An Optimal Quality Determination Method for Differentiated Power Supply for Multi-Group Users

Abstract

The present invention discloses a method for determining the optimal power supply quality with differentiation for multi-group users, belonging to the technical field of power grid power supply and consumption, including obtaining the power grid parameters of each group of power users and power suppliers, establishing a relationship model between the power quality loss and electric power of typical power quality indicators affected by time period persistence; studying the power quality cost model of each power quality problem user; establishing an aggregated power consumption model for group users; establishing a power supply cost model for power suppliers; and obtaining the optimal power supply quality for group users with the overall economic cost of both power supply and consumption considered optimally based on the aggregated power consumption model for group users and the power supply cost model for power suppliers. The present invention can solve the problem of the optimal power supply quality demand with differentiation for a large number of large-group power users emerging under the background of the current liberalization of the power sales side, and effectively promote the power sales competition decision-making of power sellers and the development of high-quality power supply parks in the power system.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid power supply and consumption, and in particular to a method for determining the optimal quality of differentiated power supply for multiple group users. Background Art

[0002] At present, the competition mode introduced on the power selling side has formed a competitive pattern of multiple market players in the power market. The accelerating process of power trading marketization urgently requires the improvement of the differentiated power supply capacity of the power system. The formation of the "multiple buyers - multiple sellers" pattern in the power selling market has made power selling companies and power users equal participants in the power market. Power users can independently select trading partners according to their differentiated power consumption quality requirements. In recent years, large group power users such as industrial and agricultural park power grids, incremental distribution power grids, microgrids, and high-tech industrial park power grids have emerged continuously, and at the same time, there are differentiated and diverse demands for power supply quality. The power quality problems of modern power grids have made the power grid pollution more and more serious. The power consumption demands of power users have gradually shifted from ordinary power supply to the purchase of high-quality power, which also indicates that the power supply objects of power grid enterprises are gradually developing towards high-quality power parks. The power grid must use customized power technology means to provide differentiated optimal power supply quality for power users to solve the current problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for determining the optimal quality of differentiated power supply for multiple group users, so as to solve the problem in the existing power supply and consumption technology field that the customized power technology means are not considered to provide the differentiated optimal power supply quality that best meets the total economic cost of both power supply and consumption parties for multiple group power users.

[0004] To solve the above technical problem, the technical solution adopted by the present invention is:

[0005] A method for determining the optimal quality of differentiated power supply for multiple group users, comprising:

[0006] Obtain the parameters of each group of power users and the parameters of the power supply side distribution network, and establish a relationship model between the power quality loss and electric power of typical power quality indicators with time-period continuous influence based on the load data and power quality data of individual users within the group of power users;

[0007] Apply the governance strategy of the power quality time series feature pattern, and establish a power quality cost model for each power quality problem user based on the "relationship model between each power quality indicator and electric power" and the "relationship model between the total economic cost of each power quality indicator and electric power".

[0008] Considering the contribution of each power quality problem user to the power quality and governance cost at the point of common coupling (PCC), an aggregated model of group users' electricity consumption is established based on the aggregation method of subjective and objective combined weights; the power supply cost model of the power supply side is established by applying the Taguchi quality evaluation theory and cost modeling method;

[0009] Finally, based on the aggregated model of group users' electricity consumption and the power supply cost model of the power supply side, the optimal power supply quality of group users considering the total economic cost of both power supply and consumption parties is obtained.

[0010] A further improvement of the technical solution of the present invention lies in that: the parameters of each group power user include the load data, power quality data, and electricity consumption cost data of its internal individual users; the description of the power quality data refers to the voltage deviation index and harmonic index; the parameters of the power supply side distribution network include power supply quality data and power supply cost data.

[0011] A further improvement of the technical solution of the present invention lies in that: the relationship model between the power quality loss and electric power of the typical power quality index affected by the time period persistence includes:

[0012] (1) The relationship model between the voltage deviation index and electric power, expressed as:

[0013]

[0014] Among them, β is the voltage deviation degree, used to measure the level of the voltage deviation index; P N0 is the no-load loss of the user's distribution transformer; P and Q are the active power and reactive power of the load; U N is the system rated voltage; R L is the equivalent resistance of the transmission line; R T is the equivalent resistance of the distribution transformer;

[0015] (2) The relationship model between the harmonic index and electric power, expressed as:

[0016]

[0017] Among them, THD I is the total harmonic distortion rate of the harmonic current, used to measure the level of the harmonic index; is the harmonic resistance correction coefficient; R T is the fundamental wave equivalent resistance of the transformer; h is the harmonic order; X T is the fundamental wave leakage reactance of the transformer; I 1 is the effective value of the fundamental wave current; p oi is the no-load loss of the i-th distribution transformer; m is the number of distribution transformers in the system; R L is the fundamental wave resistance of the line; X L is the fundamental wave reactance of the line; I Ais the effective value of the harmonic current of phase A; I A1 is the effective value of the fundamental wave current of phase A; I B is the effective value of the harmonic current of phase B; I B1 is the effective value of the fundamental wave current of phase B; I C is the effective value of the harmonic current of phase C; I C1 is the effective value of the fundamental wave current of phase C.

[0018] A further improvement of the technical solution of the present invention lies in that: the extraction of power quality time series features and pattern representation include:

[0019] The selection and representation of key trend turning points, the piecewise linear representation of power quality time series, and the feature matrix representation of power quality time series feature patterns;

[0020] (1) The selection and representation of key trend turning points of power quality time series are as follows:

[0021]

[0022] Among them, x i-1 , x i+1 are respectively two monitoring data adjacent to on the power quality time series; d v and d h are respectively the conditional expressions in the numerical and time dimensions in terms of horizontal and vertical distances;

[0023] (2) Using the least squares fitting method to perform piecewise linear representation on the power quality time series, which is as follows:

[0024]

[0025] Among them, k m is the array fitting slope in the m-th sequence segment, representing the local trend characteristics of the power quality time series; b m is the fitting intercept of the array in the m-th sequence segment; M is the number of segments of the power quality time series; s m is the time span of the power quality time series segment; t l and t 1 are respectively the terminal time point and the starting time point of the m-th power quality time series segment;

[0026] (3) The pattern feature representation of the power quality time series in the form of a feature matrix is:

[0027] [(k 1 , s 1 )(k 2 , s 2 )…(k M , s M )].

[0028] A further improvement of the technical solution of the present invention lies in that the governance strategies for various power quality problems based on the power quality time series include:

[0029] (1) The governance strategy for voltage deviation problems based on the power quality time series, expressed as:

[0030]

[0031] Wherein, and are respectively the average voltage deviation degrees of each problem time period after and before the governance of the out-of-limit time period of the power quality time series; is the average voltage deviation degree of the power quality time series time period where there is no problem of out-of-limit voltage deviation index; and are respectively the average voltage deviation degrees of the entire time period after and before the governance of the voltage deviation out-of-limit time period; β and β here 0 are respectively the index levels after and before the governance of the voltage deviation problem users; E PQ is an improvement degree index for measuring each power quality index of the entire time period of the power quality time series after the governance of each power quality out-of-limit time period relative to that before the governance;

[0032] (2) The governance strategy for harmonic problems based on the power quality time series, expressed as:

[0033]

[0034] Wherein, and are respectively the average total harmonic distortion rates of the current of each problem time period after and before the governance of the out-of-limit time period of the power quality time series; and are respectively the average total harmonic distortion rates of the current of the entire time period after and before the governance of the harmonic out-of-limit time period; THD I and THD I0 are respectively the index levels after and before the governance of the harmonic problem users.

[0035] A further improvement of the technical solution of the present invention lies in that the power quality cost model of each power quality problem user includes:

[0036] (1) The power quality cost model of the voltage deviation problem user, expressed as:

[0037]

[0038] Wherein, C J is the total economic cost corresponding to the voltage deviation index; C pProfit loss resulting in reduced production; C s Loss of equipment life; C o Loss of defective products produced; C c Initial investment cost included in power quality management cost, mainly including purchase price of equipment, labor cost, transportation and installation cost, inspection and calibration cost of equipment, etc.; C y Operation and maintenance cost included in power quality management cost, mainly including annual power consumption cost, manual inspection and maintenance cost, equipment repair and component replacement cost; R 0 Standard electricity charge; T is the life cycle of operation; λ i Electricity charge ratio in different power factor intervals; P i Active power of load at different power factors;

[0039] (2) Power quality cost model of harmonic problem users, expressed as:

[0040]

[0041] Among them, here C J Total economic cost corresponding to harmonic index; K W Current unit electricity charge.

[0042] The further improvement of the technical solution of the present invention lies in: The contributions of each power quality problem user to the power quality and governance cost at the point of common coupling (PCC) include:

[0043] (1) The contribution of voltage deviation problem users to the power quality and governance cost at the PCC, expressed as:

[0044]

[0045] Among them, Δβ is the voltage deviation problem of each user, that is, the index over-limit problem. Over-limit means exceeding the voltage deviation index level determined by the user itself. It is the change in the voltage deviation at the PCC before and after the over-limit; β N Voltage deviation level at the PCC when N users in the group user have voltage deviation problems and need to be governed; β 0 Voltage deviation level at the PCC when there are no voltage deviation problems among the users in the group user; β i Voltage deviation level of the i-th user with voltage deviation problem and needing to be governed; Δβ i The i-th voltage deviation user, which also represents the contribution of each voltage deviation user to the total voltage deviation at the PCC; ω i The proportion of the contribution of the i-th user to the change in each power quality index at the PCC to the total change in each power quality index at the PCC; C Mi The contribution of each user to the total governance cost at the PCC; CM is the total governance cost caused by various power quality problems of each user at the PCC; ω Mi is the proportion of the contribution of each user to the governance cost at the PCC in the total governance cost at the PCC;

[0046] (2) The contribution of harmonic problem users to the power quality and governance cost at the PCC is expressed as:

[0047]

[0048] Among them, ΔTHD I is the change in harmonics at the PCC before and after the occurrence of harmonic problems of each user; is the harmonic level at the PCC when N users in the group user have harmonic problems and need to be governed; is the harmonic level at the PCC when there are no harmonic problems for each user within the group user; is the level of the i-th user with harmonic problems and needs to be governed; is the total harmonic contribution of the i-th user to the PCC.

[0049] A further improvement of the technical solution of the present invention lies in that: the aggregation method based on the subjective and objective combined weights to establish an electricity aggregation model for group users includes:

[0050] (1) Obtaining the subjective and objective combined weights, which is expressed as:

[0051]

[0052] Among them, ω i and respectively represent the proportion of the power quality and corresponding governance cost of each user in the overall group user, that is, at the PCC; represents the duration span of each power quality problem; T represents the total time span of the power quality time series of each user;

[0053] (2) Aggregation of voltage deviation problem users, which is expressed as:

[0054]

[0055] Among them, C JJ is the total economic cost corresponding to the voltage deviation index of the group user. The symbols of the remaining variables have been described above and will not be repeated here. The relevant variables of the following aggregation model will not be repeated either;

[0056] (3) Aggregation of harmonic problem users, which is expressed as:

[0057]

[0058] Among them, C hereJJ The total economic cost corresponding to the harmonic index for group users.

[0059] A further improvement of the technical solution of the present invention lies in that: the establishment of the power supply cost model of the power supply side by applying the Taguchi quality evaluation theory and the cost modeling method includes:

[0060] (1) The cost representation of the Taguchi quality evaluation theory is:

[0061]

[0062] Wherein, is the quantified quality cost loss, with the unit of ¥; χ is the deviation-cost parameter; x i and x are the actual and expected product qualities respectively; σ 2 and are the variance and mean value of the product quality x respectively;

[0063] (2) The relationship model between the voltage deviation index of the power supply side and the total economic cost is expressed as:

[0064]

[0065] Wherein, C GJ is the total economic cost of the power supply side corresponding to the voltage deviation index; C 1 is the economic cost caused by the equipment; C 2 is the economic compensation cost; C 3 is the user responsibility compensation income; C 4 is the cost of loss of power sales profit; here, β and β 0 are the final and initial supply voltage deviation index values of the power supply side to the group users respectively, and β 0 is considered a known fixed value;

[0066] (3) The relationship model between the harmonic index of the power supply side and the total economic cost is expressed as:

[0067]

[0068] Wherein, here C GJ is the total economic cost of the power supply side corresponding to the harmonic index; THD I and are the final and initial supply harmonic index values of the power supply side to the group users respectively, is considered a known fixed value.

[0069] A further improvement of the technical solution of the present invention lies in that: the optimal power supply quality of group users with the overall consideration of the total economic costs of both the power supply and power consumption sides is obtained based on the power consumption aggregation model of group users and the power supply cost model of the power supply side;

[0070] Adding the aggregated power consumption models of group users corresponding to each power quality index and the power supply cost models of power suppliers yields the relationship models between each power quality index and the comprehensive total economic cost of both power supply and consumption sides; based on the models obtained above, the values of each power quality index that minimize the comprehensive total economic cost of both power supply and consumption sides are obtained, and these power quality index values are the optimal power supply quality finally and uniquely obtained by the group users, which is optimal in terms of the total economic cost for both group users and power suppliers.

[0071] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is as follows:

[0072] 1. With the ultimate goal of optimizing the total economic cost of both group users and power suppliers and enabling each group user to obtain differentiated optimal power supply quality, the present invention utilizes the relationship model between the power quality loss and electric power of individual users with each power quality problem, the typical power quality time series with time period continuous influence characteristics and corresponding governance strategies, the weighted summation aggregation method of subjective and objective combined weights, and the solution method of the power supplier's power quality cost model applying Taguchi quality evaluation theory and cost modeling. Finally, based on the aggregated power consumption model of group users and the power supply cost model of power suppliers, the optimal power supply quality of group users with the lowest comprehensive total economic cost of both power supply and consumption sides is obtained, solving the problem in current power supply and consumption technologies that the use of customized power technology means to provide differentiated optimal power supply quality for multiple group power users is not considered, improving the differentiated power supply ability of the power supplier's distribution network, and meeting the differentiated optimal power supply quality requirements on the user side and the vision of building a high-quality power park.

[0073] 2. The present invention can enable each group user to obtain differentiated optimal power supply quality while ensuring the lowest comprehensive total economic cost of both group users and power suppliers. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 is a schematic flow chart of the method for determining the optimal differentiated power supply quality for multiple group users provided by an embodiment of the present invention;

[0075] Figure 2 is a pattern feature diagram of the power quality time series provided by an embodiment of the present invention;

[0076] Figure 3 is a time series diagram of the typical time period of power quality provided by an embodiment of the present invention;

[0077] Figure 4 is a power quality cost curve diagram of typical harmonic problem users within a group user provided by an embodiment of the present invention;

[0078] Figure 5 is an aggregated power consumption curve diagram of the harmonic index of group users provided by an embodiment of the present invention;

[0079] Figure 6 is the power supply cost curve of the harmonic index of the power supply side provided by the embodiment of the present invention;

[0080] Figure 7 is the result diagram of the optimal voltage deviation index of the group users considering both the power supply and power consumption sides provided by the embodiment of the present invention;

[0081] Figure 8 is the result diagram of the optimal harmonic index of the group users considering both the power supply and power consumption sides provided by the embodiment of the present invention. Specific implementation manners

[0082] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0083] In one embodiment, as Figure 1 shown, a method for determining the optimal power supply quality with differentiation for multiple group users is described in detail as follows:

[0084] S101: Obtain the power grid parameters of each group of power users and the power supply side. The parameters of each group of power users include the load data, power quality data (all descriptions of power quality data involved in the present invention refer to voltage deviation index and harmonic index), and power consumption cost data of each individual user within them. The power grid parameters of the power supply side include power supply quality data and power supply cost data;

[0085] S102: Based on the load data and power quality data of the individual users within the group users, establish a relationship model between the power quality loss and electric power of the typical power quality indexes with time - period continuous influence;

[0086] In this embodiment, the multi - group user population is mainly analyzed with a single typical group user. At the same time, each group of users contains an uncertain number of individual users. The subsequent embodiment analysis can assume the number of individual users according to specific situations. The typical power quality indexes considering time - period continuous influence include voltage deviation and harmonics;

[0087] S103: Apply the governance strategy of the power quality time - series characteristic mode, and establish a power quality cost model for each power quality user based on the "relationship model between each power quality index and electric power" and the "relationship model between the total economic cost of each power quality index and electric power";

[0088] S104: Study the contribution of each power quality user to the power quality and governance cost at the point of common coupling (PCC), and study the aggregated power consumption model of group users based on the aggregation method of subjective and objective combined weights; Apply the Taguchi quality evaluation theory and cost modeling method to establish a power supply cost model for the power supply side;

[0089] In this embodiment, the PCC is regarded as the connection point between the group users and the power supply side's distribution network. Then, the contribution of individual users within the group users to the power quality and governance cost at the PCC can be regarded as the corresponding contribution to the power quality and governance cost of the group users. The Taguchi quality assessment theory and cost modeling method are mainly used for the analysis and modeling of the product supplier (referring to the power supply side in this embodiment), and are not applicable to the product users (referring to the group users in this embodiment).

[0090] S105: Based on the group users' aggregated power consumption model and the power supply side's power supply cost model, obtain the optimal power supply quality of the group users that comprehensively considers the total economic cost of both the power supply and consumption sides.

[0091] In this embodiment, adding the group users' aggregated power consumption model and the power supply side's power supply cost model gives the relationship model considering the power quality and the comprehensive total economic cost of both the power supply and consumption sides. At the same time, the corresponding result curve obtained by adding the group users' aggregated power consumption curve and the power supply side's power supply cost curve can also show the relationship between each power quality index and the comprehensive total economic cost of both the power supply and consumption sides. Furthermore, the optimal power supply quality corresponding to each power quality index of the group users with the lowest comprehensive total economic cost of both the power supply and consumption sides can be obtained by solving the added model or analyzing the result curve.

[0092] In the method for determining the optimal power supply quality with differentiation for multiple group users provided in the embodiments of this application, with the ultimate goal of the best total economic cost of the group users and the power supply side and each group user being able to obtain differentiated optimal power supply quality, using the relationship model between the power quality loss of individual users with each power quality problem and the electric power, the typical power quality time series with the characteristic of time - period continuous influence and the corresponding governance strategies, the weighted summation aggregation method of the subjective - objective combined weight, and the method for solving the power supply side's power quality cost model applying the Taguchi quality assessment theory and cost modeling. Finally, based on the group users' aggregated power consumption model and the power supply side's power supply cost model, obtain the optimal power supply quality of the group users that comprehensively considers the lowest total economic cost of both the power supply and consumption sides, solve the problem in the current power supply and consumption technology that does not consider using customized power technology means to provide differentiated optimal power supply quality for multiple group power users. This method, while ensuring the lowest total economic cost of the group users and the power supply side, enables each group user to obtain differentiated optimal power supply quality, improves the differentiated power supply ability of the power supply side's distribution network, meets the differentiated optimal power supply quality requirements on the user side, and greatly reduces the total economic cost of the power quality of both the power supply and consumption sides.

[0093] In this embodiment, the multi-group user population takes a single typical representative group user as the main analysis object. At the same time, each group user contains an uncertain number of individual users, but the subsequent embodiment analysis can assume the number of individual users according to specific circumstances. The typical power quality indicators considered in this embodiment that are continuously affected by time include voltage deviation and harmonics;

[0094] In one embodiment, the power quality loss and electric power relationship model of the typical power quality indicators affected by time persistence includes:

[0095] (1) The relationship model between the voltage deviation index and electric power is expressed as:

[0096]

[0097] In formula (1), β is the voltage deviation degree, used to measure the level of the voltage deviation index; P N0 is the no-load loss of the user distribution transformer; P and Q are the active power and reactive power of the load; U N is the system rated voltage; R L is the equivalent resistance of the transmission line; R T is the equivalent resistance of the distribution transformer;

[0098] (2) The relationship model between the harmonic index and electric power is expressed as:

[0099]

[0100] In formula (2), THD I is the total harmonic distortion rate of the harmonic current, used to measure the level of the harmonic index; is the harmonic resistance correction coefficient; R T is the fundamental equivalent resistance of the transformer; h is the harmonic order; X T is the fundamental leakage reactance of the transformer; I 1 is the effective value of the fundamental current; p oi is the no-load loss of the i-th distribution transformer; m is the number of distribution transformers in the system; R L is the fundamental resistance of the line; X L is the fundamental reactance of the line; I A is the effective value of the harmonic current of phase A; I A1 is the effective value of the fundamental current of phase A; I B is the effective value of the harmonic current of phase B; I B1 is the effective value of the fundamental current of phase B; I C is the effective value of the harmonic current of phase C; I C1 is the effective value of the fundamental current of phase C;

[0101] In one embodiment, the extraction of power quality time series features and pattern representation includes:

[0102] (1) The selection and representation of the key trend turning points of the power quality time series are as follows:

[0103]

[0104] In formula (3), x i-1 and x i+1 are respectively two adjacent monitoring data on the power quality time series (the power quality time series refers to the respective time series of voltage deviation indicators and harmonic indicators); d and d v and d h are respectively the conditional expressions in terms of numerical value and time dimension for the horizontal and vertical distances;

[0105] (2) Using the least - squares fitting method, the piece - wise linear representation of the power quality time series is as follows:

[0106]

[0107] In formula (4), k m is the fitting slope of the array in the m - th sequence segment, representing the local trend characteristics of the power quality time series; b m is the fitting intercept of the array in the m - th sequence segment; M is the number of segments of the power quality time series; s m is the time span of the m - th sequence segment in the power quality time series segment; t l and t 1 are respectively the terminal time point and the starting time point of the m - th power quality time series segment;

[0108] (3) The pattern characteristics of the power quality time series are represented in the form of a feature matrix as:

[0109] [(k 1 , s 1 )(k 2 , s 2 )…(k M , s M )] (5)

[0110] In this embodiment, the above - mentioned key trend turning points and representations of the power quality time series, and the piece - wise linear representation of the power quality time series can all be effectively demonstrated in Figure 2 , Figure 2 reflecting the pattern characteristics and various local trend characteristics of the power quality time series.

[0111] In one embodiment, the governance strategies for various power quality problems based on the power quality time series include:

[0112] (1) The governance strategy for the voltage deviation problem based on the power quality time series is expressed as:

[0113]

[0114] In formula (6), and are respectively the average voltage deviation degrees of each problem time period after and before the treatment of the over-limit time period of the power quality time series; is the average voltage deviation degree of the power quality time series time period where there is no problem of over-limit of voltage deviation index; and are respectively the average voltage deviation degrees of the whole time period after and before the treatment of the voltage deviation over-limit time period; β and β here 0 are respectively the index levels after and before the treatment of the users with voltage deviation problems; E PQ is an improvement degree index of each power quality index of the whole time period of the power quality time series after the treatment of each power quality over-limit time period relative to that before the treatment;

[0115] (2) The harmonic problem treatment strategy based on the power quality time series, expressed as:

[0116]

[0117] In formula (7), and are respectively the average total harmonic distortion rates of the current of each problem time period after and before the treatment of the over-limit time period of the power quality time series; and are respectively the average total harmonic distortion rates of the current of the whole time period after and before the treatment of the harmonic over-limit time period; THD I and are respectively the index levels after and before the treatment of the users with harmonic problems;

[0118] In this embodiment, the treatment strategies of each power quality problem related to the above continuous influence characteristics are all analyzed based on Figure 3 the typical power quality time series diagram shown, Figure 3 which reflects that the power quality has typical continuous influence characteristics and typical over-limit (over-limit means that each power quality index exceeds the power quality index treatment level of the user's own decision represented in, for example, Figure 3 ) situation, and then the corresponding treatment strategy analysis is carried out for each power quality over-limit situation.

[0119] In one embodiment, the power quality cost model of each power quality problem user includes:

[0120] (1) The power quality cost model of the user with voltage deviation problem, expressed as:

[0121]

[0122] In Equation (8), C J is the total economic cost corresponding to the voltage deviation index; C p is the profit loss caused by production reduction; C s is the equipment life loss; C o is the loss of defective products produced; C c is the initial investment cost included in the power quality management cost (mainly including the purchase price of equipment, labor costs, transportation and installation costs, equipment inspection and calibration costs, etc.); C y is the operation and maintenance cost included in the power quality management cost (mainly including annual power consumption costs, manual inspection and maintenance costs, equipment repair and component replacement costs); R 0 is the standard electricity charge; T is the life cycle of operation; λ i is the electricity charge ratio in different power factor intervals; P i is the active power of the load at different power factors;

[0123] Exemplarily, as shown in Table 1, according to the relationship between the total economic cost and the electric power of the user with voltage deviation problems, combined with the relationship model between the voltage deviation index and the electric power in Equation (1), the power quality cost model of the user with voltage deviation problems in Equation (8) can be obtained, and then the relevant parameters and results can be obtained.

[0124] Table 1

[0125] β / ％ 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 ΔP / kW 4.2 4.8 5.5 6.6 8.7 12.6 16.5 20.6 24.9 26.9 <![CDATA[C J / ten thousand yuan]]> 2.9 3.2 4.7 5.2 6.8 8.1 12.8 14.3 18.9 23.6

[0126] (2) The power quality cost model of the user with harmonic problems is expressed as:

[0127]

[0128] In Equation (9), here C J is the total economic cost corresponding to the harmonic index; K W is the current unit electricity charge;

[0129] Exemplarily, as shown in Table 2, according to the relationship between the total economic cost and the electric power of the user with harmonic problems, combined with the relationship model between the harmonic index and the electric power in Equation (2), the power quality cost model of the user with harmonic problems in Equation (9) can be obtained, and then the relevant parameters and results can be obtained. Further, according to Equation (9), Figure 4 the power quality cost curve of the user with harmonic problems shown can be obtained. From Figure 4 it can clearly show the mutual relationship between the harmonic index (measured and represented by the total harmonic distortion rate of harmonic current) and the corresponding total economic cost, Figure 4The relationship trend characteristics shown in [Table 1] can also be reflected according to certain values in [Table 2]; the power quality cost curve of users with voltage deviation problems is similar to that of users with harmonic problems, and will not be repeatedly reflected and elaborated in this invention.

[0130] Table 2

[0131] <![CDATA[THD I / %]]> 0.3 0.6 0.9 1.2 1.5 1.8 2.4 2.7 3.3 3.6 ΔP / kW 0.8 1.4 2.6 3.9 4.6 5.6 6.8 8.8 13.7 18.4 <![CDATA[C J / ten thousand yuan]]> 3.2 3.8 3.9 4.2 5.4 6.4 9.6 12.9 15.9 19.2

[0132] In this embodiment, the connection point at the PCC is regarded as the connection position between the group users and the power supply side's distribution network. Then, the contribution of each individual user within the group users to the power quality and governance cost at the PCC can be regarded as the corresponding contribution to the power quality and governance cost of the group users. The Taguchi quality assessment theory and cost modeling method applied in this embodiment are mainly applicable to the analysis and modeling of product suppliers with quality differences, and are not applicable to product users. In this embodiment, they are applied to the cost modeling of power product suppliers (i.e., the power supply side) with power quality differences.

[0133] In one embodiment, the contribution of each user with power quality problems to the power quality and governance cost at the point of common coupling (PCC) includes:

[0134] (1) The contribution of users with voltage deviation problems to the power quality and governance cost at the PCC, expressed as:

[0135]

[0136] In Equation (10), Δβ is the change in the voltage deviation at the PCC before and after the occurrence of the voltage deviation problem of each user (i.e., the index exceeding the limit problem, and exceeding the limit means exceeding the voltage deviation index level determined by the user itself. Similar explanations apply to the relevant parts later); β N is the voltage deviation level at the PCC when N users within the group users have voltage deviation problems and need to be governed; β 0 is the voltage deviation level at the PCC when no voltage deviation problems occur among the users within the group users; β i is the voltage deviation level of the i-th user with a voltage deviation problem that needs to be governed; Δβ i is the contribution of the i-th voltage deviation user (also representing each voltage deviation user) to the total voltage deviation at the PCC; ω i is the proportion of the contribution of the i-th user to the change in each power quality index at the PCC to the total change in each power quality index at the PCC; is the contribution of each user to the total governance cost at the PCC; C M is the total governance cost caused by each user's power quality problems at the PCC; is the proportion of the contribution of each user to the governance cost at the PCC to the total governance cost at the PCC;

[0137] Exemplarily, as shown in Table 3, the relevant parameter results of the users with voltage deviation problems at the PCC in Equation (10) are calculated. In this embodiment, it is assumed that there are 4 users with voltage deviation problems in the group users that need to be considered and rectified, and the same assumption is made for the subsequent users with harmonic problems.

[0138] Table 3

[0139]

[0140] (2) The contribution of users with harmonic problems to the power quality and rectification cost at the PCC is expressed as:

[0141]

[0142] In Equation (11), ΔTHD I is the change in harmonics at the PCC before and after the harmonic problems of each user occur; is the harmonic level at the PCC when there are N users with harmonic problems in the group users that need to be rectified; is the harmonic level at the PCC when there are no harmonic problems for each user in the group users; is the harmonic level of the i-th user with harmonic problems that needs to be rectified; is the total harmonic contribution of the i-th user to the PCC;

[0143] Exemplarily, as shown in Table 4, the relevant parameter results of the users with harmonic problems at the PCC in Equation (11) are calculated.

[0144] Table 4

[0145]

[0146] In one embodiment, the aggregation method based on the subjective and objective combined weights to establish the electricity consumption aggregation model of group users includes:

[0147] (1) Obtaining the subjective and objective combined weights, expressed as:

[0148]

[0149] In Equation (12), ω i and are respectively the share ratios of the power quality and the corresponding rectification cost of each user in the total of the group users (i.e., at the PCC); is the duration span of each power quality problem; T is the total time span of the power quality time series of each user;

[0150] (2) Aggregation of users with voltage deviation problems, expressed as:

[0151]

[0152] In Equation (13), C JJ is the total economic cost corresponding to the voltage deviation index of group users. The symbols of the other variables have been explained above and will not be repeated here. Nor will the relevant harmonic indexes be repeated later.

[0153] Exemplarily, as shown in Table 5, based on the subjective and objective combined weights of each user with voltage deviation problems obtained from Equation (12), further according to the electricity aggregation model of the voltage deviation index of group users in Equation (13), the parameter results of the voltage deviation index and the corresponding total economic cost can be calculated.

[0154] Table 5

[0155] β / ％ 0.8 1.4 2.0 2.6 3.2 3.8 4.4 5.0 5.6 6.2 <![CDATA[C JJ / ten thousand yuan]]> 4.2 7.9 10.2 11.4 13.9 16.4 17.2 18.9 21.8 24.8

[0156] (3) Aggregation of users with harmonic problems, expressed as:

[0157]

[0158] In Equation (14), here C JJ is the total economic cost corresponding to the harmonic index of group users;

[0159] Exemplarily, as shown in Table 6, based on the subjective and objective combined weights of each user with harmonic problems obtained from Equation (12), further according to the electricity aggregation model of the harmonic index of group users in Equation (14), the parameter calculation results of the harmonic index and the corresponding total economic cost can be calculated. Further according to Equation (14), the electricity aggregation curve graph corresponding to the harmonic index of group users as shown in Figure 5 can be obtained. From Figure 5 it can clearly show the mutual relationship trend between the harmonic index of group users (measured and represented by the total harmonic distortion rate of harmonic current) and the corresponding total economic cost. Figure 5 The relationship trend characteristics shown in

[0160] Table 6 can also be correspondingly reflected according to certain values. At the same time, it can be seen that the trend characteristics of each user with harmonic problems for aggregation and the display of a certain aggregation process; the electricity aggregation curve graph and analysis corresponding to the voltage deviation index of group users are similar to those of the harmonic index and will not be repeatedly shown and described in this embodiment.

[0161] <![CDATA[THD I / %]]> 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 <![CDATA[C JJ / ten thousand yuan]]> 4.6 5.4 6.2 7.8 8.8 10.8 12.9 14.7 16.2 19.4

[0162] In one embodiment, the establishment of the power supply cost model of the power supply side by applying the Taguchi quality evaluation theory and the cost modeling method includes:

[0163] (1) Cost representation of the Taguchi quality evaluation theory, which is:

[0164]

[0165] In formula (15), is the quantified quality cost loss, with the unit of ¥; χ is the deviation-cost parameter; x i and x are the actual and expected product qualities respectively; σ 2 and are the variance and mean value of the product quality x respectively;

[0166] (2) The relationship model between the voltage deviation index of the power supply side and the total economic cost is expressed as:

[0167]

[0168] In formula (16), C GJ is the total economic cost of the power supply side corresponding to the voltage deviation index; C 1 is the economic cost caused by the equipment; C 2 is the economic compensation cost; C 3 is the user liability compensation income; C 4 is the cost of loss of power sales profit; here, β and β 0 are the final and initial supply voltage deviation index values of the power supply side to the group users respectively, and β 0 is considered as a known fixed value;

[0169] Exemplarily, as shown in Table 7, based on considering various economic costs brought by the voltage deviation problem to the power supply side, the parameters such as the voltage deviation index of the power supply side and the corresponding total economic cost can be calculated using formula (16).

[0170] Table 7

[0171]

[0172] (3) The relationship model between the harmonic index of the power supply side and the total economic cost is expressed as:

[0173]

[0174] In formula (17), here C GJ is the total economic cost of the power supply side corresponding to the harmonic index; THD I and are the final and initial supply harmonic index values of the power supply side to the group users respectively, which are considered as known fixed values.

[0175] Exemplarily, as shown in Table 8, based on considering various economic costs brought by the harmonic problem to the power supply side, the parameters such as the harmonic index of the power supply side and the corresponding total economic cost can be calculated using formula (17), and further, according to formula (17),Figure 6 The power supply cost curve corresponding to the harmonic index of the power supply side shown can clearly show the mutual relationship trend between the harmonic index of the power supply side (measured and represented by the total harmonic distortion rate of harmonic current) and the corresponding total economic cost. Figure 6 The relationship trend characteristics shown can also be reflected according to certain values in Table 8; the power supply cost curve and analysis corresponding to the voltage deviation index of the power supply side are similar to the harmonic index, and will not be repeatedly reflected and elaborated in this embodiment. Figure 6

[0176] Table 8

[0177]

[0178] In one embodiment, the optimal power supply quality of the group user with the lowest total economic cost of both the power supply and power consumption sides is obtained based on the power consumption aggregation model of the group user and the power supply cost model of the power supply side.

[0179] Adding the power consumption aggregation model of the group user corresponding to each power quality index and the power supply cost model of the power supply side gives the relationship model between each power quality index and the comprehensive total economic cost of both the power supply and power consumption sides. According to the obtained model, the values of each power quality index that minimize the comprehensive total economic cost of both the power supply and power consumption sides can be obtained. This power quality index value is the only optimal power supply quality that is optimal for both the total economic cost of the group user and the power supply side.

[0180] Figure 7 Exemplarily, as shown in Table 9, adding Equation (13) and Equation (16) gives the relationship model between the voltage deviation index and the comprehensive total economic cost of both the power supply and power consumption sides. Further, according to this model, Figure 7 the result curve graph of the optimal voltage deviation index of the group user considering both the power supply and power consumption sides shown can clearly show the mutual relationship trend between the comprehensive total economic cost of both the power supply and power consumption sides and the voltage deviation index (measured and represented by the voltage deviation degree). The optimal voltage deviation index of the group user and related parameter values are obtained through analysis. Further, using Table 9 and Figure 7 it can be concluded that the only optimal voltage deviation index value β for the group user is 1.6%. Then, based on the initial voltage deviation index value β 0 supplied by the power supply side to the group user being 3.8%, it can be calculated that the improvement degree E PQ of the voltage deviation index of the group user is 57.9%; when the group user obtains the optimal voltage deviation index value β of 1.6%, the corresponding total economic costs C JJ and C GJ of the group user and the power supply side respectively are 83,000 yuan and 56,000 yuan. Then, at this time, the comprehensive total economic cost C ZJ ​​(The comprehensive total economic cost is C JJ and C GJ The sum of which) is 139,000 yuan. Furthermore, according to the voltage deviation index value β 0 corresponding to the initial supply of the group user by the power supply, the comprehensive total economic cost of both the power supply and the user is 168,000 yuan. It can be calculated that the degree of savings in the comprehensive total economic cost E ZJ of the group user and the power supply is 17.3%.

[0181] Table 9

[0182]

[0183] Exemplarily, as shown in Table 10, by adding Equation (14) and Equation (17), a relationship model between the harmonic index and the comprehensive total economic cost of both the power supply and the user is obtained. Further, based on this model, Figure 8 the curve graph of the optimal harmonic index result of the group user considering both the power supply and the user is obtained as shown. From Figure 8 it can clearly show the mutual relationship trend between the comprehensive total economic cost of both the power supply and the user and the harmonic index (measured and represented by the total harmonic distortion rate of the harmonic current). By analysis, the optimal harmonic index and related parameter values of the group user are obtained. Further, using Table 10 and Figure 8 it can be concluded that the only optimal harmonic index value THD I obtainable by the group user finally is 2.1%. Again, according to the initial harmonic index value supplied by the power supply to the group user, which is 3.2%, it can be calculated that the improvement degree E PQ of the harmonic index of the group user is 34.4%. When the group user obtains the optimal harmonic index value THD I of 2.1%, the respective total economic costs C JJ and C GJ of the group user and the power supply are 88,000 yuan and 61,000 yuan respectively. Then, at this time, the comprehensive total economic cost C ZJ of both the power supply and the user is 149,000 yuan. Furthermore, according to the comprehensive total economic cost corresponding to the initial harmonic index value supplied by the power supply to the group user which is 185,000 yuan, it can be calculated that the degree of savings in the comprehensive total economic cost E ZJ of the group user and the power supply is 19.5%.

[0184] Table 10

[0185]

[0186] In summary, the present invention can ensure that each group user obtains the optimal power supply quality with differentiation while minimizing the total economic cost of the group users and the power supply side.

Claims

1. A method for determining the optimal power supply quality with differentiation for multi-group users, characterized in that: It includes: Obtain the parameters of each group of power users and the distribution network parameters of the power supply side, and establish a relationship model between the power quality loss and electric power of typical power quality indicators with time-period persistence impact based on the load data and power quality data of individual users within the group of power users; The relationship model between the power quality loss and electric power of typical power quality indicators with time-period persistence impact includes: (1) The relationship model between the voltage deviation index and electric power, expressed as: Among them, β is the voltage deviation degree, used to measure the voltage deviation index level; P N0 is the no-load loss of the user's distribution transformer; P and Q are the active power and reactive power of the load; U N is the system rated voltage; R L is the equivalent resistance of the transmission line; R T is the equivalent resistance of the distribution transformer; (2) The relationship model between the harmonic index and electric power, expressed as: Among them, THD I is the total harmonic distortion rate of harmonic current, which is used to measure the harmonic index level; is the harmonic resistance correction coefficient; R T is the fundamental wave equivalent resistance of the transformer; h is the harmonic order; X T is the fundamental wave leakage reactance of the transformer; I 1 is the effective value of the fundamental wave current; p oi is the no-load loss of the i-th distribution transformer; m is the number of distribution transformers in the system; R L is the fundamental wave resistance of the line; X L is the fundamental wave reactance of the line; I A is the effective value of the harmonic current of phase A; I A1 is the effective value of the fundamental wave current of phase A; I B is the effective value of the harmonic current of phase B; I B1 is the effective value of the fundamental wave current of phase B; I C is the effective value of the harmonic current of phase C; I C1 is the effective value of the fundamental wave current of phase C; Apply the governance strategy of the power quality time series feature pattern, and establish the power quality cost model of each power quality problem user based on the "relationship model between each power quality indicator and electric power" and the "relationship model between the total economic cost of each power quality indicator and electric power"; The power quality cost model of each power quality problem user includes: (1) The power quality cost model of users with voltage deviation problems, expressed as: Among them, C J is the total economic cost corresponding to the voltage deviation index; C p is the profit loss caused by production reduction; C s is the equipment life loss; C o is the loss of defective products produced; C c is the initial investment cost included in the power quality governance cost, including the purchase price of equipment, labor costs, transportation and installation costs, inspection and calibration costs of equipment; C y is the operation and maintenance cost included in the power quality governance cost, including annual power consumption costs, manual inspection and maintenance costs, equipment repair and component replacement costs; R 0 is the standard electricity charge; T is the life cycle of being put into operation; λ i is the electricity charge ratio in different power factor intervals; P i is the active power of the load at different power factors; (2) The power quality cost model of users with harmonic problems, expressed as: Among them, C here J is the total economic cost corresponding to the harmonic index; K W is the current unit electricity cost; Considering the contribution of each power quality problem user to the power quality and governance cost at the point of common coupling (PCC), establish a power consumption aggregation model for group users based on the aggregation method of subjective and objective combined weights; Apply the Taguchi quality evaluation theory and cost modeling method to establish the power supply cost model of the power supply side; The establishment of the power consumption aggregation model for group users based on the aggregation method of subjective and objective combined weights includes: (1) Obtaining the subjective and objective combined weights, expressed as: Among them, ω i and respectively represent the share of each user's power quality and the corresponding governance cost in the overall group of users, i.e., at the PCC; represents the duration span of each power quality problem; T represents the total time span of the power quality time series of each user. (2) Aggregation of users with voltage deviation problems, expressed as: Among them, C JJ is the total economic cost corresponding to the voltage deviation index of group users; (3) Aggregation of users with harmonic problems, expressed as: Among them, C here JJ is the total economic cost corresponding to the harmonic index of group users; The establishment of the power supply cost model of the power supply side by applying the Taguchi quality evaluation theory and cost modeling method includes: (1) The cost representation of the Taguchi quality evaluation theory, which is: Among them, is the quantified quality cost loss, with the unit of ¥; χ is the deviation-cost parameter; x i and x are the actual and expected product quality respectively; σ 2 and are the variance and mean value of the product quality x respectively; (2) The relationship model between the voltage deviation index of the power supply side and the total economic cost, expressed as: Among them, C GJ is the total economic cost of the power supply side corresponding to the voltage deviation index; C 1 is the economic cost caused by the equipment; C 2 is the economic compensation cost; C 3 is the compensation income for user liability; C 4 is the cost of loss of power sales profit; here, β and β 0 are respectively the final and initial supply voltage deviation index values of the power supply side to the group users, and β 0 is considered as a known fixed value; (3) The relationship model between the harmonic index of the power supply side and the total economic cost, expressed as: Among them, C here GJ is the total economic cost of the power supply side corresponding to the harmonic index; THD I and THD I0 are the final and initial harmonic index values supplied by the power supply side to the group users respectively, and THD I0 is considered as a known fixed value; Finally, based on the power consumption aggregation model of group users and the power supply cost model of the power supply side, obtain the optimal power supply quality of group users that comprehensively considers the total economic cost of both power supply and consumption parties.

2. A method for determining the optimal power supply quality with differentiation for multi-group users according to claim 1, characterized in that: The parameters of each group of power users include the load data, power quality data, and power consumption cost data of individual users within it; The description of the power quality data refers to both the voltage deviation index and the harmonic index; The distribution network parameters of the power supply side include power supply quality data and power supply cost data.

3. A method for determining the optimal power supply quality with differentiation for multi-group users according to claim 1, characterized in that: The extraction and pattern representation of the power quality time series features include: The selection and representation of key trend turning points, the piecewise linear representation of the power quality time series, and the feature matrix representation of the power quality time series feature pattern; (1) The selection and representation of key trend turning points of the power quality time series, which is: where x i-1 and x i+1 are two adjacent monitoring data in the power quality time series with respect to ; d v and d h are conditional expressions in terms of numerical value and time dimension in the horizontal and vertical distances, respectively. (2) Using the least squares fitting method to perform piecewise linear representation on the power quality time series, which is: Among them, k m is the fitting slope of the array in the m-th sequence segment, representing the local trend feature of the power quality time series; b m is the fitting intercept of the array in the m-th sequence segment; M is the number of segments of the power quality time series; s m is the time span of the power quality time series segment; t l and t 1 are the end time point and the start time point of the m-th power quality time series segment respectively; (3) The pattern features of the power quality time series are represented in the form of a feature matrix as follows: [(k 1 , s 1 )(k 2 , s 2 )…(k M , s M )]。 4. A method for determining the optimal power quality of differential power supply for multiple group users according to claim 1, characterized in that: The governance strategies for each power quality problem based on the power quality time series include: (1) The governance strategy for the voltage deviation problem based on the power quality time series, expressed as: Among them, and are the average voltage deviation degrees of each problem time period after and before the treatment of the over-limit time period of the power quality time series respectively; is the average voltage deviation degree of the power quality time series time period without over-limit problems of other voltage deviation indicators; and are the average voltage deviation degrees of the entire time period after and before the treatment of the voltage deviation over-limit time period respectively; β and β here 0 are the index levels after and before the treatment of users with voltage deviation problems respectively; E PQ is an improvement index to measure the power quality indicators of the entire time period of the power quality time series after the treatment of each power quality over-limit time period relative to before the treatment; (2) The governance strategy for the harmonic problem based on the power quality time series, expressed as: Among them, and are respectively the average current total harmonic distortion rates of each problem time period after and before the treatment of the out-of-limit time period of the power quality time series; and are respectively the average current total harmonic distortion rates of the entire time period after and before the treatment of the harmonic out-of-limit time period; THD I and are respectively the index levels after and before the treatment of harmonic problem users.

5. A method for determining the optimal power quality of differential power supply for multiple group users according to claim 1, characterized in that: The contributions of each power quality problem user to the power quality and governance cost at the point of common coupling (PCC) include: (1) The contribution of the voltage deviation problem user to the power quality and governance cost at the PCC, expressed as: Among them, Δβ is the voltage deviation problem of each user, that is, the problem of index exceeding the limit. The limit exceeding means exceeding the voltage deviation index level determined by the user itself, and it is the change in the voltage deviation at the PCC before and after the occurrence; β N is the voltage deviation level at the PCC when there are N users with voltage deviation problems in the group user and need to be rectified; β 0 is the voltage deviation level at the PCC when there are no voltage deviation problems for each user in the group user; β i is the voltage deviation level of the i-th user with a voltage deviation problem and needs to be rectified; Δβ i is the i-th voltage deviation user, and it also represents the contribution of each voltage deviation user to the total voltage deviation at the PCC; ω i is the proportion of the contribution of the i-th user to the change in each power quality index at the PCC to the total change in each power quality index at the PCC; C Mi is the contribution of each user to the total rectification cost at the PCC; C M is the total rectification cost caused by each user's power quality problems at the PCC; is the proportion of the contribution of each user to the rectification cost at the PCC to the total rectification cost at the PCC; (2) The contribution of the harmonic problem user to the power quality and governance cost at the PCC, expressed as: Among them, ΔTHD I is the harmonic variation at the PCC before and after the harmonic problems of each user occur; is the harmonic level at the PCC when there are N users with harmonic problems in the group users and need to be rectified; is the harmonic level at the PCC when there are no harmonic problems for each user in the group users; is the level of the i-th user with harmonic problems and needs to be rectified; is the total harmonic contribution of the i-th user to the PCC.

6. A method for determining the optimal power quality of differential power supply for multiple group users according to claim 1, characterized in that: The optimal power supply quality of the group users that comprehensively considers the total economic cost of both the power supply and consumption sides is obtained based on the power consumption aggregation model of the group users and the power supply cost model of the power supply side; Adding the power consumption aggregation model of the group users corresponding to each power quality index and the power supply cost model of the power supply side gives the relationship model between each power quality index and the comprehensive total economic cost of both the power supply and consumption sides; according to the model obtained above, the values of each power quality index that minimize the comprehensive total economic cost of both the power supply and consumption sides are obtained, and this power quality index value is the final and only optimal power supply quality obtained by the group users, which is optimal for both the total economic cost of the group users and the power supply side.

Images