A distributed power supply control method based on edge computing

Abstract

The present invention discloses a distributed power control method based on edge computing, which belongs to the field of distributed power regulation technology. The method includes the following steps: first, based on the low-voltage distributed photovoltaic power station's feeder voltage level regulation requirements, data collection of distributed power intelligent gateway devices is carried out; power automatic control technology based on edge computing is proposed, and a distributed power intelligent gateway on-site control method is established; voltage regulation is performed according to on-site active / reactive control requirements; based on the performance requirements of the distributed power intelligent gateway device, hardware of the distributed power intelligent gateway device that supports information encryption and wireless communication is designed; and the proposed method is verified. The active distribution network based on distributed power provided by the present invention does not need to transmit data to the upper system for analysis as much as possible, and has good guiding significance for information access of the power grid dispatching system, distributed power control, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed power supply control, and in particular to a distributed power supply control method based on edge computing. Background Art

[0002] The continuous occurrence of smog weather in many places across the country and the severe ecological pressure have forced people to re-examine the energy supply structure. The willingness to use and develop pollution-free distributed renewable green energy is unprecedentedly strong. Distributed energy, mainly photovoltaic power generation and wind power generation, will be unstoppable, and it will be an inevitable trend to gradually replace coal as the new energy source. At present, with the rapid development of distributed power supply technology, the penetration rate of photovoltaic power is getting higher and higher, and problems such as feeder power flow reverse transmission and local overvoltage have emerged, affecting power supply safety. In the distributed power supply access link, State Grid Corporation has raised information security to an unprecedented level, and the security reinforcement of distributed power supply access information is imminent. With the gradual advancement and construction of the ubiquitous power Internet of Things, the information collection and on-site control of low-voltage distributed power sources are an important basis for building the perception layer of the ubiquitous power Internet of Things of State Grid Corporation.

[0003] In order to cope with the challenges brought by high-density distributed power sources to the future development of power grids, it is necessary to explore and research more effective technologies such as distributed power source information access and local control. Through the relevant technical research of distributed power source intelligent gateway devices, the information security access and local control of distributed power sources can be realized, and the comprehensive utilization efficiency of distributed renewable energy can be improved, thereby maximizing the utilization of social resources. With the access of large-scale distributed photovoltaic power generation and the widespread application of intelligent devices, the information access and control response pressure of the power grid dispatching system is increasing. The traditional cloud computing model is difficult to achieve real-time data, short cycle, local decision-making scenarios, etc. Summary of the invention

[0004] In response to the above problems, the present invention proposes a distributed power supply control method based on edge computing. This model avoids transmitting data to the upper system for analysis as much as possible, so as to reduce the waiting time and network bandwidth cost of data going back and forth to the upper system, and uploads the valid data after analysis and processing to the upper system to achieve data optimization. It has great guiding significance for information access of power grid dispatching system, distributed power supply control, etc.

[0005] In order to achieve the above-mentioned purpose, the present invention is achieved through the following technical solutions:

[0006] The present invention is a distributed power supply control method based on edge computing, comprising the following steps:

[0007] S1. Real-time data collection of distributed power intelligent gateway devices based on the feeder voltage level adjustment requirements of low-voltage distributed photovoltaic power stations;

[0008] S2. Based on the power automatic control technology of edge computing, a PTN physical architecture model of active distribution network with distributed power sources is established;

[0009] S3. According to the local active / reactive power control requirements, the voltage of the photovoltaic grid connection point is adjusted in different regions;

[0010] S4. Design distributed power intelligent gateway device hardware that supports information encryption and wireless communication based on the performance requirements of distributed power intelligent gateway devices;

[0011] S5. Guide the device hardware development and verify the proposed method based on the hardware platform and actual data.

[0012] A further improvement of the present invention is that the data of the distributed power supply intelligent gateway device in S1 are the three-phase voltage and current of the photovoltaic grid-connected point.

[0013] A further improvement of the present invention is that the specific operation of regulating the voltage of the photovoltaic grid-connected point in different regions in S3 is:

[0014] S3.1, setting includes voltage upper limit adjustment threshold U hdb , Locking voltage upper limit adjustment threshold U hlmt , Voltage lower limit adjustment threshold U ldb , Locking voltage lower limit adjustment threshold U llmt , Voltage regulation return threshold U th The voltage setting value;

[0015] S3.2, divide the area according to the voltage setting;

[0016] S3.3, determine the area where the voltage of the photovoltaic grid-connected point is located;

[0017] S3.4: According to the result of S3.3, the voltage of the photovoltaic grid-connected point is adjusted by region.

[0018] A further improvement of the present invention is that the relationship between the voltage constants in S3.1 is: U llmt ldb ldb +U th hdb -U th hdb hlmt .

[0019] The further improvement of the present invention is that: S3.2 divides 7 areas, namely: (0, U llmt ]、(U llmt , U ldb ]、(U ldb , U ldb +U th ]、(U​​​​​ldb +U th , U hdb -U th ), [U hdb -U th ,U hdb ), [U hdb ,U hlmt ), [U hlmt ,+∞).

[0020] The further improvement of the present invention is that the control strategy of S3.4 is specifically:

[0021] The specific control strategy of S3.4 is:

[0022] a. Locked and immobile;

[0023] b. Increase active power;

[0024] c. Reduce active power;

[0025] d. Increase reactive power;

[0026] e. Reduce reactive power;

[0027] When the voltage of the photovoltaic grid-connected point is in the area (0, U llmt ]、[U hdb -U th ,U hdb )、(U ldb , U ldb +U th ]、

[0028] [U hlmt ,+∞) adopts voltage regulation strategy a;

[0029] When the voltage of the photovoltaic grid-connected point is in the area (U llmt , U ldb ], and Q+ΔQ≤Q max , adopt voltage regulation strategy d;

[0030] When the voltage of the photovoltaic grid-connected point is in the area [U hdb ,U hlmt ), if Q-ΔQ≥Q min Adopt voltage regulation strategy e, otherwise, further judge, if P-ΔP≥P min Adopt voltage regulation strategy c, otherwise adopt voltage regulation strategy a;

[0031] When the voltage of the photovoltaic grid-connected point is in the area (U ldb +U th , U hdb -U th), if the active power is limited, the voltage regulation strategy b is adopted; if the active power is not limited, it is determined whether the reactive power is zero. If so, the voltage regulation strategy a is adopted; if not, the voltage regulation strategy e is adopted to make the reactive power zero.

[0032] A further improvement of the present invention is that the hardware of the distributed power intelligent gateway device in S4 includes an encryption chip, which is connected to the device CPU using an SPI interface, and the CPU provides a 3.3V working power supply for the encryption chip.

[0033] The beneficial effects of the present invention are:

[0034] 1. Avoid uploading data to the upper system for analysis as much as possible, which reduces the waiting time and network bandwidth cost of data going back and forth to the upper system. Upload the valid data after analysis and processing to the upper system to achieve data optimization.

[0035] 2. Through the relevant technical research on distributed power supply intelligent gateway devices, the information security access and on-site control of distributed power supply are realized, the comprehensive utilization efficiency of distributed renewable energy is improved, and the maximum utilization of social resources is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The figure is a flow chart of a distributed power supply control method based on edge computing.

[0037] Figure 2 It is the PTN physical architecture model of the active distribution network based on edge computing and distributed power sources.

[0038] Figure 3 This is the logic block diagram of the local control strategy.

[0039] Figure 4 Voltage regulation area for local control strategy.

[0040] Figure 5 This is a diagram of the gateway device structure.

[0041] Figure 6 This is a hardware design diagram. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] like Figure 1As shown, the specific steps of a distributed power supply control method based on edge computing of the present invention are as follows:

[0044] S1. Distributed photovoltaic control device collects three-phase voltage and current of photovoltaic grid-connected points in real time to realize monitoring function;

[0045] S2. Based on the PE.P.CE structure of PTN network and the characteristics of active distribution network CPS, we established Figure 2 The PTN physical architecture model of the active distribution network based on edge computing and distributed power supply is shown;

[0046] In the model, the CE device is a terminal edge device located at the access layer of the PTN, corresponding to the unit-level CPS in the active distribution network, and has the functions of perception, calculation, interaction, extensibility, and self-decision-making. Distributed power supply intelligent gateway equipment is a typical CE device. Other terminal edge devices mainly include switchgear DTU, transformers, distribution transformers TTU, pole switches FTU, concentrators and other equipment. The CE device has a lightweight computing function, which mainly realizes the collection and control of various types of information on site and the monitoring of equipment. Due to the complexity of the equipment and environment at the access layer, there are many communication methods, including low-voltage PLC, WSN, RS485, etc. The specific gateway device structure is as follows: Figure 5 shown.

[0047] PE equipment is an edge aggregation / access device (local energy switch / aggregation switch) with aggregation function, located in the aggregation layer of PTN, corresponding to the distribution substation in the system-level CPS in the distribution network. The communication methods with the terminal edge equipment mainly include optical fiber private network, distribution line carrier, wireless private network and wireless public network. PE equipment is placed in substations or large switch stations, responsible for the data concentration and forwarding of CE equipment, and realizes the functions of information collection, processing and communication monitoring of CE equipment within the jurisdiction.

[0048] P is a core device located in the core layer of PTN, corresponding to the power distribution master station in the SoS-level CPS, and mainly communicates with the aggregation layer PE device through optical fiber transmission. The core device of this embodiment refers to the power distribution master station, which realizes the monitoring and control of the distribution network as a whole, the isolation and restoration of power supply, and the fault location, and is the core of the entire distribution network monitoring and management system.

[0049] In step S3, a method of using local power automatic control to adjust the voltage of photovoltaic grid-connected points in different regions is proposed, which can adapt to different access voltage levels and reduce the economic losses caused by voltage regulation.

[0050] The voltage regulation process adopts a successive approximation method, and each voltage regulation strategy only executes one unit adjustment: add active power, reduce active power, add reactive power, reduce reactive power, and lock without action.

[0051] Considering the stability of the system, it is necessary to limit the power regulation limit of the grid connection point (P 1mt , Q 1mt ) and the power change (AP, ΔQ) of each adjustment, therefore, the parameter k is set p , k q , k ΔP , k Δq , achieving the following results:

[0052]

[0053] Among them, P 1mt is the lower limit of the active power output of the grid-connected point, Q 1mt is the upper limit of the reactive power output of the grid-connected point, and the lower limit of the reactive power output of the grid-connected point can be expressed as -Q 1mt , AP is the step size of the single active power regulation at the grid connection point, ΔQ is the step size of the single reactive power regulation at the grid connection point, P sum is the sum of the active power output of each inverter at the current grid-connected point, S nsum is the sum of the capacities of all inverters at the grid-connected point. p k is the parameter coefficient of the lower limit of the active power output of the grid-connected point, q k is the parameter coefficient of the reactive power upper limit of the grid connection point output, ΔP , k Δq They are respectively the parameter coefficient of the active power change amount of the grid connection point single adjustment and the parameter coefficient of the reactive power change amount of the grid connection point single adjustment, k p , k q , k ΔP , k Δq No more than 0.5, k ΔP , k Δq K p , k q Be small.

[0054] Since the inverter adds active and reactive power slowly but reduces active power and adds and subtracts reactive power quickly, considering the communication delay and inverter response time, two control cycles need to be set: T1 (slow) and T2 (fast) to ensure that the unit regulation has sufficient response time.

[0055] The method for regulating the voltage of photovoltaic grid-connected points by region is as follows:

[0056] S3.1, set voltage constant;

[0057] S3.2, divide the area according to the voltage setting;

[0058] S3.3, determine the area where the voltage of the photovoltaic grid-connected point is located;

[0059] S3.4: According to the result of S3.3, the voltage of the photovoltaic grid-connected point is adjusted by region.

[0060] The voltage settings in S3.1 include: voltage upper limit adjustment threshold U hdb , Locking voltage upper limit adjustment threshold U hlmt , Voltage lower limit adjustment threshold U ldb , Locking voltage lower limit adjustment threshold U llmt , Voltage regulation return threshold U th ; The voltage values ​​satisfy the following relationship: U llmt ldb ldb +U th hdb -U th hdb hlmt .

[0061] The regions in S3.2 are divided into: (0, U llmt ]、(U llmt , U ldb ]、(U ldb , U ldb +U th ]、(U ldb +U th , U hdb -U th ), [U hdb -U th ,U hdb ), [U hdb ,U hlmt ), [U hlmt ,+∞).

[0062] The specific adjustment method of S3.4 is:

[0063] If the current sampling point voltage of the photovoltaic grid-connected point is in the area (0, U llmt ], the voltage at the current sampling point will not be adjusted;

[0064] If the current sampling point voltage of the photovoltaic grid-connected point is located in the area (U llmt , U ldb ], the reactive power of the photovoltaic inverter is increased, and the active power of the photovoltaic inverter is not adjusted, thereby increasing the voltage at the current sampling point. The specific method is:

[0065] ① Calculate the value of Q+ΔQ;

[0066] ②If Q+ΔQ≤Q max , then Q is sent to the photovoltaic inverter cmd =Q+ΔQ instruction;

[0067] ③If Q+ΔQ>Q max , then Q is sent to the photovoltaic inverter cmd =Q max ​​​​​Instructions;

[0068] Among them, Q is the reactive output of photovoltaic power before reactive power regulation, ΔQ is the step size of regulating the reactive output of photovoltaic power, and Q max is the maximum limit of the reactive power output of photovoltaic, Q cmd It is the reactive power output of photovoltaic after reactive power regulation.

[0069] If the current sampling point voltage of the photovoltaic grid-connected point is located in the area (U ldb , U ldb +U th ], the voltage at the current sampling point will not be adjusted;

[0070] If the voltage of the current sampling point of the photovoltaic grid-connected point is in the area [U hlmt ,+∞), the voltage of the current sampling point will not be adjusted;

[0071] If the voltage of the current sampling point of the photovoltaic grid-connected point is in the area [U hdb ,U hlmt ), first reduce the reactive power of the photovoltaic inverter, then reduce the active power of the photovoltaic inverter, so as to lower the current sample voltage. The specific method is:

[0072] ① Calculate the value of Q-ΔQ;

[0073] ②If Q-ΔQ≥Q min , then Q is sent to the photovoltaic inverter cmd =Q-ΔQ instruction, and no longer adjust the active power;

[0074] ③If Q-ΔQ min , then Q is sent to the photovoltaic inverter cmd =Q min The instruction is executed, and the value of P-ΔP is calculated again;

[0075] If P-ΔP≥P min , then P is sent to the photovoltaic inverter cmd =P-ΔP instruction;

[0076] If P-ΔP <P min , then P is sent to the photovoltaic inverter cmd =P min Instructions;

[0077] Among them, Q is the reactive output of photovoltaic power before reactive power regulation, ΔQ is the step size of regulating the reactive output of photovoltaic power, and Q min is the minimum limit of photovoltaic reactive output, Q cmd is the reactive power output of photovoltaic after reactive power regulation, P is the active power output of photovoltaic before active power regulation, ΔP is the step size of adjusting the active power output of photovoltaic, and P min is the minimum limit of photovoltaic active output, P cmd ​It is the active power output of photovoltaic after active power regulation.

[0078] If the current sampling point voltage of the photovoltaic grid-connected point is located in the area (U ldb +U th , U hdb -U th ), and the sampling point voltage is from the area (U llmt , U ldb ] rises to this area, the reactive power of the photovoltaic inverter is adjusted, and the active power of the photovoltaic inverter is not adjusted, thereby reducing line losses. The specific method is:

[0079] ①If Q>ΔQ / 2, then send Q to the photovoltaic inverter cmd =Q-ΔQ instruction;

[0080] ② If Q<-ΔQ / 2, Q is sent to the photovoltaic inverter. cmd =Q+ΔQ instruction;

[0081] ③If -ΔQ / 2≤Q≤ΔQ / 2, then send Q to the photovoltaic inverter cmd =0 instruction;

[0082] Among them, Q is the reactive output of photovoltaic power before reactive power regulation, ΔQ is the step size of regulating the reactive output of photovoltaic power, and Q cmd It is the reactive power output of photovoltaic after reactive power regulation.

[0083] If the current sampling point voltage of the photovoltaic grid-connected point is located in the area (U ldb +U th , U hdb -U th ), and the sampling point voltage is from the area [U hdb ,U hlmt ) drops to this area, the active power of the photovoltaic inverter is adjusted first, and then the reactive power of the photovoltaic inverter is adjusted, so as to increase the active power output of photovoltaic and reduce line loss. The specific method is:

[0084] ① Calculate the value of P+ΔP;

[0085] ②If P+ΔP≤P max , then P is sent to the photovoltaic inverter cmd =P+ΔP instruction, and no longer adjust reactive power;

[0086] ③If P+ΔP>P max , then P is sent to the photovoltaic inverter cmd =P max The command is given, and the reactive power is adjusted again;

[0087] Among them, P is the active output of photovoltaic power before active regulation, ΔP is the step size of adjusting the active output of photovoltaic power, and P maxis the maximum limit of photovoltaic active output, P cmd is the active power output of photovoltaic after active power regulation, Q is the reactive power output of photovoltaic before reactive power regulation, ΔQ is the step size for regulating the reactive power output of photovoltaic, Q cmd It is the reactive power output of photovoltaic after reactive power regulation.

[0088] S4, in response to the performance requirements of distributed power intelligent gateway devices, research lightweight hardware design solutions and 4G wireless communication technology that supports hardware information encryption;

[0089] The hardware platform of the distributed power intelligent gateway device uses a dual-core processor as the main processor, which contains an ARM processor and a DSP to complete the communication management function and the protection function respectively. The data exchange between the boards of the distributed power intelligent gateway device is completed through a high-speed internal bus to realize the intelligent configuration of the plug-in. The board configuration diagram is as follows Figure 5 The device hardware encryption communication scheme is as follows: In the distributed power intelligent gateway device hardware design scheme, the encryption chip is connected to the device CPU using the SPI interface, and the CPU provides a 3.3V working power supply for the encryption chip, such as Figure 6 shown.

[0090] S5, guide the hardware development of the device, and verify the proposed method based on the hardware platform and actual data. Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should be included in the scope of the claims.

Claims

1. A distributed power supply control method based on edge computing, characterized in that: The steps include: S1. Real-time data collection of distributed power intelligent gateway devices based on the feeder voltage level adjustment requirements of low-voltage distributed photovoltaic power stations; S2. Based on the power automatic control technology of edge computing, a PTN physical architecture model of active distribution network with distributed power sources is established; S3. According to the local active / reactive power control requirements, the voltage of the photovoltaic grid-connected point is adjusted in different regions while ensuring the stability of the system; S4. Design distributed power intelligent gateway device hardware that supports information encryption and wireless communication based on the performance requirements of distributed power intelligent gateway devices; S5. Guide the device hardware development and verify the proposed method based on the hardware platform and actual data; The specific operation of regulating the voltage of the photovoltaic grid-connected point in different regions in S3 is as follows: S3.1, setting includes voltage upper limit adjustment threshold U hdb , Locking voltage upper limit adjustment threshold U hlmt , Voltage lower limit adjustment threshold U ldb , Locking voltage lower limit adjustment threshold U llmt , Voltage regulation return threshold U th S3.2, divide the area according to the voltage setting value; S3.3, determine the area where the grid connection point voltage is located; S3.4, according to the result of S3.3, adjust the voltage of the photovoltaic grid connection point by region; The relationship between the voltage settings in S3.1 is: U llmt ldb ldb +U th hdb -U th hdb hlmt ; S3.2 is divided into 7 areas, namely: (0, U llmt ]、(U llmt , U ldb ]、(U ldb , U ldb +U th ]、(U ldb +U th , U hdb -U th ), [U hdb -U th ,U hdb ), [U hdb ,U hlmt ), [U hlmt ,+∞);​​​​​ In S3, to ensure system stability, the grid-connected point power regulation limit (P lmt , Q lmt ) and the power change (ΔP, ΔQ) of each adjustment, satisfying: Among them, P lmt is the lower limit of the active power output of the grid-connected point, Q lmt is the reactive power upper limit of the grid-connected point output, ΔP is the step length of the grid-connected point single active regulation, ΔQ is the step length of the grid-connected point single reactive regulation, P sum is the sum of the active power output of each inverter at the current grid-connected point, S nsum is the sum of the capacities of the inverters at the grid-connected point, k p k is the parameter coefficient of the lower limit of the active power output of the grid-connected point, q k is the parameter coefficient of the reactive power upper limit of the grid connection point output, ΔP , k Δq They are the parameter coefficients of the single adjustment of active power change at the grid connection point and the parameter coefficients of the single adjustment of reactive power change at the grid connection point. The specific control strategy of S3.4 is: a. Locked and immobile; b. Increase active power; c. Reduce active power; d. Increase reactive power; e. Reduce reactive power; When the voltage of the photovoltaic grid-connected point is in the area (0, U llmt ]、[U hdb -U th ,U hdb )、(U ldb , U ldb +U th ]、[U hlmt ,+∞) adopts voltage regulation strategy a; When the voltage of the photovoltaic grid-connected point is in the area (U llmt , U ldb ], and Q+ΔQ≤Q max , adopt voltage regulation strategy d; when the voltage of the photovoltaic grid-connected point is in the area [U hdb ,U hlmt ), if Q-ΔQ≥Q min Adopt voltage regulation strategy e, otherwise, further judge, if P-ΔP≥P min Adopt voltage regulation strategy c, otherwise adopt voltage regulation strategy a; When the voltage of the photovoltaic grid-connected point is in the area (U ldb +U th , U hdb -U th ), if the active power is limited, the voltage regulation strategy b is adopted; if the active power is not limited, it is determined whether the reactive power is zero. If so, the voltage regulation strategy a is adopted; if not, the voltage regulation strategy e is adopted to make the reactive power zero.

2. According to the distributed power supply control method based on edge computing of claim 1, it is characterized by: The data of the distributed power intelligent gateway device in S1 are the three-phase voltage and current of the photovoltaic grid-connected point.

3. According to the distributed power supply control method based on edge computing of claim 1, it is characterized by: The distributed power intelligent gateway device hardware in S4 includes an encryption chip, which is connected to the device CPU using the SPI interface, and the CPU provides 3.3V working power for the encryption chip.

Images