BG2183U1 - PHOTOVOLTAIC SYSTEM FOR GENERATION AND SUBMISSION OF ELECTRICITY TO THE STANDING NETWORK AND THE CONSUMER IN IT - Google Patents

Abstract

The system is designed for self-supplying or supplementing electricity to existing DC-based networks, such as the public transport network. It is efficient and with high security in terms of voltage control during operation. The system comprises a photovoltaic field (2) consisting of at least one photovoltaic structure (3) representing a single photovoltaic panel (4) or a group (5) of photovoltaic panels (4) and a negative terminal (8) to which an optimizer (12) is connected whose terminals are connected to one another and / or in the corresponding configuration of the photovoltaic field in a known manner to the common outgoing lines (9, 10). A security unit (11) is mounted to at least one of the common outgoing lines (9, 10) which are connected to the DC network (1). Each optimizer (12) is selected from a specific type which, when operating together in the photovoltaic field (2), satisfies a group of conditions simultaneously. 8 claims, 5 figures

Description

(54) PHOTOVOLTAIC SYSTEM FOR GENERATION AND SUPPLY OF ELECTRICITY TO THE DC NETWORK AND ITS CONSUMERS

Field of technology

The photovoltaic system is designed for use as a stand-alone power supply or as a supplement to electricity to existing networks using direct current, such as those of public transport trolleybus, tram, subway.

BACKGROUND OF THE INVENTION

A photovoltaic system is known, used to supplement electricity to an existing trolleybus network. It includes a photovoltaic field composed of photovoltaic structures, representing single photovoltaic panels or groups of photovoltaic panels, the location of which photovoltaic structures is determined depending on the specific conditions - climate, geography, energy, installation and others. Each of the photovoltaic structures has a positive terminal and a negative terminal connected in a known manner to a common positive output line and a common negative output line. To each of the two common output lines there is a first protection unit, including protection-switching equipment, interrupting the electrical circuit in case of greater electric current than allowed, and then a second protection unit, including inductors, removing the pulsations of direct current from the photovoltaic. field. After the two protection units, a two-way high-speed switch is mounted to each of the common output lines, shutting off all or part of the system when the voltage increases, followed by a high-pass filter forming a control unit. Appropriate control is also provided for actuating the control unit. At the end of the two common output lines, in front of the place of their connection to the direct current network for the consumers, manual switches are installed. The disadvantages of the known system are related to the fact that the provided protection against overvoltage actually ensures the shutdown of photovoltaic structures or

U1 the entire photovoltaic field of the network, the excess voltage is not supplied to the network. Ie during the switch-off time the corresponding part of the system does not function. There are also problems with the security of the system, manifested in cases such as, for example, failure of a high-speed circuit breaker or its control, when the overvoltage can be applied to the mains. In addition, even when the high-speed circuit breakers are fully operational, they operate after the event, ie. after the voltage has reached an exceeded value. In case of greatly reduced or zero consumption of the network '5 by the photovoltaic field, its voltage increases, whereby, according to the existing solution, photovoltaic structures or the whole photovoltaic 2Q field are disconnected from the network in order to protect the network from the increased voltage. Under the current solution, there is no system to support the operation of photovoltaic panels at the point of maximum power, relying on them to work most of the time "around and close" to the point of maximum power, whereby the losses from inefficiency they are not so big and can be accepted. In general, the 5 θ disadvantages of the known photovoltaic system consist in the complex circuit and the many elements included in the protection and control unit, which are difficult to synchronize in such a way as to keep the whole system efficient and with 3 5 high voltage security during operation.

Technical essence of the utility model

The task of the utility model is to create a photovoltaic system for generating and supplying 40 electricity to the DC network and consumers in it, which will maintain a stable operating voltage at the point of maximum power of photovoltaic structures and provide an output voltage corresponding to the nominal voltage in the direct current network, at which to avoid inadmissible excess of the voltage in the network at reduced consumption or lack of such.

The problem is solved with a photovoltaic system 50 for generating and supplying electricity to the DC network and consumers

2183 UI therein, including a photovoltaic field composed of at least one photovoltaic structure. Each photovoltaic structure is either a single photovoltaic panel or a group of photovoltaic panels. The photovoltaic field has a corresponding voltage, and each of the photovoltaic structures has a positive terminal and a negative terminal. A common positive output line and a common negative output line are also provided, as well as a protection unit with protective switching equipment. According to the utility model, an optimizer is connected to the terminals of each of the photovoltaic structures forming the photovoltaic field, the terminals of which are connected to each other and / or in the corresponding photovoltaic configuration in a known manner to the common positive output line and the common negative output line. The protection unit is mounted to at least one of the common output lines that are connected to the DC network.

The photovoltaic system, as an option, includes a photovoltaic field formed by a photovoltaic structure, the optimizer connected between its positive terminal and the negative terminal being one, and the outputs thereof being the common positive output line and the common negative output line.

The photovoltaic structure may be a group of single photovoltaic panels connected in series.

It is also possible that the photovoltaic structure is a single photovoltaic panel.

Another option is for the photovoltaic field to include a group of at least two photovoltaic structures connected in a known manner.

As a suitable embodiment, it is possible for at least one of the group of photovoltaic structures to be a single photovoltaic panel.

It is also appropriate for at least one of the group of photovoltaic structures to be a "smart photovoltaic panel" in which the optimizer is built.

Also as an embodiment, at least one of the group of photovoltaic structures is a group of single photovoltaic panels, in which a group of series-connected optimizers is formed from the optimizers included in their terminals.

The advantages of the utility model consist in the achieved synchronization of the operation of the security elements of the system with the operation of the photovoltaic field and the maintenance of a working 5 point corresponding to the point of maximum power. When used, the system remains permanently connected to the DC mains and even at very low consumption, the system works, does not interrupt its work and generates energy for this very small consumption, the latter being provided entirely by the photovoltaic system. Overall, the system is efficient and highly secure with respect to the operating voltage control 15. In addition, the possibility has been achieved for the present technical solution to be applied for the reconstruction of existing photovoltaic fields by connecting to their photovoltaic structures the optimizers, according to the utility model.

Explanations of the attached figures

Figure 1 is a schematic block diagram of a photovoltaic system for generating and supplying electricity to the direct current network and the consumers in it;

Figure 2 is a block diagram according to one embodiment 30 of a photovoltaic system;

Figure 3 is a block diagram according to a second embodiment of a photovoltaic system;

Figure 4 is a block diagram according to another embodiment of a photovoltaic system;

Figure 5 is a block diagram according to a further embodiment of a photovoltaic system for generating and supplying electricity to the DC network and the consumers therein.

Examples of implementation of the utility model

The photovoltaic system for generating and supplying electricity to the direct current network and the consumers in it is illustrated in the attached figures by its application for powering the direct current network 1 of public transport and in particular, of a trolleybus network. The photovoltaic system includes a photovoltaic field 2 composed of at least one photovoltaic structure 3. The photovoltaic structure 3 is a single photovoltaic 5θ panel 4 or a group of photovoltaic panels 5. Since the DC network 1 for a trolleybus

2183 UI transport requires, normally, a nominal voltage of 660 V, the figures do not show the use of a photovoltaic field 2 composed of only one photovoltaic structure 3, which is a photovoltaic panel 4, although for other types of consumer networks operating with lower voltages, this is possible. It is envisaged that this technical solution will be used for DC networks 1 with a voltage of 25 V to 1000 V. The arrangement of the photovoltaic structures 3, whether single photovoltaic panels 4 or groups of photovoltaic panels 5, and a combination thereof, as shown in FIG. 1, is determined depending on the specific conditions - climatic, geographical, energy, installation, etc., as the composition and the specific location of the photovoltaic structures 3 in the photovoltaic field 2 is not subject to this technical solution. Each photovoltaic field 2 has a corresponding voltage. Each of the photovoltaic structures 3 included in the photovoltaic field 2 has a positive terminal 7 and a negative terminal 8. The photovoltaic field 2 also has a common positive output line 9 and a common negative output line 10. A protection unit 11 is provided, including a corresponding standard protection switching equipment with circuit breakers and fuse. According to the utility model, and as shown in each of the attached figures, an optimizer 12 is connected to the terminals of each of the photovoltaic structures 3.

The terminals of each of the optimizers 12 are interconnected and / or in the corresponding configuration of the photovoltaic field in a known manner to the common positive output line 9 and the common negative output line 10. The specific connection depends on the configuration of each photovoltaic field 2 and the specific location and type of the photovoltaic structures 3 included therein. In this case, the provided protection unit 11 is mounted to at least one of the common output lines 9, 10, which, in turn, are connected to the DC network 1. In the figures, the protection unit 11 is shown connected to the common positive output line 9, but the location it depends on the application of this technical solution to a specific network and consumers. It is possible that the protection unit 11 is located to both common output lines 9, 10, and only to the common negative output line 10. The number and the specific choice with respect to the protection unit 11 depends on the application of the solution to a specific DC network.

Each optimizer 12 is of a type that allows the following conditions for the complete configured system with optimizers to be satisfied simultaneously in the photovoltaic field 2:

- The nominal voltage of the photovoltaic field should be equal to the operating voltage of the network and the consumers in it.

- The nominal input voltage to each optimizer, which is determined by the voltage at the point of maximum power of the photovoltaic structures 3 connected to it to be higher than the nominal output voltage of the respective optimizer 12. The nominal output voltage of each optimizer 12 is determined by the mains voltage and the way of composing the group of optimizers 12.

- The nominal input voltage to each optimizer 12, which is determined by the voltage at the point of maximum power of the photovoltaic structures connected to it, should be lower than the maximum output voltage of the respective optimizer. The maximum output voltage of each optimizer 12 is its catalog parameter.

- The maximum output voltage of the photovoltaic field, which is determined by the maximum output voltages of the group of optimizers 12, depending on the way they are composed - to be less than the maximum allowable operating voltage of the network and consumers in it.

The present technical solution can independently supply the direct current network 1, as well as be included as a supplementary power supply to the direct current network 1, supplied mainly by an alternating current source 13 supplied to it as direct current by a rectifier 14. This is well shown in the attached figures.

In more detail, the present photovoltaic system for generating and supplying electricity to the DC network and the consumers therein is illustrated by several embodiments, one of which is shown in FIG. 2, wherein the photovoltaic field includes a photovoltaic structure 3, between the positive terminal 7 and the negative terminal 8, to which an optimizer 12 is connected. The outputs of this optimizer 12 are the common positive output line 9 and the common negative output line 10 of the photovoltaic field 2. In this case, the photovoltaic structure 3 represents a group 5 of single photovoltaic panels connected in series. The optimizer 12 is selected to satisfy the above conditions, in particular - the nominal input voltage to the optimizer 12, determined by the voltage at the point of maximum power of the photovoltaic structure 3 to which it is connected, is higher than the nominal output voltage of this optimizer 12 and lower than its maximum catalog output voltage, wherein the photovoltaic field 2 has a nominal voltage equal to the operating voltage of the DC network 1 and a maximum output voltage of the photovoltaic field - less than the maximum the permissible voltage of the direct current network 1. Since the example refers to additional power supply of the direct current network 1 of public transport, in this case - trolleybus, the figure also shows the rectifier 14, through which the main part of the required power supply of the direct current network 1 is supplied. In the indications of FIG. 2, for example, the protection unit 11 is connected to the common positive output line 9.

Similarly, the photovoltaic structure 3 can be only one photovoltaic panel 4, between the positive terminal 7 and the negative terminal 8 to which an optimizer 12 is connected, the outputs of which are the common positive output line 9 and the common negative output line 10. This variant does not is shown separately in the figures, as all the connections and selection conditions are identical to those already explained for the example of fig. 2.

In FIG. 3 shows a variant of the photovoltaic system according to the utility model, in which the photovoltaic field 2 is formed by several, at least two, photovoltaic structures 3, each of which represents a single, so-called "smart photovoltaic panel" 6. They are connected in series and have built-in optimizers 12 meeting the above conditions. This embodiment is equivalent to the implementation of the photovoltaic field of several photovoltaic structures 3, each of which represents a single photovoltaic panel 5, to the terminals of each of which has an optimizer 12, as shown in FIG. 4. In both equivalent embodiments, the optimizers 12, built-in or optionally mounted, are। θ connected in series with each other and form a group of series-connected optimizers, wherein one of the terminals of the first and last of this group of optimizers 12 is the common positive output line 9 and the common 15 negative output line 10.

In FIG. 5 shows an embodiment of the photovoltaic field 2 generated by several photovoltaic structures 3 representing ^{a group} as 2Q 5 of unit photovoltaic cells 4. The groups may include the same or a different number of photovoltaic panels 4, for example, similar to that shown photovoltaic structure shown in Fig. 2, the number included in the group 5 photo25 volt panels 4 is determined by the conditions in which the group 5 is placed. In this case, between the positive terminal 7 and the negative terminal 8 of each photovoltaic structure 3 is included an optimizer 12, forming a group of series-connected optimizers 12, wherein one of the pins of the first and last of this group of optimizers 12 is the common positive output line 9 and the common 3 5 negative output line 10. The optimizers 12 are selected to simultaneously satisfy the conditions mentioned above.

Application of the utility model When using the utility model, the solar radiation entering the photovoltaic panels is converted into direct current (DC) electricity. This energy, from the terminals of each photovoltaic structure 3, formed by the photovoltaic panels 4, enters the input of the corresponding optimizer 12. It converts 45 electrical quantities from the photovoltaic panels 4 - voltage and current (U, I), which are input values for the optimizer 12, in which at its output electrical quantities are obtained in a different ratio (U, I), but preserving the power (the product of U and I), excluding the losses in the optimizer itself. This is due to the conditions on which

2183 UI is made the choice of optimizer, or group of optimizers. The common output lines 9 and 10 of the optimizer 12 or, respectively, of the group of optimizers 12 are connected directly to the DC network, of course through at least one protection unit 11 depending on the specific need.

In general, the voltage at the point of maximum power of the panels is variable depending on the temperature, radiation, shading, aging and degradation of the panel, etc., and the mains voltage also varies depending on the load, tolerance and voltage variation in the electricity transmission and distribution network, recuperation of vehicles powered by the DC network, etc. Through the function determined by the optimizer selection conditions, each optimizer keeps the voltage of the photovoltaic panels and / or the photovoltaic structures 3 exactly at the point of maximum power, regardless of the mains voltage. Thus, the optimizer / group of optimizers ensures the operation of the panels of each photovoltaic structure at the optimal operating point, although the panel voltage and the mains voltage are not the same.

In case of reduction or, in the extreme case, loss of consumption and / or in emergency modes of switching off the consumers, the photovoltaic panels of the photovoltaic structures 3 of the photovoltaic field 2 remain idle and their output voltage increases. At this point, each optimizer 12 limits the voltage, and despite the higher value of the voltage from the photovoltaic structure, which is the input voltage for the optimizer, it has an output voltage for supply to the DC network, which is not higher than the preset value when choosing an optimizer. This limited value of the output voltage does not change, regardless of the higher input voltage from the panels. This automatically solves the problem of voltage regulation, preventing the introduction of a higher voltage than the photovoltaic field in the DC network and the whole system works with high security.

Claims (8)

A photovoltaic system for generating and supplying electricity to a direct current network (1) and its consumers, comprising a photovoltaic field (2) composed of at least one photovoltaic structure (3), representing a single photovoltaic panel (4) or a group 5) photovoltaic panels (4), which 1 θ photovoltaic field has a corresponding voltage, and each of the photovoltaic structures (3) has a positive terminal (7) and a negative terminal (8), and there is a common positive output line (9) and a common negative output line (10), as well as a protection unit (11) with protective switching equipment, characterized in that to the terminals (7, 8) of each of the photovoltaic structures (3) forming the photovoltaic field (2) is an optimizer (12) is connected, the terminals of which are connected to each other and / or in the corresponding configuration of the photovoltaic field to the common positive output line 25 (9) and the common negative output line (10), wherein the protection unit (11) is mounted to at least one o t the common output lines (9,10) which are connected to the direct current network (1). Photovoltaic system according to claim 1, characterized in that the photovoltaic field (2) is formed by a photovoltaic structure (3), the outputs of the optimizer connected between its positive terminal (7) 35 and the negative terminal (8). 12) are the common positive output line (9) and the common negative output line (10). Photovoltaic system according to claim 2, characterized in that the photovoltaic structure (3) is a group (5) of 40 single photovoltaic panels (4) connected in series. Photovoltaic system according to claim 2, characterized in that the photovoltaic structure (3) is a single photovoltaic panel (4). 45 _is a Photovoltaic system according to claim 1, characterized in that the photovoltaic field (2) comprises two connected photovoltaic structures (3). Photovoltaic system according to claim 5, characterized in that at least one of the photovoltaic structures (3) is a single photovoltaic panel (4). 2183 UI Photovoltaic system according to claim 5, characterized in that at least one of the photovoltaic structures (3) is a "smart photovoltaic panel" (6) in which the optimizer (12) is integrated. Photovoltaic system according to claim 5, characterized in that at least one of the photovoltaic structures (3) is a group (5) of single photovoltaic panels (4), wherein a group of optimizers (12) is formed from the optimizers connected to their terminals. series optimizers (12).