Power generation and energy storage integrated power supply method and system

Abstract

The invention provides a power generation and energy storage integrated power supply method. The power supply method comprises the following steps: S1, supplying power to a load through commercial power and rural photovoltaic; s2, when the commercial power is cut off, a generator set is connected, and power is supplied to a load through the generator set and rural photovoltaic; s3, when the generator set supplies power to the load, detecting the unbalance degree of the three-phase current of the generator set; and S4, according to the unbalance degree of the three-phase current, the energy storage device is connected to adjust the three-phase current of the generator set. By arranging the generator set, power can be quickly supplied during maintenance and first-aid repair of the urban residential district, and the safety and stability of power supply are ensured. Through the balanced three-phase current of the energy storage device, the additional loss of the generator set, the power transmission line and the transformer is rapidly reduced, the power supply quality and the economic operation of the low-voltage power distribution network are improved, and during closing, the generation of electric arcs can be avoided and the power supply safety is enhanced through the balanced three-phase current.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply systems, and in particular to a method and system for power supply integrating power generation and energy storage. Background Art

[0002] The power supply vehicle is a special vehicle equipped with a power supply device, which is equipped with a generator set and energy storage device. The power supply vehicle is particularly suitable for fast power supply during maintenance and emergency repairs of important power users and urban residential areas, which can save power supply preparation time and improve power supply safety.

[0003] Common power supply vehicles are used for power supply. At present, with the rapid development of the national economy, people's quality of life has been greatly improved. The number and types of electrical appliances used in each household have gradually increased, and various nonlinear and impact loads have increased significantly. Because the household loads of ordinary residents are mostly single-phase loads, the increase in load will bring about uneven distribution of residents' electricity consumption, resulting in three-phase current imbalance in the low-voltage distribution network. The low-voltage distribution network is a three-phase four-wire system. The asymmetry of the three-phase load generally does not lead to three-phase voltage deviation, but it will cause serious three-phase current asymmetry and produce large negative-sequence and zero-sequence currents. Its fundamental negative-sequence current will cause serious additional losses in generators, transmission lines and transformers, resulting in a large amount of zero-sequence current flowing through the neutral line, increasing the neutral line loss and neutral point offset and the phase asymmetry of the current between phases, causing the output of the distribution transformer to decrease, endangering its safety and service life, and seriously affecting the power supply quality and the economic operation of the low-voltage distribution network. In the process of closing the switch and introducing the generator set, arcs will also be generated due to the imbalance of the three-phase current, which is easy to induce safety accidents. Summary of the invention

[0004] The object of the present invention is to provide a method and system for power supplying integrated power generation and energy storage to solve the problem of unbalanced three-phase current.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for power supply integrating power generation and energy storage, the power supply method comprising the following steps: S1, supplying power to the load through the mains and rural photovoltaics; S2, when the mains is disconnected, connecting the generator set, and supplying power to the load through the generator set and rural photovoltaics; S3, when the generator set supplies power to the load, detecting the imbalance of the three-phase current of the generator set; S4, according to the imbalance of the three-phase current, connecting the energy storage device to adjust the three-phase current of the generator set.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting up rural photovoltaics, a rural photovoltaic / mains grid-connected joint power supply system is formed, which ensures that the load can obtain stable power on the basis of energy conservation, and by setting up a generator set, power can be quickly supplied during maintenance and emergency repairs in urban residential areas, ensuring the safety and stability of power supply. By balancing the three-phase current of the energy storage device, the additional losses of the generator set, transmission line and transformer are quickly reduced, the power supply quality and the economic operation of the low-voltage distribution network are improved, and when closing the switch, by balancing the three-phase current, the generation of arcs can be avoided, enhancing the safety of power supply.

[0007] Preferably, the above S1 further comprises the following steps:

[0008] S11, connecting rural photovoltaic to load through DC-DC converter;

[0009] S12, connecting the mains to the load via a bidirectional AC-DC converter;

[0010] S13. Determine the power supply strategy based on the output power of rural photovoltaics and the power required by the load.

[0011] Preferably, the power supply strategy in the above step S13 is as follows: when the output power of the rural photovoltaic is equal to the power required by the load; turn off the bidirectional AC / DC converter, control the DC-DC converter to work in a voltage-stabilizing state, control the output voltage of the DC-DC converter, and the rural photovoltaic alone provides the power required by the load;

[0012] When the output power of rural photovoltaic is less than the power required by the load, the DC-DC converter is controlled to work in MPPT mode, and the bidirectional AC / DC converter works in rectification state to provide insufficient power.

[0013] When the output power of rural photovoltaic is greater than the power required by the load, the DC-DC converter is controlled to work in MPPT mode, and the bidirectional AC / DC converter works in inverter mode, and the excess power is connected to the grid.

[0014] When rural photovoltaic power cannot work at night or in rainy weather, the DC-DC converter is turned off, the bidirectional AC / DC converter works in the rectification state, and the mains alone provides all the power required by the load.

[0015] Preferably, in the above step S2, the generator set is connected to the load via a bidirectional AC / DC converter.

[0016] Preferably, in the above step S3, the method for calculating the unbalance degree of the three-phase current is as follows:

[0017] The three-phase current i is measured by the detector a 、ib 、i c , calculate the mean of the three-phase current:

[0018]

[0019] Calculate the unbalance of the three-phase current according to the mean value of the three-phase current:

[0020]

[0021] Where: k represents the degree of imbalance, i max Represents the three-phase current i a 、i b 、i c The maximum value in .

[0022] Preferably, the above step S4 further includes the following steps:

[0023] S41. Detect the current components other than the fundamental positive sequence active current in the three-phase current; the detection means are as follows:

[0024] Any three-phase current in a three-phase system is expressed as a certain mathematical expression:

[0025]

[0026] Where: I 1n represents the effective value of the positive sequence component, φ 1n represents the initial angle of the positive sequence component, I 2n represents the effective value of the negative sequence component, φ 2n Represents the initial angle of the negative sequence component, I 0n represents the effective value of the zero-sequence component, φ 0n represents the initial angle of the zero-sequence component, and n represents the various components corresponding to the nth harmonic;

[0027] Transform the reference frame to make it consistent with dq:

[0028]

[0029] i d By DC component and AC component Composition, i q By DC component and AC component constitute, will Setting it to zero gives:

[0030]

[0031] Then according to the inverse coordinate change, we can get:

[0032]

[0033] Where: l, f are positive integers, i azl Indicates i a The DC component, i bzl Indicates i b The DC component, i czl Indicates i c The DC component, C -1 is the transposed matrix of C;

[0034] S42: Determine a compensation signal according to the detection result.

[0035] Preferably, the calculation method of the compensation signal in the above step S42 is as follows:

[0036]

[0037] Where: i a补 、i b补 、i c补 They represent the corresponding compensation signals respectively.

[0038] Based on another object of the present invention, the present invention provides the following technical solution: a power supply system integrating power generation and energy storage, the power supply system using the power supply method as described above, the power supply system comprising;

[0039] The mains power supply module is used to supply power to the load through the mains power and rural photovoltaics;

[0040] The generator set combined power supply module connects to the generator set when the city power is disconnected, and supplies power to the load through the generator set and rural photovoltaics;

[0041] The imbalance calculation module detects the imbalance of the three-phase current of the generator set when the generator set supplies power to the load;

[0042] The adjustment module is used to access the energy storage device to adjust the three-phase current of the generator set according to the imbalance of the three-phase current.

[0043] Based on another object of the present invention, the present invention provides the following technical solution: a storage medium having a computer program stored thereon, wherein the computer program implements the power supply method as described above when executed by a processor.

[0044] Based on another purpose of the present invention, the present invention provides the following technical solution: a computer, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the power supply method as described above when executing the computer program. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0046] Figure 1 A technical roadmap for a method of integrated power generation and energy storage;

[0047] Figure 2 It is a system architecture diagram of the present invention.

[0048] In the figure: a power supply system 10 , a city power combined power supply module 110 , a generator set combined power supply module 120 , an imbalance calculation module 130 , and an adjustment module 140 . DETAILED DESCRIPTION

[0049] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0050] In this article, the terms "upper, lower, inside, outside" and the like are established based on the positional relationships shown in the drawings. The corresponding positional relationships may also change depending on the drawings, and therefore cannot be understood as absolute limitations on the scope of protection; moreover, relational terms such as "first" and "second" and the like are merely used to distinguish one component from another with the same name, and do not necessarily require or imply any actual relationship or order between these components.

[0051] Embodiment 1

[0052] like Figure 1 As shown, this embodiment provides a method for power supply with integrated power generation and energy storage, and the power supply method includes the following steps: S1, powering the load through the city power and rural photovoltaics; in order to overcome the shortcomings of rural photovoltaic power generation, such as instability, discontinuity, and the influence of light intensity, ambient temperature and seasonal climate, the city power is added as a supplementary energy source to form a rural photovoltaic / city power grid-connected combined power supply system, which ensures that the load can obtain stable electricity on the basis of energy conservation. Rural photovoltaics include necessary electrical components such as photovoltaic panels. Since they are mature existing technologies, they will not be repeated here. Preferably, rural photovoltaics also include batteries. When the output power of rural photovoltaics is surplus, it can be imported into the batteries for storage.

[0053] S2. When the city power is disconnected, the generator set is connected to supply power to the load through the generator set and rural photovoltaic power generation; the generator set can quickly supply power during the inspection and emergency repair of important power users and urban residential areas, and the generator set can save power supply preparation time and ensure the safety and stability of power supply. The generator set is preferably a diesel generator set.

[0054] S3. When the generator set supplies power to the load, detect the imbalance of the three-phase current of the generator set; according to the "Distribution Network Operation and Maintenance Regulations" (Q / GDW1519-2014), the imbalance of the generator set shall not be greater than 15%. To ensure the safety of power supply, the imbalance of the generator set is continuously monitored here. When the imbalance is greater than 10%, the energy storage device is introduced for adjustment to avoid excessive differences in the three-phase current.

[0055] S4. According to the imbalance of the three-phase current, the energy storage device is connected to adjust the three-phase current of the generator set. By balancing the three-phase current of the energy storage device, the additional losses of the generator set, transmission line and transformer are quickly reduced, the power supply quality and the economic operation of the low-voltage distribution network are improved, and when closing the switch, by balancing the three-phase current, the arc can be avoided and the safety of power supply can be enhanced.

[0056] Specifically, by setting up rural photovoltaics, a rural photovoltaic / mains grid-connected joint power supply system is formed. On the basis of energy conservation, it ensures that the load can obtain stable electricity. By setting up generator sets, power can be quickly supplied during maintenance and emergency repairs in urban residential areas to ensure the safety and stability of power supply. By balancing the three-phase current of the energy storage device, the additional losses of the generator set, transmission line and transformer are quickly reduced, the power supply quality and the economic operation of the low-voltage distribution network are improved, and when closing the switch, by balancing the three-phase current, the generation of arcs can be avoided, enhancing the safety of power supply.

[0057] Furthermore, the above S1 further includes the following steps:

[0058] S11, connecting the rural photovoltaic to the load through a DC-DC converter; the load is provided with a bus, and the rural photovoltaic is connected to the bus;

[0059] S12, connecting the mains to the load through a bidirectional AC-DC converter; the mains is connected to the busbar and connected in parallel with the rural photovoltaic;

[0060] S13. Determine the power supply strategy based on the output power of rural photovoltaic power generation and the power required by the load;

[0061] The power supply strategy in the above step S13 is as follows: when the output power of the rural photovoltaic is equal to the power required by the load; turn off the bidirectional AC / DC converter, control the DC-DC converter to work in a voltage-stabilized state, control the output voltage of the DC-DC converter, and the rural photovoltaic alone provides the power required by the load;

[0062] When the output power of rural photovoltaic is less than the power required by the load, the DC-DC converter is controlled to work in MPPT mode, and the bidirectional AC / DC converter works in rectification state, and the mains power provides insufficient power.

[0063] When the output power of rural photovoltaic is greater than the power required by the load, the DC-DC converter is controlled to work in MPPT mode, and the bidirectional AC / DC converter works in inverter mode, and the excess power is integrated into the mains.

[0064] When rural photovoltaic power cannot work at night or in rainy weather, the DC-DC converter is turned off, the bidirectional AC / DC converter works in the rectification state, and the mains alone provides all the power required by the load. Through the above power supply strategy, photovoltaic resources can be effectively utilized.

[0065] Furthermore, in the above step S2, the generator set is connected to the load via a bidirectional AC / DC converter. The energy storage device is connected to the load via a bidirectional AC / DC converter. The joint power supply strategy of the generator set and rural photovoltaics is the same as the joint power supply strategy of the city power and rural photovoltaics, which will not be repeated here.

[0066] Furthermore, in the above step S3, the method for calculating the unbalance degree of the three-phase current is as follows:

[0067] The three-phase current i is measured by the detector a 、i b 、i c , calculate the mean of the three-phase current:

[0068]

[0069] Calculate the unbalance of the three-phase current according to the mean value of the three-phase current:

[0070]

[0071] Where: k represents the degree of imbalance, i max Represents the three-phase current i a 、i b 、i c The maximum value in .

[0072] Furthermore, the above step S4 further includes the following steps:

[0073] S41. Detect the current components other than the fundamental positive sequence active current in the three-phase current; the detection means are as follows:

[0074] Any three-phase current in a three-phase system is expressed as a certain mathematical expression:

[0075]

[0076]

[0077] Where: I 1n represents the effective value of the positive sequence component, φ 1n represents the initial angle of the positive sequence component, I 2n represents the effective value of the negative sequence component, φ 2n Represents the initial angle of the negative sequence component, I 0n represents the effective value of the zero-sequence component, φ 0n represents the initial angle of the zero-sequence component, and n represents the various components corresponding to the nth harmonic;

[0078] Transform the reference frame to make it consistent with dq:

[0079]

[0080] i d By DC component and AC component Composition, i q By DC component and AC component constitute, will Setting it to zero gives:

[0081]

[0082] Then according to the inverse coordinate change, we can get:

[0083]

[0084]

[0085] Where: l, f are positive integers, i azl Indicates i a The DC component, i bzl Indicates i b The DC component, i czl Indicates i c The DC component, C -1 is the transposed matrix of C;

[0086] S42, determine the compensation signal according to the detection result. The above calculation method only needs two coordinate changes to obtain the measurement result, which simplifies the calculation to a certain extent, enhances the effectiveness of the compensation current, has good applicability, and can also measure the local distortion and voltage imbalance more accurately.

[0087] Furthermore, the calculation method of the compensation signal in the above step S42 is as follows:

[0088]

[0089] Where: i a补 、i b补 、i c补 The corresponding compensation signals are respectively represented. A compensation current consistent with the compensation signal is obtained according to the compensation signal, and the three-phase current is balanced according to the compensation current.

[0090] Embodiment 2

[0091] The same parts in this embodiment as those in the first embodiment are given the same figure marks, and the same text descriptions are omitted.

[0092] like Figure 2 As shown, this embodiment discloses a power supply system integrating power generation and energy storage. The power supply system 10 uses the power supply method in the first embodiment. The power supply system 10 includes:

[0093] The mains power combined power supply module 110 is used to supply power to the load through the mains power and rural photovoltaics;

[0094] The generator set combined power supply module 120 is connected to the generator set when the city power is disconnected, and the load is powered by the generator set and rural photovoltaics;

[0095] The imbalance calculation module 130 detects the imbalance of the three-phase current of the generator set when the generator set supplies power to the load;

[0096] The adjustment module 140 is used to access the energy storage device to adjust the three-phase current of the generator set according to the imbalance of the three-phase current.

[0097] Embodiment 3

[0098] The same parts as those in the first and second embodiments of the present embodiment are given the same reference numerals, and the same text descriptions are omitted.

[0099] This embodiment discloses a storage medium on which a computer program is stored. When the computer program is executed by a processor, the power supply method in the first embodiment is implemented.

[0100] Embodiment 4

[0101] The same parts as those in the first, second and third embodiments of the present embodiment are given the same reference numerals, and the same textual descriptions are omitted.

[0102] This embodiment discloses a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the power supply method in the first embodiment is implemented.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for integrated power generation and energy storage, characterized in that: The power supply method comprises the following steps: S1, power the load through the city power and rural photovoltaic; S2. When the city power is disconnected, the generator set is connected, and the load is powered by the generator set and the rural photovoltaic system; S3. When the generator set supplies power to the load, detecting the imbalance of the three-phase current of the generator set; S4. According to the imbalance of the three-phase current, an energy storage device is connected to adjust the three-phase current of the generator set.

2. The method for integrated power generation and energy storage according to claim 1, characterized in that: The above S1 further includes the following steps: S11, connecting the rural photovoltaic to the load through a DC-DC converter; S12, connecting the mains power to the load through a bidirectional AC-DC converter; S13: Determine a power supply strategy according to the output power of the rural photovoltaic system and the power required by the load.

3. The method for integrated power generation and energy storage according to claim 2, characterized in that: The power supply strategy in the above step S13 is as follows: when the output power of the rural photovoltaic is equal to the power required by the load; turn off the bidirectional AC / DC converter, control the DC-DC converter to work in a voltage stabilization state, control the output voltage of the DC-DC converter, and the rural photovoltaic alone provides the power required by the load; When the output power of the rural photovoltaic is less than the power required by the load, the DC-DC converter is controlled to work in the MPPT mode, and the bidirectional AC / DC converter works in the rectification state to provide insufficient power; When the output power of the rural photovoltaic system is greater than the power required by the load, the DC-DC converter is controlled to work in the MPPT mode, and the bidirectional AC / DC converter is operated in the inverter state, and the excess power is connected to the grid; When the rural photovoltaic system cannot work at night or in rainy weather, the DC-DC converter is turned off, the bidirectional AC / DC converter works in a rectifying state, and the mains electricity alone provides all the power required by the load.

4. The method for integrated power generation and energy storage according to claim 2, characterized in that: In the above step S2, the generator set is connected to the load via a bidirectional AC / DC converter.

5. The method for integrated power generation and energy storage according to claim 2, characterized in that: In the above step S3, the method for calculating the unbalance degree of the three-phase current is as follows: The three-phase current i is measured by the detector a 、i b 、i c , calculate the mean value of the three-phase current: Calculate the unbalance of the three-phase current according to the mean value of the three-phase current: Where: k represents the degree of imbalance, i max Represents the three-phase current i a 、i b 、i c The maximum value in .

6. The method for integrated power generation and energy storage according to claim 2, characterized in that: The above step S4 further includes the following steps: S41. Detect the current components other than the fundamental positive sequence active current in the three-phase current; the detection means are as follows: Any three-phase current in a three-phase system is expressed as a certain mathematical expression: Where: I 1n represents the effective value of the positive sequence component, φ 1n represents the initial angle of the positive sequence component, I 2n represents the effective value of the negative sequence component, φ 2n Represents the initial angle of the negative sequence component, I 0n represents the effective value of the zero-sequence component, φ 0n represents the initial angle of the zero-sequence component, and n represents the various components corresponding to the nth harmonic; Transform the reference frame to make it consistent with dq: i d By DC component and AC component Composition, i q By DC component and AC component constitute, will Setting it to zero gives: Then according to the inverse coordinate change, we can obtain: Where: l, f are positive integers, i azl Indicates i a The DC component, i bzl Indicates i b The DC component, i czl Indicates i c The DC component, C -1 is the transposed matrix of C; S42. Determine a compensation signal according to the detection result.

7. The method for integrated power generation and energy storage according to claim 6, characterized in that: The calculation method of the compensation signal in the above step S42 is as follows: Where: i a补 、i b补 、i c补 Respectively represent the corresponding compensation signals.

8. A power supply system integrating power generation and energy storage, wherein the power supply system uses the power supply method according to any one of claims 1 to 7, characterized in that: The power supply system comprises: The mains power supply module is used to supply power to the load through the mains power and rural photovoltaics; A generator set combined power supply module, when the city power is disconnected, the generator set is connected, and the load is powered by the generator set and the rural photovoltaic; an imbalance calculation module, for detecting the imbalance of the three-phase current of the generator set when the generator set supplies power to the load; The adjustment module is used to access the energy storage device to adjust the three-phase current of the generator set according to the imbalance of the three-phase current.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the power supply method according to any one of claims 1 to 7 is implemented.

10. A computer comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the power supply method according to any one of claims 1 to 7 is implemented.

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