south. 10.-At this moment the local control (5), before disconnecting the load and leaving free

10 consumption to the condenser, it will program the clock (15) to wake up a little after the next morning, then proceed to disconnect the load causing a flip-flop (SR in figure 3) to disconnect the switch (17) of the monitoring circuit (16). It will also be possible to program the awakening at regular time intervals, in order to wait for the

15 climatic conditions improve to wake up the heliostat and continue the operation with the day already started. 11.-When the light conditions are very low and there is hardly any light left on the horizon, the relay of the surveillance device (16) will be deactivated since the photovoltaic panel (9) does not generate enough voltage to maintain it. This will cause a

20 disconnection, if not previously done by the local control (5), of the load in order to ensure an energy store for the next day.

Claims (3)

1.-Autonomous solar concentrator with electrical storage through condenser characterized by comprising: a mirrored surface (2) one or more drives that consume electrical energy (8) for the movement of the mirrored surface (2) angular position readers of the hub axles and limit switches (7 and 7 ') . one or more photovoltaic panels (9) with its non-return diode (12) electrical capacitors (4) a wind switch (1 O) a radio modem (11) to communicate each autonomous concentrator to a local control cabinet (5) 2.-Autonomous solar concentrator according to claim 1, characterized because the local control (5) comprises: A control board (13) managed by the microcontroller (22) and which also incorporates a battery-maintained real-time clock (15) Control cards for the electric drive (14). A monitoring device (16) Electrical or electronic switches (17) 3.-Method of operation with strategies for saving and energy management of the autonomous solar concentrator described in the preceding claims, characterized in that it comprises the following stages:

•

Automatic connection of the consumption of the hub in conditions of: -wake up time by clock (15) and -presence of light detected by the photovoltaic panel (9).

•

Start of the maneuver to raise the hubs to the position of

solar monitoring or descent to the abatement position in the case of: -having more than the minimum solar radiation established for the operation of the plant (depending on the conditions of the solar receiver) and -having an operating voltage in the condenser (4) • Flow of the concentrator to its safe position in conditions of: -low voltage in the condenser and not having a solar radiation higher than the minimum established for the operation of the plant (will depend on the conditions of the solar receiver) or -very high wind • Disconnection of the consumptions of the concentrator in conditions of: -night time or absence of light detected by the photovoltaic panel (9) or -decision of the control board (13) due to very low voltage in the condenser (4) with the concentrator in folding or folding position or by order of end of operation.