Bidirectional regulation type voltage stabilization compensation device suitable for double buses

Abstract

The invention provides a two-way adjusting type voltage stabilization compensation device suitable for double buses, and relates to the field of 110 kV voltage class voltage stabilization compensation, which comprises a first 110 kV compensation outgoing line interval part, a second 110 kV compensation outgoing line interval part and a third 110 kV compensation outgoing line interval part, a first 110kV bus incoming line spacing part; a first outdoor primary device; a first indoor control system; a second 110kV compensation outgoing line interval part; a second 110kV bus inlet wire interval part; a second outdoor primary device; and a second indoor control system. According to the invention, the problems of unqualified voltage quality and unbalanced reactive power flow of a 110kV level of a region caused by over-high voltage of the third winding of the transformer and incapability of effectively compensating reactive power capacity required by a 110kV side by a 35kV or 10kV capacitor bank although the system lacks reactive power due to no outgoing line load or small outgoing line load of the third winding of the transformer of the 220 / 330kV transformer substation are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 110kV voltage level voltage stabilization compensation, in particular, to a two-bus two-way regulation type voltage stabilization compensation device. BACKGROUND

[0002] With the rise of new energy industry, especially the increase of a large number of high-energy consumption electric arc furnaces such as industrial silicon and ferroalloy, the power grid load grows rapidly. Such enterprises generally use 110kV (or 220kV / 330kV) power grid for power supply, and 110kV becomes the main load side of the substation of such electric arc furnace smelting enterprises. 110kV direct hanging compensation also becomes the key consideration object of the substation construction of such electric arc furnace smelting enterprises. At present, the substation of such electric arc furnace smelting enterprises mostly uses third winding compensation or 110kV grouping switching for compensation. However, the following problems exist in the actual application and need to be solved.

[0003] 1. Problems existing in third winding compensation. At present, the design and installation mode of the reactive power compensation device of the 220kV (or 330kV) substation of the power grid mostly selects the third winding (35kV or 10kV voltage level side) of the transformer. However, this third winding compensation mode has the following shortcomings.

[0004] (1) The third winding of the transformer of the 220kV substation has no or small out-line load, which causes the system to lack reactive power. However, due to the excessively high voltage of the third winding of the transformer, the 35kV or 10kV capacitor bank cannot effectively compensate the required reactive power capacity of the 110kV side, thereby causing the voltage quality of the 110kV level to be unqualified and the reactive power flow to be unbalanced.

[0005] (2) It cannot meet the requirement of the national standard GB50227—2017 "Design Specification for Shunt Capacitor Device" that "high-voltage shunt capacitor device should be installed at the main load side of the transformer". At the same time, the shunt capacitor is configured at the third winding, i.e. the 35kV or 10kV side, of the transformer. Due to the limitation of the rated current, the single capacity of the shunt capacitor bank cannot be too large.

[0006] (3) In the case of the existence of the out-line of the transformer, due to the large through impedance between the medium voltage side and the low voltage side of the transformer, the reactive power capacity of the third winding is difficult to compensate to the medium voltage side. At the same time, the through reactive power flow of the system increases the load rate of the transformer and increases the loss of the transformer.

[0007] 2. Problems existing in the 110kV grouping switching mode. In view of the shortcomings of the third winding compensation, in recent years, the 220kV or 330kV substation directly configures the shunt compensation complete device with the grouping switching mode at the main load side of 110kV. However, the grouping switching mode also has the following prominent problems:

[0008] (1) Large switching inrush current: capacitor grouping compensation adopts full voltage switching circuit breaker, resulting in large switching inrush current, frequent switching will cause capacitor membrane breakdown, and switching circuit breaker contacts are often damaged, affecting the service life of the capacitor.

[0009] (2) Overvoltage of parallel capacitor group operation: when the capacitor group is switched, arc reignition sometimes occurs at the breaking point of the circuit breaker, causing reignition overvoltage, and the equipment is seriously damaged, which seriously affects the service life of the capacitor.

[0010] (3) Easy over-compensation or under-compensation: due to fewer groups and larger capacity of each group, over-compensation or under-compensation is easy to occur. Switching of large-capacity capacitors will cause fluctuations in bus voltage.

[0011] (4) Large floor area and high civil engineering cost: the more groups, the larger the floor area and the more investment.

[0012] (5) Low degree of automation: 110kV capacitors generally use manual switching operation, which has low degree of automation, long operation time, and poor reactive power following.

[0013] (6) Unable to adjust capacitive reactive power: the enterprise load hour, the measurement point power factor is ahead, resulting in penalty.

[0014] 3. The existing reactive power of 110kV substation is ahead of the problem. The substation or switch station of the electric arc furnace smelting enterprise is usually a special line construction, and the line property belongs to the enterprise. The property boundary point is at the junction of the outgoing line of the upper substation, and the measurement point is set in the upper substation. Therefore, the electric arc furnace smelting enterprise generally has a long incoming line and a large charging power, and the charging power of the cable incoming line is even multiplied. Therefore, when the enterprise is lightly loaded, the measurement point power factor is ahead of the line charging and even lower than 0.9, which brings the enterprise to the power adjustment electricity penalty, increasing the operating cost of the enterprise.

[0015] 4. The existing compensation cannot meet the demand of full automation operation. In order to increase the stability of power supply, the 110kV or above power supply bus of the high-energy-consuming electric arc furnace smelting enterprise of industrial silicon and ferroalloy adopts double bus structure. At present, 110kV compensation is mostly operated manually, and there is no 110kV direct hanging compensation full-automatic control system for this double bus structure on the market, which increases a lot of work for the automatic operation of the substation, and the compensation following is very poor, which has a great impact on production.

[0016] In view of the problems in the related art, no effective solution has been proposed so far. SUMMARY

[0017] Therefore, the present application provides a double bus bidirectional regulation type voltage stabilizing compensation device, which solves the above-mentioned problems.

[0018] To solve the above problems, the specific technical solutions adopted by the present application are as follows:

[0019] A two-mother-line bidirectional regulation type voltage stabilizing compensation device, comprising:

[0020] A first 110kV compensation outgoing line interval part, and the first 110kV compensation outgoing line interval part is connected with the 110kV double bus, and the first 110kV compensation outgoing line interval part is used for feeding the adjusted reactive current into the 110kV double bus;

[0021] A first 110kV bus incoming line interval part, and the first 110kV bus incoming line interval part is connected with the 110kV double bus, and the first 110kV bus incoming line interval part is used for feeding electric energy into the 110kV double bus;

[0022] A first outdoor primary equipment, which is arranged at one end of the first 110kV compensation outgoing line interval part, and the first outdoor primary equipment is used for changing the output reactive current through gear adjustment;

[0023] A first indoor control system, which is connected with the first outdoor primary equipment through a secondary signal cable, and the first indoor control system is used for automatically judging the bus operation mode according to the positions of the disconnectors and circuit breakers in the first outdoor primary equipment, and automatically calculating and selecting the compensation target;

[0024] A second 110kV compensation outgoing line interval part, and the second 110kV compensation outgoing line interval part is connected with the 110kV double bus, and the second 110kV compensation outgoing line interval part is used for feeding the adjusted reactive current into the 110kV double bus;

[0025] A second 110kV bus incoming line interval part, and the second 110kV bus incoming line interval part is connected with the 110kV double bus, and the second 110kV bus incoming line interval part is used for feeding electric energy into the 110kV double bus;

[0026] A second outdoor primary equipment, which is arranged at one end of the second 110kV compensation outgoing line interval part, and the second outdoor primary equipment is used for changing the output reactive current through gear adjustment;

[0027] A second indoor control system, which is connected with the second outdoor primary equipment through a secondary signal cable, and the second indoor control system is connected with the first indoor control system, and the second indoor control system is used for automatically judging the bus operation mode according to the positions of the disconnectors and circuit breakers in the second outdoor primary equipment, and automatically calculating and selecting the compensation target.

[0028] Preferably, the first outdoor primary equipment comprises: a disconnecting switch QS, a voltage regulator T, a current transformer TA4, a capacitive compensation branch and an inductive compensation branch;

[0029] The disconnecting switch QS is used for electrical disconnection of the first outdoor primary equipment during operation and maintenance, and is connected to the first 110kV compensation outgoing line interval through overhead lines or cables, and the disconnecting switch QS contains a grounding switch QG1.

[0030] The voltage regulator T is arranged at one end of the disconnecting switch QS.

[0031] The current transformer TA4 is arranged at one end of the voltage regulator T and is used to provide a current signal.

[0032] The capacitive compensation branch is used to compensate for inductive reactive power generated during normal operation of the load.

[0033] The inductive compensation branch is used to compensate for the capacitive reactive power of the cable during light load.

[0034] One end of the capacitive compensation branch and the inductive compensation branch is connected to one end of the current transformer TA4.

[0035] Preferably, the capacitive compensation branch comprises: a capacitive branch installation circuit breaker QF1, a capacitive branch series reactor L1, an overvoltage damping device, a lightning arrester FV, a capacitor bank C and a grounding switch QG2.

[0036] The capacitive branch installation circuit breaker QF1 is arranged at one end of the current transformer TA4.

[0037] The capacitive branch series reactor L1 is arranged at the other end of the capacitive branch installation circuit breaker QF1.

[0038] The overvoltage damping device is connected in parallel across the capacitive branch series reactor L1, and is used to suppress overvoltage on the capacitor bank C.

[0039] The lightning arrester FV is arranged at one end of the capacitive branch series reactor L1.

[0040] The capacitor bank C is arranged at one end of the lightning arrester FV.

[0041] The grounding switch QG2 is arranged at one end of the capacitor bank C.

[0042] Preferably, the overvoltage damping device is composed of a resistor R and a gap G.

[0043] One end of the resistor R is connected with one end of the capacitive branch installation circuit breaker QF1, the other end of the resistor R is connected with one end of the gap G, the other end of the gap G is connected with the other end of the capacitive branch series reactor L1 and the other end of the lightning arrester FV.

[0044] Preferably, the inductive compensation branch includes: an inductive branch installation circuit breaker QF2 and an inductive branch shunt reactor L2.

[0045] The inductive branch installation circuit breaker QF2 is arranged at one end of the current transformer TA4 and connected with one end of the capacitive branch installation circuit breaker QF1.

[0046] The inductive branch shunt reactor L2 is arranged at one end of the inductive branch installation circuit breaker QF2.

[0047] Preferably, the capacitor bank C is composed of a frame type, and the capacitor bank C is divided into four bridge arms in a single-phase frame, and a bridge differential current transformer ΔI is connected across the four bridge arms.

[0048] Preferably, the first indoor control system includes a reactive power controller K1, a differential protection device K2, a capacitor protection device K3, a voltage regulating controller K4 and a monitoring background K5.

[0049] The reactive power controller K1 is used for automatically calculating and selecting control targets according to the switch positions of the 110kV double bus, and obtaining the heavy gas, light gas, pressure release, oil surface and winding temperature signals of the voltage regulator T, and performing non-electric quantity protection on the voltage regulator T.

[0050] The differential protection device K2 is used for collecting the in-line current transformer T3 signal and out-line current transformer TA4 signal of the voltage regulator T, and performing differential protection on the voltage regulator T.

[0051] The capacitor protection device K3 is used for operating the protection tripping circuit of the reactive power controller K1 and the differential protection device K2 to realize the operation of the circuit breaker.

[0052] The voltage regulating controller K4 is used for receiving the regulating signal of the reactive power controller K1, and performing up-down regulating operation on the voltage regulator T, and uploading the gear position information of the voltage regulator T to the reactive power controller K1.

[0053] The monitoring background K5 is used for monitoring the running state of the equipment by the operator, and manually operating the switch and the gear position of the voltage regulator T.

[0054] Preferably, the collecting the in-line current transformer T3 signal and out-line current transformer TA4 signal of the voltage regulator T, and performing differential protection on the voltage regulator T includes:

[0055] The incoming line side current and outgoing line side current of the voltage regulator T are collected by the current transformer TA3 and the current transformer TA4 respectively; and the current actual gear position signal is read from the voltage regulator controller K4;

[0056] Based on the change trend of the incoming line side current and the outgoing line side current, the credibility and stability coefficient of the current actual gear position are evaluated by using a niche width calculation algorithm;

[0057] When the credibility is greater than a preset threshold and exceeds the stability coefficient, the current actual gear position is taken as an effective gear position, and the differential protection setting value corresponding to the effective gear position is obtained from a pre-stored constant value area mapping table;

[0058] The gear position signal jump and current mutation are monitored in real time, when the gear position switching is detected, the gear shifting transient window is entered, and the ratio differential protection is shielded in the window;

[0059] After the gear shifting transient window ends, the latest effective gear position and the differential protection setting value corresponding thereto are obtained, and the ratio differential protection criterion is calculated and monitored in real time; when the criterion continuously satisfies a preset action condition, a trip instruction is issued to isolate the voltage regulator T;

[0060] The trip instruction is executed, and the voltage regulator T power side circuit breaker is driven to open; the event recording and fault recording are started, and the blocking state of the gear position switching function of the reactive power controller K1 is maintained until manual reset.

[0061] Preferably, the credibility of the current actual gear position based on the change trend of the incoming line side current and the outgoing line side current by using the niche width calculation algorithm comprises:

[0062] The incoming line side current and the outgoing line side current are normalized respectively, and the normalized incoming line side current and the normalized outgoing line side current are taken as state representing the current state;

[0063] The current change rates of the incoming line side current and the outgoing line side current are calculated respectively, and the current change rates are normalized to obtain the incoming line side current change rate normalized value and the outgoing line side current change rate normalized value representing the current dynamic trend;

[0064] Based on the niche width calculation model, the state representing the current state and the potential representing the current dynamic trend are weighted to obtain the credibility of the current actual gear position;

[0065] Based on the normalized incoming line side current and the normalized outgoing line side current, and combined with the stability coefficient calculation method in the Lotka-Volterra model, the stability coefficient of the current actual gear position is calculated.

[0066] Preferably, the calculation of the stability coefficient of the current actual gear based on the normalized incoming line side current and outgoing line side current and combined with the stability coefficient calculation method in the Lotka-Volterra model comprises the following steps:

[0067] Based on the normalized incoming line side current and outgoing line side current, the current relative change rate at the current time is calculated respectively;

[0068] According to the current relative change rate at the current time, the next time current relative change rate is calculated by using the first-order difference extrapolation method;

[0069] According to the stability coefficient calculation method in the Lotka-Volterra model, the relative coefficient of the incoming line side current and the outgoing line side current is calculated respectively by using the current relative change rate at the current time and the next time current relative change rate;

[0070] The relative coefficients of the incoming line side current and the outgoing line side current are weighted and averaged to obtain the final stability coefficient used for the current actual gear credibility joint determination.

[0071] The beneficial effects of the present application are:

[0072] 1. The present application solves the problem that the third winding of the transformer in the 220 / 330kV substation has no outgoing line load or small outgoing line load, causing the system to lack reactive power, but due to the high voltage of the third winding of the transformer, the 35kV or 10kV capacitor bank cannot effectively compensate the required reactive power capacity on the 110kV side, thereby causing the voltage quality of the regional 110kV level to be unqualified and the reactive power flow to be unbalanced.

[0073] 2. The present application solves the problem that the capacitive power caused by the cable charging power during light load of the enterprise is too large, resulting in power penalty.

[0074] 3. Compared with the SVG (static var generator) and MCR (magnetic control reactor type reactive power compensation device) type reactive power compensation device, the power consumption of the present application is greatly reduced, the equipment is relatively simple, and the operation and maintenance are convenient.

[0075] 4. Due to the existence of the transition circuit in the voltage regulation tap changer adjustment process, the inrush current is small during switching, which solves the problem of switch service life caused by excessive inrush current during grouping switching of traditional 110kV compensation capacitor banks, and the problem of large influence on bus voltage fluctuation.

[0076] 5. Since the capacitor bank and the reactor in the present application usually work below the rated bus voltage, the probability of overvoltage of the capacitor and the reactor is small, and the service life is longer.

[0077] 6. Since the voltage regulator in this invention can be designed with up to 14 levels, and more levels can be set according to project needs, the voltage adjustment range can be as low as 40%Un; thus, the reactive power output range of the capacitor is large and the adjustment is precise. Attached Figure Description

[0078] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0079] Figure 1 This is a schematic diagram of the principle of a bidirectional adjustable voltage stabilizing and compensating device for dual busbars according to an embodiment of the present invention;

[0080] Figure 2 This is a schematic diagram of a voltage regulator structure applicable to a dual-bus bidirectional adjustable voltage stabilization and compensation device according to an embodiment of the present invention.

[0081] Figure 3 This is a schematic diagram of the control system composition in a dual-bus bidirectional regulating voltage stabilizing and compensating device according to an embodiment of the present invention;

[0082] Figure 4 This is a schematic diagram of the switch position of a 110kV double busbar structure in a double busbar bidirectional regulating voltage stabilizing and compensating device according to an embodiment of the present invention;

[0083] Figure 5 This is a schematic diagram of a bidirectional adjustable voltage stabilizing and compensating device for dual busbars according to an embodiment of the present invention. Detailed Implementation

[0084] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0085] According to an embodiment of the present invention, a dual-bus bidirectional adjustable voltage stabilizing compensation device is provided.

[0086] Specifically, the 110kV double bus two-way regulating type voltage stabilizing compensation device, the basic compensation principle is to change the voltage regulator output voltage by adjusting, so as to change the end voltage of the parallel capacitor or the parallel reactor, according to the Q c =2πfCU 2 (capacitive) and Q L =U 2 / 2πfL(inductive) principle to change the output capacity (Q c represents the reactive power output of the capacitor bank, f represents the system frequency, C represents the capacitance value, U represents the end voltage of the capacitor bank or the reactor, Q L represents the reactive power output of the parallel reactor, L represents the inductance value of the parallel reactor). The total capacity of the parallel capacitor bank and the parallel reactor is unchanged, when the end voltage is reduced from 100%Ue to 50%Ue, the output capacity can be changed between (100%-25%)xQ, and the output is adjusted in multiple gears (at least 14 gears) in the adjustment range, the difference is small, the compensation is fine, and the overcompensation and undercompensation conditions are eliminated.

[0087] The present application is directed to the 110kV double bus structure, two sets of the same compensation equipment are used to compensate two groups of buses, when two groups of 110kV buses are operated in parallel, that is, the 110kV bus is divided, each set of device compensates one group of bus through the isolation switch. When two groups of 110kV buses are operated in parallel, that is, the 110kV bus is combined, or only one set of bus is operated, two sets of compensation devices can be operated in parallel and work coordinately. The control system needs to automatically judge the bus operation mode according to the position of the isolation switch and the circuit breaker, and automatically calculate and select the compensation target.

[0088] When the 110kV double bus two-way regulating type voltage stabilizing compensation device is normally operated, the software is limited to the lowest gear for switching, that is, 50%Ue for switching, which greatly reduces the impact of the inrush current on the equipment when the capacitor is put into operation, and reduces the risk of capacitor operating overvoltage.

[0089] In the present application, the reactor and the capacitor are designed according to the 110kV full insulation, and in operation, because the output voltage of the voltage regulator is step-down regulation, the capacitor and the reactor are always operated at rated voltage, which reduces the impact on the insulation of the equipment and increases the service life of the equipment.

[0090] The voltage regulator adopts a regulating mode of not less than 14 gears to reduce the gear voltage difference; measures are taken to reduce the inrush current during gear shifting; because the production process of large-scale smelting enterprises generates harmonics to the power grid, the 110kV voltage regulator needs to take measures to suppress the influence of harmonics on the equipment and increase the stability of the voltage regulator operation.

[0091] In the protection aspect, the 110kV voltage regulator adopts multi-gear regulation, each gear corresponds to different variable ratio of the voltage regulator, and the secondary side voltage of the voltage regulator changes between 50%~100%. The voltage regulator differential protection device is required to receive the gear signal of the voltage regulator, and different settings can be set for different transformer gears to ensure that the voltage regulator differential protection does not refuse to act or misoperate when the voltage regulator fails in each gear, to realize fine protection for each gear of the voltage regulator and increase the safety of the system.

[0092] In the control aspect, the characteristics of the 110kV double bus structure can be met, the control system can collect the positions of each circuit breaker and disconnector, can collect two sets of incoming line currents and two sets of bus voltages, can automatically judge the bus operation mode according to the switch position, and can automatically calculate the target parameters. When the two sets of compensation devices are connected in parallel, the two sets of voltage regulators can alternately raise and lower the gears to meet the load balance of the two sets of compensation devices and balance the service life of the two sets of equipment.

[0093] The application will be further described in combination with the drawings and specific embodiments, as shown in the drawings, Figure 5 The double bus bidirectional regulation type voltage stabilizing compensation device according to the embodiment of the application comprises:

[0094] A first 110kV compensation outgoing line interval part, and the first 110kV compensation outgoing line interval part is connected with the 110kV double bus, and the first 110kV compensation outgoing line interval part is used for feeding the adjusted reactive current into the 110kV double bus; specifically, the capacitive or inductive current is input to the power grid, so that the system power factor meets the interval range required by the power grid.

[0095] A first 110kV bus incoming line interval part, and the first 110kV bus incoming line interval part is connected with the 110kV double bus, and the first 110kV bus incoming line interval part is used for feeding electric energy into the 110kV double bus; specifically, the bus incoming line interval part is connected with the main transformer of the transformer substation at the upper end, and the interval part feeds electric energy into the 110kV double bus.

[0096] A first outdoor primary equipment is arranged at one end of the first 110kV compensation outgoing line interval part, and the first outdoor primary equipment is used for changing the output reactive current through gear adjustment; specifically, the basic principle of the first outdoor primary equipment is to change the output voltage of the voltage regulator by changing the gear of the voltage regulator T, so as to change the terminal voltage of the capacitor or the reactor at the back end, and then change the reactive power output, that is, change the size of the reactive current of the capacitor or the reactor.

[0097] The first indoor control system is connected with the first outdoor primary equipment through a secondary signal cable, and is used for automatically judging a bus operation mode according to positions of disconnectors and circuit breakers in the first outdoor primary equipment, and automatically calculating and selecting a compensation target; specifically, the control system, namely a control panel, is arranged in a control room and connected with the outdoor primary equipment through the secondary signal cable, the outdoor primary equipment transmits switch, current and voltage signals to the control system, and the control system adjusts and controls the outdoor primary equipment after processing the secondary signals.

[0098] The second 110kV compensation outgoing line interval part is connected with the 110kV double bus, and is used for feeding the adjusted reactive current into the 110kV double bus;

[0099] The second 110kV bus incoming line interval part is connected with the 110kV double bus, and is used for feeding electric energy into the 110kV double bus;

[0100] The second outdoor primary equipment is arranged at one end of the second 110kV compensation outgoing line interval part, and is used for changing the output reactive current through gear adjustment;

[0101] The second indoor control system is connected with the second outdoor primary equipment through a secondary signal cable, and is connected with the first indoor control system, and is used for automatically judging a bus operation mode according to positions of disconnectors and circuit breakers in the second outdoor primary equipment, and automatically calculating and selecting a compensation target.

[0102] It should be noted that the second 110kV compensation outgoing line interval part has the same structure as the first 110kV compensation outgoing line interval part, the second 110kV bus incoming line interval part has the same structure as the first 110kV bus incoming line interval part, the second outdoor primary equipment has the same structure as the first outdoor primary equipment, and the second indoor control system has the same structure as the first indoor control system.

[0103] As a preferred embodiment, the first outdoor primary equipment comprises a disconnecting switch QS, a voltage regulator T, a current transformer TA4, a capacitive compensation branch and an inductive compensation branch.

[0104] The disconnecting switch QS is used for an electrical disconnection point of the first outdoor primary equipment in operation and maintenance, and is connected with the first 110kV compensation outgoing line interval part through an overhead line or a cable, and contains a grounding switch QG1.

[0105] A voltage regulator T is arranged at one end of the disconnector QS;

[0106] A current transformer TA4 is arranged at one end of the voltage regulator T, and is used to provide a current signal;

[0107] The capacitive compensation branch is used to compensate for inductive reactive power generated by normal operation of the load;

[0108] The inductive compensation branch is used to compensate for capacitive reactive power of the cable in light load;

[0109] One end of the capacitive compensation branch and one end of the inductive compensation branch are connected to one end of the current transformer TA4.

[0110] As a preferred embodiment, the capacitive compensation branch comprises a capacitive branch-mounted circuit breaker QF1, a capacitive branch series reactor L1, an overvoltage damping device, a surge arrester FV, a capacitor bank C, and a grounding switch QG2.

[0111] The capacitive branch-mounted circuit breaker QF1 is arranged at one end of the current transformer TA4; the reactance rate of the capacitive branch-mounted circuit breaker QF1 is set according to the system harmonic condition, and the reactor plays a role in suppressing the inrush current.

[0112] The capacitive branch series reactor L1 is arranged at the other end of the capacitive branch-mounted circuit breaker QF1.

[0113] The overvoltage damping device is connected in parallel between the two ends of the capacitive branch series reactor L1, and is used to suppress overvoltage on the capacitor bank C.

[0114] The surge arrester FV is arranged at one end of the capacitive branch series reactor L1; and can protect the capacitor from surge overvoltage.

[0115] The capacitor bank C is arranged at one end of the surge arrester FV.

[0116] The grounding switch QG2 is arranged at one end of the capacitor bank C, i.e., is connected to the neutral bus of the capacitor bank C; when the capacitor bank C is shut down for maintenance, the grounding switch is closed to ground the neutral point of the capacitor bank C, thereby avoiding live maintenance operation of the equipment.

[0117] As a preferred embodiment, the overvoltage damping device is composed of a resistor R and a gap G; one end of the resistor R is connected to one end of the capacitive branch-mounted circuit breaker QF1, the other end of the resistor R is connected to one end of the gap G, and the other end of the gap G is connected to the other end of the capacitive branch series reactor L1 and the other end of the surge arrester FV.

[0118] Specifically, for the minimum shunt capacitor group micro-operation overvoltage, an overvoltage damping device is configured, which is connected in series with a gap G and is connected in parallel at both ends of a capacitive branch series reactor L1 connected in series with the capacitor group C. When the voltage acting on the capacitive branch series reactor L1 exceeds the gap breakdown voltage, the gap breakdown will connect the resistor of the overvoltage damping device into the circuit and consume the electromagnetic oscillation energy, thereby inhibiting the overvoltage on the capacitor group.

[0119] As a preferred embodiment, the inductive compensation branch includes: an inductive branch installation circuit breaker QF2 and an inductive branch shunt reactor L2.

[0120] The inductive branch installation circuit breaker QF2 is arranged at one end of the current transformer TA4 and connected with one end of the capacitive branch installation circuit breaker QF1.

[0121] The inductive branch shunt reactor L2 is arranged at one end of the inductive branch installation circuit breaker QF2, i.e. installed at the rear end of the circuit breaker QF2, and the capacity thereof is set according to the charging power of the enterprise incoming line. If there is no need to compensate for the charging reactive power of the incoming line cable, the inductive branch can not be configured.

[0122] As a preferred embodiment, the capacitor group C adopts a frame type structure, and the capacitor group C in a single-phase frame is divided into four bridge arms, and a bridge differential current transformer ΔI is connected across the four bridge arms. When the capacitor fails, the transformer will generate unbalanced current, and then the capacitor protection device will act to cut off the incoming line circuit breaker of the complete compensation device, thereby avoiding further expansion of the accident.

[0123] Specifically, as shown in Figure 1 , the primary equipment, i.e. the first outdoor primary equipment or the second outdoor primary equipment, needs to install a disconnecting switch QS in the incoming line of the primary equipment, which includes a grounding switch QG1. The incoming line terminal of the disconnecting switch QS is connected with the front-end interval equipment through overhead lines or cables. The disconnecting switch QS ensures that there is a clear electrical disconnection point when the equipment is in operation, thereby ensuring the safety of the operation and maintenance personnel. When the equipment is out of operation, the front-end disconnecting switch QS is opened, and the grounding switch QG1 is closed, thereby ensuring reliable grounding of the rear-end equipment. Figure 1

[0124] 110kV voltage regulator T in Figure 1 , the 110kV voltage regulator T is installed at the rear end of the disconnecting switch QS. The voltage regulator T adopts a self-coupling balanced winding structure, as shown in Figure 2 . Because of this connection mode, the electromagnetic capacity is small, the overall loss of the complete device can be reduced, and the self-loss of the 110kV voltage regulator is less than 0.15%. Compared with the SVG and MCR type compensation devices, the equipment loss is greatly reduced, and the operation cost is reduced.

[0125] ​The voltage regulator T installs the outgoing bushing mutual inductor or a separate external current mutual inductor to provide a current signal for the multi-step differential protection device. The voltage regulator T adopts a transition resistance circuit with a compensation capacity during the switching process, such as the resistance R1 and the resistance R2 in Figure 2 , which reduces the polar difference voltage inrush current through the transition circuit during the switching process, and solves the current impact of the voltage regulator switching on the equipment. As shown in Figure 2 , the contact position of the contacts from 1 step to 2 step is: 1 and 1-2 and 2-3 and 4, Figure 2 , wherein Pa, Pb, Pc and Py represent the lead-out connection points of the balance winding, A, B and C represent the high-voltage three-phase input lines of the voltage regulator, a, b and c represent the low-voltage three-phase output lines of the voltage regulator, U1 represents the 1 step voltage, and U2 represents the 2 step voltage.

[0126] In the compensation of the substation of such a mineral furnace enterprise, the 110kV voltage regulator needs to be configured with a balance winding, as shown in Figure 2 , the balance winding adopts a 10kV grade winding, which is arranged in the inner coil of each phase core, connected into an open delta inside the voltage regulator T, and the two open ends and the other two ends are all led out. When used, the two open ends need to be connected by a copper bar, and directly introduced into the grounding net through a grounding copper bar or cable to avoid the influence of point suspension. The balance winding adopts a delta connection, which can provide a path for 3N (N=1, 2, 3…) harmonic waves, improve the induced electromotive force waveform of the voltage regulator core, ensure that the output voltage of the regulator is a sine wave, ensure that the reactive compensation current is a sine wave without harmonic pollution to the system, and also ensure the operation stability of the reactive compensation equipment.

[0127] Compared with the existing SVG and MCR type dynamic compensation equipment, the 110kV voltage regulator does not have too many semiconductor devices and electronic control circuits, has a simple structure, stable operation, low maintenance technical threshold, and convenient operation and maintenance, and also increases the operation stability of the equipment.

[0128] In addition, considering the safe operation distance, the capacitive branch series reactor L1, the overvoltage damping device, the arrester FV and the capacitor frame in the complete set are installed inside the fence. The capacitive branch installation circuit breaker QF1, disconnector QS, voltage regulator T, grounding switch QG2 and grounding switch QG1 can be placed outside the fence for local manual operation.

[0129] As a preferred embodiment, the first indoor control system comprises a reactive power controller K1, a differential protection device K2, a capacitor protection device K3, a voltage regulating controller K4 and a monitoring background K5;

[0130] The reactive power controller K1 is used to automatically calculate and select control targets according to the switch positions of the 110kV double bus, and to obtain the heavy gas, light gas, pressure release, oil surface and winding temperature signals of the voltage regulator T, so as to perform non-electricity protection on the voltage regulator T.

[0131] The differential protection device K2 is used to collect the in-line current transformer T3 signal and out-line current transformer TA4 signal of the voltage regulator T, and to perform differential protection on the voltage regulator T.

[0132] The capacitance protection device K3 is used to operate the protection tripping circuit of the reactive power controller K1 and the differential protection device K2, so as to operate the circuit breaker.

[0133] The voltage regulation controller K4 is used to receive the regulation signal of the reactive power controller K1, and to perform upshift and downshift operations on the voltage regulator T, while uploading the gear position information of the voltage regulator T to the reactive power controller K1.

[0134] The monitoring background K5 is used for the operator to monitor the running state of the equipment, and to manually operate the switch and the gear position of the voltage regulator T.

[0135] As a preferred embodiment, the collection of the in-line current transformer T3 signal and out-line current transformer TA4 signal of the voltage regulator T, and the differential protection on the voltage regulator T include:

[0136] The in-line side current and out-line side current of the voltage regulator T are collected by the current transformer TA3 and the current transformer TA4 respectively, and the current actual gear position signal is read from the voltage regulator controller K4.

[0137] Based on the change trend of the in-line side current and the out-line side current, the niche width calculation algorithm is used to evaluate the credibility and stability coefficient of the current actual gear position.

[0138] When the credibility is greater than the preset threshold and exceeds the stability coefficient, the current actual gear position is taken as the effective gear position, and the differential protection setting corresponding to the effective gear position is obtained from the pre-stored setting area mapping table.

[0139] It should be noted that during the device initialization stage, according to the theoretical variable ratio corresponding to each gear position of the voltage regulator T, a plurality of sets of differential protection parameters are pre-adjusted, including the differential starting threshold, the ratio braking slope and the differential speed setting value, which are stored in the setting area mapping table. Once it is determined that a gear position is an effective gear position, the corresponding setting area parameters are automatically loaded into the protection logic module.

[0140] The gear position signal jump and the current sudden change are monitored in real time, when the gear switching is detected, the gear shifting transient window is entered, and the ratio differential protection is shielded in the window.

[0141] Specifically, by synchronously collecting the gear signal output by the voltage regulator controller K4 and the current signals at the input and output sides of the voltage regulator T at a high sampling frequency, for example, at 1-10 kHz, the digital gear code output by the voltage regulator controller K4 is continuously compared. If the gear value in the current sampling period is inconsistent with that in the previous period, that is, a jump occurs, it is preliminarily determined that there may be a gear shifting operation. At the same time, the instantaneous change amount of the current at the input or output side is calculated, for example, using the half-wave Fourier algorithm or the difference method. If the change amplitude of the current at either side within one power frequency period exceeds the preset mutation threshold, for example, ≥15% of the rated current, it is considered that there is a significant electrical disturbance. Only when the gear signal jump and the current mutation threshold exceed the two conditions coincide in time, for example, occur synchronously or the interval does not exceed 10 ms, it is finally determined that the gear shifting has started. Once the gear shifting is confirmed, a configurable transient locking window is immediately opened, with an initial duration of 150-300 ms. During the effective period of the transient window, the ratio braking differential protection logic is temporarily exited, but the high threshold differential speed break protection is retained as a backup, for example, with a setting of 8-10 times the rated current, to ensure that the fault can be quickly removed in the event of a serious internal short circuit during gear shifting. If the stability coefficient monitoring, when and for a certain period of time, for example, 20 ms, it indicates that the current has stabilized, and the transient window can be ended in advance to restore the ratio differential protection, thereby improving the protection speed.

[0142] After the end of the gear shifting transient window, the latest effective gear and the differential protection setting value corresponding thereto are obtained, and the ratio differential protection criterion is calculated and monitored in real time. When the criterion continuously meets the preset action condition, a trip command is issued to isolate the voltage regulator T;

[0143] It should be noted that at the end of the transient window, the current gear output by the voltage regulator controller K4 is confirmed as the effective gear. Once the effective gear is confirmed, the device retrieves the differential protection parameters corresponding to the gear from the pre-stored multi-setting zone mapping table, including: the differential starting threshold, the ratio braking slope, the secondary harmonic / third harmonic locking ratio, and the differential speed break setting value. These settings are pre-adjusted according to the theoretical transformation ratio and unbalanced current characteristics of the voltage regulator T at this gear, to ensure that the protection does not malfunction during normal operation and has high sensitivity during internal faults. After loading the new settings, the device begins to calculate the differential current and braking current reduced to the same reference side in real time, and continuously monitors whether the ratio differential criterion meets the preset action condition. Specifically, it includes: calculating the input side current and the output side current according to the theoretical transformation ratio corresponding to the current effective gear to unify the currents on both sides to the same electrical reference, usually to the high-voltage side or the low-voltage side, and calculating the differential current and the braking current ; and real-time determine whether any of the following action logic is satisfied:

[0144] (1) Rate differential action condition: , wherein is the differential starting threshold, is the rate braking slope;

[0145] (2) Differential fast-break action condition: , for fast removal of severe internal faults;

[0146] In addition, in order to prevent false operation caused by transient interference, the above action condition must be continuously satisfied for not less than two power frequency cycles, i.e. ≥40ms, and the differential current must continuously exceed the threshold value, so as to confirm the internal fault; once the fault is confirmed, the protection device immediately outputs a high-level trip signal, which drives the voltage regulator T power side breaker to trip. The trip command is generated.

[0147] The trip command is executed, and the voltage regulator T power side breaker is driven to trip; the event recording and fault recording are started, and the lock state of the gear switching function of the reactive power controller K1 is maintained until manual reset. In practice, K1 is a controller for full-automatic operation of the device, and K1 changes the gear of the voltage regulator T by sending a gear adjustment command to K4.

[0148] As a preferred embodiment, the evaluation of the credibility of the current actual gear based on the change trend of the incoming line current and the outgoing line current includes:

[0149] The incoming line current and the outgoing line current are normalized respectively, and the normalized incoming line current and the normalized outgoing line current are taken as the state of the current state.

[0150] Specifically, when the voltage regulator T incoming line current and the outgoing line current (unit: A) are collected, the sampling frequency is usually 1-10 kHz; by statistical analysis of the current sequence in the historical data window (such as the last 30 seconds), the minimum value and the maximum value are obtained; then the original current is mapped to the interval [0, 1] by using the Min-Max normalization method.

[0151] The current change rate of the incoming line current and the outgoing line current is calculated respectively, and the current change rate is normalized to obtain the incoming line current change rate normalized value and the outgoing line current change rate normalized value for representing the current dynamic trend.

[0152] Specifically, the Min-Max normalization is also used for the change rate sequence.

[0153] The state representing the current state of the current is calculated based on the niche width calculation model.

[0154] It should be noted that when the state representing the current state of the current is calculated based on the niche width calculation model, a dimension conversion coefficient is introduced That is, the commonly used value in reference ecology research is ensured to be reasonable.

[0155] Among them, the incoming / outgoing line current amplitude is regarded as the state of the system currently in; the current change rate is regarded as the dynamic response trend of the system to external disturbance (such as gear shifting) and is defined as the potential; through the niche width calculation model, it can be judged whether the current current distribution conforms to the steady-state operation characteristics under a certain gear. In specific implementation, the niche component is constructed for the incoming line side and the outgoing line side respectively, and the unilateral niche component calculation formula is:

[0156]

[0157] In the formula, represents the incoming line side niche component, represents the outgoing line side niche component, represents the normalized current amplitude, i.e. the state; represents the normalized current change rate, i.e. the potential; represents the dimension conversion coefficient.

[0158] Based on the niche width calculation model, the credibility of the current actual gear is calculated, and the calculation formula is:

[0159]

[0160] In the formula, C represents the credibility of the current actual gear.

[0161] Based on the normalized incoming line current and outgoing line current, and combined with the stable coefficient calculation method in the Lotka-Volterra model, the stable coefficient of the current actual gear is calculated.

[0162] It should be noted that the Lotka-Volterra model, also known as the predator-prey model, is used to describe the dynamic evolution relationship between two interacting populations (such as predators and prey) in an ecological system. The core feature of this model is that it can produce periodic oscillation, and the system stability coefficient can be introduced to judge whether the population tends to be balanced. The population number in ecology is replaced by the normalized current signal, and the relative growth rate is replaced by the current relative change rate. The stability coefficient is used as a quantitative index to judge whether the voltage regulator completes gear shifting and whether the current returns to a steady state.​​

[0163] As a preferred embodiment, the calculation of the stability coefficient of the current actual gear position based on the normalized incoming line side current and outgoing line side current and combined with the stability coefficient calculation method in the Lotka-Volterra model includes the following steps:

[0164] Based on the normalized incoming line side current and outgoing line side current, the current relative change rate at the current time is calculated respectively;

[0165] It should be noted that based on the normalized incoming line side current and outgoing line side current , the current relative change rate at the current time , i.e. the growth rate, is calculated respectively, which is defined as the relative increment between adjacent sampling points. This index can effectively reflect the instantaneous dynamic trend of the current and has high sensitivity to the sudden change caused by voltage regulation action.

[0166] According to the current relative change rate, the current relative change rate at the next time is calculated by using the first-order difference extrapolation method;

[0167] It should be noted that the first-order difference extrapolation method is used, i.e. assuming that the change rate remains constant or linearly continues in the short term, the relative change rate at the current time is directly taken as the predicted value of the next time , i.e. .

[0168] According to the stability coefficient calculation method in the Lotka-Volterra model, the relative coefficients of the incoming line side current and the outgoing line side current are calculated respectively by using the current relative change rate and the next time relative change rate;

[0169] Specifically, the classical formula for measuring the stability of the population system in the Lotka-Volterra model is: .

[0170] By calculating the respective stability relative coefficients and for the incoming line side and the outgoing line side respectively, when (i.e. no change in current), let , indicating that the system is in ideal steady state; indicates that the current change tends to be stable, then it indicates that the change is violent and the system is in non-equilibrium transient state.

[0171] The relative coefficients of the incoming line side current and the outgoing line side current are weighted and averaged to obtain the final stability coefficient used for the current actual gear position credibility joint determination.

[0172] Specifically, in the weighted average processing, the weight can be set according to the proportion of the theoretical current on both sides under the rated operating condition, such as being distributed in inverse proportion to the variable ratio, or using equal weight simplification processing, and finally obtaining the comprehensive stability coefficient.

[0173] It should be noted that at present, 110kV reactive power compensation is mostly TBB group compensation or transformer third winding compensation. In 110kV TBB group compensation, the operator generally manually switches the capacitor according to the system reactive power demand from the background, while the third winding compensation often uses the high-voltage side incoming line reactive power as the control target, and the control target does not switch according to the different switch positions. However, in the 110kV double bus structure system, due to the complex isolating switch switching situation and flexible power supply, the current compensation control system cannot meet the automation needs of 110kV double bus direct compensation. In addition, the voltage regulator used in the compensation device has many gears, and the commonly used differential protection device on the market is configured with only one set of fixed value and does not have the function of multi-gear fixed value switching, so the protection precision is low. An integrated control scheme is proposed and verified in practice, as described below:

[0174] As shown in Figure 3 , the control system includes a reactive power controller K1, a differential protection device K2, a capacitor protection device K3, a voltage regulator controller K4, and a monitoring background K5,

[0175] The reactive power controller K1 collects the positions of each circuit breaker and isolating switch according to the double bus structure. In the automatic operation process, the control system determines the operation mode according to the switch position, selects the control target parameter according to the operation mode, compares the control target parameter with the system fixed value to perform up-down gear operation, thereby changing the capacitor terminal voltage and the capacitor output, to meet the system demand for reactive power. The reactive power controller K1 also collects the heavy gas, light gas, pressure release, oil level, and winding temperature signals of the voltage regulator, and performs non-electric quantity trip protection or alarm output on the voltage regulator.

[0176] The voltage regulator controller K4 receives the gear shifting signal of the reactive power controller K1, performs up-down gear operation on the voltage regulator, and uploads the gear position information of the voltage regulator to the reactive power controller K1 and the differential protection device K2.

[0177] The differential protection device K2 collects the voltage regulator incoming and outgoing line current transformer signals to perform differential protection on the voltage regulator. In particular, the differential protection device needs to be compatible with the voltage regulator multi-gear deep adjustment, can receive the voltage regulator gear signal, and is not less than 14 gears. The different setting value zones can be automatically switched according to the gear information in real time. Each voltage regulator gear corresponds to a setting value zone. The gear adjustment process is "old gear - random gear in transient state - new gear". The protection device needs to consider the "gear determination time" in the transient process to avoid protection misoperation caused by random gear during gear shifting. It has the functions of ratio differential, differential speed break, and CT line break.

[0178] The capacitor protection device K3 needs to meet the three-phase unbalanced current protection, two-section timed overcurrent protection, and independent operation circuit. The protection tripping circuit of the reactive power controller K1 and the differential protection device K2 can operate the circuit breaker through the capacitor protection device operation circuit.

[0179] The 110kV double bus power supply structure needs to be provided with two sets of compensation equipment, as shown in Figure 4 The control systems of the two sets of compensation equipment exchange data through communication and interoperate the operating state. When the two sets of compensation equipment are operated in parallel, the two sets of compensation equipment adopt the alternating ascending and descending gears to avoid affecting the life balance due to too much difference in the total operation time of the two sets of compensation equipment.

[0180] The overall two sets of compensation equipment control systems are connected with the background. The operating personnel can monitor the equipment operating state through the background or manually operate the switch opening and closing and the gear of the voltage regulator from the background.

[0181] In addition, power supply safety is the top priority for large industrial and mining enterprises. Therefore, the 110kV and above power supply system of the electric arc furnace smelting enterprise adopts a double bus structure, as shown in Figure 4 There are two sets of incoming power sources that can supply power to two sets of buses at the same time. The two sets of buses can be operated simultaneously or one main and one backup. Therefore, two sets of 110kV direct-hanging compensation equipment need to be configured in such a structure system. However, in actual automatic operation, the compensation target power factor, reactive power, and bus voltage of each set of equipment will be different according to the circuit breaker and disconnector switching position. Each set of compensation equipment may have 1# incoming line, 2# incoming line, or parallel parameters (1# and 2# incoming lines operating in parallel) as the control target. Therefore, in this scheme, the control system needs to collect all disconnector and circuit breaker position signals to automatically determine the system operating mode through these switch states.

[0182] As shown in Figure 4 According to the different switch positions, the automatic control targets are different, as shown in the following Table 1:

[0183]

[0184] In this context, "open" indicates that the switch is in the open state; "closed" indicates that the switch is in the closed state; and " / " indicates that it can be either open or closed.

[0185] The above examples of control target determination are only a partial list, used to illustrate the method for determining the automatic control target of the reactive power compensation device. The calculation of the control target parameters is as follows:

[0186] The target power factor for control #1 is calculated based on the incoming current of #1 and the voltage of the supplied bus (when QS1 is closed and QS2 is open, the voltage of bus I is used; when QS1 is open and QS2 is closed, the voltage of bus II is used).

[0187] The target power factor for control #2 is calculated based on the incoming current of #2 and the voltage of the supplied bus (when QS3 is closed and QS4 is open, the voltage of bus I is used; when QS3 is open and QS4 is closed, the voltage of bus II is used).

[0188] The target power factor for parallel operation is calculated as follows:

[0189] = + ;

[0190] = + ;

[0191] = / ;

[0192] In the formula, P1 represents the active power of incoming line #1, P2 represents the active power of incoming line #2, Q1 represents the reactive power of incoming line #1, Q2 represents the reactive power of incoming line #2, and P... 并列 Q represents the total active power when incoming lines #1 and #2 are running in parallel. 并列 This represents the total reactive power when incoming lines #1 and #2 are running in parallel. This indicates the target power factor for parallel operation.

[0193] During automatic operation, the control system determines the operating mode based on the switch position, selects the target control parameters based on the operating mode, compares the target control parameters with the system setpoint to perform upshifting or downshifting operations, thereby changing the capacitor terminal voltage and thus changing the capacitor output to meet the system's reactive power requirements.

[0194] In summary, the present application carries out technical research on the configuration of fine reactive power and two-way adjustment compensation device on the 110kV main load side of the substation of the electric arc furnace smelting enterprise. Through this scheme, the quality stability of the electric energy of the electric arc furnace smelting enterprise can be solved, the loss is reduced, the economic benefit of the enterprise is improved, and the equipment performance can be improved in the following aspects: the equipment can be adjusted in two directions, the problem of light load leading reactive power is solved. It can meet the automatic control of 110kV double bus structure. The equipment compensation is more fine, and it will not cause overcompensation and undercompensation; reduce the impact of large-capacity capacitor bank switching inrush on capacitors and switching devices; reduce the insulation damage of capacitor bank equipment caused by capacitor bank switching overvoltage; reduce the power consumption of the equipment itself, reduce the operating cost; the equipment maintenance is convenient, and the conventional substation operation and maintenance personnel can operate by themselves.

[0195] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage and the like) embodying computer usable program code.

[0196] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars, characterized in that, include: The first 110kV compensation outgoing line section is connected to the 110kV double busbar. The first 110kV compensation outgoing line section is used to feed the adjusted reactive current into the 110kV double busbar. The first 110kV busbar incoming section is connected to the 110kV double busbar. The first 110kV busbar incoming section is used to feed electrical energy into the 110kV double busbar. The first outdoor primary equipment is installed at one end of the first 110kV compensation outgoing line bay. The first outdoor primary equipment is used to change the output reactive current through the adjustment of the range. The first indoor control system is connected to the first outdoor primary equipment via a secondary signal cable. The first indoor control system is used to automatically determine the bus operation mode based on the position of the disconnecting switch and circuit breaker in the first outdoor primary equipment, and to automatically calculate and select the compensation target. The second 110kV compensation outgoing line section is connected to the 110kV double busbar. The second 110kV compensation outgoing line section is used to feed the adjusted reactive current into the 110kV double busbar. The second 110kV busbar incoming section is connected to the 110kV double busbar. The second 110kV busbar incoming section is used to feed electrical energy into the 110kV double busbar. The second outdoor primary equipment is installed at one end of the second 110kV compensation outgoing line section. The second outdoor primary equipment is used to change the output reactive current through the range adjustment. The second indoor control system is connected to the second outdoor primary equipment via a secondary signal cable, and the second indoor control system is also connected to the first indoor control system. The second indoor control system is used to automatically determine the bus operation mode based on the position of the disconnecting switch and circuit breaker in the second outdoor primary equipment, and to automatically calculate and select the compensation target.

2. The voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 1, characterized in that, The first outdoor primary equipment includes: disconnecting switch QS, voltage regulator T, current transformer TA4, capacitive compensation branch and inductive compensation branch; The disconnecting switch QS is used to provide an electrical disconnect point for the first outdoor primary equipment during operation and maintenance; and the disconnecting switch QS is connected to the first 110kV compensation outgoing line bay via an overhead line or cable, and the disconnecting switch QS includes a grounding switch QG1; A voltage regulator T is disposed at one end of the disconnecting switch QS; A current transformer TA4 is located at one end of the voltage regulator T and is used to provide a current signal; The capacitive compensation branch is used to compensate for the inductive reactive power generated during normal load operation; The inductive compensation branch is used to compensate for the capacitive reactive power of cable charging under light load conditions. One end of each of the capacitive compensation branch and the inductive compensation branch is connected to one end of the current transformer TA4.

3. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 1, characterized in that, The capacitive compensation branch includes: a capacitive branch circuit breaker QF1, a capacitive branch series reactor L1, an overvoltage damping device, a surge arrester FV, a capacitor bank C, and a grounding switch QG2. The capacitive branch circuit is equipped with a circuit breaker QF1, which is located at one end of the current transformer TA4; The capacitive branch series reactor L1 is located at the other end of the capacitive branch circuit breaker QF1; The overvoltage damping device is connected in parallel across the two ends of the capacitive branch series reactor L1, and the overvoltage damping device is used to suppress overvoltage on the capacitor bank C. The surge arrester FV is installed at one end of the capacitive branch series reactor L1; The capacitor bank C is disposed at one end of the surge arrester FV; The grounding switch QG2 is located at one end of the capacitor bank C.

4. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 1, characterized in that, The overvoltage damping device consists of a resistor R and a gap G; One end of the resistor R is connected to one end of the capacitive branch circuit breaker QF1, and the other end of the resistor R is connected to one end of the gap G. The other end of the gap G is connected to the other end of the capacitive branch series reactor L1 and the other end of the surge arrester FV.

5. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 2, characterized in that, The inductive compensation branch includes: an inductive branch circuit breaker QF2 and an inductive branch parallel reactor L2; The inductive branch circuit breaker QF2 is installed at one end of the current transformer TA4 and connected to one end of the capacitive branch circuit breaker QF1. The inductive branch parallel reactor L2 is installed at one end of the inductive branch where the circuit breaker QF2 is installed.

6. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 3, characterized in that, The capacitor bank C is composed of a frame structure. In the single-phase frame, the capacitor bank C is divided into four bridge arms, and a protective differential current transformer ΔI is connected between the four bridge arms.

7. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 1, characterized in that, The first indoor control system includes a reactive power controller K1, a differential protection device K2, a capacitor protection device K3, a voltage regulator K4, and a monitoring backend K5; The reactive power controller K1 is used to automatically calculate and select control targets based on the switch positions of the 110kV double busbar, and to acquire heavy gas, light gas, pressure release, oil level and winding temperature signals of the voltage regulator T, and to provide non-electrical protection for the voltage regulator T. The differential protection device K2 is used to collect the signal from the incoming current transformer T3 and the outgoing current transformer TA4 of the voltage regulator T, and to provide differential protection for the voltage regulator T. The capacitor protection device K3 is used to operate the protection trip circuit of the reactive power controller K1 and the differential protection device K2 to realize the operation of the circuit breaker. The voltage regulator K4 is used to receive the gear adjustment signal from the reactive power controller K1, and to perform gear shifting operations on the voltage regulator T, while uploading the gear information of the voltage regulator T to the reactive power controller K1. The monitoring backend K5 is used by operators to monitor the operating status of the equipment and to manually operate the switches and the voltage regulator T.

8. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 1, characterized in that, The process of acquiring the signals from the incoming current transformer T3 and the outgoing current transformer TA4 of the voltage regulator T, and performing differential protection on the voltage regulator T, includes: The input and output currents of the voltage regulator T are collected by current transformers TA3 and TA4 respectively; and the current actual gear signal is read from the voltage regulator controller K4. Based on the changing trends of incoming and outgoing currents, the reliability and stability coefficient of the current actual gear position are evaluated using a niche width calculation algorithm. When the confidence level is greater than the preset threshold and exceeds the stability coefficient, the current actual gear position is taken as the effective gear position, and the differential protection setting corresponding to the effective gear position is obtained from the pre-stored setting area mapping table. Real-time monitoring of gear position signal jumps and current surges; when gear shifting is detected to start, enter the shifting transient window and disable ratio differential protection within the window; After the shift transient window ends, the latest valid gear and its corresponding differential protection setting are obtained, and the ratio differential protection criterion is calculated and monitored in real time. When the criterion continuously meets the preset action conditions, a trip command is issued to isolate the voltage regulator T. Execute the trip command and drive the voltage regulator T power supply side circuit breaker to open; start event recording and fault recording, and maintain the locked state of the reactive power controller K1's gear switching function until manual reset.

9. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 8, characterized in that, The assessment of the reliability of the current actual gear position based on the changing trends of the incoming and outgoing currents, using a niche width calculation algorithm, includes: The incoming current and outgoing current are normalized respectively, and the normalized incoming current and outgoing current are used as states to characterize the current state. The current change rates of the incoming and outgoing currents are calculated separately, and the current change rates are normalized to obtain the normalized values ​​of the incoming and outgoing current change rates, which are used as potentials to characterize the dynamic trend of the current. Based on the niche width calculation model, the state, which represents the current state, and the potential, which represents the current dynamic trend, are weighted and calculated to obtain the credibility of the current actual gear position. Based on the normalized incoming and outgoing currents, and combined with the stability coefficient calculation method in the Lotka-Volterra model, the stability coefficient of the current actual gear is calculated.

10. A voltage stabilizing and compensating device suitable for bidirectional regulation of dual busbars according to claim 9, characterized in that, The calculation of the stability coefficient for the current actual gear position, based on the normalized input and output currents and combined with the stability coefficient calculation method in the Lotka-Volterra model, includes the following steps: Based on the normalized incoming and outgoing currents, the relative rate of change of current at the current moment is calculated respectively. The relative rate of change of current at the current moment is used to calculate the relative rate of change of current at the next moment using the first-order difference extrapolation method; Based on the stability coefficient calculation method in the Lotka-Volterra model, the relative coefficients of the incoming current and the outgoing current are calculated using the current relative change rate at the current moment and the current relative change rate at the next moment. The relative coefficients of the incoming and outgoing currents are weighted and averaged to obtain the final stability coefficient used for joint determination of the reliability of the current actual gear position.

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