Power distribution network cooperative voltage regulation method and system considering transformer area overvoltage responsibility and regulation fairness

Abstract

The invention discloses a power distribution network cooperative voltage regulation method and system considering transformer area overvoltage responsibility and regulation fairness. The method comprises the following steps: establishing a regulation and control model of a transformer area power regulation domain, a photovoltaic inverter and a reactive capacitor bank; dividing overvoltage responsibilities to be borne by voltage out-of-limit caused by the transformer area, measuring technical overvoltage responsibilities of the transformer area by utilizing a voltage sensitivity matrix and a power transmission distribution factor, and measuring economical overvoltage responsibilities of the transformer area by utilizing photovoltaic reverse transmission quantity; the technical overvoltage responsibility and the economical overvoltage responsibility are averaged to obtain the overvoltage responsibility coefficient of each transformer area; the responsibility coefficient is introduced into a voltage regulation optimization model, and reactive compensation equipment and a transformer area regulation and control strategy are obtained by taking minimization of the transformer area active regulation quantity as an optimization target; according to the method, the transformer area adjusting tasks can be distributed fairly while the voltage qualification rate is ensured, and the fairness and flexibility of voltage adjustment of the power distribution network are improved.

Description

Technical Field

[0001] The present invention relates to the technology of regulating the voltage of a distribution network, and particularly to a method and system for collaborative voltage regulation of a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation. Background Art

[0002] The high proportion of distributed photovoltaic power access, especially in medium and low voltage distribution networks, has significantly changed the power flow distribution and voltage characteristics of traditional distribution networks. Due to the significant intermittency and volatility of photovoltaic power generation, under the condition of high penetration rate, the problem of supply-demand imbalance between the power source and load has become more prominent, and the voltage over-limit caused by reverse power flow has become the core problem in the operation of medium and low voltage distribution networks, seriously threatening the safe and reliable operation of the distribution network.

[0003] Traditional voltage regulation methods mainly rely on technologies such as reactive power regulation, on-load tap-changing transformers, and network reconfiguration. However, these traditional methods have problems such as slow response and significant losses, and can no longer meet the voltage regulation requirements. The current large emergence of source-load resources such as distributed photovoltaic power, energy storage, electric vehicles, and air conditioners on the substation area side makes the substation area a natural load aggregator, and the substation area can effectively assist the superior power grid in voltage regulation by using internal flexible resources.

[0004] The current technologies for multiple substation areas to assist the superior power grid in voltage regulation still aim at economy or minimum voltage deviation, and are global optimizations based on active power voltage sensitivity analysis. Due to the differences in topological location and power demand, the active power voltage sensitivities of substation areas are different and uncontrollable. In the existing voltage regulation technologies, the substation areas with higher sensitivities often undertake more regulation tasks, and this distribution method violates the fairness principle and damages the enthusiasm of substation areas to participate in regulation. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a method and system for collaborative voltage regulation of a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation. It realizes the quantification of the overvoltage responsibility for the voltage over-limit caused by the reverse power flow of photovoltaic power in the substation area, and assigns corresponding regulation tasks according to the voltage over-limit responsibility to be borne by each substation area, ensuring the fairness of the substation area's participation in the voltage regulation of the distribution network.

[0006] In order to achieve the above invention purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, a method for collaborative voltage regulation of a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation includes the following steps:

[0008] Establish a regulation model for the power regulation domain of the substation area, photovoltaic inverters, and reactive power capacitor banks;

[0009] The overvoltage responsibilities caused by voltage violation due to substation area division include technical overvoltage responsibility and economic overvoltage responsibility. The technical overvoltage responsibility of the substation area is measured by using the voltage sensitivity matrix and the power transfer distribution factor, and the influence weights of the reverse power flow of the substation area photovoltaic on the overall line voltage and the influence weights of the reverse power flow of the substation area photovoltaic on the key node voltage are obtained; the economic overvoltage responsibility of the substation area is measured by using the reverse power flow of the photovoltaic, and the influence weight of the reverse power flow behavior of the substation area photovoltaic on causing voltage violation is obtained.

[0010] The average value of the influence weight of the reverse power flow of the substation area photovoltaic on the overall line voltage, the influence weight of the reverse power flow of the substation area photovoltaic on the key node voltage, and the influence weight of the reverse power flow behavior of the substation area photovoltaic on causing voltage violation is obtained to get the overvoltage responsibility coefficient of each substation area.

[0011] The overvoltage responsibility coefficient of the substation area is introduced into the voltage regulation optimization model. The voltage regulation optimization model takes minimizing the active power regulation amount of the substation area as the optimization goal, and under the constraints of the substation area power regulation domain, the reactive capacitor bank, the photovoltaic inverter, and the power flow, the voltage regulation optimization model is solved to obtain the reactive power equipment and the substation area control strategy.

[0012] Furthermore, the substation area power regulation domain model is specifically:

[0013]

[0014] In the formula, Ω B is the substation area flexibility regulation domain; P grid is the substation area operating power, is the equivalent electricity quantity of the substation area at time t; P t grid and respectively represent the minimum and maximum operating powers of the substation area at time t; and respectively represent the minimum and maximum equivalent electricity quantities of the substation area at time t; Δt is the regulation time interval.

[0015] Furthermore, the control model of the photovoltaic inverter is specifically:

[0016]

[0017] In the formula, is the reactive power output power of the photovoltaic inverter, is the maximum reactive power output power of the photovoltaic at time t, which is obtained based on the photovoltaic inverter capacity and the predicted value of the active power output obtained.

[0018] Furthermore, the control model of the reactive capacitor bank is specifically:

[0019]

[0020] In the formula, is the reactive power output of the capacitor bank, is the rated reactive power output of a single capacitor, is the number of capacitor switching in the t period, is the maximum number of capacitor switching of the capacitor at node i, and T is the total number of periods, is the upper limit of the maximum number of capacitor switching at node i during the day-ahead scheduling period.

[0021] Furthermore, the voltage sensitivity matrix is used to measure the responsibility of technical overvoltage in the distribution area, and the influence weight of PV reverse power flow in the distribution area on the voltage of key nodes is obtained. Specifically:

[0022] Using the voltage sensitivity matrix to measure the influence of the power fed into the distribution area on the node voltage amplitude:

[0023]

[0024] In the formula, S U-P is the active voltage sensitivity matrix; S U-Q is the reactive voltage sensitivity matrix; G and B are the real and imaginary parts of the node admittance matrix respectively, which are determined by the network topology; P and Q are the active and reactive power injections at the nodes; ΔP and ΔQ are the change vectors of the active and reactive power injections at the nodes respectively; ΔU is the node voltage change vector;

[0025] Using the analytic hierarchy process to calculate the ranking of the influence of PV reverse power flow in each distribution area on the node voltage, and obtaining the influence weight of PV reverse power flow in the distribution area on the voltage of key nodes.

[0026] Furthermore, the power transfer distribution factor is used to measure the responsibility of technical overvoltage in the distribution area, and the influence weight of PV reverse power flow in the distribution area on the voltage of the whole line is obtained. Specifically:

[0027] Using the power transfer distribution factor to measure the influence of the power fed into the distribution area on the power flow of the whole line:

[0028]

[0029] In the formula, P node is the active power injection at the node; B x is the node susceptance matrix; θ is the voltage phase angle; P line is the active power flowing through the line; B line is the line-node susceptance matrix; S ptdf is the power transfer distribution factor matrix, with the dimension of the number of branches × the number of nodes;

[0030] Using the analytic hierarchy process to calculate the ranking of the influence of PV reverse power flow in each distribution area on the line power flow, and obtaining the influence weight of the distribution area on the voltage of the whole line.

[0031] Further, the economic over-voltage responsibility of the substation area is measured by the reverse power injection of photovoltaic power, and the economic over-voltage responsibility weight of the substation area for photovoltaic reverse power injection is obtained, specifically as follows:

[0032]

[0033] In the formula, is the economic over-voltage responsibility weight vector of the i-th substation area for photovoltaic reverse power injection; P i export is the reverse power injection of the i-th substation area for photovoltaic power, is the total reverse power injection of photovoltaic power of K substation areas.

[0034] Further, the distribution network voltage regulation model introducing the over-voltage responsibility coefficient of the substation area is expressed as:

[0035]

[0036] In the formula, minf represents the objective function of minimizing the active power regulation amount of the substation area, and Ω n is the set of substation area nodes; is the interactive power between the i-th substation area and the superior power grid after regulation at time t; is the interactive power between the i-th substation area and the superior power grid without regulation at time t; w i,t is the over-voltage responsibility coefficient of the i-th substation area at time t, and T is the total number of time periods;

[0037] The optimization model constraints include: substation area power regulation range constraints, reactive capacitor bank regulation constraints, photovoltaic inverter regulation constraints, and power flow constraints:

[0038]

[0039] In the formula, P ij,t and Q ij,t are the active and reactive powers flowing through branch ij respectively; u(j) and v(j) are the sets of the parent node and child node of node j respectively; P j,t and Q j,t are the active and reactive powers injected into node j respectively; and are the load of node j, the interactive power between the substation area and the superior power grid, and the active power of distributed photovoltaic injected into node j respectively; and are the reactive load of node j, the reactive power of photovoltaic inverter and capacitor bank injected into node j respectively; V min and V max are the upper and lower limits of the node voltage respectively; is the maximum apparent power allowed to flow through branch ij; V0 is the voltage amplitude of the balanced node; rij and x ij are the resistance and reactance of branch ij respectively.

[0040] In a second aspect, a coordinated voltage regulation system for a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation includes:

[0041] An active and reactive power regulation model construction module for establishing regulation models for the power regulation range of the substation area, photovoltaic inverters, and reactive capacitor banks;

[0042] An overvoltage responsibility division and weight calculation module for dividing the overvoltage responsibilities borne by all substation areas causing voltage overlimits into technical overvoltage responsibilities and economic overvoltage responsibilities, using the voltage sensitivity matrix and power transfer distribution factors to measure the technical overvoltage responsibilities of the substation areas, obtaining the influence weights of photovoltaic reverse power flow in the substation area on the overall line voltage and the influence weights of photovoltaic reverse power flow in the substation area on the key node voltage; using the photovoltaic reverse power flow volume to measure the economic overvoltage responsibilities of the substation areas, obtaining the influence weights of the photovoltaic reverse power flow behavior in the substation area on causing voltage overlimits

[0043] An overvoltage responsibility coefficient calculation module for averaging the influence weights of photovoltaic reverse power flow in the substation area on the overall line voltage, the influence weights of photovoltaic reverse power flow in the substation area on the key node voltage, and the influence weights of the photovoltaic reverse power flow behavior in the substation area on causing voltage overlimits to obtain the overvoltage responsibility coefficient of each substation area;

[0044] A voltage regulation optimization module for introducing the overvoltage responsibility coefficient of the substation area into the voltage regulation optimization model and solving the model. The voltage regulation optimization model takes minimizing the active power regulation amount of the substation area as the optimization goal, and under the constraints of the power regulation range of the substation area, reactive capacitor bank constraints, photovoltaic inverter constraints, and power flow constraints, solves the voltage regulation optimization model to obtain reactive power equipment and substation area regulation strategies.

[0045] In a third aspect, the present invention also provides a computer device, including: one or more processors; a memory; and one or more programs, where the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and when the program is executed by the processor, it implements the coordinated voltage regulation method for a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation as described in the first aspect.

[0046] In a fourth aspect, the present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the coordinated voltage regulation method for a distribution network considering the overvoltage responsibility of a substation area and the fairness of regulation as described in the first aspect.

[0047] Compared with the prior art, the present invention has the following beneficial effects: dividing the overvoltage responsibility for voltage overlimit caused by each substation area and calculating the overvoltage responsibility coefficient, introducing the overvoltage responsibility coefficient of the substation area into the active-reactive coordinated voltage regulation model of the distribution network, and allocating corresponding regulation tasks for each substation area according to the voltage overlimit responsibility to be borne, so as to ensure the fairness of the substation area participating in the voltage regulation of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flowchart of a coordinated voltage regulation method for a distribution network considering the overvoltage responsibility and regulation fairness of a substation area provided by an embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the structure of a distribution network provided by an embodiment of the present invention;

[0050] Figure 3 It is a diagram of the interactive power between a substation area and a superior power grid without regulation provided by an embodiment of the present invention;

[0051] Figure 4 It is a power regulation domain diagram of four substation areas provided by an embodiment of the present invention;

[0052] Figure 5 It is a predicted photovoltaic power output diagram provided by an embodiment of the present invention;

[0053] Figure 6 It is a 24-hour voltage curve diagram without regulation provided by an embodiment of the present invention;

[0054] Figure 7 It is a 24-hour voltage curve diagram after regulation provided by an embodiment of the present invention;

[0055] Figure 8 It is an optimized result diagram of reactive power capacitors provided by an embodiment of the present invention;

[0056] Figure 9 It is the power regulation amount of a substation area provided by an embodiment of the present invention;

[0057] Figure 10 It is a schematic diagram of the structure of the distribution network after position adjustment provided by an embodiment of the present invention;

[0058] Figure 11 It is a 24-hour voltage curve diagram without regulation after position adjustment provided by an embodiment of the present invention;

[0059] Figure 12 It is the power regulation amount of the substation area after position adjustment provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0060] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings.

[0061] An embodiment of the present invention provides a coordinated voltage regulation method for a distribution network considering the responsibility of overvoltage in a substation area and the fairness of regulation. Referring to Figure 1 , the method includes the following steps:

[0062] S1. Establish a regulation model for the power regulation domain of the substation area, photovoltaic inverters, and reactive capacitor banks;

[0063] Among them, the power regulation domain model of the substation area is specifically:

[0064] The adjustable domains of all flexible resources in the substation area can be regarded as a high-dimensional polyhedron, expressed as:

[0065] Ω1 = {[x, P grid T | Ex ≤ f, P grid = Cx + d}

[0066] In the formula, x is the state variable in the high-dimensional space, which is composed of the power decision variables of flexible resources in different time periods in the substation area; E and f are the constant matrix and vector that constitute the operation constraint parameters of these flexible resources; P grid is the variable in the low-dimensional space, which is composed of the interactive power between the substation area and the superior power grid in different time periods; C and d are respectively the constant matrix and vector that constitute the power balance constraint parameters, representing the linear mapping parameters from the high-dimensional state x to the interactive power.

[0067] The above adjustable domain Ω1 describes the possible operating states of all adjustable flexible resources. By projecting the high-dimensional region Ω1 onto the substation area dimension, the low-dimensional power regulation domain is obtained:

[0068] Ω2 = {P grid | dP grid ≤ g}

[0069] In the formula, d is the linear constraint matrix in the low-dimensional space, which describes the boundary direction of the polyhedron after projection; g is the right-hand term vector in the low-dimensional space, which describes the boundary position of the polyhedron in each direction; they define the interactive power region between the substation area and the superior power grid at the point of common coupling. Therefore, the essence of solving the power regulation domain of the substation area is to obtain the description in the low-dimensional space, that is, (d, g), from the constraints in the high-dimensional space through projection and elimination.

[0070] The above formula describes the power flexibility region of each time period in the substation area, which is a static regulation domain that only considers the power limit at the current moment and has not introduced the time coupling characteristic. For this reason, the flexibility regulation domain of the substation area can be approximated as an equivalent energy storage model:

[0071]

[0072] In the formula, P t grid 、​ It is the flexibility adjustment parameter for the substation area.

[0073] The flexibility adjustment parameter is obtained by using an iterative method. The principle is to make Ω as large as possible on the premise of satisfying Ω B ∈Ω1. The first iteration: B The area is larger. The first iteration:

[0074]

[0075] In the formula, and are the adjustment parameters obtained from the first iteration respectively, and can be obtained by solving the minimization optimization problem.

[0076] After obtaining the initial parameters and based on the boundary contraction method of the polyhedron, the parameters of are gradually adjusted during the iteration process to make it continuously contract and cover all infeasible points, and finally satisfy

[0077] The specific photovoltaic inverter regulation model is as follows:

[0078]

[0079] In the formula, is the reactive power output power of the photovoltaic inverter at time t, is the maximum reactive power output power of the photovoltaic at time t, which is obtained based on the capacity of the photovoltaic inverter and the predicted value of the active power output is obtained.

[0080] The specific regulation model of the reactive power capacitor bank is as follows:

[0081]

[0082] In the formula, is the reactive power output power of the capacitor bank, is the rated reactive power output of a single capacitor, is the number of capacitor switching operations at time t, is the maximum number of capacitor switching operations of the capacitor at node i, is the upper limit of the maximum number of capacitor switching operations at each node within the day-ahead scheduling period.

[0083] S2. Divide the overvoltage responsibilities borne by all voltage violations caused by reverse power flow of photovoltaic power in the substation area, and use the voltage sensitivity matrix and power transfer distribution factor to measure the technical overvoltage responsibilities in the substation area;

[0084] Among them, using the power transfer distribution factor to measure the responsibility of technical overvoltage in the substation area is specifically as follows: using the power transfer distribution factor to measure the impact of the feed-in power in the substation area on the power flow of the entire line, which is expressed as:

[0085]

[0086] In the formula, P node is the active power injected into the node; B x is the nodal susceptance matrix; θ is the voltage phase angle; P line is the active power flowing through the line; B line is the line-node susceptance matrix; S ptdf is the power transfer distribution factor matrix, also known as the PTDF (Power Transfer Distribution Factor) matrix, with a dimension of the number of branches × the number of nodes. B line and B x are known parameters of the feeder, and S is calculated according to ptdf , P node is the active power injected into the node. When P node is known, using P node and S ptdf , P line can be obtained.

[0087] Using the voltage sensitivity matrix to measure the responsibility of technical overvoltage in the substation area is specifically as follows: using the voltage sensitivity matrix to measure the impact of the reverse power flow of photovoltaic power fed into the substation area on the node voltage amplitude, which is expressed as:

[0088]

[0089] In the formula, S U-P is the active voltage sensitivity matrix; S U-Q is the reactive voltage sensitivity matrix; G and B are the real part (conductance) and imaginary part (susceptance) of the nodal admittance matrix, respectively, which are determined by the network topology; P and Q are the active and reactive power injected into the node. ΔP and ΔQ are the change vectors of the active / reactive power injection at the node; ΔU is the change vector of the node voltage.

[0090] Using the analytic hierarchy process to calculate the above two parts of the technical overvoltage responsibility coefficients in the substation area, that is, the influence weight of the reverse power flow of photovoltaic power in the substation area on the overall line voltage and the influence weight of the reverse power flow of photovoltaic power in the substation area on the key node voltage. The specific steps are as follows:

[0091] 1) Calculate the comprehensive impact of the reverse power flow of photovoltaic power in the substation area

[0092] Each column of the PTDF matrix represents the impact of the reverse power flow of photovoltaic power in each substation area on the power flow of different branches. To calculate the comprehensive impact of each substation area, sum the PTDF matrix by column:

[0093]

[0094] Wherein, I k is the comprehensive influence of the k-th power distribution area; is the influence degree of the k-th power distribution area on l branches.

[0095] 2) Construct a judgment matrix

[0096] According to the comprehensive influence value I k of the k-th power distribution area, construct a judgment matrix A for pairwise comparison. The element a ij in the judgment matrix represents the relative importance of the photovoltaic reverse power transmission between the i-th power distribution area and the j-th power distribution area:

[0097]

[0098] Wherein, if I i > I j , then a ij > 1, and there is a ij = 1 / a ji , and the elements on the diagonal are 1, that is, a ii = 1.

[0099] 3) Normalize the judgment matrix

[0100] Perform a normalization operation on the judgment matrix A:

[0101]

[0102] Wherein, n ij is the element of the normalized judgment matrix.

[0103] 4) Calculate the weight vector

[0104] Calculate the average value of each row of the normalized matrix N to obtain the weight of each power distribution area. The i-th element w i of the weight vector w is the average value of the i-th row:

[0105]

[0106] Wherein, is the weight of the i-th power distribution area, indicating the influence degree of the i-th power distribution area on the line power flow, that is, the overvoltage responsibility coefficient of the i-th power distribution area.

[0107] 5) Consistency check

[0108] To ensure the consistency of the judgment matrix, it is necessary to calculate the consistency index CI and the consistency ratio CR.

[0109] Calculate the maximum eigenvalue λ max:

[0110]

[0111] where rowsum i is the sum of each row of the judgment matrix.

[0112] Calculate the consistency index CI:

[0113]

[0114] Calculate the consistency ratio CR:

[0115]

[0116] where RI is the random consistency index and can be obtained by looking up the table.

[0117] If the consistency ratio CR is less than 0.1, generally, the consistency of the matrix can be considered acceptable, that is, the judgment matrix is reasonable; if it is greater than 0.1, it indicates that there are significant inconsistencies in the judgment matrix and the judgment matrix needs to be revised.

[0118] Similarly, the calculation method of the weight vector of the impact of PV reverse power injection in the i-th substation area on the node voltage is the same. It will not be elaborated here.

[0119] S3. Measure the economic overvoltage responsibility of the substation area using the PV reverse power injection;

[0120] Among them, the calculation method of the economic overvoltage responsibility of the substation area is specifically:

[0121]

[0122] where is the weight vector of the economic overvoltage responsibility of PV reverse power injection in the i-th substation area; P i export is the PV reverse power injection in the i-th substation area. is the total PV reverse power injection of K substation areas.

[0123] S4. Average the technical and economic overvoltage responsibilities to obtain the overvoltage responsibility coefficient of each substation area;

[0124] Among them, the calculation method of the overvoltage responsibility coefficient of each substation area is specifically:

[0125]

[0126] S5. Introduce the responsibility coefficient into the voltage regulation optimization model, and take minimizing the active power regulation amount of the substation area as the optimization goal to obtain the reactive power equipment and the substation area control strategy;

[0127] Among them, the modeling method of the distribution network voltage regulation model is specifically as follows:

[0128] The objective function is to minimize the regulation cost of the substation area:

[0129]

[0130] In the formula, Ω n is the set of substation area nodes; is the interactive power between the i-th substation area and the superior power grid after regulation at time t; is the interactive power between the i-th substation area and the superior power grid without regulation at time t; w i,t is the overvoltage responsibility coefficient of the i-th substation area at time t.

[0131] The constraint conditions of the optimization model include the regulation constraints of the reactive power capacitor bank, the regulation constraints of the photovoltaic inverter, the regulation constraints of the flexibility regulation domain of the substation area (these constraints refer to the constraints on their capacity, switching times and other indicators when establishing the regulation models of the photovoltaic inverter and the reactive power capacitor bank in step S1, and the regulation of them needs to meet the equality and inequality constraints shown in the formula), and the following network power flow constraints:

[0132]

[0133] In the formula: P ij,t and Q ij,t are the active / reactive power flowing through branch ij respectively; u(j) and v(j) are the sets of the parent node and the child node of node j respectively; P j,t and Q j,t are the active / reactive power injected into node j respectively; and are the load of node j, the interactive power between the substation area and the superior power grid, and the active power of the distributed photovoltaic injected into node j respectively; and are the reactive power load of node j, the reactive power of the photovoltaic inverter and the capacitor bank injected into node j respectively; V min and V max are the upper and lower limits of the node voltage respectively; is the maximum apparent power allowed to flow through branch ij. V0 is the voltage amplitude of the balancing node; r ij and x ij are the resistance and reactance of branch ij respectively.

[0134] To enable those skilled in the art to better understand the present invention, the following will be further elaborated with specific examples.

[0135] The topology of the distribution network is as Figure 2 shown, nodes 4, 16, 24 and 33 are substation area nodes, and the power adjustable domain is shown in Figure 3As shown, the power exchanged with the superior power grid without regulation is shown in Figure 4 As shown. Capacitor banks are installed at nodes 15 and 31. The unit capacity of the capacitor at each node is 80 kVar, the maximum switching number per unit time is 4, and the maximum adjustment times of the capacitor at each node throughout the day is 5 times. Distributed photovoltaics are connected to nodes 7, 12, 17, and 30, and the power is shown in Figure 5 As shown. The rated capacity of the photovoltaic inverter is 1.5 MVA. The allowable voltage range of the node is [0.93, 1.07] p.u.

[0136] Substitute the distributed photovoltaic output and the load data of the distribution area into the 33-node model for power flow calculation to obtain the node voltage change curve for 24 hours, as shown in Figure 6 . It can be seen from the figure that there are obvious voltage over-limit problems in this feeder, mainly manifested as significant characteristics in the spatial and temporal distribution. In terms of temporal distribution, the phenomenon of voltage exceeding the upper limit is concentrated in the time period from 11:00 to 14:00, which corresponds to the peak period of photovoltaic reverse power transmission. Especially at 13:00 at noon, the over-limit is the most serious; the voltage falling below the lower limit is concentrated in two time periods: 00:00 - 03:00 and 19:00 - 23:00. In these two time periods, the basic load of some distribution areas is relatively high, and the distributed photovoltaics do not generate power. In terms of spatial distribution, the situation of exceeding the upper limit is mainly concentrated in nodes 9 - 18 and nodes 27 - 33. These nodes are distributed in areas where photovoltaic reverse power transmission is relatively concentrated or located in the end area of the network, and the voltage sensitivity is relatively high; the situation of falling below the lower limit is mainly concentrated in the end nodes 14 - 18 and 30 - 33 that are far from the power source.

[0137] Select 12:00 and 13:00 as the case analysis times, substitute the power exchanged between the distribution area and the superior power grid and the topology data into the overvoltage responsibility coefficient calculation model, and calculate the overvoltage responsibility coefficients of the four distribution areas, as shown in Tables 1 and 2.

[0138] Table 1 Overvoltage responsibility coefficients of the distribution area at 12:00

[0139]

[0140] Table 2 Overvoltage responsibility coefficients of the distribution area at 13:00

[0141]

[0142] It can be seen from Table 1 that the overvoltage responsibility coefficients at 12:00 from large to small are: distribution areas 16, 33, 4, and 24. In terms of the economic overvoltage responsibility, since the photovoltaic reverse power transmission amounts of distribution areas 16 and 24 are relatively large, so w export is relatively large, while the opposite is true for distribution areas 4 and 33. In terms of the technical overvoltage responsibility, distribution area 4 is located in the area of the main line close to the balanced node, w ptdf is relatively large, wvsm is small, indicating that its reverse power has a significant indirect impact on the voltages of other nodes and a relatively low direct impact. Substations 24 and 33 are located at the ends of the main lines, and w vsm is significantly higher than w ptdf . As the most terminal node, substation 33 has w vsm higher, but w ptdf is lower, showing a significant impact of the reverse power of the terminal node on local voltage violation.

[0143] It can be seen from Table 2 that the overvoltage responsibility coefficients at 13:00 are, in descending order: substations 16, 24, 33, 4. The w ptdf is the same for both periods. The change in overvoltage responsibility is due to the changes in w vsm and w export caused by power changes. Compared with the 12:00 period, the overvoltage responsibility of substation 24 has increased significantly, mainly due to the increase in w export ; the overvoltage responsibilities of substations 33 and 4 have decreased, mainly due to the decrease in w vsm .

[0144] Calculate the overvoltage responsibility coefficients of all substations at all times and substitute them into the voltage regulation strategy model to obtain the three-dimensional voltage map after regulation, as shown in Figure 7 . It can be seen that the voltages of all nodes do not exceed the limit within 24 hours after regulation.

[0145] The optimization results of the reactive power capacitor banks are shown in Figure 8 . It can be seen from the figure that within the 24-hour time interval, the capacitor banks of each node are switched on and off in different periods. The node voltages are adjusted through reactive power compensation, and on the premise of ensuring voltage stability, the switching times are controlled to not exceed 5 times a day to reduce equipment losses and operating frequencies. In multiple periods from 0:00 to 9:00 and 18:00 to 23:00, the capacitor banks deployed at two nodes are put into operation to prevent the node voltages from falling below the lower limit and ensure power supply quality. While from 9:00 to 18:00, due to the PV output, the overall voltage level rises and the system reactive power demand decreases, so there is no need to put the capacitor banks into operation at this time.

[0146] The optimization results of the PV inverter reactive power are shown in Table 3.

[0147] Table 3 Optimization Results of PV Inverter Reactive Power (Unit: MVar)

[0148]

[0149]

[0150] As can be seen from Table 3, the PV inverter provides capacitive reactive power during the periods of 0:00 - 10:00 and 16:00 - 23:00, raising the feeder voltage; while it provides inductive reactive power during the period of 11:00 - 15:00, reducing the feeder voltage. In addition, when the PV output is zero, the inverter operates as a static synchronous compensator, and all its capacity is used to provide reactive power support.

[0151] The active power regulation amounts of the four substations are shown in Figure 9 , and as can be seen from the figure, the active power regulation of the four substations mainly focuses on the periods of 0:00 - 3:00, 10:00 - 15:00, and 20:00 - 23:00. Among them, during the periods of 0:00 - 3:00 and 20:00 - 23:00, since the node voltage is lower than the lower limit, the substation reduces the interaction power to assist the capacitor bank and the PV inverter in raising the voltage; during the period of 10:00 - 15:00, since the node voltage is higher than the upper limit, the substation increases the interaction power to absorb more PV output and assist the PV inverter in reducing the voltage. In addition, at 12:00, the order of the active power regulation amounts of the four substations from large to small is Substation 16, 33, 4, 24; at 13:00, the order of the active power regulation amounts of the four substations from large to small is Substation 16, 24, 33, and 4, corresponding to the overvoltage responsibility coefficients of the four substations during this period shown in Table 1 and Table 2, that is, the four substations undertake the corresponding active power regulation according to their own overvoltage responsibilities.

[0152] Figure 9 The obtained active power regulation amounts of the four substations are based on the fairness adjustment principle. The optimization result of substituting the overvoltage responsibility coefficient of the substation into the objective function is used in the present invention, and a comparative analysis is carried out with the optimization result without considering the overvoltage responsibility coefficient. The active power regulation amounts during the periods of 12:00 and 13:00 are shown in Tables 4 and 5 below.

[0153] Table 4 Comparison of substation regulation amounts with and without considering the overvoltage responsibility coefficient at 12:00 (unit: MW)

[0154]

[0155] Table 5 Comparison of substation regulation amounts with and without considering the overvoltage responsibility coefficient at 13:00 (unit: MW)

[0156]

[0157] As can be seen from the table, when not considering the overvoltage responsibility coefficient, the active power regulation amounts of the four substations in the 12:00 period from large to small are substation 33, 16, 4, and 24, and the total regulation amount is lower than the optimization result of the present invention. Combining Table 1, it can be known that the overvoltage responsibility coefficient of substation 16 in this period is greater than that of substation 33. In the 13:00 period, the active power regulation amounts of the four substations from large to small are substation 16, 33, 24, and 4, and the total regulation amount is lower than the optimization result of the present invention. Combining Table 2, it can be known that the overvoltage responsibility coefficient of substation 33 in this period is less than that of substation 24. Therefore, only taking the lowest active power regulation cost as the optimization goal without considering the overvoltage responsibility of the substation can reduce the overall regulation cost, but it will violate the fairness regulation principle and reduce the regulation willingness of the substation. On the contrary, the voltage regulation strategy proposed by the present invention, although the total regulation amount has increased, takes into account the overvoltage responsibilities of different substations, distributes the regulation tasks according to the size of the responsibilities, and reflects the fairness regulation principle.

[0158] To further verify the influence of the substation location on the overvoltage responsibility and the amount of participation in regulation of the substation, without changing the power regulation range of the four substations, adjust their positions in the distribution network topology. Among them, the substation at node 4 in the original topology is adjusted to node 6, the substation at node 16 is adjusted to node 13, node 24 is adjusted to node 22, and node 33 is adjusted to node 29. The configuration and position of the photovoltaic inverter and the reactive power capacitor bank remain unchanged. The adjusted distribution network topology is as Figure 10 shown.

[0159] Substitute the distributed photovoltaic output and the adjusted substation load data into the 33-node model for power flow calculation to obtain the node voltage change curve for 24 hours. It can be seen that after the substation position is adjusted, the situation of the feeder node voltage exceeding the upper limit has been alleviated, but there are still voltage limit violations at multiple times and multiple nodes, such as Figure 11 shown.

[0160] Select 12:00 and 13:00 as the case analysis time, substitute the interactive power and topology data between the substation and the superior power grid into the overvoltage responsibility coefficient calculation model, and calculate the overvoltage responsibility coefficients of the four substations after the position adjustment, as shown in Tables 6 and 7.

[0161] Table 6 Overvoltage responsibility coefficient at 12:00 after substation position adjustment

[0162]

[0163] Table 7 Overvoltage responsibility coefficient of the substation at 13:00 after substation position adjustment

[0164]

[0165] Substitute the overvoltage responsibility coefficient into the voltage regulation optimization model, the voltage qualification rate reaches 100%, and the power regulation amounts of the four substations are optimized, asFigure 12 as shown

[0166] Combined with Tables 6 and 7 and Figure 11 and 12 it can be seen that the four substations increase the interactive power during the period when the feeder voltage exceeds the upper limit and decrease the interactive power during the period when it is below the lower limit. Since the amplitude of the feeder node voltage exceeding the upper limit has decreased compared with that before the adjustment of the substation location, the overall adjustment amount of the four substations during the period when the voltage exceeds the upper limit is less. In addition, the active power adjustment amounts of the four substations at 12:00 from large to small are: Substation 13, 6, 29, 22; the active power adjustment amounts of the four substations at 13:00 from large to small are: Substation 22, 13, 6, 29. Corresponding to the overvoltage responsibility coefficients of the four substations during this period shown in Tables 4-7 and 4-8, that is, the four substations undertake the corresponding active power adjustment amounts according to their own overvoltage responsibilities.

[0167] Similarly, the optimization results of the present invention without considering the overvoltage responsibility coefficient are compared and analyzed with it. The respective active power regulation amounts at 12:00 are shown in Table 8 below, and the respective active power regulation amounts at 13:00 are shown in Table 9 below.

[0168] Table 8 Comparison of Substation Regulation Amounts at 12:00 After Substation Location Adjustment with and without Considering Overvoltage Responsibility Coefficient (Unit: MW)

[0169]

[0170] Table 9 Comparison of Substation Regulation Amounts at 13:00 After Substation Location Adjustment with and without Considering Overvoltage Responsibility Coefficient (Unit: MW)

[0171]

[0172] It can be seen from the table that when not considering the overvoltage responsibility coefficient, the active power adjustment amounts of the four substations at 12:00 from large to small are Substation 29, 13, 22, 6, and the total adjustment amount is lower than the optimization result of the present invention. Combining with Table 6, it can be known that the overvoltage responsibility coefficients of the four substations during this period from large to small are: Substation 13, 6, 29, 22. The active power adjustment amounts of the four substations at 13:00 from large to small are Substation 22, 13, 29, and 6, and the total adjustment amount is lower than the optimization result of the present invention. Combining with Table 7, it can be known that the active power adjustment amounts of the four substations during this period from large to small are: Substation 22, 13, 6, 29. Therefore, only taking the lowest active power adjustment cost as the optimization goal without considering the overvoltage responsibility of the substations can reduce the overall adjustment cost, but it will violate the fairness adjustment principle and reduce the adjustment willingness of the substations. On the contrary, the voltage regulation strategy proposed by the present invention, although the total adjustment amount has increased, takes into account the overvoltage responsibilities of different substations and distributes the adjustment tasks according to the size of the responsibilities, reflecting the fairness adjustment principle.

[0173] Based on the same technical concept as the method embodiment, another embodiment of the present invention provides a distribution network collaborative voltage regulation system considering the overvoltage responsibility of the substation area and the fairness of regulation, including:

[0174] An active and reactive power regulation model construction module for establishing regulation models for the power regulation domain of the substation area, photovoltaic inverters, and reactive capacitor banks;

[0175] An overvoltage responsibility division and weight calculation module for dividing the overvoltage responsibilities borne by the substation area causing voltage over-limit into technical overvoltage responsibility and economic overvoltage responsibility, measuring the technical overvoltage responsibility of the substation area using the voltage sensitivity matrix and power transfer distribution factor, and obtaining the influence weight of the photovoltaic reverse power transmission in the substation area on the overall line voltage and the influence weight of the photovoltaic reverse power transmission in the substation area on the key node voltage; measuring the economic overvoltage responsibility of the substation area using the photovoltaic reverse power transmission amount, and obtaining the influence weight of the photovoltaic reverse power transmission behavior in the substation area on causing voltage over-limit;

[0176] An overvoltage responsibility coefficient calculation module for averaging the influence weight of the photovoltaic reverse power transmission in the substation area on the overall line voltage, the influence weight of the photovoltaic reverse power transmission in the substation area on the key node voltage, and the influence weight of the photovoltaic reverse power transmission behavior in the substation area on causing voltage over-limit to obtain the overvoltage responsibility coefficient of each substation area;

[0177] A voltage regulation optimization module for introducing the overvoltage responsibility coefficient of the substation area into the voltage regulation optimization model and solving the model. The voltage regulation optimization model takes minimizing the active power regulation amount of the substation area as the optimization goal, and under the constraints of the power regulation domain of the substation area, reactive capacitor bank constraints, photovoltaic inverter constraints, and power flow constraints, solves the voltage regulation optimization model to obtain reactive power equipment and substation area regulation strategies.

[0178] It should be understood that the distribution network collaborative voltage regulation system considering the overvoltage responsibility of the substation area and the fairness of regulation in this embodiment can implement all the technical solutions in the above method embodiment. The functions of its respective functional modules can be specifically implemented according to the methods in the above method embodiment, and the specific implementation process can refer to the relevant descriptions in the above embodiment, which will not be elaborated here.

[0179] Another embodiment of the present invention provides a computer device, including: one or more processors; a memory; and one or more programs, where the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and when the programs are executed by the processors, they implement the distribution network collaborative voltage regulation method considering the overvoltage responsibility of the substation area and the fairness of regulation as described above.

[0180] Another embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the distribution network collaborative voltage regulation method considering the overvoltage responsibility of the substation area and the fairness of regulation as described above.

[0181] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, an apparatus (system), a computer device, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0182] The present invention is described with reference to the flowchart of a method according to an embodiment of the present invention. It should be understood that each process in the flowchart and the combination of processes in the flowchart can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one process or multiple processes.

[0183] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one process or multiple processes.

[0184] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable devices provide steps for implementing the functions specified in Figure 1 one process or multiple processes.

Claims

1. A coordinated voltage regulation method for distribution networks considering the responsibility of overvoltage in the substation area and the fairness of regulation, characterized in that It includes the following steps: Establish the regulation models of the substation area power regulation domain, photovoltaic inverter, and reactive capacitor bank; Divide the overvoltage responsibility for voltage over-limit caused by reverse power flow of photovoltaic in the substation area into technical overvoltage responsibility and economic overvoltage responsibility. Use the voltage sensitivity matrix and power transfer distribution factor to measure the technical overvoltage responsibility of the substation area, and obtain the influence weight of photovoltaic reverse power flow in the substation area on the overall line voltage and the influence weight of photovoltaic reverse power flow in the substation area on the voltage of key nodes; Use the photovoltaic reverse power flow to measure the economic overvoltage responsibility of the substation area, and obtain the influence weight of the photovoltaic reverse power flow behavior in the substation area on causing voltage over-limit; Average the influence weight of photovoltaic reverse power flow in the substation area on the overall line voltage, the influence weight of photovoltaic reverse power flow in the substation area on the voltage of key nodes, and the influence weight of the photovoltaic reverse power flow behavior in the substation area on causing voltage over-limit to obtain the overvoltage responsibility coefficient of each substation area; Introduce the overvoltage responsibility coefficient of the substation area into the voltage regulation optimization model. The voltage regulation optimization model takes minimizing the active power regulation amount of the substation area as the optimization goal, and under the constraints of the substation area power regulation domain, reactive capacitor bank regulation, photovoltaic inverter regulation, and power flow, solve the voltage regulation optimization model to obtain the reactive power equipment and substation area regulation strategy.

2. The collaborative voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that The specific model of the substation area power regulation domain is: Where, Ω B is the flexibility regulation domain of the substation area; P grid is the operating power of the substation area; is the equivalent electricity quantity of the substation area at time t; and respectively represent the minimum and maximum operating powers of the substation area at time t; and respectively represent the minimum and maximum equivalent electricity quantities of the substation area at time t; Δt is the regulation time interval.

3. The coordinated voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that The specific model of the photovoltaic inverter regulation is: In the formula, is the reactive power output of the PV inverter; is the maximum reactive power output of the PV during the t period, obtained based on the PV inverter capacity and the predicted value of the active power output obtained.

4. The cooperative voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that The specific model of the reactive capacitor bank regulation is: Wherein, is the reactive power output of the capacitor bank; is the rated reactive power output of a single capacitor; is the number of switched-in and -out capacitors in the t period; is the maximum number of switched-in and -out capacitors of the capacitor at node i; T is the total number of periods; is the upper limit of the maximum number of switched-in and -out times of the capacitor at node i within the day-ahead scheduling period.

5. The coordinated voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that Use the voltage sensitivity matrix to measure the technical overvoltage responsibility of the substation area and obtain the influence weight of photovoltaic reverse power flow in the substation area on the voltage of key nodes. Specifically: Use the voltage sensitivity matrix to measure the influence of the feed-in power of the substation area on the node voltage amplitude: where S U-P is the active voltage sensitivity matrix; S U-Q is the reactive voltage sensitivity matrix; G and B are the real and imaginary parts of the nodal admittance matrix respectively, which are determined by the network topology; P and Q are the active and reactive power injections at the nodes; ΔP and ΔQ are the change vectors of the active and reactive power injections at the nodes respectively; ΔU is the change vector of the nodal voltage; Use the analytic hierarchy process to calculate the ranking of the influence of photovoltaic reverse power flow in each substation area on the node voltage, and obtain the influence weight of photovoltaic reverse power flow in the substation area on the voltage of key nodes.

6. The coordinated voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that Use the power transfer distribution factor to measure the technical overvoltage responsibility of the substation area and obtain the influence weight of photovoltaic reverse power flow in the substation area on the overall line voltage. Specifically: Use the power transfer distribution factor to measure the influence of the feed-in power of the substation area on the power flow of the whole line: Where, P node is the active power injected at the node; B x is the nodal susceptance matrix; θ is the voltage phase angle; P line is the active power flowing through the line; B line is the line-nodal susceptance matrix; S ptdf is the power transfer distribution factor matrix, with dimensions of number of branches × number of nodes; Use the analytic hierarchy process to calculate the ranking of the influence of photovoltaic reverse power flow in each substation area on the line power flow, and obtain the influence weight of the substation area on the overall line voltage.

7. The coordinated voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that Use the photovoltaic reverse power flow to measure the economic overvoltage responsibility of the substation area and obtain the economic overvoltage responsibility weight of photovoltaic reverse power flow in the substation area. Specifically: In the formula, is the economic overvoltage liability weight vector of the i-th substation area for reverse power transmission of photovoltaic power; is the reverse power transmission amount of photovoltaic power in the i-th substation area, is the total reverse power transmission amount of photovoltaic power in K substation areas.

8. The coordinated voltage regulation method for a distribution network considering the responsibility of substation area overvoltage and the fairness of regulation according to claim 1, characterized in that The distribution network voltage regulation model introducing the overvoltage responsibility coefficient of the substation area is expressed as: In the formula, minf represents the objective function of minimizing the active power regulation amount of the transformer substation area, and Ω n is the set of transformer substation area nodes; is the interactive power between the i-th transformer substation area and the superior power grid after regulation at time t; is the interactive power between the i-th transformer substation area and the superior power grid without regulation at time t; w i,t is the overvoltage responsibility coefficient of the i-th transformer substation area at time t, and T is the total number of time periods; The optimization model constraints include: the substation area power regulation domain constraint, reactive capacitor bank regulation constraint, photovoltaic inverter regulation constraint, and power flow constraint: Where, P ij,t and Q ij,t are the active and reactive powers flowing through branch ij respectively; u(j) and v(j) are the sets of the parent node and child node of node j respectively; P j,t and Q j,t are the active and reactive powers injected into node j respectively; and are the active power of the load at node j, the interactive power between the substation area and the upper-level power grid, and the active power of distributed PV injected into node j respectively; and are the reactive power load at node j, the reactive power of the PV inverter and the capacitor bank injected into node j respectively; V min and V max are the upper and lower limits of the node voltage respectively; is the maximum apparent power allowed to flow through branch ij; V0 is the voltage amplitude of the slack node; r ij and x ij are the resistance and reactance of branch ij respectively.

9. A coordinated voltage regulation system for a distribution network that takes into account the responsibility of overvoltage in the substation area and the fairness of regulation, characterized in that It includes: The active and reactive power regulation model construction module is used to establish the regulation models of the substation area power regulation domain, photovoltaic inverter, and reactive capacitor bank; The overvoltage responsibility division and weight calculation module is used to divide the overvoltage responsibility for voltage over-limit borne by the substation area into technical overvoltage responsibility and economic overvoltage responsibility, use the power transfer distribution factor and voltage sensitivity matrix to measure the technical overvoltage responsibility of the substation area, and obtain the influence weight of photovoltaic reverse power flow in the substation area on the overall line voltage and the influence weight of photovoltaic reverse power flow in the substation area on the voltage of key nodes; Use the photovoltaic reverse power flow to measure the economic overvoltage responsibility of the substation area, and obtain the influence weight of the photovoltaic reverse power flow behavior in the substation area on causing voltage over-limit; An overvoltage responsibility coefficient calculation module calculates the average value of the influence weight of the reverse power transmission of the photovoltaic power in the substation area on the overall line voltage, the influence weight of the reverse power transmission of the photovoltaic power in the substation area on the key node voltage, and the influence weight of the reverse power transmission behavior of the photovoltaic power in the substation area on causing voltage overlimit, so as to obtain the overvoltage responsibility coefficient of each substation area; A voltage regulation optimization module is used to introduce the overvoltage responsibility coefficient of the substation area into a voltage regulation optimization model. The voltage regulation optimization model takes minimizing the active power regulation amount of the substation area as the optimization goal, and solves the voltage regulation optimization model under the constraints of the substation area power regulation domain, the reactive power capacitor bank constraint, the photovoltaic inverter constraint, and the power flow constraint to obtain reactive power equipment and substation area control strategies.

10. A computer device, comprising: One or more processors; A memory; And one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors. When the program is executed by the processor, it implements the distribution network collaborative voltage regulation method considering the overvoltage responsibility of the substation area and the regulation fairness as described in any one of claims 1-8.

11. A computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the distribution network collaborative voltage regulation method considering the overvoltage responsibility of the substation area and the regulation fairness as described in any one of claims 1-8.

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