Decision-making method and device for distributed photovoltaic auxiliary power quality management

Abstract

The invention discloses a decision-making method and device for distributed photovoltaic auxiliary electric energy quality management, and the method comprises the steps: carrying out the division of various states when distributed photovoltaic participates in an application scene of electric energy quality adjustment according to the demands of electric energy supply and electric energy quality management; based on the historical power consumption data of the user, the probability of occurrence of various states in the current treatment period is evaluated; respectively establishing two different expected profit and loss models in a grid-connected power generation mode in which the electric energy quality participates in auxiliary electric energy management; and with maximization of expected benefits of grid-connected power generation as a target, one of the grid-connected power generation modes is decided as a strategy for distributed photovoltaic to participate in auxiliary power quality treatment in the current treatment period. The method can effectively deal with the increasingly prominent electric energy quality problem in a power distribution network under the background of rapid development of a novel electric power system, gives full play to the electric energy quality regulation and control function of the photovoltaic grid-connected inverter, and provides important support for safe and stable operation of the electric power system.

Description

Technical Field

[0001] The present invention relates to the field of power market-assisted power quality management services, and in particular to a decision-making method and device for distributed photovoltaic-assisted power quality management. Background Art

[0002] With the development of society and the upgrading of industry, the current distribution network is experiencing an increasing number of power quality interference users and power quality sensitive devices, jointly driving the progress of power quality management. Typically, power quality management in distribution networks relies on the installation of appropriate power quality control equipment. However, in the current environment where a large number of distributed power sources, primarily photovoltaics, are connected to the grid, the grid-connected inverters required for distributed photovoltaic grid connection have a topology similar to that of static VAR compensation devices (SVGs). Existing research has demonstrated that after meeting the photovoltaic active output requirements, photovoltaic grid-connected inverters can fully utilize their remaining capacity to participate in the management of various power quality issues, providing a new approach to power quality management for power systems.

[0003] At present, research on the application of distributed photovoltaics in power quality management mainly focuses on improving its control strategy to optimize and enhance its compensation capability. For example, some literature proposes a dual closed-loop control strategy based on the differential component of the inductor voltage and the grid-connected current feedback to reduce the impact of external factors on the grid-connected inverter's participation in power quality regulation. In addition, most existing studies also believe that photovoltaic users can freely adjust the capacity allocation of the two tasks of power supply and power quality management. Therefore, in order to ensure that the distribution network can operate at the best power quality level as much as possible, the active output of photovoltaics can be reduced when necessary to have more sufficient remaining capacity to participate in power quality management. It can be seen that current research all believes that distributed photovoltaics are fully controllable units in power grid dispatching. However, in fact, the rooftop distributed photovoltaics currently widely installed in the distribution network belong to the rooftop owners, and the income generated by the surplus power connected to the grid through photovoltaic power generation is closely related to the power generation. Therefore, for distributed photovoltaic users, out of consideration for their own interests, they usually only hope to generate as much electricity as possible, and will not actively participate in the management of power quality. Therefore, in order to encourage distributed photovoltaic users to actively allocate surplus capacity to assist the distribution network in power quality management while undertaking basic grid-connected power generation work, it is urgent to study a decision-making method for auxiliary power quality management for distributed photovoltaic entities. Summary of the Invention

[0004] To address the deficiencies in the prior art, the present invention provides a decision-making method and device for distributed photovoltaic-assisted power quality management, which can effectively address the increasingly prominent power quality issues in distribution networks under the background of the rapid development of new power systems, give full play to the power quality control function of photovoltaic grid-connected inverters, and provide important support for the safe and stable operation of power systems.

[0005] The present invention adopts the following technical solutions.

[0006] In a first aspect, the present invention provides a decision-making method for distributed photovoltaic-assisted power quality management, the method comprising:

[0007] Based on the needs of power supply and power quality management, the various states faced by distributed photovoltaics in the application scenarios of power quality regulation are divided;

[0008] Evaluate the probability of each state occurring based on the user's historical electricity consumption data;

[0009] Combined with the probability of occurrence of various states, expected profit and loss models are established for two different power quality modes of grid-connected power generation participating in auxiliary power management.

[0010] With the goal of maximizing the expected benefits of grid-connected power generation, one of the grid-connected power generation modes is decided as a strategy for distributed photovoltaics to participate in auxiliary power quality management during the current management cycle.

[0011] Optionally, the various states include: high power demand and high power quality demand, high power demand and low power quality demand, low power demand and high power quality demand, and low power demand and low power quality demand;

[0012] If the proportion of the load of the supplied user to the rated capacity of the distributed photovoltaic system is lower than the first set proportion value, the power supply demand is low; otherwise, the power supply demand is high.

[0013] If the proportion of users with power quality problems among the supplied users to the total number of users is lower than a second set proportion value, the power supply quality requirement is low; otherwise, the power supply quality requirement is high.

[0014] Optionally, the expressions of the four states are as follows:

[0015] S ij =[S HH ,S HL ,S LH ,S LL ]

[0016]

[0017] Where S ijIndicates the state where the power supply demand is i and the power supply quality demand is j; i represents the degree of demand for power supply, j represents the degree of demand for power quality, H represents a high degree of demand; L represents a low degree of demand; S Load Indicates the load size of the power supply user, S N Indicates the rated capacity of the grid-connected inverter, X1 is the first set ratio value; N exceed Indicates the number of users with power quality problems among the users supplied with power, N total represents the total number of users supplied with electricity, and X2 is the second set ratio value.

[0018] Optionally, users with power quality problems refer to users with power quality indicators exceeding limits, and the power quality indicators include voltage deviation, three-phase imbalance and harmonic distortion rate.

[0019] Optionally, the step of respectively evaluating the probability of occurrence of various states based on the user's historical electricity usage data includes:

[0020] The daily status of the power users is classified, and the frequency of occurrence of various statuses is counted on an annual time scale. The ratio of the frequency of occurrence of various statuses to the number of days in a year is used as the probability of occurrence of the corresponding status.

[0021] Optionally, the grid-connected power generation mode includes:

[0022] Model 1: A grid-connected power generation model that combines power supply with power quality management. In this model, the total amount of power provided by distributed photovoltaic users should not exceed their rated capacity. The goal of participating in grid-connected power generation is to maximize profits under different electricity prices and management costs determined according to different power quality levels.

[0023] Mode 2: Considering a grid-connected power generation model in which power supply and power quality management are independent, in this mode, the constraint condition is that the sum of the capacity occupied by grid-connected power generation and the capacity occupied by power quality management does not exceed the rated capacity of the photovoltaic grid-connected inverter, and the goal is to participate in grid-connected power generation with the goal of maximizing profits under the unit price adjusted according to power quality issues.

[0024] Optionally, the expressions of the expected profit and loss models for two different power qualities participating in the grid-connected power generation mode of auxiliary power management are as follows:

[0025]

[0026] Where, E(W1) is the expected profit and loss value of grid-connected power generation in mode 1, P k and C kThey represent the unit price and unit cost of electricity of the kth power quality level, K represents the number of power quality levels, Q k,ij Indicates state S ij The energy supply of the next k-th level of electricity, C E It represents the total cost of purchasing electricity from the upper power grid, T ij Indicates state S ij The probability of occurrence; E(W2) is the expected profit and loss value of grid-connected power generation under mode 2, P and P pq They represent the conventional unit price of electricity and the unit price of power quality management respectively; Q ij and Q pq,ij Represents state S respectively ij The power supply under the condition of C and the capacity used to participate in power quality management, the superscript T indicates transposition; gci Indicates the unit cost of power quality management required by the remaining capacity of the PV inverter.

[0027] In a second aspect, the present invention provides a decision-making device for distributed photovoltaic-assisted power quality management, which executes the steps of any method described in the first aspect of the present invention, and the device includes:

[0028] The state division unit is used to divide the various states faced by distributed photovoltaics in the application scenarios of power quality regulation according to the needs of power supply and power quality management;

[0029] An evaluation probability unit is used to evaluate the probability of occurrence of various states based on the user's historical electricity consumption data;

[0030] Establish a model unit to combine the probability of occurrence of various states and establish expected profit and loss models for two different power quality modes of grid-connected power generation participating in auxiliary power management;

[0031] The decision-making management unit, with the goal of maximizing the expected benefits of grid-connected power generation, decides on one of the grid-connected power generation modes as a strategy for distributed photovoltaics to participate in auxiliary power quality management within the current management cycle.

[0032] In a third aspect, the present invention provides a terminal including a processor and a storage medium;

[0033] The storage medium is used to store instructions;

[0034] The processor is configured to operate according to the instructions to execute the steps of any one of the methods described in the first aspect of the present invention.

[0035] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any one of the methods described in the first aspect of the present invention.

[0036] The beneficial effects of the present invention are as follows:

[0037] (1) The present invention fully mobilizes the enthusiasm of the growing number of distributed photovoltaic users to manage the power quality problems of the distribution network by maximizing the benefits of distributed photovoltaics, thereby effectively responding to the increasingly prominent power quality problems in the distribution network under the background of the rapid development of new power systems; and by setting up two different grid-connected power generation modes for participating in auxiliary power management, it is conducive to promoting distributed photovoltaic users to actively participate in the regulation of power quality problems while grid-connected power generation, and give full play to the power quality regulation function of photovoltaic grid-connected inverters. Compared with existing research, the grid-connected power generation mode designed by the present invention more fully considers the capacity allocation intentions of distributed photovoltaic users themselves, is more in line with the application in actual power grids, improves the overall benefits while promoting the level of photovoltaic resource consumption, and provides important support for the safe and stable operation of the power system.

[0038] (2) In order to encourage distributed photovoltaic users to participate more actively in the regulation of power quality issues, the present invention solves the problem by adopting a decision-making method based on expected profit and loss value based on the analysis and evaluation of the benefits of two grid-connected power generation models, and makes decisions with the goal of maximizing the expected benefits of grid-connected power generation. The power quality auxiliary management solution determined has better applicability to scenarios with differentiated power quality requirements.

[0039] In summary, the present invention will be conducive to promoting the implementation of power quality control based on photovoltaic grid-connected inverters in actual power grids, and is of great significance for maintaining a high level of power quality in distribution networks and ensuring safe and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the process of the decision-making method for distributed photovoltaic-assisted power quality management in the present invention;

[0041] Figure 2 This is a block diagram of the structural principles of the decision-making device for distributed photovoltaic-assisted power quality management in the present invention. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. The embodiments described in the present invention are only part of the embodiments of the present invention, not all of the embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Example 1:

[0044] Reference Figure 1The embodiment of the present invention provides a decision-making method for distributed photovoltaic-assisted power quality management, which specifically includes the following steps:

[0045] Step 1: Based on the requirements for power supply and power quality management, the various states faced by distributed photovoltaics in power quality regulation application scenarios are divided;

[0046] Step 2: Evaluate the probability of each state occurring based on the user's historical electricity consumption data;

[0047] Step 3: Based on the probability of occurrence of various states, establish the expected profit and loss models for two different power quality modes of grid-connected power generation participating in auxiliary power management;

[0048] Step 4: With the goal of maximizing the expected benefits of grid-connected power generation, decide on one of the grid-connected power generation modes as a strategy for distributed photovoltaics to participate in auxiliary power quality management during the current management cycle.

[0049] It should be noted that, in the context of power quality, distributed photovoltaic users have two ideas for grid-connected power generation that integrate power quality. On the one hand, distributed photovoltaic users can directly combine power quality management with grid-connected power generation to provide differentiated power quality. On the other hand, they can also use power quality management as an auxiliary service to provide additional services after meeting basic power supply tasks. Therefore, the embodiment of the present invention establishes two different grid-connected power generation mode strategies to participate in the management of power quality in the auxiliary power market; the details are as follows:

[0050] (1) Model 1: A grid-connected power generation model that considers the combination of power supply and power quality management. In this model, the total amount of power provided by distributed photovoltaic users should not exceed the size of their rated capacity, and the goal of participating in grid-connected power generation is to maximize the benefits under different electricity prices and management costs determined according to different power quality levels. Further analysis is as follows:

[0051] When distributed photovoltaics participate in the electricity market by combining power supply with power quality management, power quality management will be a necessary task. Therefore, the management cost required to adjust power quality must be considered. To this end, distributed photovoltaics can first classify power quality according to user needs. Electricity of different power quality levels can be expressed as follows:

[0052] Q=[Q1,Q2,…,Q K ] (1)

[0053] Where Q K= represents the electric energy of the Kth power quality level. Therefore, since different quality levels of electric energy mean different management costs, they also correspond to different unit electricity prices. The higher the quality level, the higher the unit electricity price. Ultimately, the unit electricity price and unit management cost under different power quality levels can be expressed as:

[0054] P=[P1,P2,…,P K ] (2)

[0055] C=[C1,C2,…,C K ] (3)

[0056] Where, P K and C K Respectively represent the unit price and unit cost of electricity with power quality level K. At this time, since power quality management is a service that distributed photovoltaics must provide, if the remaining capacity of the distributed photovoltaic inverter cannot meet the power quality management requirements, it is still necessary to configure a power quality control device to ensure that the provided electricity meets user requirements. That is, the cost of managing power quality level K can be expressed as:

[0057] C K =C gci +C dev (4)

[0058] Where C gci and C dev They represent the unit cost of power quality control through the inverter's remaining capacity and through power quality control equipment. Furthermore, considering that the power generation of distributed photovoltaics is significantly affected by climate, after reaching a power supply agreement with the user, it is necessary to consider purchasing power from the upper-level power grid when necessary. Therefore, there is also a possible power purchase cost, which can be expressed as follows:

[0059] C E =C e ×Q e (5)

[0060] Where C E represents the total cost of purchasing electricity from the upper grid, C e and Q e Represent the unit electricity purchase cost and total electricity purchase capacity respectively.

[0061] Therefore, for distributed photovoltaic users who consider combining power supply with power quality management, the profit calculation formula with the goal of maximizing profits under different electricity prices and management costs according to different power quality levels is expressed as follows:

[0062]

[0063] Where W1 represents the economic benefits of distributed photovoltaics, P k 、C k and Q k They respectively represent the unit electricity price, unit governance cost and supply quantity of the kth power quality level electricity, and K represents the number of power quality levels.

[0064] Correspondingly, in this scenario, since the power quality management task can also be fully achieved by configuring additional management devices, the constraint condition of mode 1 is that the total amount of electricity provided by distributed photovoltaic users should not exceed their rated capacity, which can be expressed as follows:

[0065]

[0066] Where S N Indicates the rated capacity of the distributed photovoltaic grid-connected inverter, S k Indicates the capacity occupied by the electric energy of the kth quality level.

[0067] (2) Model 2: Considering a grid-connected power generation model where power supply and power quality management are independent, in this model, the sum of the capacity occupied by grid-connected power generation and the capacity occupied by power quality management does not exceed the rated capacity of the photovoltaic grid-connected inverter, and the goal of participating in grid-connected power generation is to maximize the profit under the unit price adjusted according to power quality issues; further analysis is as follows:

[0068] When distributed photovoltaic entities participate in the electricity market in a form of independent power supply and power quality management, grid-connected power generation capacity and power quality regulation will become two independent grid-connected tasks; therefore, the power quality management service unit price can be formulated according to different power quality management targets. Considering that the power quality issues considered in the current power system are mainly voltage deviation, harmonic distortion and three-phase imbalance, the power quality regulation unit price can be expressed as follows:

[0069] P pq =[P U ,P H ,P B ] (8)

[0070] In the formula, U, H, and B represent the three power quality problems of voltage deviation, harmonic distortion, and three-phase imbalance, respectively.

[0071] Secondly, because the amount of remaining capacity available for power quality regulation is closely related to the occupancy of photovoltaic power generation, this resource will have different levels of tension at different times and climate conditions. For example, it is usually most tense during the day and most abundant at night; it is most tense under sunny conditions and most abundant under cloudy conditions. Therefore, to avoid capacity waste and encourage distributed photovoltaics to sell as much remaining capacity as possible to participate in power quality regulation when the power generation occupancy is low, the power quality regulation unit price under the two time periods can be further differentiated as follows:

[0072] P pq =(α / β)×[P U ,P H ,P B ] (9)

[0073] Here, α and β represent the power quality adjustment price coefficients for daytime and nighttime, respectively. Typically, α ≥ β. Under this mechanism, power quality control is merely an ancillary service provided by distributed PV utilizing excess capacity. Therefore, only the cost of controlling power quality through the inverter needs to be considered. However, power purchase from the higher-level grid also exists when necessary.

[0074] In summary, for distributed photovoltaic systems that consider the independence of power supply and power quality management, the profit calculation formula with the goal of maximizing the profit under the adjustment of unit price according to power quality issues is expressed as follows:

[0075]

[0076] Where W2 represents the economic benefits of distributed photovoltaics, P and Q represent the unit price and supply of electricity respectively; P pq and They represent the unit price and capacity of various power quality problem treatment vectors. It should be noted that the superscript T of the treatment capacity represents transposition, so it can be specifically expressed as

[0077] Correspondingly, in this scenario, since the grid-connected inverter will bear the capacity of both grid-connected power generation and power quality management, the adoption of Mode 2 requires that the sum of the capacity occupied by grid-connected power generation and the capacity occupied by power quality management does not exceed the rated capacity of the photovoltaic grid-connected inverter, which can be expressed as follows:

[0078] S N ≥S U +S H +S B +S (11)

[0079] Where S U 、S H 、SB They represent the capacities corresponding to the three types of power quality issues; S N It represents the rated capacity of the distributed photovoltaic grid-connected inverter, and S represents the capacity occupied by the distributed photovoltaic active output.

[0080] Further explanation: To safeguard their own interests, distributed photovoltaic users must make decisions about their grid-connected power generation methods based on real-time electricity prices and user demand, with the goal of maximizing their own benefits. However, in actual distribution networks, influenced by user electricity usage habits and seasonal time characteristics, distributed photovoltaics face complex and variable grid-connected power generation and power quality management requirements, which are subject to significant uncertainty. Therefore, the embodiments of the present invention describe the decision-making problem of distributed photovoltaic users assisting in power quality management as a risky decision.

[0081] At present, the solution to risk decision-making problems can be mainly divided into two perspectives according to the different focuses: minimizing risk and maximizing expected value. The former is based on the judgment of the probability of occurrence of different events. By ignoring low-probability events, the scenario with strong uncertainty is characterized as the corresponding scenario with the maximum probability, thereby making a decision; the latter is based on the expected value, fully considering the possibility of different events, and thus expressing the scenario with uncertainty through the expected value, and then comparing and further deciding the object with the best expected value. It can be seen that the solution method based on expected value can better consider the complex and changeable differentiated power supply demand scenarios, and the decision results can have better universality, so it is more suitable for solving the decision-making problem of distributed photovoltaic assisted power quality management, and maximizing economic benefits as the goal to encourage distributed photovoltaic users to actively participate in power quality management. In summary, the present invention adopts a decision-making method based on expected profit and loss value as a solution tool for decision-making problems. Therefore, it is necessary to construct a corresponding risk decision model based on expected profit and loss value, which is specifically described as follows:

[0082] First, the decision-making goal is to drive distributed photovoltaic users to participate in the regulation of power quality issues in the distribution network with economic benefits. Therefore, in the solution framework based on expected profit and loss values, the objective function can be expressed as maximizing the expected benefits of grid-connected power generation, and can be described as follows:

[0083] max[max{E(W1),E(W2)}](12)

[0084] Where E represents expectation, W1 and W2 represent the economic benefits under two grid-connected power generation modes respectively.

[0085] Secondly, the core of risk decision-making lies in classifying the various states of uncertain scenarios and assessing the probabilities of each state. Therefore, model construction involves both defining the states and analyzing the probabilities. Considering that data monitoring and statistics in the current distribution network are already very complete, user electricity usage data can be collected and counted, and the severity of power quality issues in the distribution network can be analyzed, thus completing the model construction.

[0086] On the one hand, in the application scenario of power quality regulation through distributed photovoltaics, distributed photovoltaics, as the main body of demand response, can simultaneously provide two services: grid-connected power generation and power quality management. Therefore, the status should describe the user's demand for the two services.

[0087] A preferred but non-limiting embodiment divides each state into four states: high power supply demand and high power supply quality demand, high power supply demand but low power supply quality demand, low power supply demand but high power supply quality demand, and low power supply demand and low power supply quality demand; among which, if the proportion of the load of the powered users to the rated capacity of the distributed photovoltaic is lower than a first set proportion value, the power supply demand is low, otherwise the power supply demand is high; if the proportion of the number of users with power quality problems among the powered users to the total number of users is lower than a second set proportion value, the power supply quality demand is low, otherwise the power supply quality demand is high.

[0088] As an embodiment of the present invention, the expressions of the four states are as follows:

[0089] S ij =[S HH ,S HL ,S LH ,S LL ] (13)

[0090] Where S ij Indicates the state where the power supply demand is i and the power supply quality demand is j; i represents the degree of demand for power supply, j represents the degree of demand for power quality, H represents a high degree of demand, and L represents a low degree of demand. The degree of demand for grid-connected power generation can be divided according to the load size of the power supply user, and the rules are as follows:

[0091]

[0092] Where S Load Indicates the load size of the power supply user; S N Indicates the rated capacity of the grid-connected inverter; X1 is the first set ratio value, preferably, X1 = 50% in this embodiment; that is, the above rule is described in words as: if the load of the powered user accounts for 50% or more of the rated capacity of the distributed photovoltaic, then the grid-connected power generation demand is high.

[0093] The degree of demand for power quality management can be divided according to the statistical results of the power quality levels of the users supplied with power. The rules are as follows:

[0094]

[0095] Where N exceed Indicates the number of users whose power quality indicators exceed the limit among the users supplied with power; N total represents the total number of users supplied with power, and X2 is the second set ratio. Preferably, in this embodiment, X2 = 50%. It should be noted that power quality indicators primarily consider voltage deviation, three-phase imbalance, and harmonic distortion. If any of these indicators exceeds the limit, the user is considered to have power quality issues. Therefore, the above rule can be described as follows: if the number of users with power quality issues among the supplied users accounts for 50% or more of the total number of users, the need for power quality management is high.

[0096] On the other hand, to evaluate the probability of the four states mentioned above, it is obvious that the most direct and effective method is to use historical electricity consumption statistics based on users. Since the grid-connected power generation mode of distributed photovoltaics should generally remain fixed over a long period of time, the daily states of the users supplied with power can be classified based on the above rules, and the frequency of each state can be counted on an annual time scale. The ratio of the frequency of each state to the number of days in the year is used as the probability of the corresponding state occurring, expressed as follows:

[0097] T ij =[T HH ,T HL ,T LH ,T LL ] (16)

[0098] Where, T ij Indicates state S ij Probability of occurrence.

[0099] In a preferred but non-limiting embodiment, multiple years of historical data may be selected, and the ratio of the frequency of occurrence of various states to the total number of days in the multiple years may be used as the probability of occurrence of the corresponding state.

[0100] In summary, the expected profit and loss values ​​under different grid-connected power generation modes can be calculated. The calculation formula is as follows:

[0101] E(W a )=∑ i∈H,L ∑ j∈H,L W a (S ij )×T ij (17)

[0102] Where, E(W a ) represents the expected profit and loss value under the a-th grid-connected power generation mode; T ij Indicates state S ij The probability of occurrence, W a (S ij ) indicates that the a-th grid-connected power generation mode is in state S ij The following income.

[0103] Specifically, in the grid-connected power generation mode that combines power supply with power quality management, it will affect the supply of power of different qualities, so it can be further described as follows:

[0104]

[0105] That is, the expression of the expected profit and loss model under the grid connection strategy of mode 1 is:

[0106]

[0107] Where, E(W1) is the expected profit and loss value of grid-connected power generation in mode 1, P k and C k They represent the unit price and unit cost of electricity of the kth power quality level, K represents the number of power quality levels, Q k,ij Indicates state S ij The energy supply of the next k-th level of electricity, C E It represents the total cost of purchasing electricity from the upper power grid, T ij Indicates state S ij Probability of occurrence.

[0108] In the case of a grid-connected power generation model where power supply and power quality management are considered to be independent, this will affect the capacity allocation of photovoltaic power generation and power quality, and can be further described as follows:

[0109]

[0110] That is, the expression of the expected profit and loss model under the grid connection strategy of Mode 2 is:

[0111]

[0112] Where, E(W2) is the expected profit and loss value of grid-connected power generation under mode 2, Q ij and Q pq,ij Represents state S respectively ij The amount of power supply under the current situation and the capacity used to participate in power quality management.

[0113] In summary, the decision-making implementation process of the distributed photovoltaic-assisted power quality management of the present invention includes: first, according to the needs of power supply and power quality management, the different states that may be faced in the scene with uncertainty are determined. It should be noted that as the number of factors to be considered increases, those skilled in the art can further subdivide the definition of the state according to the different situations in the actual scene. Secondly, based on the user's historical electricity consumption data, the frequency of occurrence of different states is counted as the probability that different states may occur; it is further noted that as the number of historical sample data used increases, the estimation result of the probability will be more accurate, and those skilled in the art can decide the number of historical sample data to be used according to the specific situation. Furthermore, according to the grid-connected power generation model under two different forms of power quality management participation, the economic benefits of distributed photovoltaics in different states are calculated respectively. Finally, the expected economic benefits under different grid-connected power generation modes are calculated according to the expected profit and loss value calculation formula, so as to determine the participation mode of distributed photovoltaics in power quality management based on the expected benefit of maximizing grid-connected power generation: max[max{E(W1),E(W2)}].

[0114] The beneficial effects of the present invention are as follows:

[0115] (1) The present invention fully mobilizes the enthusiasm of the growing number of distributed photovoltaic users to manage the power quality problems of the distribution network by maximizing the benefits of distributed photovoltaics, thereby effectively responding to the increasingly prominent power quality problems in the distribution network under the background of the rapid development of new power systems; and by setting up two different grid-connected power generation modes for participating in auxiliary power management, it is conducive to promoting distributed photovoltaic users to actively participate in the regulation of power quality problems while grid-connected power generation, and give full play to the power quality regulation function of photovoltaic grid-connected inverters. Compared with existing research, the grid-connected power generation mode designed by the present invention more fully considers the capacity allocation intentions of distributed photovoltaic users themselves, is more in line with the application in actual power grids, improves the overall benefits while promoting the level of photovoltaic resource consumption, and provides important support for the safe and stable operation of the power system.

[0116] (2) In order to encourage distributed photovoltaic users to participate more actively in the regulation of power quality issues, the present invention solves the problem by adopting a decision-making method based on expected profit and loss value based on the analysis and evaluation of the benefits of two grid-connected power generation models, and makes decisions with the goal of maximizing the expected benefits of grid-connected power generation. The power quality auxiliary management solution determined has better applicability to scenarios with differentiated power quality requirements.

[0117] In summary, the present invention will be conducive to promoting the implementation of power quality control based on photovoltaic grid-connected inverters in actual power grids, and is of great significance for maintaining a high level of power quality in distribution networks and ensuring safe and stable operation.

[0118] Example 2:

[0119] like Figure 2 As shown, the present invention provides a decision-making device for distributed photovoltaic-assisted power quality management, which is used to implement the steps of the method in the above embodiment 1, and specifically includes:

[0120] The state division unit is used to divide the various states faced by distributed photovoltaics in the application scenarios of power quality regulation according to the needs of power supply and power quality management;

[0121] An evaluation probability unit is used to evaluate the probability of occurrence of various states based on the user's historical electricity consumption data;

[0122] Establish a model unit to combine the probability of occurrence of various states and establish expected profit and loss models for two different power quality modes of grid-connected power generation participating in auxiliary power management;

[0123] The decision-making management unit, with the goal of maximizing the expected benefits of grid-connected power generation, decides on one of the grid-connected power generation modes as a strategy for distributed photovoltaics to participate in auxiliary power quality management within the current management cycle.

[0124] The decision-making device for distributed photovoltaic-assisted power quality management provided in the embodiment of the present invention and the decision-making method for distributed photovoltaic-assisted power quality management provided in Example 1 are based on the same technical concept, and can produce the beneficial effects as described in Example 1. For the contents not described in detail in this embodiment, please refer to Example 1.

[0125] Example 3:

[0126] An embodiment of the present invention provides a terminal comprising a processor and a storage medium, the terminal being an embedded computer system device. The terminal's storage medium is used to store instructions, and the memory comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database; the internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium; and the database stores instruction data. The terminal's processor is configured to operate according to the instructions provided by the storage medium to execute the steps of the decision-making method for distributed photovoltaic-assisted power quality management described in any one of the first embodiments.

[0127] Example 4:

[0128] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps of the method described in any one of the first embodiments are implemented.

[0129] The present invention may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present invention.

[0130] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0131] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0132] The computer program instructions for performing the operation of the present invention can be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. The computer readable program instructions can be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), is personalized by utilizing the state information of the computer readable program instructions, and the electronic circuit can execute the computer readable program instructions, thereby realizing various aspects of the present invention.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A decision-making method for distributed photovoltaic-assisted power quality management, characterized in that the method include: Based on the needs of power supply and power quality management, the various states faced by distributed photovoltaics in the application scenarios of power quality regulation are divided; Evaluate the probability of each state occurring based on the user's historical electricity consumption data; Combined with the probability of occurrence of various states, expected profit and loss models are established for two different power quality modes of grid-connected power generation participating in auxiliary power management. With the goal of maximizing the expected benefits of grid-connected power generation, one of the grid-connected power generation modes is decided as a strategy for distributed photovoltaics to participate in auxiliary power quality management during the current management cycle.

2. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 1 is characterized in that: The various states include: high power demand and high power quality demand, high power demand and low power quality demand, low power demand and high power quality demand, and low power demand and low power quality demand; If the proportion of the load of the supplied user to the rated capacity of the distributed photovoltaic system is lower than the first set proportion value, the power supply demand is low; otherwise, the power supply demand is high. If the proportion of users with power quality problems among the supplied users to the total number of users is lower than a second set proportion value, the power supply quality requirement is low; otherwise, the power supply quality requirement is high.

3. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 2 is characterized in that: The expressions of the four states are as follows: S ij =[S HH ,S HL ,S LH ,S LL ] Where S ij Indicates the state where the power supply demand is i and the power supply quality demand is j; i represents the degree of demand for power supply, j represents the degree of demand for power quality, H represents a high degree of demand; L represents a low degree of demand; S Load Indicates the load size of the power supply user, S N Indicates the rated capacity of the grid-connected inverter, X1 is the first set ratio value; N exceed Indicates the number of users with power quality problems among the users supplied with power, N total represents the total number of users supplied with electricity, and X2 is the second set ratio value.

4. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 2 or 3 is characterized in that: Users with power quality problems refer to users whose power quality indicators exceed the limit. The power quality indicators include voltage deviation, three-phase imbalance and harmonic distortion rate.

5. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 1 is characterized in that: The step of respectively evaluating the probability of occurrence of various states based on the user's historical electricity usage data includes: The daily status of the power users is classified, and the frequency of occurrence of various statuses is counted on an annual time scale. The ratio of the frequency of occurrence of various statuses to the number of days in a year is used as the probability of occurrence of the corresponding status.

6. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 3 is characterized in that: The grid-connected power generation modes include: Model 1: A grid-connected power generation model that combines power supply with power quality management. In this model, the total amount of power provided by distributed photovoltaic users should not exceed their rated capacity. The goal of participating in grid-connected power generation is to maximize profits under different electricity prices and management costs determined according to different power quality levels. Mode 2: Considering a grid-connected power generation model in which power supply and power quality management are independent, in this mode, the constraint condition is that the sum of the capacity occupied by grid-connected power generation and the capacity occupied by power quality management does not exceed the rated capacity of the photovoltaic grid-connected inverter, and the goal is to participate in grid-connected power generation with the goal of maximizing profits under the unit price adjusted according to power quality issues.

7. The decision-making method for distributed photovoltaic-assisted power quality management according to claim 6 is characterized in that: The expressions of the expected profit and loss models for two different power quality modes participating in auxiliary power management are as follows: Where, E(W1) is the expected profit and loss value of grid-connected power generation in mode 1, P k and C k They represent the unit price and unit cost of electricity of the kth power quality level, K represents the number of power quality levels, Q k,ij Indicates state S ij The energy supply of the next k-th level of electricity, C E It represents the total cost of purchasing electricity from the upper power grid, T ij Indicates state S ij The probability of occurrence; E(W2) is the expected profit and loss value of grid-connected power generation under mode 2, P and P pq They represent the conventional unit price of electricity and the unit price of power quality management respectively; Q ij and Q pq,ij Represents state S respectively ij The power supply under the current situation and the capacity used to participate in power quality management, the superscript T indicates transposition; C gci Indicates the unit cost of power quality management required by the remaining capacity of the PV inverter.

8. A decision-making device for distributed photovoltaic-assisted power quality management, running the decision-making method for distributed photovoltaic-assisted power quality management according to any one of claims 1 to 7, characterized in that: The device includes: The state division unit is used to divide the various states faced by distributed photovoltaics in the application scenarios of power quality regulation according to the needs of power supply and power quality management; An evaluation probability unit is used to evaluate the probability of occurrence of various states based on the user's historical electricity consumption data; Establish a model unit to combine the probability of occurrence of various states and establish expected profit and loss models for two different power quality modes of grid-connected power generation participating in auxiliary power management; The decision-making management unit, with the goal of maximizing the expected benefits of grid-connected power generation, decides on one of the grid-connected power generation modes as a strategy for distributed photovoltaic participation in auxiliary power quality management within the current management cycle.

9. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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