Power distribution network distributed photovoltaic active power control method considering voltage constraint

Abstract

The invention provides a power distribution network distributed photovoltaic active power control method considering voltage constraint, and belongs to the technical field of power distribution network distributed photovoltaic active power automatic adjustment. The method comprises the steps that when each control cycle arrives, the active control mode of the controllable distributed photovoltaic in the power distribution network is determined according to the active target value and the current active value of the power distribution network, and if the active target value is smaller than the difference between the current active value and the active control qualified dead zone of the power distribution network, distributed photovoltaic active power reduction control is carried out; if the active target value is greater than the sum of the current active value and the power distribution network active control qualified dead zone, distributed photovoltaic active control is carried out; otherwise, determining that the current active value of the power distribution network is qualified, and performing distributed photovoltaic active replacement control when the voltage exceeds the upper limit. The method aims at keeping the distributed photovoltaic voltage to operate at the level as low as possible, and is beneficial to reducing the voltage out-of-limit problem caused by the active change of the distributed photovoltaic, thereby improving the safe operation level of the voltage of the whole active power distribution network.

Description

Technical Field

[0001] The invention belongs to the technical field of automatic regulation of distributed photovoltaic active power in distribution networks, and in particular relates to a distributed photovoltaic active power control method for distribution networks considering voltage constraints. Background Art

[0002] With the widespread construction of distributed renewable energy, higher requirements are placed on the scientific operation of new power systems with renewable energy as the main body. Active distribution network dispatching faces the problem of operation and regulation after the participation of large-scale distributed renewable energy, which increases the risk and difficulty of grid operation and management.

[0003] The impact of a large number of distributed photovoltaic access on the distribution network includes: increasing the voltage at the access point, causing voltage fluctuations, injecting current harmonics and DC components, and grounding faults on the DC side. After the photovoltaic power source is connected, the transmission power on the feeder is reduced, which raises the voltage at each load node along the feeder, which may cause the voltage deviation of some load nodes to exceed the standard. The problem of voltage increase at the access point caused by the large active power of distributed photovoltaics is particularly serious. How to keep the voltage stable when the active power changes after the large-scale integration of distributed photovoltaics into the distribution network is a key problem we need to solve. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a distributed photovoltaic active power control method for a distribution network considering voltage constraints. The present invention aims to keep the distributed photovoltaic voltage running at the lowest possible level, which helps to reduce the voltage over-limit problem caused by the change of distributed photovoltaic active power, thereby improving the voltage safety operation level of the entire active distribution network.

[0005] The embodiment of the present invention provides a distributed photovoltaic active power control method for a distribution network considering voltage constraints, including:

[0006] At the arrival of each control cycle, the active power control mode of the controllable distributed photovoltaic in the distribution network is determined according to the active power target value and the current active power value of the distribution network, wherein:

[0007] If the active power target value is less than the difference between the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power reduction control is performed;

[0008] If the active power target value is greater than the sum of the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power increase control is performed;

[0009] Otherwise, the current active power value is qualified, and distributed photovoltaic active power replacement control is performed when the voltage exceeds the upper limit.

[0010] In a specific embodiment of the present invention, the distributed photovoltaic active power reduction control includes:

[0011] 1) The minimum real-time voltage of all controllable distributed photovoltaics in the distribution network is recorded as U min ;

[0012] Calculate the active power that needs to be reduced when each controllable distributed photovoltaic voltage drops to Umin, δPd1[i], i = 1, ..., I, and the expression is as follows:

[0013] δPd1[i]=(U[i]-Umin) / Sp[i] (1)

[0014] Where I is the total number of controllable distributed photovoltaics in the distribution network, U[i] is the real-time voltage of the i-th controllable distributed photovoltaic, and Sp[i] is the sensitivity of the active power change of the i-th controllable distributed photovoltaic to the terminal voltage;

[0015] Calculate the sum of δPd1[i] and record it as δPd1:

[0016]

[0017] 2) Judgment:

[0018] If δPd1≤(P0-Pset), proceed to step 3);

[0019] If δPd1>(P0-Pset), go to step 4);

[0020] Among them, P0 is the current active value of the distribution network, and Pset is the active target value of the distribution network;

[0021] 3) When the distribution network reaches the active target value Pset, the controllable distributed photovoltaic voltage is Uset1, and the calculation expression of Uset1 is as follows:

[0022]

[0023] Calculate each controllable distributed photovoltaic active power setting value Pset1[i], i=1,…,I, the expression is as follows:

[0024] Pset1[i]=P[i]-(U[i]-Uset1) / Sp[i] (4)

[0025] Send the I controllable distributed photovoltaic active power setting value Pset1[i] to the corresponding photovoltaic inverter to perform active power regulation;

[0026] 4) When the distribution network reaches the active target value Pset, the partially controllable distributed photovoltaic voltage is Uset2. The calculation method of Uset2 is as follows:

[0027] 4-1) Arrange the controllable distributed photovoltaics in descending order according to their voltage U[i], and renumber all controllable distributed photovoltaics according to the arrangement result to obtain the current controllable distributed photovoltaic sequence;

[0028] 4-2) Let the current accumulated number m = 1;

[0029] 4-3) The cumulative amount of δPd1[i] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence obtained in step 4-1) is recorded as δP align [m], the calculation expression is as follows:

[0030]

[0031] 4-4) Determine the result of step 4-3):

[0032] If δP align If [m]≥δPd1, stop accumulating, and then calculate Uset2 as follows:

[0033]

[0034] Then proceed to step 5);

[0035] If δP align [m] < δPd1, then set m = m + 1, and then return to step 4-3);

[0036] 5) The active power setting values ​​corresponding to the m controllable distributed photovoltaics obtained in step 4) are recorded as Pset2[i], i=1,…,m, and the expression is as follows:

[0037] Pset2[i]=P[i]-(U[i]-Uset2) / Sp[i] (7)

[0038] The Pset2[i] of the m controllable distributed photovoltaics are respectively sent to the corresponding photovoltaic inverters to perform active power regulation.

[0039] In a specific embodiment of the present invention, the distributed photovoltaic active power increase control includes:

[0040] 1) Count the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit in the distribution network, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], where n=1,…,N, and N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit;

[0041] The controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit in the distribution network are counted and arranged in ascending order according to the real-time voltage. The controllable distributed photovoltaics whose voltage is less than or equal to the upper limit are renumbered according to the arrangement result to obtain the current controllable distributed photovoltaic sequence; wherein the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax;

[0042] 2) Based on the result of step 1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd2[n], n=1,…,N, and the expression is as follows:

[0043] δPd2[n]=(Uover[n]-Umax[n]) / Sp[n] (8)

[0044] Calculate the controllable distributed photovoltaic active power setting value Pset3[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows:

[0045] Pset3[n]=Pover[n]- δPd2[n] (9)

[0046] Send the controllable distributed photovoltaic active power setting value Pset3[n] whose real-time voltage is greater than the upper limit to the corresponding photovoltaic inverter to perform active power regulation;

[0047] 3) Based on the result of step 2), the total active power is calculated and recorded as δPu1, which is expressed as follows:

[0048]

[0049] 4) Based on the result of step 1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated and recorded as δPu1[j], j=1,…,J, and the expression is as follows:

[0050] δPu1[j]=(Uemax-Ue[j]) / Sp[j] (11)

[0051] 5) Let the current accumulated number m = 1;

[0052] 6) Calculate the cumulative amount P of δPu1[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows:

[0053]

[0054] 7) Determine the result of step 6):

[0055] 7-1) If P align [m]≥δPu1, then stop accumulating and calculate Uset3 according to the following formula:

[0056]

[0057] Among them, Uset3 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPu1;

[0058] The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset3[j], j = 1, ..., m, and the expression is as follows:

[0059] Pset3[j]=Pe[j]+(Uset3-Ue[j]) / Sp[j] (14)

[0060] Send the m controllable distributed photovoltaic active power setting values ​​Pset3[j] to the corresponding photovoltaic inverter to perform active power regulation;

[0061] 7-2) If P align [m]<δPu1, then m is determined as follows:

[0062] If m﹤J, set m=m+1 and then return to step 6);

[0063] If m=J, Uset4 is calculated as follows:

[0064]

[0065] Among them, Uset4 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPu1;

[0066] The voltage value after the active power adjustment of the J controllable distributed photovoltaics is recorded as Uset4[j]; wherein, if Uset4>Umax[j], let Uset4[j]=Umax[j]; if Uset4≤Umax[j], let Uset4[j]=Uset4;

[0067] The active power setting value of the J controllable distributed photovoltaics is calculated and recorded as Pset4[j], j = 1, ..., J, and the expression is as follows:

[0068] Pset4[j]=Pe[j]+(Uset4[j]-Ue[j]) / Sp[j] (16)

[0069] The active power setting value Pset4[j] of the J controllable distributed photovoltaics is sent to the corresponding photovoltaic inverter to perform active power regulation. In a specific embodiment of the present invention, the distributed photovoltaic active power replacement control when the voltage exceeds the upper limit includes:

[0070] 1) Count the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit in the distribution network, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], where n=1,…,N, and N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit;

[0071] Count the controllable distributed photovoltaics in the distribution network whose real-time voltage is less than or equal to the upper limit and arrange them in order from small to large according to the real-time voltage. Renumber the controllable distributed photovoltaics according to the arrangement result to obtain the current controllable distributed photovoltaic sequence; wherein, the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax;

[0072] 2) Based on the result of step 1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd3[n], n=1,…,N, and the expression is as follows:

[0073] δPd3[n]=(Uover[n]–U max [n]) / Sp[n] (17)

[0074] Calculate the controllable distributed photovoltaic active power setting value Pset5[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows:

[0075] Pset5[n]=Pover[n]–δPd3[n] (18)

[0076] Send the controllable distributed photovoltaic active power setting value Pset5[n] whose real-time voltage is greater than the upper limit to the corresponding photovoltaic inverter to perform active power regulation;

[0077] 3) Based on the result of step 2), calculate the sum of δPd3[n] and record it as δPd3:

[0078]

[0079] 4) Based on the result of step 1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated and recorded as δPu2[j], j=1,…,J, and the expression is as follows:

[0080] δPu2[j]=(Uemax-Ue[j]) / Sp[j] (20)

[0081] 5) Let the current accumulated number m = 1;

[0082] 6) Calculate the cumulative amount P of δPu2[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows:

[0083]

[0084] 7) Determine the result of step 6):

[0085] 7-1) If P align [m]≥δPd3, stop accumulating and calculate Uset6 according to the following formula:

[0086]

[0087] Among them, Uset6 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPd3;

[0088] The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset6[j], j = 1, ..., m, and the expression is as follows:

[0089] Pset6[j]=Pe[j]+(Uset6-Ue[j]) / Sp[j] (23)

[0090] Send the m controllable distributed photovoltaic active power setting values ​​Pset6[j] to the corresponding photovoltaic inverter to perform active power regulation;

[0091] 7-2) If P align [m]<δPd3, then determine m:

[0092] If m﹤J, set m=m+1 and then return to step 6);

[0093] If m=J, then Uset7 is calculated as follows:

[0094]

[0095] Among them, Uset7 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPd3;

[0096] The J controllable distributed photovoltaics are made to perform active power regulation, and the voltage value after active power regulation of the J controllable distributed photovoltaics is recorded as Uset7[j]; wherein, if Uset7>Umax[j], then Uset7[j]=Umax[j]; if Uset7≤Umax[j], then Uset7[j]=Uset7;

[0097] Calculate the active power setting value of the J controllable distributed photovoltaics and record it as P set7 [j], j = 1, ..., J, the expression is as follows:

[0098] Pset7[j]=Pe[j]+(U set7 [j]-Ue[j]) / Sp[j] (25)

[0099] The active power setting values ​​Pset7[j] of the J controllable distributed photovoltaics are sent to the corresponding photovoltaic inverters to perform active power regulation.

[0100] The characteristics and advantages of the method of the present invention are:

[0101] When the present invention performs distributed photovoltaic active power reduction control, the photovoltaic with high voltage is adjusted first; when the distributed photovoltaic active power increase control is performed, the photovoltaic with low voltage is adjusted first, and the voltage upper limit is not exceeded after adjustment; when the current active power value of the distribution network meets the superior target requirements, the distributed photovoltaic with voltage exceeding the upper limit is processed to reduce active power to eliminate the voltage exceeding the limit, and the photovoltaic active power with qualified voltage is increased to maintain the total active power stability. The control process of the present invention always aims to keep the distributed photovoltaic voltage running at the lowest possible level, which helps to reduce the voltage exceeding the limit problem caused by the change of distributed photovoltaic active power, thereby improving the voltage safety operation level of the entire active distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Figure 1 The present invention is an overall flow chart of a method for controlling distributed photovoltaic active power in a distribution network taking voltage constraints into consideration according to an embodiment of the present invention. DETAILED DESCRIPTION

[0103] The present invention proposes a distributed photovoltaic active power control method for a distribution network considering voltage constraints, which is further described in detail below with reference to the accompanying drawings and specific implementations.

[0104] This embodiment proposes a distributed photovoltaic active power control method for a distribution network considering voltage constraints, including:

[0105] At the arrival of each control cycle, the active power control mode of the controllable distributed photovoltaic in the distribution network is determined according to the active power target value and the current active power value of the distribution network, wherein:

[0106] If the active power target value is less than the difference between the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power reduction control is performed;

[0107] If the active power target value is greater than the sum of the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power increase control is performed;

[0108] Otherwise, the current active power value is qualified, and distributed photovoltaic active power replacement control is performed when the voltage exceeds the upper limit.

[0109] In a specific embodiment of the present invention, the overall process of the distributed photovoltaic active power control method of the distribution network considering voltage constraints is as follows: Figure 1 As shown, the following steps are included:

[0110] 1) When the current control cycle arrives, the current active value of the distribution network is obtained and recorded as P0, and the active target value is recorded as Pset; the real-time active power of the i-th controllable distributed photovoltaic in the distribution network is recorded as P[i], and the real-time voltage of the i-th controllable distributed photovoltaic is recorded as U[i], i=1,…,I; I is the total number of controllable distributed photovoltaics in the distribution network;

[0111] The sensitivity of the active power change of the i-th controllable distributed photovoltaic to the terminal voltage is denoted as Sp[i], the voltage upper limit of the i-th controllable distributed photovoltaic is denoted as Umax[i], i=1,…,I; the qualified dead zone of active power control of the distribution network is denoted as Pband.

[0112] determination:

[0113] If Pset<(P0-Pband), the distributed photovoltaic active power reduction control is performed and the process goes to step 2);

[0114] If Pset>(P0+Pband), the distributed photovoltaic active power increase control is performed and the process goes to step 3);

[0115] If (P0-Pband)≤Pset≤(P0+Pband), the current active value of the distribution network is qualified, and the distributed photovoltaic active power replacement control is performed when the voltage exceeds the upper limit, and the process goes to step 4).

[0116] 2) Distributed photovoltaic active power reduction control; the specific steps are as follows:

[0117] 2-1) The minimum real-time voltage of all controllable distributed photovoltaics is recorded as U min .

[0118] Calculate the active power δPd1[i] that needs to be reduced for each controllable distributed photovoltaic voltage to drop to Umin, i = 1, ..., I, as shown in the following expression:

[0119] δPd1[i]=(U[i]-Umin) / Sp[i] (1)

[0120] Calculate the sum of δPd1[i] and record it as δPd1:

[0121]

[0122] 2-2) Judgment:

[0123] If δPd1≤(P0-Pset), it means that when all controllable distributed photovoltaics reduce the voltage to Umin by reducing the active power, the total active power reduction cannot meet the active power target value Pset, and it is necessary to continue to reduce the active power to achieve it, then go to step 2-3);

[0124] If δPd1>(P0-Pset), it means that when some controllable distributed photovoltaics reduce the voltage to Umin by reducing the active power, the total active power reduction brought about can meet the active power target value Pset, then go to step 2-4);

[0125] 2-3) When the distribution network reaches the active target value Pset, the controllable distributed photovoltaic voltage is Uset1, and Uset1 can be calculated by the following formula:

[0126]

[0127] Calculate each controllable distributed photovoltaic active power setting value Pset1[i], i=1,…,I, the expression is as follows:

[0128] Pset1[i]=P[i]-(U[i]-Uset1) / Sp[i] (4)

[0129] The I controllable distributed photovoltaic active power setting values ​​Pset1[i] are sent to the corresponding photovoltaic inverter to perform active power regulation, and then go to step 5).

[0130] 2-4) When the distribution network reaches the active target value Pset, the partially controllable distributed photovoltaic voltage is Uset2, which can be calculated by the following method:

[0131] 2-4-1) Arrange the controllable distributed photovoltaics in descending order according to their voltage U[i], and renumber all controllable distributed photovoltaics according to the arrangement results to obtain the current controllable distributed photovoltaic sequence.

[0132] 2-4-2) Let the current accumulated number m=1.

[0133] 2-4-3) Calculate the cumulative amount of δPd1[i] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence obtained in step 2-4-1) and record it as δPalign [m], the calculation expression is as follows:

[0134]

[0135] 2-4-4) Determine the result of step 2-4-3):

[0136] If δP align If [m]≥δPd1, stop accumulating, and then calculate Uset2 as follows:

[0137]

[0138] Then proceed to step 2-5).

[0139] If δP align [m]﹤δPd1, then set m=m+1, and then return to step 2-4-3).

[0140] 2-5) The active power setting values ​​corresponding to the m controllable distributed photovoltaics obtained in step 2-4) are recorded as Pset2[i], i = 1, ..., m, and the expression is as follows:

[0141] Pset2[i]=P[i]-(U[i]-Uset2) / Sp[i] (7)

[0142] The Pset2[i] of the m controllable distributed photovoltaics are respectively sent to the corresponding photovoltaic inverters to perform active power regulation, and then proceed to step 5).

[0143] 3) Distributed photovoltaic active power control; the specific steps are as follows:

[0144] 3-1) Count the controllable distributed photovoltaics in the distribution network whose real-time voltage is greater than the upper limit, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], n=1,…,N, N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit.

[0145] The controllable distributed photovoltaics with real-time voltage less than or equal to the upper limit in the distribution network are counted and arranged in order from small to large according to the real-time voltage, and the controllable distributed photovoltaics with voltage less than or equal to the upper limit are renumbered according to the arrangement result to obtain the current controllable distributed photovoltaic sequence. Among them, the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics with real-time voltage less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax.

[0146] 3-2) Based on the result of step 3-1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd2[n], n=1,…,N, and the expression is as follows:

[0147] δPd2[n]=(Uover[n]-Umax[n]) / Sp[n] (8)

[0148] Calculate the controllable distributed photovoltaic active power setting value Pset3[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows:

[0149] Pset3[n]=Pover[n]- δPd2[n] (9)

[0150] The controllable distributed photovoltaic active power setting value Pset3[n] whose real-time voltage is greater than the upper limit is sent to the corresponding photovoltaic inverter to perform active power regulation.

[0151] 3-3) Based on the result of step 3-2), calculate the sum of δPd2[n], and then add the active power required by the active power target value of the distribution network to obtain the total active power increase, which is recorded as δPu1 and expressed as follows:

[0152]

[0153] 3-4) Based on the result of step 3-1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated as δPu1[j], j=1,…,J, and the expression is as follows:

[0154] δPu1[j]=(Uemax-Ue[j]) / Sp[j] (11)

[0155] 3-5) Let the current accumulated number m = 1;

[0156] 3-6) Calculate the cumulative amount P of δPu1[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows:

[0157]

[0158] 3-7) Determine the result of step 3-6):

[0159] 3-7-1) If P align [m]≥δPu1, then stop accumulating and calculate Uset3 according to the following formula:

[0160]

[0161] Among them, Uset3 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPu1.

[0162] The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset3[j], j = 1, ..., m, and the expression is as follows:

[0163] Pset3[j]=Pe[j]+(Uset3-Ue[j]) / Sp[j] (14)

[0164] The m controllable distributed photovoltaic active power setting values ​​Pset3[j] are sent to the corresponding photovoltaic inverters to perform active power regulation, and then go to step 5).

[0165] 3-7-2) If P align [m]<δPu1, then m is determined as follows:

[0166] If m﹤J, set m=m+1, and then return to step 3-6);

[0167] If m=J, then Uset4 is calculated as follows:

[0168]

[0169] Among them, Uset4 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPu1.

[0170] The voltage value after active power regulation of the J controllable distributed photovoltaics is recorded as Uset4[j]; if Uset4>Umax[j], let Uset4[j]=Umax[j]; if Uset4≤Umax[j], let Uset4[j]=Uset4.

[0171] The active power setting value of the J controllable distributed photovoltaics is calculated and recorded as Pset4[j], j = 1, ..., J, and the expression is as follows:

[0172] Pset4[j]=Pe[j]+(Uset4[j]-Ue[j]) / Sp[j] (16)

[0173] The active power setting values ​​Pset4[j] of the J controllable distributed photovoltaics are sent to the corresponding photovoltaic inverters to perform active power regulation, and then proceed to step 5).

[0174] 4) Distributed photovoltaic active power replacement control when the voltage exceeds the upper limit; the specific steps are as follows:

[0175] 4-1) Count the controllable distributed photovoltaics in the distribution network whose real-time voltage is greater than the upper limit, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], n=1,…,N, N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit.

[0176] The controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit in the distribution network are counted and arranged in order from small to large according to the real-time voltage. The controllable distributed photovoltaics are renumbered according to the arrangement result to obtain the current controllable distributed photovoltaic sequence. Among them, the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax.

[0177] 4-2) Based on the result of step 4-1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd3[n], n=1,…,N, and the expression is as follows:

[0178] δPd3[n]=(Uover[n]–U max [n]) / Sp[n] (17)

[0179] Calculate the controllable distributed photovoltaic active power setting value Pset5[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows:

[0180] Pset5[n]=Pover[n]–δPd3[n] (18)

[0181] The controllable distributed photovoltaic active power setting value Pset5[n] whose real-time voltage is greater than the upper limit is sent to the corresponding photovoltaic inverter to perform active power regulation.

[0182] 4-3) Based on the results of step 4-2), calculate the sum of δPd3[n] and record it as δPd3:

[0183]

[0184] 4-4) Based on the result of step 4-1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated as δPu2[j], j=1,…,J, and the expression is as follows:

[0185] δPu2[j]=(Uemax-Ue[j]) / Sp[j] (20)

[0186] 4-5) Let the current accumulated number m = 1;

[0187] 4-6) Calculate the cumulative amount P of δPu2[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows:

[0188]

[0189] 4-7) Determine the result of step 4-6):

[0190] 4-7-1) If P align [m]≥δPd3, stop accumulating and calculate Uset6 according to the following formula:

[0191]

[0192] Among them, Uset6 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPd3.

[0193] The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset6[j], j = 1, ..., m, and the expression is as follows:

[0194] Pset6[j]=Pe[j]+(Uset6-Ue[j]) / Sp[j] (23)

[0195] The m controllable distributed photovoltaic active power setting values ​​Pset6[j] are sent to the corresponding photovoltaic inverters to perform active power regulation, and then proceed to step 5).

[0196] 4-7-2) If P align [m]<δPd3, then determine m:

[0197] If m﹤J, set m=m+1, and then return to step 4-6);

[0198] If m=J, then Uset7 is calculated as follows:

[0199]

[0200] Among them, Uset7 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPd3.

[0201] The J controllable distributed photovoltaics are prepared to perform active power regulation to fully or partially compensate for the active power value of the above-mentioned photovoltaics that have exceeded the upper limit and have decreased due to eliminating the limit. The voltage value of the J controllable distributed photovoltaics after active power regulation is recorded as Uset7[j]; if Uset7>Umax[j], then Uset7[j]=Umax[j]; if Uset7≤Umax[j], then Uset7[j]=Uset7.

[0202] Calculate the active power setting value of the J controllable distributed photovoltaics and record it as P set7 [j], j = 1, ..., J, the expression is as follows:

[0203] Pset7[j]=Pe[j]+(U set7 [j]-Ue[j]) / Sp[j] (25)

[0204] The active power setting values ​​Pset7[j] of the J controllable distributed photovoltaics are sent to the corresponding photovoltaic inverters to perform active power regulation, and then proceed to step 5).

[0205] 5) This round of control ends here. When waiting for the next control cycle to arrive, return to step 1).

Claims

1. A distributed photovoltaic active power control method for distribution network considering voltage constraints, characterized in that: include: At the arrival of each control cycle, the active power control mode of the controllable distributed photovoltaic in the distribution network is determined according to the active power target value and the current active power value of the distribution network, wherein: If the active power target value is less than the difference between the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power reduction control is performed; If the active power target value is greater than the sum of the current active power value and the qualified dead zone of the distribution network active power control, the distributed photovoltaic active power increase control is performed; Otherwise, the current active power value is qualified, and distributed photovoltaic active power replacement control is performed when the voltage exceeds the upper limit.

2. The method according to claim 1, characterized in that The distributed photovoltaic active power reduction control includes: 1) The minimum real-time voltage of all controllable distributed photovoltaics in the distribution network is recorded as U min ; Calculate the active power that needs to be reduced when each controllable distributed photovoltaic voltage drops to Umin, δPd1[i], i = 1, ..., I, and the expression is as follows: δPd1[i]=(U[i]-Umin) / Sp[i] (1) Where I is the total number of controllable distributed photovoltaics in the distribution network, U[i] is the real-time voltage of the i-th controllable distributed photovoltaic, and Sp[i] is the sensitivity of the active power change of the i-th controllable distributed photovoltaic to the terminal voltage; Calculate the sum of δPd1[i] and record it as δPd1: 2) Judgment: If δPd1≤(P0-Pset), proceed to step 3); If δPd1>(P0-Pset), go to step 4); Among them, P0 is the current active value of the distribution network, and Pset is the active target value of the distribution network; 3) When the distribution network reaches the active target value Pset, the controllable distributed photovoltaic voltage is Uset1, and the calculation expression of Uset1 is as follows: Calculate each controllable distributed photovoltaic active power setting value Pset1[i], i=1,…,I, the expression is as follows: Pset1[i]=P[i]-(U[i]-Uset1) / Sp[i] (4) Send the I controllable distributed photovoltaic active power setting value Pset1[i] to the corresponding photovoltaic inverter to perform active power regulation; 4) When the distribution network reaches the active target value Pset, the partially controllable distributed photovoltaic voltage is Uset2. The calculation method of Uset2 is as follows: 4-1) Arrange the controllable distributed photovoltaics in descending order according to their voltage U[i], and renumber all controllable distributed photovoltaics according to the arrangement result to obtain the current controllable distributed photovoltaic sequence; 4-2) Let the current accumulated number m = 1; 4-3) The cumulative amount of δPd1[i] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence obtained in step 4-1) is recorded as δP align [m], the calculation expression is as follows: 4-4) Determine the result of step 4-3): If δP align If [m]≥δPd1, stop accumulating, and then calculate Uset2 as follows: Then proceed to step 5); If δP align [m] < δPd1, then set m = m + 1, and then return to step 4-3); 5) The active power setting values ​​corresponding to the m controllable distributed photovoltaics obtained in step 4) are recorded as Pset2[i], i=1,…,m, and the expression is as follows: Pset2[i]=P[i]-(U[i]-Uset2) / Sp[i] (7) The Pset2[i] of the m controllable distributed photovoltaics are respectively sent to the corresponding photovoltaic inverters to perform active power regulation.

3. The method according to claim 1, characterized in that The distributed photovoltaic active power increase control includes: 1) Count the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit in the distribution network, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], where n=1,…,N, and N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit; The controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit in the distribution network are counted and arranged in ascending order according to the real-time voltage. The controllable distributed photovoltaics whose voltage is less than or equal to the upper limit are renumbered according to the arrangement result to obtain the current controllable distributed photovoltaic sequence; wherein the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax; 2) Based on the result of step 1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd2[n], n=1,…,N, and the expression is as follows: δPd2[n]=(Uover[n]-Umax[n]) / Sp[n] (8) Calculate the controllable distributed photovoltaic active power setting value Pset3[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows: Pset3[n]=Pover[n]- δPd2[n] (9) Send the controllable distributed photovoltaic active power setting value Pset3[n] whose real-time voltage is greater than the upper limit to the corresponding photovoltaic inverter to perform active power regulation; 3) Based on the result of step 2), the total active power is calculated and recorded as δPu1, which is expressed as follows: 4) Based on the result of step 1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated and recorded as δPu1[j], j=1,…,J, and the expression is as follows: δPu1[j]=(Uemax-Ue[j]) / Sp[j] (11) 5) Let the current accumulated number m = 1; 6) Calculate the cumulative amount P of δPu1[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows: 7) Determine the result of step 6): 7-1) If P align [m]≥δPu1, then stop accumulating and calculate Uset3 according to the following formula: Among them, Uset3 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPu1; The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset3[j], j = 1, ..., m, and the expression is as follows: Pset3[j]=Pe[j]+(Uset3-Ue[j]) / Sp[j] (14) Send the m controllable distributed photovoltaic active power setting values ​​Pset3[j] to the corresponding photovoltaic inverter to perform active power regulation; 7-2) If P align [m]<δPu1, then m is determined as follows: If m﹤J, set m=m+1 and then return to step 6); If m=J, then Uset4 is calculated as follows: Among them, Uset4 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPu1; The voltage value after the active power adjustment of the J controllable distributed photovoltaics is recorded as Uset4[j]; wherein, if Uset4>Umax[j], let Uset4[j]=Umax[j]; if Uset4≤Umax[j], let Uset4[j]=Uset4; The active power setting value of the J controllable distributed photovoltaics is calculated and recorded as Pset4[j], j = 1, ..., J, and the expression is as follows: Pset4[j]=Pe[j]+(Uset4[j]-Ue[j]) / Sp[j] (16) The active power setting values ​​Pset4[j] of the J controllable distributed photovoltaics are sent to the corresponding photovoltaic inverters to perform active power regulation.

4. The method according to claim 1, characterized in that The distributed photovoltaic active power replacement control when the voltage exceeds the upper limit includes: 1) Count the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit in the distribution network, and record the real-time voltage of the controllable distributed photovoltaics whose real-time voltage is greater than the upper limit as Uover[n], and the real-time active power as Pover[n], where n=1,…,N, and N is the total number of controllable distributed photovoltaics whose real-time voltage is greater than the upper limit; Count the controllable distributed photovoltaics in the distribution network whose real-time voltage is less than or equal to the upper limit and arrange them in order from small to large according to the real-time voltage. Renumber the controllable distributed photovoltaics according to the arrangement result to obtain the current controllable distributed photovoltaic sequence; wherein, the real-time voltage of the j-th controllable distributed photovoltaic in the current controllable distributed photovoltaic sequence is recorded as Ue[j], and the real-time active power of the j-th controllable distributed photovoltaic is recorded as Pe[j], j=1,…,J, J is the total number of controllable distributed photovoltaics whose real-time voltage is less than or equal to the upper limit, and the maximum real-time voltage of the controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence is recorded as Uemax; 2) Based on the result of step 1), the active power required to reduce the voltage of the controllable distributed photovoltaic system whose real-time voltage is greater than the upper limit to its voltage upper limit Umax[n] is calculated and recorded as δPd3[n], n=1,…,N, and the expression is as follows: δPd3[n]=(Uover[n]–U max [n]) / Sp[n] (17) Calculate the controllable distributed photovoltaic active power setting value Pset5[n] when the real-time voltage is greater than the upper limit, n = 1, ..., N, the expression is as follows: Pset5[n]=Pover[n]– δPd3[n] (18) Send the controllable distributed photovoltaic active power setting value Pset5[n] whose real-time voltage is greater than the upper limit to the corresponding photovoltaic inverter to perform active power regulation; 3) Based on the result of step 2), calculate the sum of δPd3[n] and record it as δPd3: 4) Based on the result of step 1), the amount of active power required to increase when the controllable distributed photovoltaic voltage with a real-time voltage less than or equal to the upper limit rises to Uemax is calculated and recorded as δPu2[j], j=1,…,J, and the expression is as follows: δPu2[j]=(Uemax-Ue[j]) / Sp[j] (20) 5) Let the current accumulated number m = 1; 6) Calculate the cumulative amount P of δPu2[j] of the first m controllable distributed photovoltaics in the current controllable distributed photovoltaic sequence align [m], m = 1, ..., J, the expression is as follows: 7) Determine the result of step 6): 7-1) If P align [m]≥δPd3, stop accumulating and calculate Uset6 according to the following formula: Among them, Uset6 represents the voltage value that will be reached when the total active power of the m controllable distributed photovoltaics increases by δPd3; The calculated active power setting values ​​of the m controllable distributed photovoltaics are recorded as Pset6[j], j = 1, ..., m, and the expression is as follows: Pset6[j]=Pe[j]+(Uset6-Ue[j]) / Sp[j] (23) Send the m controllable distributed photovoltaic active power setting values ​​Pset6[j] to the corresponding photovoltaic inverter to perform active power regulation; 7-2) If P align [m]<δPd3, then determine m: If m﹤J, set m=m+1 and then return to step 6); If m=J, then Uset7 is calculated as follows: Among them, Uset7 represents the voltage value that will be reached when the total active power of the J controllable distributed photovoltaics increases by δPd3; The J controllable distributed photovoltaics are made to perform active power regulation, and the voltage value after active power regulation of the J controllable distributed photovoltaics is recorded as Uset7[j]; wherein, if Uset7>Umax[j], then Uset7[j]=Umax[j]; if Uset7≤Umax[j], then Uset7[j]=Uset7; Calculate the active power setting value of the J controllable distributed photovoltaics and record it as P set7 [j], j = 1, ..., J, the expression is as follows: Pset7[j]=P[j]+(U set7 [j]-Ue[j]) / Sp[j] (25) The active power setting values ​​Pset7[j] of the J controllable distributed photovoltaics are sent to the corresponding photovoltaic inverters to perform active power regulation.

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