CN110380434B - Three-phase unbalance automatic adjustment algorithm based on phase change switch - Google Patents

Abstract

The invention provides a three-phase unbalance automatic adjusting algorithm based on a phase change switch, and relates to the technical field of three-phase load adjustment of a power distribution system. The invention provides a phase change switch scheduling algorithm combining a phase separation algorithm, a dynamic programming algorithm and a greedy algorithm with the aim of reducing the station area unbalance. The algorithm evaluates the unbalance of the three-phase system at intervals, starts the phase-splitting algorithm to optimize when the evaluation result needs phase-shifting to obtain a phase-shifting switch action sequence, judges the optimization effect to decide whether to start the greedy algorithm, and selects a phase-shifting sequence with better optimization effect of the greedy algorithm and the phase-splitting algorithm. And finally, sending the commutation command to a commutation switch for execution. Due to the design of the multi-stage algorithm, the defect that the dynamic programming or greedy algorithm is trapped in local optimization can be avoided to a large extent, the operation is more stable, the three-phase unbalance is obviously reduced, and a good solution is provided for safe, stable and economic operation of the power distribution network.

Description

Three-phase unbalance automatic adjustment algorithm based on phase change switch

Technical Field

The invention relates to the technical field of three-phase load regulation of a power distribution system, in particular to a three-phase unbalance automatic regulation algorithm based on a phase change switch.

Background

The phenomenon of three-phase imbalance caused by uneven distribution of electric loads, random variation of the electric loads and the like is more and more common in the low-voltage electricity utilization field of China. Therefore, various problems which are not beneficial to the healthy operation of the power grid are generated, for the power distribution network side, the three-phase imbalance reduces the output and overload capacity of the transformer, and simultaneously increases the line loss and the transformer loss; for the user side, the three-phase imbalance increases the temperature rise of the motor and the reactive loss, so that the efficiency is reduced, and the imbalance causes a certain phase voltage to be higher, so that the power utilization quality of the user is influenced.

Currently, there are three main ways for treating three-phase imbalance: the system comprises a capacitive automatic adjusting device (such as interphase capacitance compensation), a power electronic type three-phase load adjusting device (such as a Static Var Generator (SVG)) and a commutation switch type adjusting device. The capacitance type adjusting device is poor in adjusting precision, large in equipment loss and obvious in price advantage; the power electronic type adjusting device has higher price, high adjusting precision and high response speed, and can be additionally provided with other functions for improving the quality of electric energy, such as reactive compensation, harmonic treatment and the like; the phase change switch can solve the three-phase load unbalance from the source, reduces the line loss, improves the power consumption quality of a terminal user and has moderate price.

The intelligent commutation switch is used for treating three-phase imbalance, and an efficient and optimized intelligent commutation strategy is adopted to generate an optimal switch action sequence, so that the load of each phase is adjusted to reduce the three-phase imbalance to the minimum. Therefore, the reasonable judgment logic and the optimization algorithm are the key of the three-phase unbalance treatment and directly influence the treatment effect of the three-phase load unbalance.

Disclosure of Invention

The invention aims at the defects of the prior art and provides a three-phase unbalance automatic adjusting algorithm based on a commutation switch, which generates a switch action sequence through a multi-stage optimization algorithm, reduces the three-phase unbalance degree, reduces the switching times and achieves the optimal running state.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the invention relates to a three-phase unbalance automatic adjusting algorithm based on a commutation switch, which comprises the following steps:

step 1: starting a master control terminal T₁And a phase change switch for detecting the main control terminal T₁If the operation is normal, entering the step 2 if the operation is normal, otherwise, closing and locking the controller, recording the fault reason and uploading to the master station;

step 2: setting three-phase current unbalance threshold B_thThreshold value N of number of overrun times_BthThreshold value of load factor R_thInterval time t of load state detection₁Number of overrun times N_thInitialized to 0, rated current I of transformer_N；

And step 3: main control terminal T₁Is arranged at the side of the transformer, is externally connected with a three-phase four-wire power supply and is externally connected with a current transformer CT for detecting the total current I of each phase at the outgoing line side of the transformer_A、I_B、I_C；

Calculating the current average current and the unbalance degree of the three-phase current:

I_av＝(I_A+I_B+I_C)/3

B＝[max(I_A,I_B,I_C)-min(I_A,I_B,I_C)]/max(I_A,I_B,I_C)

calculating the current load rate:

R＝max(I_A,I_B,I_C)/I_Nwherein, I_NFor rated current of transformer

And 4, step 4: if the current is three-phase unbalance degree B>＝B_thAnd R is>＝R_thThe number of overrun times N_thAdding 1 and executing step 5, if the threshold value is not exceeded, N _th0, and waiting for a time interval t₁Then continuing to execute the step 3;

and 5: will overrun the number N_thAnd an overrun number threshold N_BthComparing, if the threshold value is exceeded, executing step 6 and exceeding the limit number N_thReset to 0, if not exceeded wait for t₁Executing the step 3;

step 6: commutation switch S₁...S_i...S_N(N is the number of the phase change switches) arranged on the single-phase user side, the incoming line is a three-phase four-wire line, the outgoing line is connected with the single-phase line of the user, and the load current I of the phase change switches is detected_Si(ii) a Main control terminal T₁By Lora or carrier with commutation switch S_iCommunication, acquisition of commutation switch S_iAt the current phase P_iLoad current I_SiFault state data;

calculating the current I to be compensated for each phase_{A_comp}、I_{B_comp}、I_{C_comp}：

I_{A_comp}＝I_av-I_A；I_{B_comp}＝I_av-I_B；I_{C_comp}＝I_av-I_C

Eliminating fault reversing switch and calculating adjustable current I of each phase_{A_adj}、I_{B_adj}、I_{C_adj}：

Wherein, each phase adjustable current refers to the sum of load currents of the fault-free phase change switches, N_A、N_B、N_CThe number of the faultless commutation switches accessed by the current phase is respectively;

calculating the current I of each phase_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}：

I_{A_Nadj}＝I_A-I_{A_adj}；I_{B_Nadj}＝I_B-I_{B_adj}；I_{C_Nadj}＝I_C-I_{C_adj}

Wherein, the current which can not be adjusted refers to the sum of load currents which are not connected into the phase change switch or connected into the fault phase change switch;

and 7: judging the number k of phases with the current being larger than the average current, recording the corresponding phases, starting a phase splitting algorithm, and recording the final action sequence S of the phase change switch_eq；

And 8: switching sequence S optimized according to a phase-splitting algorithm_eqCalculating the degree of unbalance of three phases B_opt，B_{th_gre}Threshold is enabled for greedy algorithm, if B_opt>B_{th_gre}And the number k of phases with unregulated current greater than the average current<2, starting a greedy algorithm, and recording the final action sequence S of the phase change switch_{eq_gre}Sequence of actions S of a switch optimized according to a greedy algorithm_{eq_gre}Calculating the degree of unbalance of three phases B_min；

And step 9: if B after the phase-splitting algorithm is executed_optAnd B after greedy algorithm execution_minIn contrast, if B_opt>B_minAnd then a switching action sequence S generated by a greedy algorithm is adopted_{eq_gre}Otherwise, generating by adopting a split-phase algorithmSwitch operation sequence S_eq；

Step 10: main control terminal T₁Sending an optimization result, namely a switching action sequence to a phase change switch through a carrier or a Lora wireless module;

step 11: the phase change switch receives the master control terminal T through Lora or carrier communication₁And feeds back a commutation result to the main control terminal T through Lora or carrier communication₁。

Preferably, in step 7, if k is 0, step a is executed,

step a, executing an algorithm 1, comprising the steps of:

step a 1: calculating the number m of phases with positive compensation current and recording the corresponding phases, and if m is 2, firstly, P with negative compensation current_out1Partial commutation switches in phase to P with positive compensation current_{entry1_1}Phase, performing step a 2; if m ≠ 2, executing step a 4;

step a 2: executing a dynamic programming algorithm 1.1, comprising the steps of:

step a 2.1: encoding P based on 01 knapsack model_outThe phase change switch is 1_outTotal N_outAn article with addr [ i ] as address]The corresponding adjustable current is I₁...I_i...I_NoutValue for each item and the backpack space occupied, P_entry1The current whose phase needs to be compensated is I_comp1Is the total capacity of the backpack; then f (i, j) represents the preceding i (1. ltoreq. i.ltoreq.N)_out) The capacity of each article can be j (j is more than or equal to 1 and less than or equal to I)_comp1) The maximum value of the items in the backpack of (1); and initializing i-1, j-1, f (i, 0) 0, f (0, j) 0;

step a 2.2: eliminating the already-existing array adjust _ button [ ptr ]]And stores the address of the remaining commutation switch in addr [ i ]]The recoding phase change switch is 1_outCorresponding adjustable current I₁...I_i...I_NoutInitializing i to 1, j to 1, f (i, 0) to 0, and f (0, j) to 0;

step a 2.3: if i<＝N_outStep a2.4 is executed; otherwise, let i equal to N_out、j＝|I_comp1And performing step a 2.6;

step a 2.4: if j is<＝|I_comp1If yes, executing step a 2.5; otherwise i is i +1 and step a2.3 is performed;

step a 2.5: if I_iLess than j, f (I, j) equals max (f (I-1, j), f (I-1, j-I)_i)+I_i) Otherwise, f (i, j) is f (i-1, j); let j equal j +1 and perform step a 2.4;

step a 2.6: if i > -1, step a2.7 is executed; otherwise, executing step a 2.8;

step a 2.7: if j is>＝I_iAnd f (I, j) ═ f (I-1, j-I)_i)+I_iThen the address addr [ i ] of the commutation switch is saved]To the array adjust _ button [ ptr ]]And j is j-I_iI-1; otherwise, i-1, performing step a 2.6;

step a 2.8: sequentially recording the addresses in the adjust _ button [ ptr ]]The current phase and the target phase information corresponding to the phase change switch in the phase change switch system are equal, and the final phase change switch action sequence S is recorded_eq；

Step a 3: p for compensating negative current_out1The remaining phase-change switches in one phase being switched to another phase P in which the compensation current is positive_{entry1_2}Phase, the dynamic programming algorithm 1.1 step a2 is executed again;

step a 4: p for compensating negative current_{out1_1}Phase, P_{out1_2}Partial commutation switches in phase to P with positive compensation current_entry1Respectively executing the dynamic programming algorithm 1.1 step a2, and recording the final phase change switch action sequence S_eq。

Preferably, in step 7, if k is 1, step b is performed,

step b: algorithm 2 is performed, comprising the following steps:

step b 1: using unregulated currents less than average current I_avP _1 and P _2 two-phase current I₁、I₂And an adjustable current I of another phase P _3_{3_adj}Recalculating average current, compensating current I_{1_comp}、I_{2_comp}：

I_av2＝(I_{3_adj}+I₁+I₂)/2I_{1_comp}＝I_av2-I₁；I_{2_comp}＝I_av2-I₂

Wherein, P _1, P _2, P _ 3E (A, B, C), I₁、I₂∈(I_A、I_B、I_C)，I_{1_adj}、I_{2_adj}、I_{3_adj}∈(I_{A_adj}、I_{B_adj}、I_{C_adj})；

Step b 2: if I_{1_comp}<0, if I_{1_adj}<＝|I_{1_comp}If not, all the phase change switches of the two phases are switched to the P _2 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _2 phase, and then a step a2 of a dynamic programming algorithm 1.1 is executed to switch partial phase change switches of the P _1 phase to the P _2 phase;

step b 3: if I_{1_comp}>0 and I_{2_comp}<0, if I_{2_adj}<＝|I_{2_comp}If not, all the phase change switches of the two phases are switched to the P _1 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _1 phase, then a step a2 of a dynamic programming algorithm 1.1 is executed, and partial phase change switches of the P _2 phase are switched to the P _1 phase;

step b 4: if I_{1_comp}>0 and I_{2_comp}>0, if I_{1_comp}|<|I_{2_comp}Executing a step a2 to switch the P _3 phase partial commutation switch to the P _2 phase, and switch the rest commutation switches to the P _1 phase; otherwise, step a2 is executed to switch the P _3 phase commutation switch to P _1 phase, switch the rest phase commutation switches to P _2 phase, and record the final commutation switch action sequence S_eq。

Preferably, in step 7, if k is 2, step c is performed,

step c: algorithm 3 is performed to swap in a phase P, which is a phase with a non-adjustable current less than the average current_entry3All the phase change switches of the other two phases are switched to P_entry3Phase and recording the phase change switch action sequence S_eq。

Preferably, the step 8 greedy algorithm comprises in particular the following steps:

step 8.1: rejecting faulty commutation switches, according to which commutation is switched onOff current I_SiiSorting from large to small and encoding 1_iiThe current phase of the commutation switch ii is P_iiE (A, B, C), initializing ii as 1;

step 8.2: find min (I)_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) Corresponding phase X e (A, B, C), then I_{X_Nadj}∈(I_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) If ii<N_iiStep 8.3 is executed, otherwise step 9 is executed;

step 8.3: calculation of I_{X_Nadj}+＝I_Sii，X∈(A、B、C)；

Step 8.4: if P_iiPhase not X phase, then I_{Pii_sum}－＝I_SiiAnd I_{X_sum}+＝I_Sii(ii) a Otherwise, let ii be ii +1 and perform step 8.2;

step 8.5: calculating the degree of unbalance B_greIf B is_gre<B_minThen B will be_greIs assigned to B_minStep 8.2 is executed with ii ═ ii +1, and the commutation switch action sequence S is recorded_{eq_gre}(ii) a Otherwise let ii be ii +1 and perform step 8.2.

Compared with the prior art, the three-phase unbalance automatic adjusting algorithm based on the phase change switch has the following beneficial effects:

the invention provides a phase change switch scheduling algorithm combining a phase separation algorithm, a dynamic programming algorithm and a greedy algorithm with the aim of reducing the station area unbalance. The algorithm evaluates the unbalance of the three-phase system at intervals, starts the phase-splitting algorithm to optimize when the evaluation result needs phase-shifting to obtain a phase-shifting switch action sequence, judges the optimization effect to decide whether to start the greedy algorithm, and selects a phase-shifting sequence with better optimization effect of the greedy algorithm and the phase-splitting algorithm. And finally, sending the commutation command to a commutation switch for execution. Due to the design of the multi-stage algorithm, the defect that the dynamic programming or greedy algorithm is trapped in local optimization can be avoided to a large extent, the operation is more stable, and the three-phase unbalance is obviously reduced. Compared with a capacitive device, the device has higher precision and lower power consumption; compared with the power electronic device, the line loss can be reduced, and the three-phase imbalance can be treated from the source. And a good solution is provided for safe, stable and economic operation of the power distribution network.

Drawings

FIG. 1 is a flow chart of an embodiment of the present invention;

FIG. 2 is a schematic diagram of a three-phase unbalance automatic adjusting system based on a phase change switch;

FIG. 3 is a flow chart of the implementation of algorithm 1;

FIG. 4 is a flow chart of the algorithm 1.1 dynamic programming implementation;

fig. 5 is a flow chart of the implementation of algorithm 2.

Detailed Description

The following detailed description of the three-phase imbalance automatic adjustment algorithm based on the commutation switch according to the present invention is provided with reference to fig. 1-5.

As shown in fig. 1, an automatic three-phase imbalance adjusting algorithm based on a commutation switch includes the following steps:

step 1: starting a master control terminal T₁And a phase change switch for detecting the main control terminal T₁And (3) whether the operation is normal or not, if the operation is normal, entering the step (2), and if not, closing and locking the controller, recording the fault reason and uploading to the master station.

Step 2: setting three-phase current unbalance threshold B_thThreshold value N of number of overrun times_BthThreshold value of load factor R_thInterval time t of load state detection₁Number of overrun times N_thInitialized to 0, rated current I of transformer_N。

And step 3: as shown in fig. 2, the main control terminal T₁Is arranged at the side of the transformer, is externally connected with a three-phase four-wire power supply and is externally connected with a current transformer CT for detecting the total current I of each phase at the outgoing line side of the transformer_A、I_B、I_C。

Calculating the current average current and the unbalance degree of the three-phase current:

I_av＝(I_A+I_B+I_C)/3

B＝[max(I_A,I_B,I_C)-min(I_A,I_B,I_C)]/max(I_A,I_B,I_C)

calculating the current load rate:

R＝max(I_A,I_B,I_C)/I_Nwherein, I_NFor rated current of transformer

And 4, step 4: if the current is three-phase unbalance degree B>＝B_thAnd R is>＝R_thThe number of overrun times N_thAdding 1 and executing step 5, if the threshold value is not exceeded, N _th0, and waiting for a time interval t₁And then continues to step 3.

And 5: will overrun the number N_thAnd an overrun number threshold N_BthComparing, if the threshold value is exceeded, executing step 6 and exceeding the limit number N_thReset to 0, if not exceeded wait for t₁Step 3 is performed.

Step 6: as shown in fig. 2, a commutation switch S₁...S_i...S_N(N is the number of the phase change switches) arranged on the single-phase user side, the incoming line is a three-phase four-wire line, the outgoing line is connected with the single-phase line of the user, and the load current I of the phase change switches is detected_Si(ii) a Main control terminal T₁By Lora or carrier with commutation switch S_iCommunication, acquisition of commutation switch S_iAt the current phase P_iLoad current I_SiData such as fault status.

Calculating the current I to be compensated for each phase_{A_comp}、I_{B_comp}、I_{C_comp}：

I_{A_comp}＝I_av-I_A；I_{B_comp}＝I_av-I_B；I_{C_comp}＝I_av-I_C

Eliminating fault reversing switch and calculating adjustable current I of each phase_{A_adj}、I_{B_adj}、I_{C_adj}：

Wherein each phase adjustable current finger is connected with the load of the fault-free phase change switchSum of currents, N_A、N_B、N_CRespectively the number of faultless commutation switches accessed by the current phase.

Calculating the current I of each phase_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}：

I_{A_Nadj}＝I_A-I_{A_adj}；I_{B_Nadj}＝I_B-I_{B_adj}；I_{C_Nadj}＝I_C-I_{C_adj}

The non-adjustable current refers to the sum of load currents which are not connected into the phase change switch or connected into the fault phase change switch.

And 7: and judging the number k of phases with the current which cannot be regulated and larger than the average current, recording the corresponding phases, starting an phase separation algorithm, executing a step 8 if k is 0, executing a step 9 if k is 1, and executing a step 10 if k is 2.

And 8: as shown in fig. 3, executing algorithm 1 includes the following steps:

step 8.1: calculating the number m of phases with positive compensation current and recording the corresponding phases, and if m is 2, firstly, P with negative compensation current_out1Partial commutation switches in phase to P with positive compensation current_{entry1_1}And (3) executing the step 8.2; if m ≠ 2, step 8.4 is performed.

Step 8.2: as shown in fig. 4, a dynamic programming algorithm 1.1 is executed, comprising the steps of:

step 8.2.1: encoding P based on 01 knapsack model_outThe phase change switch is 1_outTotal N_outAn article with addr [ i ] as address]The corresponding adjustable current is I₁...I_i...I_NoutValue for each item and the backpack space occupied, P_entry1The current whose phase needs to be compensated is I_comp1Is the total capacity of the backpack; then f (i, j) represents the preceding i (1. ltoreq. i.ltoreq.N)_out) The capacity of each article can be j (j is more than or equal to 1 and less than or equal to I)_comp1) The maximum value of the items in the backpack of (1); and initializing i to 1, j to 1, f (i, 0) to 0, and f (0, j) to 0.

Step 8.2.2: eliminating the already-existing array adjust _ button [ ptr ]]And will remainAddress storing addr [ i ] for phase change switch]The recoding phase change switch is 1_outCorresponding adjustable current I₁...I_i...I_NoutThe initialization is 1, 0, and 0.

Step 8.2.3: if i<＝N_outThen step 8.2.4 is performed; otherwise, let i equal to N_out、j＝|I_comp1And proceeds to step 8.2.6.

Step 8.2.4: if j is<＝|I_comp1If yes, executing step 8.2.5; otherwise i +1 and step 8.2.3 is performed.

Step 8.2.5: if I_iLess than j, f (I, j) equals max (f (I-1, j), f (I-1, j-I)_i)+I_i) Otherwise, f (i, j) is f (i-1, j); let j equal j +1 and perform step 8.2.4.

Step 8.2.6: if i > -1, go to step 8.2.7; otherwise, step 8.2.8 is performed.

Step 8.2.7: if j is>＝I_iAnd f (I, j) ═ f (I-1, j-I)_i)+I_iThen the address addr [ i ] of the commutation switch is saved]To the array adjust _ button [ ptr ]]And j is j-I_iI-1; otherwise, i-1, go to step 8.2.6.

Step 8.2.8: sequentially recording the addresses in the adjust _ button [ ptr ]]The current phase and the target phase information corresponding to the phase change switch in the phase change switch system are equal, and the final phase change switch action sequence S is recorded_eq。

Step 8.3: p for compensating negative current_out1The remaining phase-change switches in one phase being switched to another phase P in which the compensation current is positive_{entry1_2}In phase, the dynamic programming algorithm 1.1, step 8.2 is executed again.

Step 8.4: p for compensating negative current_{out1_1}Phase, P_{out1_2}Partial commutation switches in phase to P with positive compensation current_entry1Respectively executing a dynamic programming algorithm 1.1 step 8.2, and recording a final phase change switch action sequence S_eq。

And step 9: as shown in fig. 5, algorithm 2 is performed, comprising the following steps:

step 9.1: using unregulated currentLess than the average current I_avP _1 and P _2 two-phase current I₁、I₂And an adjustable current I of another phase P _3_{3_adj}Recalculating average current, compensating current I_{1_comp}、I_{2_comp}：

I_av2＝(I_{3_adj}+I₁+I₂)/2 I_{1_comp}＝I_av2-I₁；I_{2_comp}＝I_av2-I₂

Wherein, P _1, P _2, P _ 3E (A, B, C), I₁、I₂∈(I_A、I_B、I_C)，I_{1_adj}、I_{2_adj}、I_{3_adj}∈(I_{A_adj}、I_{B_adj}、I_{C_adj})。

Step 9.2: if I_{1_comp}<0, if I_{1_adj}<＝|I_{1_comp}If not, all the phase change switches of the two phases are switched to the P _2 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _2 phase, and then a dynamic programming algorithm 1.1, step 8.2 is executed to switch partial phase change switches of the P _1 phase to the P _2 phase.

Step 9.3: if I_{1_comp}>0 and I_{2_comp}<0, if I_{2_adj}<＝|I_{2_comp}If not, all the phase change switches of the two phases are switched to the P _1 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _1 phase, then a dynamic programming algorithm 1.1 step 8.2 is executed, and partial phase change switches of the P _2 phase are switched to the P _1 phase.

Step 9.4: if I_{1_comp}>0 and I_{2_comp}>0, if I_{1_comp}|<|I_{2_comp}Executing step 8.2 to switch the P _3 phase partial phase change switch to the P _2 phase, and switching the rest phase change switches to the P _1 phase; otherwise, step 8.2 is executed to switch the P _3 phase part of the phase change switches to the P _1 phase, the rest phase change switches to the P _2 phase, and the final phase change switch action sequence S is recorded_eq。

Step 10: algorithm 3 is performed to swap in a phase P, which is a phase with a non-adjustable current less than the average current_entry3All the phase change switches of the other two phases are switched to P_entry3Phase and recording the phase change switch action sequence S_eq。

Step 11: calculating the three-phase unbalance degree B according to the switching action sequence optimized by the algorithm_opt，B_{th_gre}Threshold is enabled for greedy algorithm, if B_opt>B_{th_gre}And the number k of phases with unregulated current greater than the average current<2, the greedy algorithm is enabled, as shown in fig. 1, and the method comprises the following steps:

step 11.1: rejecting faulty commutation switches, according to commutation switch current I_SiiSorting from large to small and encoding 1_iiThe current phase of the commutation switch ii is P_iiE (A, B, C), initialize ii equal to 1.

Step 11.2: find min (I)_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) Corresponding phase X e (A, B, C), then I_{X_Nadj}∈(I_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) If ii<N_iiStep 11.3 is performed, otherwise step 12 is performed.

Step 11.3: calculation of I_{X_Nadj}+＝I_Sii，X∈(A、B、C)。

Step 11.4: if P_iiPhase not X phase, then I_{Pii_sum}－＝I_SiiAnd I_{X_sum}+＝I_Sii(ii) a Otherwise let ii be ii +1 and perform step 11.2.

Step 11.5: calculating the degree of unbalance B_greIf B is_gre<B_minThen B will be_greIs assigned to B_minStep 11.2 is executed with ii ═ ii +1, and the commutation switch action sequence S is recorded_{eq_gre}(ii) a Otherwise let ii be ii +1 and perform step 11.2.

Step 12: if B after the phase-splitting algorithm is executed_optAnd B after greedy algorithm execution_minIn contrast, if B_opt>B_minAnd then a switching action sequence S generated by a greedy algorithm is adopted_{eq_gre}Otherwise, adopting a switching action sequence S generated by a phase-splitting algorithm_eq。

Step 13: as shown in fig. 2, the main control terminal T₁And sending the optimization result, namely the switching action sequence to the phase change switch through a carrier or a Lora wireless module.

Step 14: as shown in fig. 2, the commutation switch receives the master control terminal T through Lora or carrier communication₁And feeds back a commutation result to the main control terminal T through Lora or carrier communication₁。

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

In addition to the technical features described in the specification, the technology is known to those skilled in the art.

Claims (5)

1. A three-phase unbalance automatic adjustment algorithm based on a phase change switch is characterized by comprising the following steps:

step 1: starting a master control terminal T₁And a phase change switch for detecting the main control terminal T₁If the operation is normal, entering the step 2 if the operation is normal, otherwise, closing and locking the controller, recording the fault reason and uploading to the master station;

step 2: setting three-phase current unbalance threshold B_thThreshold value N of number of overrun times_BthThreshold value of load factor R_thInterval time t of load state detection₁Number of overrun times N_thInitialized to 0, rated current I of transformer_N；

And step 3: main control terminal T₁Is arranged at the side of the transformer, is externally connected with a three-phase four-wire power supply and is externally connected with a current transformer CT for detecting the total current I of each phase at the outgoing line side of the transformer_A、I_B、I_C；

Calculating the current average current and the unbalance degree of the three-phase current:

I_av＝(I_A+I_B+I_C)/3

B＝[max(I_A,I_B,I_C)-min(I_A,I_B,I_C)]/max(I_A,I_B,I_C)

calculating the current load rate:

R＝max(I_A,I_B,I_C)/I_Nwherein, I_NFor rated current of transformer

And 4, step 4: if the current is three-phase unbalance degree B>＝B_thAnd R is>＝R_thThe number of overrun times N_thAdding 1 and executing step 5, if the threshold value is not exceeded, N_th0, and waiting for a time interval t₁Then continuing to execute the step 3;

and 5: will overrun the number N_thAnd an overrun number threshold N_BthComparing, if the threshold value is exceeded, executing step 6 and exceeding the limit number N_thReset to 0, if not exceeded wait for t₁Executing the step 3;

step 6: commutation switch S₁...S_i...S_N(N is the number of the phase change switches) arranged on the single-phase user side, the incoming line is a three-phase four-wire line, the outgoing line is connected with the single-phase line of the user, and the load current I of the phase change switches is detected_Si(ii) a Main control terminal T₁By Lora or carrier with commutation switch S_iCommunication, acquisition of commutation switch S_iAt the current phase P_iLoad current I_SiFault state data;

calculating the current I to be compensated for each phase_{A_comp}、I_{B_comp}、I_{C_comp}：

I_{A_comp}＝I_av-I_A；I_{B_comp}＝I_av-I_B；I_{C_comp}＝I_av-I_C

Eliminating fault reversing switch and calculating adjustable current I of each phase_{A_adj}、I_{B_adj}、I_{C_adj}：

Wherein, each phase adjustable current refers to the sum of load currents of the fault-free phase change switches, N_A、N_B、N_CThe number of the faultless commutation switches accessed by the current phase is respectively;

calculating the current I of each phase_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}：

I_{A_Nadj}＝I_A-I_{A_adj}；I_{B_Nadj}＝I_B-I_{B_adj}；I_{C_Nadj}＝I_C-I_{C_adj}

Wherein, the current which can not be adjusted refers to the sum of load currents which are not connected into the phase change switch or connected into the fault phase change switch;

and 7: judging the number k of phases with the current being larger than the average current, recording the corresponding phases, starting a phase splitting algorithm, and recording the final action sequence S of the phase change switch_eq；

And 8: switching sequence S optimized according to a phase-splitting algorithm_eqCalculating the degree of unbalance of three phases B_opt，B_{th_gre}Threshold is enabled for greedy algorithm, if B_opt>B_{th_gre}And the number k of phases with unregulated current greater than the average current<2, starting a greedy algorithm, and recording the final action sequence S of the phase change switch_{eq_gre}Sequence of actions S of a switch optimized according to a greedy algorithm_{eq_gre}Calculating the degree of unbalance of three phases B_min；

And step 9: if B after the phase-splitting algorithm is executed_optAnd B after greedy algorithm execution_minIn contrast, if B_opt>B_minAnd then a switching action sequence S generated by a greedy algorithm is adopted_{eq_gre}Otherwise, adopting a switching action sequence S generated by a phase-splitting algorithm_eq；

Step 10: main control terminal T₁Sending an optimization result, namely a switching action sequence to a phase change switch through a carrier or a Lora wireless module;

step 11: the phase change switch receives the master control terminal T through Lora or carrier communication₁And performing commutation and will commutateThe result is fed back to the main control terminal T through Lora or carrier communication₁。

2. The commutation switch-based three-phase imbalance automatic regulating algorithm according to claim 1, wherein in step 7, if k is 0, step a is executed,

step a, executing an algorithm 1, comprising the steps of:

step a 1: calculating the number m of phases with positive compensation current and recording the corresponding phases, and if m is 2, firstly, P with negative compensation current_out1Partial commutation switches in phase to P with positive compensation current_{entry1_1}Phase, performing step a 2; if m ≠ 2, executing step a 4;

step a 2: executing a dynamic programming algorithm 1.1, comprising the steps of:

step a 2.1: encoding P based on 01 knapsack model_outThe phase change switch is 1_outTotal N_outAn article with addr [ i ] as address]The corresponding adjustable current is I₁...I_i...I_NoutValue for each item and the backpack space occupied, P_entry1The current whose phase needs to be compensated is I_comp1Is the total capacity of the backpack; then f (i, j) represents the preceding i (1. ltoreq. i.ltoreq.N)_out) The capacity of each article can be j (j is more than or equal to 1 and less than or equal to I)_comp1) The maximum value of the items in the backpack of (1); and initializing i-1, j-1, f (i, 0) 0, f (0, j) 0;

step a 2.2: eliminating the already-existing array adjust _ button [ ptr ]]And stores the address of the remaining commutation switch in addr [ i ]]The recoding phase change switch is 1_outCorresponding adjustable current I₁...I_i...I_NoutInitializing i to 1, j to 1, f (i, 0) to 0, and f (0, j) to 0;

step a 2.3: if i<＝N_outStep a2.4 is executed; otherwise, let i equal to N_out、j＝|I_comp1And performing step a 2.6;

step a 2.4: if j is<＝|I_comp1If yes, executing step a 2.5; otherwise i is i +1 and step a2.3 is performed;

step a 2.5: if I_iLess than j, f (I, j) equals max (f (I-1, j), f (I-1, j-I)_i)+I_i) Otherwise, f (i, j) is f (i-1, j); let j equal j +1 and perform step a 2.4;

step a 2.6: if i > -1, step a2.7 is executed; otherwise, executing step a 2.8;

step a 2.7: if j is>＝I_iAnd f (I, j) ═ f (I-1, j-I)_i)+I_iThen the address addr [ i ] of the commutation switch is saved]To the array adjust _ button [ ptr ]]And j is j-I_iI-1; otherwise, i-1, performing step a 2.6;

step a 2.8: sequentially recording the addresses in the adjust _ button [ ptr ]]The current phase and the target phase information corresponding to the phase change switch in the phase change switch system are equal, and the final phase change switch action sequence S is recorded_eq；

Step a 3: p for compensating negative current_out1The remaining phase-change switches in one phase being switched to another phase P in which the compensation current is positive_{entry1_2}Phase, the dynamic programming algorithm 1.1 step a2 is executed again;

step a 4: p for compensating negative current_{out1_1}Phase, P_{out1_2}Partial commutation switches in phase to P with positive compensation current_entry1Respectively executing the dynamic programming algorithm 1.1 step a2, and recording the final phase change switch action sequence S_eq。

3. The commutation switch-based three-phase imbalance automatic adjustment algorithm according to claim 2, wherein in step 7, if k is 1, step b is executed,

step b: algorithm 2 is performed, comprising the following steps:

step b 1: using unregulated currents less than average current I_avP _1 and P _2 two-phase current I₁、I₂And an adjustable current I of another phase P _3_{3_adj}Recalculating average current, compensating current I_{1_comp}、I_{2_comp}：

I_av2＝(I_{3_adj}+I₁+I₂)/2；I_{1_comp}＝I_av2-I₁；I_{2_comp}＝I_av2-I₂

Wherein, P _1, P _2, P _ 3E (A, B, C), I₁、I₂∈(I_A、I_B、I_C)，I_{1_adj}、I_{2_adj}、I_{3_adj}∈(I_{A_adj}、I_{B_adj}、I_{C_adj})；

Step b 2: if I_{1_comp}<0, if I_{1_adj}<＝|I_{1_comp}If not, all the phase change switches of the two phases are switched to the P _2 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _2 phase, and then a step a2 of a dynamic programming algorithm 1.1 is executed to switch partial phase change switches of the P _1 phase to the P _2 phase;

step b 3: if I_{1_comp}>0 and I_{2_comp}<0, if I_{2_adj}<＝|I_{2_comp}If not, all the phase change switches of the two phases are switched to the P _1 phase, otherwise, all the phase change switches of the P _3 phase are switched to the P _1 phase, then a step a2 of a dynamic programming algorithm 1.1 is executed, and partial phase change switches of the P _2 phase are switched to the P _1 phase;

step b 4: if I_{1_comp}>0 and I_{2_comp}>0, if I_{1_comp}|<|I_{2_comp}Executing a step a2 to switch the P _3 phase partial commutation switch to the P _2 phase, and switch the rest commutation switches to the P _1 phase; otherwise, step a2 is executed to switch the P _3 phase commutation switch to P _1 phase, switch the rest phase commutation switches to P _2 phase, and record the final commutation switch action sequence S_eq。

4. The commutation switch-based three-phase imbalance automatic adjustment algorithm according to claim 1, wherein in step 7, if k is 2, step c is executed,

step c: algorithm 3 is performed to swap in a phase P, which is a phase with a non-adjustable current less than the average current_entry3All the phase change switches of the other two phases are switched to P_entry3Phase and recording the phase change switch action sequence S_eq。

5. The commutation switch-based three-phase imbalance automatic regulation algorithm according to any one of claims 1-4, wherein the step 8 greedy algorithm specifically comprises the following steps:

step 8.1: rejecting faulty commutation switches, according to commutation switch current I_SiiSorting from large to small and encoding 1_iiThe current phase of the commutation switch ii is P_iiE (A, B, C), initializing ii as 1;

step 8.2: find min (I)_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) Corresponding phase X e (A, B, C), then I_{X_Nadj}∈(I_{A_Nadj}、I_{B_Nadj}、I_{C_Nadj}) If ii<N_iiStep 8.3 is executed, otherwise step 9 is executed;

step 8.3: calculation of I_{X_Nadj}+＝I_Sii，X∈(A、B、C)；

Step 8.4: if P_iiPhase not X phase, then I_{Pii_sum}－＝I_SiiAnd I_{X_sum}+＝I_Sii(ii) a Otherwise, let ii be ii +1 and perform step 8.2;

step 8.5: calculating the degree of unbalance B_greIf B is_gre<B_minThen B will be_greIs assigned to B_minStep 8.2 is executed with ii ═ ii +1, and the commutation switch action sequence S is recorded_{eq_gre}(ii) a Otherwise let ii be ii +1 and perform step 8.2.

Images