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CN-118040748-B - High-safety and high-efficiency control method and system for photovoltaic energy storage system

CN118040748BCN 118040748 BCN118040748 BCN 118040748BCN-118040748-B

Abstract

The invention provides a high-safety high-efficiency control method and a high-efficiency control system for a photovoltaic energy storage system, which are characterized in that positive and negative small vectors of a high common-mode voltage are used for synthesizing reference voltage vectors, the common-mode voltage value of the vectors is not concerned any more, the variation range of the common-mode voltage in all switching sequences is limited, the common-mode voltage variation rate of the system is reduced and the leakage current is reduced under the condition that the photovoltaic voltage and the storage battery voltage are variable.

Inventors

  • XING XIANGYANG
  • LI ZHAONAN
  • LIU CHANG

Assignees

  • 山东大学

Dates

Publication Date
20260505
Application Date
20240116

Claims (9)

  1. 1. The high-safety and high-efficiency control method of the photovoltaic energy storage system is characterized by comprising the following steps of: Acquiring a reference voltage vector under an alpha beta coordinate system of a power grid, judging a large sector where the reference voltage vector is located according to the value of a phase angle of the reference voltage vector, and dividing each large sector into a first part and a second part according to the position of a middle vector; Calculating the common-mode voltage of each vector according to the photovoltaic voltage and the storage battery voltage, sequencing the common-mode voltage, and generating a vector sequence of a switching sequence; dividing four small sectors in a first part and a second part of each large sector, wherein each small sector has one or more charging sequences and discharging sequences, modulating by adopting three vector synthesis reference voltage vectors in different switching sequences of different small sectors, and calculating to obtain the action time of the corresponding vector; Calculating photovoltaic power according to the photovoltaic voltage and the photovoltaic current, generating control parameters by a direct current power control loop through a PI regulator, obtaining power control parameters by the control parameters through an amplitude limiting unit, and adjusting the use frequency of a charging sequence and a discharging sequence in real time according to the power control parameters; controlling the on-off of a power switch tube in the double-direct-current port inverter based on the action time and the switch sequence so as to control the operation of the inverter; Calculating a common-mode voltage of each vector according to the photovoltaic voltage and the storage battery voltage, and sequencing the common-mode voltage, wherein the method comprises the following steps of: The method comprises the steps of obtaining a photovoltaic voltage V PV and a storage battery voltage V Bat , calculating common-mode voltage values of all vectors, wherein the vectors correspond to eight common-mode voltage values, and sorting the vectors from low to high according to the common-mode voltage values, wherein the common-mode voltage values are divided into a first large vector, a second large vector, a middle vector, a first positive small vector, a second positive small vector, a first negative small vector, a second negative small vector and a zero vector; When the vector is 2V Bat <V PV <3V Bat , the sequence is sequentially a first negative small vector, a second negative small vector, a first large vector, a zero vector, a medium vector, a first positive small vector, a second large vector and a second positive small vector; When V PV >3V Bat , the sequence is sequentially a first negative small vector, a second negative small vector, a zero vector, a first large vector, a middle vector, a first positive small vector, a second large vector and a second positive small vector; When the vector is 3V Bat /2<V PV <2V Bat , the sequence is sequentially a first negative small vector, a first large vector, a second negative small vector, a middle vector, a zero vector, a second large vector, a first positive small vector and a second positive small vector; when V PV <3V Bat /2, the sequence is sequentially a first negative small vector, a first large vector, a second negative small vector, a middle vector, a second large vector, a zero vector, a first positive small vector and a second positive small vector.
  2. 2. The method for the high-safety and high-efficiency control of a photovoltaic energy storage system according to claim 1, Based on the principle that the common-mode voltage variation range is as small as possible, generating a vector sequence of the switching sequence comprises the following steps: Based on the principle that the common-mode voltage variation range is as small as possible, according to the ordering relation of the common-mode voltage, the switching between vectors only allows the interval not to exceed one vector, and the current ordering relation is judged according to the photovoltaic voltage and the storage battery voltage, so that the vector sequence of the switching sequence is changed in real time.
  3. 3. The method for the high-safety and high-efficiency control of a photovoltaic energy storage system according to claim 1, The first large sector first part satisfies Obtaining a first curve and a second curve for dividing 4 small sectors according to the component of the voltage space vector in the alpha coordinate axis, the component of the voltage space vector in the beta coordinate axis, the photovoltaic voltage and the storage battery voltage; V α is a component of the voltage space vector in the α axis, V β is a component of the voltage space vector in the β axis, and V PV 、V PV is a photovoltaic voltage and a battery voltage, respectively; Determining that the reference voltage vector is located in the first small sector when the reference voltage vector is located above the first curve and below the second curve, and determining that the reference voltage vector is located in the second small sector when the reference voltage vector is located below the first curve and below the second curve; the reference voltage vector is determined to be in the third small sector when the reference voltage vector is below the first curve and above the second curve, and the reference voltage vector is determined to be in the fourth small sector when the reference voltage vector is above the first curve and above the second curve.
  4. 4. A method for high safety and high efficiency control of a photovoltaic energy storage system as set forth in claim 3, The first large sector second part satisfies Obtaining a third curve and a fourth curve for dividing 4 small sectors according to the component of the voltage space vector in the alpha coordinate axis, the component of the voltage space vector in the beta coordinate axis, the photovoltaic voltage and the storage battery voltage; determining that the reference voltage vector is located in the fifth small sector when the reference voltage vector is located below the third curve and to the left of the fourth curve; determining that the reference voltage vector is located in the seventh small sector when the reference voltage vector is located above the third curve and to the right of the fourth curve; The small sectors of the other large sectors are obtained by rotation.
  5. 5. A method for high safety and high efficiency control of a photovoltaic energy storage system as set forth in any of claims 1-4, In different small sectors, three vectors are adopted to synthesize reference voltage vectors for modulation, and the action time of the corresponding vectors is calculated, specifically: , , Wherein V α is the component of the reference voltage vector V ref in the alpha coordinate axis, V β is the component of the reference voltage vector V ref in the beta coordinate axis, V iα and V iβ (i=1, 2, 3) are the coordinates of the selected nearest voltage vector V i in the alpha beta coordinate system, T i is the action time of the corresponding vector, and T S is the sampling period.
  6. 6. A method for high safety and high efficiency control of a photovoltaic energy storage system as set forth in any of claims 1-4, When the external illumination condition is poor or the load is increased, the photovoltaic power generation power cannot meet the load demand, at the moment, the power control parameter is reduced, the use frequency of a discharging sequence is increased in real time, the output power of the storage battery is increased, and the difference power between the photovoltaic power generation system and the load is made up; when the external illumination intensity is increased or the load is reduced, the photovoltaic power generation power exceeds the load demand, at the moment, the power control parameter is increased, the use frequency of the charging sequence is increased in real time, the redundant electric energy output by the photovoltaic power generation system is stored by a storage battery, and the use frequency of the charging sequence and the discharge sequence is adjusted in real time through the power control parameter.
  7. 7. A high safety and high efficiency control system for a photovoltaic energy storage system, comprising: The reference voltage vector calculation module is configured to acquire a reference voltage vector under an alpha beta coordinate system of the power grid, judge a large sector where the reference voltage vector is positioned according to the value of a phase angle of the reference voltage vector, and divide each large sector into a first part and a second part according to the position of a middle vector; the vector common-mode voltage sequencing module is configured to calculate the common-mode voltage of each vector according to the photovoltaic voltage and the storage battery voltage, sequence the common-mode voltage and generate a vector sequence of a switching sequence; The sector dividing module is configured to divide four small sectors in a first part and a second part of each large sector respectively, wherein each small sector has one or more charging sequences and discharging sequences; The power regulating module is configured to calculate photovoltaic power according to the photovoltaic voltage and the photovoltaic current, generate control parameters after passing through the PI regulator by the direct current power control loop, obtain power control parameters by passing through the amplitude limiting unit by the control parameters, and regulate the use frequency of the charging sequence and the discharging sequence in real time according to the power control parameters; The inverter control module is configured to control the on-off of a power switch tube in the double-direct-current port inverter based on the action time and the switch sequence so as to control the operation of the inverter; Calculating a common-mode voltage of each vector according to the photovoltaic voltage and the storage battery voltage, and sequencing the common-mode voltage, wherein the method comprises the following steps of: The method comprises the steps of obtaining a photovoltaic voltage V PV and a storage battery voltage V Bat , calculating common-mode voltage values of all vectors, wherein the vectors correspond to eight common-mode voltage values, and sorting the vectors from low to high according to the common-mode voltage values, wherein the common-mode voltage values are divided into a first large vector, a second large vector, a middle vector, a first positive small vector, a second positive small vector, a first negative small vector, a second negative small vector and a zero vector; When the vector is 2V Bat <V PV <3V Bat , the sequence is sequentially a first negative small vector, a second negative small vector, a first large vector, a zero vector, a medium vector, a first positive small vector, a second large vector and a second positive small vector; When V PV >3V Bat , the sequence is sequentially a first negative small vector, a second negative small vector, a zero vector, a first large vector, a middle vector, a first positive small vector, a second large vector and a second positive small vector; When the vector is 3V Bat /2<V PV <2V Bat , the sequence is sequentially a first negative small vector, a first large vector, a second negative small vector, a middle vector, a zero vector, a second large vector, a first positive small vector and a second positive small vector; when V PV <3V Bat /2, the sequence is sequentially a first negative small vector, a first large vector, a second negative small vector, a middle vector, a second large vector, a zero vector, a first positive small vector and a second positive small vector.
  8. 8. A computer readable storage medium having a program stored thereon, which when executed by a processor, implements the steps in a method of high-safety and high-efficiency control of a photovoltaic energy storage system according to any of claims 1-6.
  9. 9. An electronic device comprising a memory, a processor and a program stored on the memory and executable on the processor, wherein the processor performs the steps in the method for high-safety and high-efficiency control of a photovoltaic energy storage system according to any one of claims 1-6 when the program is executed by the processor.

Description

High-safety and high-efficiency control method and system for photovoltaic energy storage system Technical Field The invention relates to the technical field of control of photovoltaic energy storage systems, in particular to a high-safety and high-efficiency control method and system of a photovoltaic energy storage system. Background The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art. Due to the advantages of green environmental protection, no pollution and the like, the photovoltaic power generation is rapidly developed. However, photovoltaic power generation is limited by the environment, has obvious intermittence and randomness, and the generated power and load cannot reach an equilibrium state, so that the stability of the whole power grid system is further affected. The photovoltaic energy storage system can store the redundant electric energy output by the photovoltaic power generation system by using a storage battery when the load is low, fills the load low, releases the stored electric energy when the load is high, compensates the difference power between the photovoltaic power generation system and the load, and reduces the load high. Because the peak-valley difference of the power grid load can be reduced, the power generation and the power consumption tend to be balanced, and the photovoltaic energy storage system has wide application prospect. In a photovoltaic energy storage system, a double-direct-current port inverter can be used as an independent power conversion stage, and the direct-current side of the double-direct-current port inverter is directly connected with a photovoltaic panel and a storage battery, but the inventor finds that the photovoltaic voltage and the storage battery voltage change along with the change of external environment, so that a non-constant high common-mode voltage is caused, and a larger common-mode current is generated, so that the normal operation of the system is influenced. Disclosure of Invention In order to solve the defects of the prior art, the invention provides a high-safety and high-efficiency control method and a high-efficiency control system for a photovoltaic energy storage system, which limit the variation range of vector common-mode voltage of all switching sequences and reduce leakage current, and the application of positive and negative small vectors of the high common-mode voltage provides more redundant switching states and redundant switching sequences, and the switching sequences with middle vectors can also be used as an independent control sequence to realize the power regulation of the photovoltaic energy storage system. In order to achieve the above purpose, the present invention adopts the following technical scheme: In a first aspect, the invention provides a high-safety and high-efficiency control method of a photovoltaic energy storage system. A high-safety and high-efficiency control method of a photovoltaic energy storage system comprises the following steps: Acquiring a reference voltage vector under an alpha beta coordinate system of a power grid, judging a large sector where the reference voltage vector is located according to the value of a phase angle of the reference voltage vector, and dividing each large sector into a first part and a second part according to the position of a middle vector; Calculating the common-mode voltage of each vector according to the photovoltaic voltage and the storage battery voltage, sequencing the common-mode voltage, and generating a vector sequence of a switching sequence; dividing four small sectors in a first part and a second part of each large sector, wherein each small sector has one or more charging sequences and discharging sequences, modulating by adopting three vector synthesis reference voltage vectors in different switching sequences of different small sectors, and calculating to obtain the action time of the corresponding vector; Calculating photovoltaic power according to the photovoltaic voltage and the photovoltaic current, generating control parameters by a direct current power control loop through a PI regulator, obtaining power control parameters by the control parameters through an amplitude limiting unit, and adjusting the use frequency of a charging sequence and a discharging sequence in real time according to the power control parameters to realize power regulation; and controlling the on-off of a power switch tube in the double-direct-current port inverter based on the action time and the switch sequence so as to control the operation of the inverter. As a further limitation of the first aspect of the invention, calculating the common mode voltage of each vector from the photovoltaic voltage and the battery voltage, ordering the common mode voltages, comprises: The method comprises the steps of obtaining a photovoltaic voltage V PV and a storage battery voltage V Bat, cal