Power-balanced photovoltaic power generation system

Abstract

The invention discloses a power balance photovoltaic power generation system, which comprises a plurality of groups of photovoltaic arrays (PV1, PV2 and PVn), direct current switches (K1, K2 and Kn), an inverter (CV), a power grid (Grid), a power detection unit (A) and a monitoring unit (ST), the plurality of groups of photovoltaic arrays (PV1, PV2 and PVn) are connected to the input end of the inverter (CV) through the direct current switches (K1, K2 and Kn), the inverter (CV) converts photovoltaic direct current into alternating current and transmits the alternating current to the power grid (Grid), and the monitoring unit (ST) monitors the alternating current. The output side of the inverter (CV) is connected with a power detection unit (A), and the monitoring unit (ST) is respectively connected with the direct current switches (K1, K2 and Kn), the inverter (CV) and the power detection unit (A). According to the invention, multiple groups of photovoltaic modules are configured, and the number of input arrays is switched according to different illuminance, so that the output power is close to a rated value as much as possible, an actually friendly power grid enters, and the power generation benefit is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a power-balanced photovoltaic power generation system. Background Art

[0002] Photovoltaic power generation has been vigorously developed as a green energy source favored by users around the world. However, due to the unevenness of climate and light, the power generation fluctuates and has a serious impact on the power grid. Therefore, power supply departments in various regions have formulated strict requirements for the grid connection of photovoltaic power stations. For example, limiting the scale of power stations also limits the maximum grid-connected power.

[0003] Despite this, the drastic change in grid-connected power caused by the change in light from sunny to rainy days in photovoltaic power plants has not been fundamentally changed. On the other hand, users can only design a certain number of components based on the scale of the power plant reviewed by the power supply department to avoid exceeding the maximum allowable power. In this way, because the average duration of rainy days far exceeds the duration of sunny days, the power plant is in a state of insufficient power generation most of the time, perhaps only 1 / 3~1 / 5 of the maximum allowable power, which has caused a great waste of investment in the power plant and also wasted precious grid-connected power indicators. For a long time, the majority of power plant investors have had to endure this fact, and the return on investment is far away, which has affected investors' confidence in investing in photovoltaic power plants. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a power-balanced photovoltaic power generation system which configures multiple groups of photovoltaic modules and switches the number of arrays put into use according to different light intensities, so that the output power is as close to the rated value as possible, the actual friendly grid access is achieved, and the power generation efficiency is greatly improved.

[0005] To achieve the above object, the present invention provides the following technical solutions: A power-balanced photovoltaic power generation system comprises a plurality of photovoltaic arrays (PV1, PV2, PVn), direct current switches (K1, K2, Kn), an inverter (CV), a power grid (Grid), a power detection unit (A), and a monitoring unit (ST), wherein the plurality of photovoltaic arrays (PV1, PV2, PVn) are connected to an input end of an inverter (CV) via direct current switches (K1, K2, Kn), the inverter (CV) converts photovoltaic direct current into alternating current and transmits it to a power grid (Grid), the output side of the inverter (CV) is connected to a power detection unit (A), and the monitoring unit (ST) is respectively connected to the direct current switches (K1, K2, Kn), the inverter (CV), and the power detection unit (A).

[0006] Furthermore, the monitoring unit (ST) is used to receive signals from the inverter (CV) and the power detection unit (A), and then output control signals to the DC switches (K1, K2, Kn).

[0007] Furthermore, the power detection unit (A) can monitor the output power of the inverter (CV) at all times.

[0008] Furthermore, the monitoring unit (ST) is preset with the maximum allowable power of the system and the power value of each photovoltaic array.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention configures multiple groups of photovoltaic modules and switches the number of arrays put into use according to different light intensities, so that the output power is as close to the rated value as possible, the actual friendly grid is entered, and the power generation efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 is a schematic diagram of Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of a photovoltaic array combination meter with an output power of 80KW in the first embodiment of the present invention. DETAILED DESCRIPTION

[0011] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0012] See also Figure 1 As shown, a power-balanced photovoltaic power generation system includes multiple photovoltaic arrays PV1, PV2, PVn, DC switches K1, K2, Kn, inverters CV, a power grid Grid, a power detection unit A, and a monitoring unit ST, characterized in that: the multiple photovoltaic arrays PV1, PV2, PVn are connected to the input end of the inverter CV through the DC switches K1, K2, Kn, the inverter CV converts photovoltaic DC power into AC power and transmits it to the power grid Grid, the output side of the inverter CV is connected to the power detection unit A, and the monitoring unit ST is respectively connected to the DC switches K1, K2, Kn, the inverter CV, and the power detection unit A.

[0013] The monitoring unit ST is used to receive signals from the inverter CV and the power detection unit A, and then output control signals to the DC switches K1, K2, Kn.

[0014] Its working logic is as follows: (1) The maximum allowable power of the system and the power value of each photovoltaic array are preset in the monitoring unit ST; (2) The power detection unit A can monitor the output power of the inverter CV at all times; (3) If the monitoring unit ST determines that the output power is less than the maximum rated power and remains stable for a period of time (e.g., 3 minutes), the monitoring unit ST determines which switches K1, K2, and Kn are turned on and which are turned off based on the calculation results, so that the output power is as close to the full grid-connected power as possible; (4) If the monitoring unit determines that the output power is close to the maximum rated power, the monitoring unit ST promptly adjusts the switches K1, K2, and Kn according to the calculation result to prevent the output power from exceeding the rated value. Embodiment 1

[0015] See also Figure 2 and Figure 3 As shown, this embodiment is configured with 4 photovoltaic arrays, namely PV1, PV2 PV3, and PV4. Taking the maximum power of 80KW approved by the power supply department as an example, PV1, PV2 PV3, and PV4 are configured with 80KW, 40KW, 20KW, and 10KW power respectively. Through the combination of switches K1, K2, K3, and K4, the actual output power under different light effects is formed; output power value = combination power * light efficiency; light efficiency = output power / combination power, with this, the switch combination for maintaining the output power close to the rated power under different light effects can be obtained; The actual output power can be measured by the power detection unit A, or it can be obtained through the feedback value of the inverter CV. For example, the current value is 80KW. Assuming that the current combination of K1~K4 is 1010, the combined theoretical power is 100KW (obtained by looking up the table).

[0016] Then the light efficiency at this time = 80 / 100*100%=80%; That is to say, when the light efficiency is 80%, if the switch combination is 1010, the output power is exactly 80KW; If the light becomes weaker and the output power decreases, the light efficiency will also decrease. For example, if it is lower than 72.7% and stabilizes for a certain period of time, assuming it is 5 minutes, the monitoring unit ST reaches the switching condition according to the logic in the built-in table. ST issues a command to switch K1~K4 to "1011", and the output power rises to 79.97KW, reaching the rated output value. On the contrary, if the light becomes stronger and the lighting effect increases, the monitoring unit ST will readjust the K1~K4 combination according to the values ​​in the built-in table to make the output power close to the rated value again. Of course, in order to prevent frequent action of the critical point, a certain delay and hysteresis value can be set during actual operation.

[0017] In summary, the present invention can effectively solve the damage to the diode caused by destructive pulses generated by poor contact and device instability during detection through the design of a controller with a controllable current source, and has the advantages of low manufacturing cost and easy use.

[0018] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A power-balanced photovoltaic power generation system, comprising a plurality of photovoltaic arrays (PV1, PV2, PVn), DC switches (K1, K2, Kn), an inverter (CV), a power grid (Grid), a power detection unit (A), and a monitoring unit (ST), characterized in that: The plurality of photovoltaic arrays (PV1, PV2, PVn) are connected to an input end of an inverter (CV) through DC switches (K1, K2, Kn); the inverter (CV) converts photovoltaic DC power into AC power and transmits it to a power grid (Grid); a power detection unit (A) is connected to an output side of the inverter (CV); and the monitoring unit (ST) is respectively connected to the DC switches (K1, K2, Kn), the inverter (CV), and the power detection unit (A).

2. A power-balanced photovoltaic power generation system according to claim 1, characterized in that: The monitoring unit (ST) is used to receive signals from the inverter (CV) and the power detection unit (A), and then output control signals to the DC switches (K1, K2, Kn).

3. A power-balanced photovoltaic power generation system according to claim 1, characterized in that: The power detection unit (A) can monitor the output power of the inverter (CV) at all times, and the monitoring unit (ST) is preset with the maximum allowable power of the system and the power value of each photovoltaic array.

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