CN201887525U - Hybrid energy storage system for photovoltaic power generation system - Google Patents

Abstract

A hybrid energy storage system for photovoltaic power generation systems, which is used to solve the problems of low power density and short service life of traditional battery energy storage systems. The technical solution is that it includes a chopper circuit, a first boost circuit, a second boost circuit, a battery pack and a supercapacitor pack, the high voltage side of the chopper circuit is connected to the DC bus of the photovoltaic power generation system, and the low voltage side is connected to the battery pack , the low-voltage side of the first boost circuit is connected to the battery pack, the high-voltage side is connected to the super capacitor bank, the low-voltage side of the second boost circuit is connected to the super capacitor bank, and the high-voltage side is connected to the DC bus of the photovoltaic power generation system. Compared with the traditional energy storage device, the utility model has the advantages of high energy density of the storage battery and high power density of the supercapacitor, which greatly improves the quality of the output power of the photovoltaic power generation system, and has a long service life, reducing the comprehensive operating cost of the photovoltaic power generation system .

Description

A hybrid energy storage system for photovoltaic power generation system

technical field

The utility model relates to a hybrid energy storage system for a photovoltaic power generation system, which uses a supercapacitor and a storage battery as energy storage elements, and belongs to the technical field of power generation.

Background technique

Photovoltaic power generation systems are different from conventional power generation systems. Affected by natural factors such as light intensity and temperature, the output power of photovoltaic power sources will fluctuate greatly, so that they cannot supply power to conventional loads. In order to suppress this fluctuation, it is necessary to install an energy storage system in the photovoltaic power generation system. At present, the commonly used energy storage device in the photovoltaic power generation system is the energy storage battery. The production technology of the battery is mature, the energy density is high, and the price is relatively low. Guaranteed. However, the power density of the battery is low, which is not suitable for high-power power supply occasions, and its cycle life is short. The small cycle charge and discharge phenomenon of the energy storage system caused by light changes and frequent load fluctuations will shorten the service life of the battery, resulting in a comprehensive photovoltaic power generation system. Running costs increase.

Supercapacitor is a new energy storage device with long cycle life, fast charging and discharging speed and high power density. Therefore, supercapacitor is suitable for occasions where the output power of photovoltaic power supply changes frequently and for short-term high-power loads. . Moreover, these characteristics of supercapacitors can just complement the advantages of batteries. In view of the energy storage characteristics of supercapacitors and batteries, some experts and scholars have proposed a hybrid energy storage mode that combines the two components in recent years, but so far, there is no feasible technical solution.

Utility model content

The utility model is used to overcome the defects of the prior art and provide a hybrid energy storage system for a photovoltaic power generation system with high energy density and power density and long service life.

The said problem of the utility model is realized with following technical scheme:

A hybrid energy storage system for a photovoltaic power generation system, comprising a chopper circuit, a first boost circuit, a second boost circuit, a battery pack and a supercapacitor pack, the high voltage side of the chopper circuit is connected to photovoltaic power generation The DC bus of the system, the low-voltage side is connected to the battery pack, the low-voltage side of the first boost circuit is connected to the battery pack, the high-voltage side is connected to the super capacitor bank, the low-voltage side of the second boost circuit is connected to the super capacitor bank, and the high-voltage side is connected to the DC of the photovoltaic power generation system busbar.

In the above hybrid energy storage system for a photovoltaic power generation system, the chopper circuit is composed of a first insulated gate bipolar transistor, a first inductor, a first diode and a first capacitor, and the first insulated gate bipolar transistor The collector of the photovoltaic power generation system is connected to the positive pole of the DC bus bar of the photovoltaic power generation system, the emitter is charged to the battery pack through the first inductor, the base is connected to the control circuit, the first diode is a freewheeling diode, and the first capacitor is the output filter capacitor of the chopper circuit; The first step-up circuit is composed of a second insulated gate bipolar transistor, a second inductance and a second diode, one end of the second inductance is connected to the positive pole of the battery pack, and the other end charges the supercapacitor bank through the second diode, The collector of the second insulated gate bipolar transistor is connected to the series connection point of the second inductance and the second diode, the emitter is connected to the common negative pole of the supercapacitor bank, the battery pack and the DC bus of the photovoltaic power generation system, and the base is connected to the control circuit; The second boost circuit is composed of a third insulated gate bipolar transistor, a third inductance, a third diode and a second capacitor. One end of the third inductance is connected to the positive pole of the supercapacitor bank, and the current output from the other end passes through the third The diode is sent to the positive pole of the DC bus of the photovoltaic power generation system, the collector of the third insulated gate bipolar transistor is connected to the series connection point of the third inductor and the third diode, the emitter is connected to the negative pole of the supercapacitor bank, and the base is connected to the control circuit , the second capacitor is an output filter capacitor of the second boost circuit.

The utility model uses a supercapacitor group and a storage battery group as the energy storage elements of the photovoltaic power generation system, thus having the advantages of high energy density of the storage battery and high power density of the supercapacitor, and greatly improving the output power quality of the photovoltaic power generation system. The chopper circuit and two booster circuits are used to precisely control the charging and discharging process of the supercapacitor bank and the battery bank, so that the advantages of the supercapacitor bank's high power density, long cycle life, and high energy density of the battery can be fully utilized, and prevent the battery from The overcharge and overdischarge of the battery can reduce or even avoid the occurrence of small battery charging and discharging cycles, prolong the service life of the battery to the greatest extent, and reduce the comprehensive operating cost of the photovoltaic power generation system.

Description of drawings

Figure 1 is a block diagram of the electrical principle of the photovoltaic power generation system;

Fig. 2 is the electrical schematic diagram of the present utility model;

Fig. 3 is a calculation flow chart of the hybrid energy storage system capacity optimal configuration method.

The symbols in the figure are: DC/DC1, chopper circuit; DC/DC2, first booster circuit, DC/DC3, second booster circuit; B, battery pack; EDLC, supercapacitor pack; T1, T2, T3 , Insulated gate bipolar transistor; L1, L2, L3, inductor; C1, C2, capacitor; D1, D2, D3, diode.

Detailed ways

Referring to Fig. 1 and Fig. 2, the utility model is mainly composed of five parts, namely: chopper circuit DC/DC1, first boost circuit DC/DC2, second boost circuit DC/DC3, supercapacitor bank EDLC and storage battery Group B.

The high-voltage side of the chopper circuit DC/DC1 is directly connected to the DC bus bar of the photovoltaic power generation system, the low-voltage side is connected to the battery pack B, the low-voltage side of the first step-up circuit DC/DC2 is connected to the battery pack B, and the high-voltage side is connected to the supercapacitor bank EDLC. The low-voltage side of the second step-up circuit DC/DC3 is connected to the supercapacitor bank EDLC, and the high-voltage side is directly connected to the DC bus of the photovoltaic power generation system; the hybrid energy storage system can be based on the power demand on the DC bus of the photovoltaic power generation system, through the chopper circuit DC /DC1, the first boost circuit DC/DC2, and the second boost circuit DC/DC3 perform flexible charge and discharge control on the battery pack B and the supercapacitor pack EDLC to solve the problem of unbalanced power supply and consumption of the photovoltaic power generation system; the system The power in the chopper circuit DC/DC1, the first step-up circuit DC/DC2, and the second step-up circuit DC/DC3 all flow in one direction, which is faster in response than the bidirectional controller; the first step-up circuit DC/DC DC2 can connect supercapacitor bank EDLC and battery bank B with different terminal voltages, so that the capacity configuration of the two can be more flexible; the second boost circuit DC/DC3 controls the discharge mode of the hybrid energy storage system, and can also stabilize the energy storage system. The effect of the DC bus voltage suppresses the influence of the EDLC terminal voltage change of the supercapacitor bank on the load power supply, and improves the power quality of the load power supply.

Due to the high power density and long cycle life of the supercapacitor group EDLC, and the short cycle life of the battery group B, the charging and discharging conditions are relatively strict. Therefore, when the photovoltaic power output fluctuates or the load power fluctuates, the charging and discharging of the hybrid energy storage system should be flexibly controlled. , while ensuring the power quality of the system power supply, optimize the charging and discharging process of the battery and prolong its service life.

The utility model should optimize the capacity of the supercapacitor group EDLC and battery group B according to local climate characteristics, photovoltaic power generation system scale and technical indicators, load characteristics and other factors. The specific optimal configuration method is as follows:

(1) Analyze local radiation data and temperature data to obtain representative daily radiation and daily temperature changes;

(2) Obtain the daily power generation curve of the photovoltaic power generation system according to the photovoltaic cell parameters, the scale of the photovoltaic power generation system, the daily temperature change law and the daily radiation change law;

(3) Analyze the local electricity load to obtain load parameters that can characterize the local load characteristics;

(4) According to the power generation characteristics of the photovoltaic power generation system, load operation characteristics, charging and discharging characteristics of the supercapacitor group EDLC and battery group B, and according to various technical indicators of the photovoltaic power generation system, list the energy storage for the supercapacitor group EDLC and battery group B Capacity and charge and discharge power requirements;

(5) Taking the various technical indicators of the photovoltaic power generation system as the constraints and the overall economics of the energy storage system as the optimization goal, after linearizing the constraints, the simplex method is used to solve the mathematical optimization problem, so as to obtain the supercapacitor bank The optimal configuration scheme of EDLC and battery pack B.

Aiming at the above optimization configuration method, the utility model develops hybrid energy storage system capacity optimization configuration software on the platform of VC++6.0, and inputs corresponding characteristic parameters for photovoltaic power generation systems of different regions, different scales and different load characteristics, namely The optimal configuration scheme of supercapacitor and storage battery can be obtained.

During the charging and discharging process, the working states of the chopper circuit DC/DC1, the first boosting circuit DC/DC2, and the second boosting circuit DC/DC3, as well as the charging and discharging characteristics of the supercapacitor bank and the battery pack have the following modes:

(1) During the period of sufficient sunlight during the day, the output power of the photovoltaic power supply is relatively large, and the load power is also relatively large. The remaining power on the DC bus is within the range required by the safe charging power of the battery. At this time, the chopper circuit DC/DC1 The energy storage state works in the three-stage charging mode, and the output power of DC/DC2 and DC/DC3 is zero. In this working mode, the photovoltaic busbar charges the battery pack, and the supercapacitor pack neither charges nor discharges;

(2) During the period of sufficient sunlight during the day, the photovoltaic power supply generates a large power, the load power is small, and the remaining power on the DC bus is greater than the upper limit of the safe charging power of the battery. At this time, DC/DC1 works at three In stage charging mode, the output power of DC/DC2 is the difference between the total charging power of the system and the safe charging power of the battery pack, and the output power of DC/DC3 is zero. In this working mode, the photovoltaic busbar charges the battery pack, and the supercapacitor pack is in a charging state to absorb excess electric energy to protect the battery pack;

(3) When the photovoltaic power generation system is blocked by short-term clouds or the impact of high-power loads causes the photovoltaic power supply to fail to supply power to the load normally for a short time, the output power of DC/DC1 is zero, the output power of DC/DC2 is zero, and the output power of DC/DC3 is constant Voltage mode output power. In this working mode, the battery pack is neither charged nor discharged, and the supercapacitor pack is in the discharge state to provide short-term energy demand for the load, thereby preventing the small cycle of charge and discharge of the battery pack and prolonging the service life of the battery pack;

(4) When it is in the time of insufficient light such as morning and evening or the time of no light such as rainy and nighttime, the photovoltaic power supply cannot supply power to the load normally, the output power of DC/DC1 is zero, and the output power of DC/DC2 is in the mode of constant inductor current. For the average power of the load during this period, DC/DC3 outputs power in constant voltage mode. In this working mode, the battery pack is discharged in cross-current mode, and the discharge power is the average power of the load during this period. When the load power is higher than the average power, the supercapacitor bank is discharged, and the discharge power is the difference between the load power and the discharge power of the battery pack. ; When the load power is lower than the average power, the discharge power of the storage battery meets the demand of the load work, and the remaining power is used to charge the supercapacitor bank to prepare for the next load peak. In this way, the power output capability of the energy storage system is improved and the discharge process of the battery pack is optimized.

Claims (2)

1. A hybrid energy storage system for a photovoltaic power generation system, characterized in that the composition includes a chopper circuit (DC/DC1), a first boost circuit (DC/DC2), a second boost circuit (DC/DC DC3), battery pack (B) and supercapacitor pack (EDLC), the high-voltage side of the chopper circuit (DC/DC1) is connected to the DC bus of the photovoltaic power generation system, the low-voltage side is connected to the battery pack (B), and the first booster circuit The low-voltage side of (DC/DC2) is connected to the battery pack (B), the high-voltage side is connected to the supercapacitor bank (EDLC), the low-voltage side of the second boost circuit (DC/DC3) is connected to the supercapacitor bank (EDLC), and the high-voltage side is connected to the photovoltaic The DC bus of the power generation system. 2. The hybrid energy storage system for photovoltaic power generation system according to claim 1, characterized in that, the chopper circuit (DC/DC1) is composed of a first insulated gate bipolar transistor (T1), a first inductor ( L1), the first diode (D1) and the first capacitor (C1), the collector of the first insulated gate bipolar transistor (T1) is connected to the positive pole of the DC bus of the photovoltaic power generation system, and the emitter is connected to the first inductor (L1) ) to charge the battery pack (B), the base is connected to the control circuit, the first diode (D1) is a freewheeling diode, and the first capacitor (C1) is the output filter capacitor of the chopper circuit (DC/DC1); A boost circuit (DC/DC2) is composed of a second insulated gate bipolar transistor (T2), a second inductor (L2) and a second diode (D2), and one end of the second inductor (L2) is connected to the battery pack ( B) positive pole, the other end charges the supercapacitor bank (EDLC) through the second diode (D2), and the collector of the second insulated gate bipolar transistor (T2) is connected to the second inductor (L2) and the second diode The series connection point of the tube (D2), the emitter is connected to the common negative pole of the supercapacitor bank (EDLC), the battery pack (B) and the DC bus of the photovoltaic power generation system, and the base is connected to the control circuit; the second booster circuit (DC/DC3 ) consists of a third insulated gate bipolar transistor (T3), a third inductor (L3), a third diode (D3) and a second capacitor (C2), and one end of the third inductor (L3) is connected to a supercapacitor bank ( EDLC) positive pole, the current output from the other end is connected to the positive pole of the DC bus of the photovoltaic power generation system through the third diode (D3), and the collector of the third insulated gate bipolar transistor (T3) is connected to the third inductor (L3) and the first The series connection point of the three diodes (D3), the emitter is connected to the negative pole of the super capacitor bank (EDLC), the base is connected to the control circuit, and the second capacitor (C2) is the output filter capacitor of the second boost circuit (DC/DC3).

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