CN203301400U - A solar photovoltaic power generation system circuit - Google Patents

Abstract

The utility model discloses a solar photovoltaic power generation system circuit comprising a solar battery array, a storage battery group, a load, a unidirectional converter, a bidirectional converter, and a DC bus. The output of the solar battery array is connected with the DC bus via the unidirectional converter. The storage battery group is connected with the DC bus via the bidirectional converter. The load is connected with the DC bus. The number of the solar battery array and storage battery group connected in series or in parallel is not required to satisfy a strict matching relation and flexible selection and design can be executed according to circuit structure and power capacity. The high-voltage end of the bidirectional converter is connected with the DC bus in parallel. Optimal design can be executed on the bidirectional converter. Energy required by system overload is provided by the discharging of storage batteries. The power grade of the solar batteries is just configured according to the rated power of a system so as to reduce system cost. The solar photovoltaic power generation system circuit has simple system structure and may control the charging and discharging current of the storage batteries with the bidirectional converter so as to protect the storage batteries against damage.

Description

A solar photovoltaic power generation system circuit

technical field

The utility model relates to a solar photovoltaic power generation system circuit, which belongs to the technical field of new energy power generation.

Background technique

With the rapid consumption of fossil energy, and the resulting energy crisis and environmental pollution, in recent years, countries all over the world are actively looking for and developing new, clean and renewable energy. Solar energy has the characteristics of inexhaustible, inexhaustible, clean and safe, and is an ideal renewable energy source. Solar photovoltaic power generation is of great significance to alleviating the energy crisis and reducing environmental pollution, and has broad application prospects.

A solar photovoltaic power generation system with batteries as energy storage units generally consists of solar cells, batteries, unidirectional converters, bidirectional converters and DC loads. Due to the introduction of batteries, the energy required for system overload can be provided by the discharge of batteries, and the power level of solar cells only needs to be configured according to the rated power of the system, thereby reducing system costs. At present, in engineering practice, when many enterprises actually configure and design the capacity of solar photovoltaic power generation systems, they generally design according to engineering experience rather than according to actual application conditions. On the one hand, this may lead to unreasonable system capacity allocation and waste of resources. On the one hand, it may cause the system to fail to work normally due to insufficient capacity at certain times.

Utility model content

Aiming at the above-mentioned problems existing in the solar photovoltaic power generation system circuit in the prior art, the utility model provides a solar photovoltaic power generation system circuit. the

The technical scheme of the utility model is:

A solar photovoltaic power generation system circuit, including a solar cell array, a battery pack, a load, a unidirectional converter, a bidirectional converter, and a DC bus; the solar battery array is output to the DC bus through the unidirectional converter, and the battery pack is connected through the bidirectional converter To the DC bus, the load is connected to the DC bus.

Further, the solar battery array is used as a power supply unit, the battery pack is used as an energy storage unit, and the load is used as a power consumption unit.

Furthermore, the number of series and parallel connections between the solar cell array and the battery pack does not have to satisfy a strict matching relationship, and can be selected according to the circuit structure and power capacity.

Further, the charging and discharging of the battery pack share a bidirectional converter, and the charging and discharging current of the battery is controlled through the bidirectional converter.

Further, the inclination angle Φ of the solar cell array is 37°.

The beneficial effects of the utility model are:

(1) The number of series and parallel connections between the solar cell array and the battery pack does not have to meet a strict matching relationship, and can be flexibly selected and designed according to the circuit structure and power capacity;

(2) The high-voltage end of the bidirectional converter is connected in parallel with the DC bus, and the voltage of the DC bus is stable, so the bidirectional converter can be optimally designed;

(3) Due to the introduction of battery packs, the energy required for system overload can be provided by battery discharge, and the power level of solar cells only needs to be configured according to the rated power of the system, thereby reducing system costs;

(4) The system structure is relatively simple, and the charging and discharging of the battery is realized by using a bidirectional converter, which can reduce the weight of the system. At the same time, the charging and discharging current of the battery can be controlled through the bidirectional converter to protect the battery from damage.

Description of drawings

Fig. 1 is a circuit structure diagram of the solar photovoltaic power generation system of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in further detail.

The circuit structure of a solar photovoltaic power generation system of the utility model is shown in Figure 1, including: solar cell array, battery pack, load, unidirectional converter, bidirectional converter, DC bus (DC Bus), etc. The solar battery array is output to the DC bus through a unidirectional converter, the battery pack is connected to the DC bus through a bidirectional converter, the load is connected to the DC bus, the solar battery array is used as a power supply unit, the battery pack is used as an energy storage unit, and the load is used as a power consumer. unit.

The utility model relates to a capacity design method of a solar photovoltaic power generation system circuit, which is to design a reliable and economical photovoltaic power generation system according to the specific environmental conditions (geographic location, solar radiation energy, climate and weather, etc.) where the solar cell array is located. . The output power of the solar cell array is related to the number of solar cell modules connected in series and parallel. The series connection is to obtain the required operating voltage, and the parallel connection is to obtain the required operating current. An appropriate number of components are connected in series and parallel to form the required solar cell array. . According to the load condition, the storage battery needs to be used both when there is sunlight and when there is no sunshine, and the charging and discharging of the storage battery is used to meet the requirements of the actual operation of the system. Changes in the weather in the area where the solar array is installed will directly affect its power generation. If it encounters rainy weather for several consecutive days, the solar array can hardly generate electricity, and the battery can only be used to supply power to the load. When the sunlight is sufficient, the excess energy emitted by the solar cell will charge the battery again. The total solar radiation or total sunshine hours provided by the regional meteorological station are indispensable data for determining the capacity of the battery.

The utility model is described below in conjunction with the actual conditions of the region.

The solar cell capacity design and storage battery capacity design described in the utility model are based on the solar radiation energy data data of the last ten years provided by Nanjing Meteorological Observatory, Jiangsu Province:

Latitude and longitude of Nanjing area: east longitude 118° 48', north latitude 32°; the longest continuous rainy days in Nanjing area in the last ten years is 12 days, the shortest is 6 days, and the average is N _d = 8 days; the annual average of Nanjing area in the last ten years The solar radiation is 4468.4 MJ/m ² (the total solar radiation received by each square meter area in one year).

The load requirements of this system are: rated voltage V _o =100VDC; rated power P _o =500W; assuming that the daily working time of the load is t _d =7 hours (h), then the daily power consumption of the load E _Ld = P _o × t _d =3500Wh, during 8 consecutive days of cloudy and rainy days, the total continuous working time of the load is T = t _d × N _d =56 hours (h).

(1) Capacity design of solar cell array

In order to simplify the control of the photovoltaic power generation system and consider meeting the load demand in different seasons, the inclination angle of the solar cell array can be determined according to the following rules, namely:

Considering that the energy of the solar cell array can be optimally utilized throughout the year, the installation inclination angle Ф of the array is 5 ^o more than the local latitude. When the system is actually installed, the installation inclination angle of the solar cell array is Ф=37 ^o .

According to the above-mentioned annual average solar radiation of 4468.4 MJ/m ² in Nanjing in the last ten years, it can be calculated that the daily average solar radiation is 12242 kJ/m ² (calculated as 365 days in a year). Considering the installation inclination angle of the solar cell array and introducing the slope correction coefficient (the empirical value is generally 1.1), the daily average solar radiation H _t = 13466 kJ/m ² on the slope of the solar cell array is obtained. Further convert the daily average radiation amount H _t into the daily average radiation hours H under the standard light intensity (1000W/ m ² ):

H = H _t ×2.778/10000h=13466 kJ/ m ² ×(2.778/10000)＝3.74 (h)

In the formula, 2.778/10000 (h·m ² /kJ) is the coefficient for converting the daily average radiation dose into the daily average radiation hours under standard light intensity.

Since the daily power consumption of the load is 3500Wh, and the efficiency of the unidirectional converter is set to 95%, the energy E _PV (watt-hours, Wh) that needs to be provided by the solar cell array every day is:

Considering the losses caused by the combination of solar cell components, attenuation, dust, charging efficiency, etc., a correction factor for solar cell components is introduced, which is generally 0.8. Therefore, it can be concluded that the battery module output peak power P _m required by the system is:

(2) Capacity design of the battery

The capacity of the battery is very important to ensure the continuous power supply of the load. In a year, the power generation of solar cell arrays varies greatly from month to month. When the power generation cannot meet the power demand of the load, the battery needs to be discharged to make up for it; in the month that exceeds the power demand of the load, the excess power is charged to the battery And store it. Because the load power during continuous rainy days must be obtained from the battery, the battery capacity is much larger than the power required by the load.

The energy storage device of the solar photovoltaic power generation system mainly uses lead-acid maintenance-free batteries at present. The experimental system uses a lead-acid battery with a nominal voltage of 48V. The battery capacity (Ah) required by the system can be calculated according to the commonly used empirical formula for engineering design:

In the formula, C _B -battery capacity (Ampere hours, Ah);

E _LBd - the amount of power supplied by the battery to the load per day, 3500Wh;

N _d - the number of consecutive rainy days, 8 days;

R _B - Correction coefficient of battery discharge efficiency, generally 1.05;

U _B - battery rated voltage, 48V;

η _Boost - bidirectional converter efficiency, take 95%;

F _D - the depth of discharge of the battery, generally 0.75;

L _B - The maintenance rate of the storage battery, generally taken as 0.9.

According to the calculation results of the above formula, the nominal lead-acid battery of 48V/1000Ah is theoretically selected.

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. All modifications, equivalent replacements and improvements made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (5)

1. a solar photovoltaic generation system circuit, is characterized in that: comprise solar battery array, batteries, load, monotonic transformation device, reversible transducer, DC bus; Solar battery array exports DC bus to by the monotonic transformation device, and batteries is connected to DC bus by reversible transducer, and load is connected on DC bus.

2. a kind of solar photovoltaic generation system circuit according to claim 1, it is characterized in that: described solar battery array is as power supply unit, and described batteries is as energy-storage units, and described load is as power unit.

3. a kind of solar photovoltaic generation system circuit according to claim 1, it is characterized in that: the connection in series-parallel number of described solar battery array and batteries needn't meet strict matching relationship, can select according to circuit structure and power capacity.

4. a kind of solar photovoltaic generation system circuit according to claim 1 is characterized in that: discharging and recharging of described batteries shares a reversible transducer, by reversible transducer, controls the accumulator cell charging and discharging electric current simultaneously.

5. a kind of solar photovoltaic generation system circuit according to claim 1, it is characterized in that: the inclination angle Ф of described solar battery array is 37 ^o.

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