CN106300369B - A kind of Hierarchical Voltage Control System and method based on equivalent voltage landing index - Google Patents

Abstract

The invention discloses a layered voltage control system based on an equivalent voltage drop index, which includes: a regional coordination voltage controller oriented to the substation level, and a local voltage controller oriented to the feeder level; The internal voltage distribution is estimated, and the equivalent voltage drop index is calculated on this basis; after the voltage exceeds the limit, the local voltage controller determines the input of reactive power equipment in the area based on the voltage estimation result and the equivalent voltage drop index. If the regulation fails, The regional coordinated voltage controller is used for auxiliary adjustment to realize the recovery of voltage exceeding the limit. At the same time, the invention also discloses a control method corresponding to the above system. The system and method comprehensively consider the characteristics of insufficient observable points in the distribution network, and make full use of distributed power sources and reactive power adjustment equipment in the distribution network based on the equivalent voltage drop index to achieve fast and efficient voltage control of the distribution network.

Description

A hierarchical voltage control system and method based on equivalent voltage drop index

technical field

The invention relates to the technical field of smart grid voltage control, in particular to a layered voltage control system and method based on an equivalent voltage drop index.

Background technique

Intermittent energy access in the distribution network puts forward higher requirements for voltage control. At the same time, the addition of controllable elements such as controllable distributed power sources, energy storage devices, and new DFACTs equipment has increased the power distribution network to a considerable extent. The complexity of grid voltage control challenges the existing control methods. The IEEE1547 standard stipulates the longest action time for cutting off the distributed power supply when the output voltage fluctuates. In order to make the distributed power supply better play its benefits and try to avoid its quitting operation when the voltage fluctuates, a higher level of control is required to comprehensively utilize power distribution. The controllable elements of the network always maintain the voltage within the normal range, or limit the time of voltage fluctuation not to exceed the maximum action time. However, due to investment cost considerations in the medium-voltage distribution network, reactive power compensation devices and voltage regulation devices are rarely installed on the feeder; Without observability, many effective control strategies cannot be implemented due to lack of data protection.

At present, there are mainly three methods for distribution network voltage control technology:

(1) Distributed voltage control, which is characterized by direct control of reactive power equipment based on local information;

(2) Centralized voltage control based on voltage over-limit recovery. This voltage control strategy directly triggers a predetermined control process through a heuristic algorithm or a certain control logic based on the value collected in real time to perform voltage over-limit recovery.

(3) Centralized voltage control based on voltage optimization. This control strategy is based on the values collected in real time, while taking into account the characteristics of the network structure. Through a certain algorithm, the action modes of all control devices are output uniformly, and then Issue control commands.

However, there are considerable constraints in the three technologies mentioned at this stage. Distributed voltage control, as a voltage control method based on local information, can easily lead to errors due to the inability to consider the impact of voltage rise brought by distributed power sources after the distributed power sources are connected. action. Centralized voltage control based on voltage over-limit recovery, it is difficult to choose the action dead zone range. If the sensitivity is too high, the device will vibrate repeatedly, and if the dead zone is set too large, it will lead to failure to respond in time to situations such as short-term voltage violations caused by some intermittent energy fluctuations. Centralized voltage control based on voltage optimization needs to add sensors, remote control, and arrange communication networks. At the same time, it must ensure the reliability of SCADA channels. It is quite difficult to implement in medium-voltage distribution networks with a low proportion of three remotes. Considerably increase the cost of control.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the present invention proposes a layered voltage control system and method based on the equivalent voltage drop index, and uses the equivalent voltage drop index to perform layered voltage control on the distribution network, which is easy to implement and control High precision and low cost.

In order to solve the problems of the technologies described above, the present invention is achieved through the following technical solutions:

The present invention provides a layered voltage control system based on an equivalent voltage drop index, which includes: a local voltage controller and a regional coordinated voltage controller, the local voltage controller is oriented to a single feeder, and the regional coordinated voltage controller is oriented to Substation level, affecting all feeders subordinate to said substation;

The local voltage controller includes a voltage estimation unit, an equivalent voltage drop index calculation unit and a local adjustment unit;

said voltage estimating unit is adapted to collect real-time quantity measurements of compartmentalized areas managed by said local voltage controller, from which voltage limits are estimated;

The equivalent voltage drop index calculation unit is used to calculate the equivalent voltage drop index of the partition area managed by the local voltage controller;

The local adjustment unit is used to judge whether there is a voltage in the separated area that exceeds the preset range of the voltage limit value. If the voltage recovery fails, an assist control request command will be sent to the regional coordination voltage controller; when the voltage exceeds the lower limit of the voltage limit, the local adjustment unit is used to judge the partition it manages Whether the equivalent voltage drop index in the area is within the preset range of the voltage limit, if it is within the preset range, control the reactive equipment in the separated area it manages to restore the voltage, if it is within the preset range Otherwise, control the reactive equipment in the separated area it manages to restore the voltage, or control the reactive equipment in the separated area it manages and outside the separated area to restore the voltage, and if the voltage recovery fails, coordinate with the area The voltage controller sends an assist control request command;

The regional coordinated voltage controller is used to receive the assist control request command sent by the local regulation unit, and is used to calculate the gear position of the on-load tap changer after receiving the assist control request command, so that the voltage values in all separated areas are within the preset range of the voltage limit.

Preferably, when the voltage exceeds the upper limit of the voltage limit, the local voltage controller is used to control the reactive equipment in the separated area it manages to restore the voltage. Manage reactive equipment in the separated area until the voltage is restored;

When the voltage exceeds the lower limit of the voltage limit, the local voltage controller is used to judge whether the equivalent voltage drop index in the separated area managed by it is within the preset range of the voltage limit, if it is within the preset range Within the range, control the reactive equipment in the separated area it manages to restore the voltage. If it is outside the preset range, control the reactive equipment in the separated area it manages and outside the separated area to restore the voltage. Specifically: The local voltage controller is used to judge whether the equivalent voltage drop index in the separated area it manages is within the preset range of the voltage limit, and if it is within the preset range, it will sequentially put into the separated area it manages. If it is outside the preset range, all reactive devices in the separated area managed by it will be put into operation, and the reactive devices outside the separated area managed by it will be put in sequentially until the voltage is restored.

Preferably, the upper limit of the voltage limit is the maximum value of the voltage at the location of the distributed power supply and the transformer outlet node in the separated area, and the lower limit of the voltage limit is the minimum voltage likelihood value in the separated area .

Preferably, the separation region includes two types: a single-port region and a dual-port region, and the calculation formula of the minimum voltage likelihood value in the two types of separation regions is:

For the single-port zone:

Among them, P ₁ is the active power of the single-port area, Q ₁ is the reactive power of the single-port area, U ₁ is the voltage measurement value of the single-port area; R is the total resistance of the line in the single-port area, and X is the single-port area The total reactance value of the inner line;

For the dual port region:

Among them, P ₁ ′, P ₂ ′ represent the active power at both ends of the dual-port area, Q ₁ ′, Q ₂ ′ represent the reactive power at both ends of the dual-port area, U ₁ ′, U ₂ ′ represent the two R' is the total resistance of the line in the two-port area, and X' is the total reactance value of the line in the two-port area.

Preferably, the equivalent voltage drop index is used to measure the adjustable capacity of reactive power equipment in the separated area, and its calculation formula is:

For the single-port zone:

Q _mr = Q ₁ −Q _remain ;

Among them, Q _mr is the theoretical limit capacity of reactive power in the single-port area, and Q _remain is the remaining reactive capacity in the single-port area;

For the dual port region:

Among them, Q _mr1 and Q _mr2 are respectively the theoretical limit capacity of reactive power at both ends in the dual-port area, and Q _remain ′ is the remaining reactive capacity in the dual-port area.

The present invention also provides a hierarchical voltage control method based on an equivalent voltage drop index, which includes the following steps:

S11: The local voltage controller collects the real-time measurement of the separated areas it manages, calculates the equivalent voltage drop index based on the estimated voltage limit, and judges whether the voltage exceeds the voltage limit, and if the voltage exceeds the voltage limit upper limit, then go to step S12, if the voltage exceeds the lower limit of the voltage limit, then go to step S13;

S12: The local voltage controller controls the reactive equipment in the separated area it manages to recover the voltage, and if the voltage recovery fails, it sends an assisting control request command to the regional coordination voltage controller, and turns to step S14;

S13: The local voltage controller judges whether the equivalent voltage drop index in the partition area it manages is within the preset range of the voltage limit, and if it is within the preset range, controls the partition area it manages If it is outside the preset range, control the reactive devices in the separated area it manages to restore the voltage, or control the reactive devices in the separated area it manages and outside the separated area Make the voltage recovery, if the voltage recovery fails, send an assist control request command to the regional coordination voltage controller, and turn to step S14;

S14: The regional coordinated voltage controller receives the assist control request command sent by the local voltage controller, and calculates the gear position of the on-load tap changer after receiving the assist control request command, so that the voltage in all separated areas The values are all within the preset range of the stated voltage limit.

Preferably, the step S12 is specifically: the local voltage controller is used to sequentially cut off the reactive devices in the separated areas it manages until the voltage recovers, and if the voltage recovery fails, send an assistance control request to the regional coordination voltage controller command, proceed to step S14;

The step S13 specifically includes:

S131: The local voltage controller judges whether the equivalent voltage drop index in the partition area it manages is within the preset range of the voltage limit, and if it is within the preset range, sequentially turns on the partitions it manages. Reactive equipment in the area until the voltage recovers, if it is outside the preset range, then go to step S132;

S132: The local voltage controller controls and puts into all the reactive devices in the separated area it manages, and if the voltage has not recovered, go to step S133;

S133: The local voltage controller controls to turn on the reactive devices outside the separated area it manages until the voltage recovers, and sends an assisting control request command to the regional coordination voltage controller if the voltage recovery fails.

Preferably, the upper limit of the voltage limit is the maximum value of the voltage at the location of the distributed power supply and the transformer outlet node in the separated area, and the lower limit of the voltage limit is the minimum voltage likelihood value in the separated area .

Preferably, the separation region includes two types: a single-port region and a dual-port region, and the calculation formula of the minimum voltage likelihood value in the two types of separation regions is:

For the single-port zone:

Among them, P ₁ is the active power of the single-port area, Q ₁ is the reactive power of the single-port area, U ₁ is the voltage measurement value of the single-port area; R is the total resistance of the line in the single-port area, and X is the single-port area The total reactance value of the inner line;

For the dual port region:

Among them, P ₁ ′, P ₂ ′ represent the active power at both ends of the dual-port area, Q ₁ ′, Q ₂ ′ represent the reactive power at both ends of the dual-port area, U ₁ ′, U ₂ ′ represent the two R' is the total resistance of the line in the two-port area, and X' is the total reactance value of the line in the two-port area.

Preferably, the equivalent voltage drop index is used to measure the adjustable capacity of reactive power equipment in the separated area, and its calculation formula is:

For the single-port zone:

Q _mr = Q ₁ −Q _remain ;

Among them, Q _mr is the theoretical limit capacity of reactive power in the single-port area, and Q _remain is the remaining reactive capacity in the single-port area;

For the dual port region:

Among them, Q _mr1 and Q _mr2 are respectively the theoretical limit capacities of reactive power at both ends in the dual-port region, and Q _remain ′ is the remaining reactive capacity in the dual-port region.

Compared with the prior art, the present invention has the following advantages:

(1) The layered voltage control system and method based on the equivalent voltage drop index provided by the present invention takes into account the characteristics of insufficient observable points in the distribution network, and restores the voltage beyond the limit through the layered control framework; forms a local voltage Hierarchical voltage control represented by controllers and regional coordination voltage controllers, based on the equivalent voltage drop index, comprehensively utilizes controllable resources in the distribution network: distributed power sources, reactive power compensation devices, controllable loads, and adjustable transformers, etc. The reactive power control equipment realizes fast and high-efficiency distribution network voltage control; compared with traditional control methods, the present invention can effectively avoid the problem of increased control costs caused by the need for additional sensors, remote control, and arranging communication networks for voltage control;

(2) The present invention uses the equivalent voltage drop index to restore the voltage beyond the limit in a layered manner. The use of the equivalent node voltage drop index can effectively improve the recovery efficiency of the voltage beyond the limit, and try to use the reactive power source that is closer to the limit point Complete voltage recovery to avoid energy loss caused by long-distance reactive power transmission; at the same time, when large power fluctuations occur, this indicator can be used to speed up voltage recovery and avoid reactive power sources that take too long in sequence to cause distributed power to stop running;

(3) Through the interaction between the local voltage controller and the regional coordinated voltage controller, the present invention significantly increases the flexibility of voltage over-limit recovery. The connection of the local voltage controller can realize equipment upgrade more conveniently.

Of course, any product implementing the present invention does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

Embodiments of the present invention will be further described below in conjunction with accompanying drawings:

FIG. 1 is a schematic structural diagram of a hierarchical voltage control system based on an equivalent voltage drop index according to an embodiment of the present invention;

Fig. 2 is the structural diagram of the distribution network of the embodiment of the present invention;

FIG. 3 is a flowchart of a hierarchical voltage control method based on an equivalent voltage drop index according to an embodiment of the present invention.

Description of labels: 1-local voltage controller, 2-regional coordinated voltage controller;

11-voltage estimation unit, 12-equivalent voltage drop index calculation unit, 13-local regulation unit.

detailed description

The following is a detailed description of the embodiments of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

In combination with Fig. 1-Fig. 2, the layered voltage control system based on the equivalent voltage drop index of the present invention is described in detail, and its structural diagram is shown in Fig. 1, which includes: a local voltage controller 1 and a regional coordination voltage controller 2 , the local voltage controller 1 is oriented to a single feeder, and the coordinated voltage controller 2 is oriented to the substation level, affecting all feeders under the substation. The structure diagram of the distribution network installed with the modified control system is shown in Figure 2. The two-way arrows in Figure 2 indicate mutual information interaction. The local voltage controller 1 and the regional coordinated voltage controller 2 work together. From the perspective of the distribution network Complete the efficient recovery of distribution network voltage overrun based on finite quantity measurement. Wherein, the local voltage controller 1 includes: a voltage estimation unit 11, an equivalent voltage drop index calculation unit 12, and a local adjustment unit 13. The voltage estimation unit 11 is used for collecting the data of the separated areas managed by the local voltage controller. Real-time measurement, according to the estimated voltage limit; the equivalent voltage drop index calculation unit 12 is used to calculate the equivalent voltage drop index of the separated area managed by the local voltage controller; the local adjustment unit 13 is used to judge whether in the separated area If the voltage exceeds the preset range of the voltage limit, when the voltage exceeds the upper limit of the voltage limit, the local adjustment unit 13 is used to control the reactive equipment in the separated area it manages to restore the voltage, and if the voltage recovery fails, it will coordinate with the area The voltage controller sends an assist control request command; when the voltage exceeds the lower limit of the voltage limit, the local regulation unit is used to judge whether the equivalent voltage drop index in the separated area it manages is within the preset range of the voltage limit , if it is within the preset range, control the reactive devices in the separated area it manages to restore the voltage, if it is outside the preset range, control the reactive devices in the separated area it manages to restore the voltage, or Control the reactive devices in the separated area and outside the separated area it manages to restore the voltage, if the voltage recovery fails, send an assistance control request command to the regional coordination voltage controller; the regional coordination voltage controller is used to receive the assistance sent by the local regulation unit The control request command is used to calculate the gear position of the on-load tap changer after receiving the assist control request command, so that the voltage values in all partitioned areas are within the preset range of the voltage limit.

In a preferred embodiment, the specific adjustment method of the local adjustment unit 13 is: when the voltage exceeds the upper limit of the voltage limit, the local adjustment unit is used to sequentially cut off the reactive devices in the separated area it manages until the voltage recovers; when the voltage When the lower limit of the voltage limit is exceeded, the local adjustment unit is used to judge whether the equivalent voltage drop index in the separated area it manages is within the preset range of the voltage limit, and if it is within the preset range, it will turn on all of its The reactive equipment in the separated area under management shall be operated until the voltage recovers. If it is outside the preset range, all the reactive equipment in the separated area under management shall be put into operation, and the reactive devices outside the separated area under management shall be put into operation in turn until the voltage is restored. voltage recovery.

In this embodiment, the voltage estimating unit adopts the method of estimating the distribution network in separate areas, and divides the distribution network into several continuous separate areas according to the real-time measurement acquisition points, and the upper limit of the voltage limit is the point where the distributed power sources in the separate areas are located and the maximum value of the voltage in the transformer outlet node, the lower limit of the voltage limit is the minimum voltage likelihood value in this separation area.

In a preferred embodiment, the real-time quantity measurement includes the active power of each distributed power source in the distribution network, the voltage measurement value of the reactive power meter, and the like.

In a preferred embodiment, the separation region includes two types: a single-port region and a dual-port region, and the calculation formula of the minimum voltage likelihood value in the two types of separation regions is:

For single-port zones:

Among them, P ₁ is the active power of the single-port area, Q ₁ is the reactive power of the single-port area, U ₁ is the voltage measurement value of the single-port area; R is the total resistance of the line in the single-port area, and X is the single-port area The total reactance value of the inner line;

For dual port regions:

Among them, P ₁ ′, P ₂ ′ represent the active power at both ends of the dual-port area, Q ₁ ′, Q ₂ ′ represent the reactive power at both ends of the dual-port area, U ₁ ′, U ₂ ′ represent the two R' is the total resistance of the line in the two-port area, and X' is the total reactance value of the line in the two-port area.

The equivalent voltage drop index uses the reactive power output to estimate the remaining reactive capacity in the separated area, so as to calculate the voltage level of the line when the reactive power in the separated area reaches the maximum; this index is mainly used to measure the reactive power in the separated area. Function equipment can be adjusted to improve control efficiency. The calculation formula is:

For single-port zones:

Q _mr = Q ₁ −Q _remain ;

Among them, Q _mr is the theoretical limit capacity of reactive power in the single-port area, and Q _remain is the remaining reactive capacity in the single-port area;

For dual port regions:

Among them, Q _mr1 and Q _mr2 are respectively the theoretical limit capacities of reactive power at both ends in the dual-port region, and Q _remain ′ is the remaining reactive capacity in the dual-port region.

From the above description, it can be seen that the equivalent voltage drop index proposed by the present invention is a sufficient non-comparison condition to ensure that the estimated likelihood value of the minimum voltage in the area can be adjusted by the equipment in the area to achieve normal voltage. Whether the regional equivalent voltage drop index is within the preset range of the voltage limit determines the process of putting reactive power equipment into operation. If the equivalent voltage drop index is within the preset range of the voltage limit, it can be guaranteed that the voltage will return to normal through the adjustment of the equipment in the area, so choose to put in the reactive equipment in the separated area where the over-limit point is located until the voltage recovers. This kind of control The method can effectively improve the recovery efficiency of the voltage exceeding the limit, try to use the reactive power source close to the exceeding point to complete the voltage recovery, and avoid the energy loss caused by the long-distance reactive power transmission; if it is outside the preset range, it cannot be guaranteed to be within the utilization area After the reactive equipment completes the voltage recovery, in order to avoid the distributed power supply exiting operation due to the excessively long action time of the reactive equipment, directly put into all the reactive equipment in the separation area where the over-limit point is located, and put in the reactive equipment outside the separation area in turn until the voltage recovers , if the adjustment fails, an assist control request command is sent to the regional coordination voltage controller 2 . The regional coordination voltage controller 2 calculates the action command of the on-load tap changer after receiving the assistance request command, and cooperates with the local voltage controller 1 to complete the voltage coordination control, so that the voltage values of all nodes of the distribution network are within the required preset range Inside.

In conjunction with FIG. 3, the layered voltage control method based on the equivalent voltage drop index of the present invention is described in detail. FIG. 3 is a flow chart thereof, which includes the following steps:

S11: The local voltage controller obtains real-time measurement through the RTU, calculates the equivalent voltage drop index based on the estimated voltage level, and judges whether the voltage exceeds the voltage limit. If the voltage exceeds the upper limit of the voltage limit, turn to Step S12, if the voltage exceeds the lower limit of the voltage limit, then go to step S13;

S12: The local voltage controller controls the reactive equipment in the separated area it manages to restore the voltage, and if the voltage restore fails, it sends an assisting control request command to the regional coordination voltage controller, and turns to step S14;

S13: The local voltage controller determines whether the equivalent voltage drop index in the separated area it manages is within the preset range of the voltage limit, and if it is within the preset range, controls the voltage drop in the separated area it manages. The reactive device restores the voltage. If it is outside the preset range, it controls the reactive device in the separated area it manages to restore the voltage, or controls the reactive device in the separated area it manages and outside the separated area to restore the voltage. Recovery, if the voltage recovery fails, send an assisting control request command to the regional coordination voltage controller, and turn to step S14;

S14: The regional coordination voltage controller receives the assistance control request command sent by the local voltage controller, and calculates the gear position of the on-load tap changer after receiving the assistance control request command, so that the voltage values in all separated areas are at the voltage within the preset limits.

In this embodiment, step S12 is specifically: the local voltage controller is used to sequentially cut off the reactive devices in the separated areas it manages until the voltage recovers; Enter step S14;

Step S13 specifically includes:

S131: The local voltage controller judges whether the equivalent voltage drop index in the separated area it manages is within the preset range of the voltage limit, and if it is within the preset range, puts it into the separated area it manages in turn until the voltage recovers, if it is outside the preset range, then go to step S132;

S132: The local voltage controller controls all the reactive devices that are put into the separated area it manages, and if the voltage has not recovered, go to step S133;

S133: The local voltage controller controls to turn on the reactive devices outside the separated area it manages until the voltage recovers, and if the voltage recovery fails, it sends an assist control request command to the regional coordination voltage controller.

To sum up, the present invention comprehensively considers the characteristics of insufficient observable points in the distribution network, recovers the voltage beyond the limit through the layered control framework; forms a layered voltage represented by the local voltage controller and the regional coordinated voltage controller Control, based on the equivalent voltage drop index, comprehensively utilizes reactive power control equipment such as distributed power sources, reactive power compensation devices, controllable loads, and adjustable transformers in the distribution network to achieve fast and efficient distribution network voltage control.

What is disclosed here are only preferred embodiments of the present invention. The purpose of selecting and describing these embodiments in this description is to better explain the principle and practical application of the present invention, not to limit the present invention. Any modifications and changes made by those skilled in the art within the scope of the description shall fall within the protection scope of the present invention.

Claims (6)

1. A layered voltage control system based on an equivalent voltage drop index, characterized in that it comprises: a local voltage controller and a regional coordination voltage controller, the local voltage controller faces a single feeder, and the regional coordination voltage control The switch faces the substation level and affects all feeders under the substation; The local voltage controller includes a voltage estimation unit, an equivalent voltage drop index calculation unit and a local adjustment unit; said voltage estimating unit is adapted to collect real-time quantity measurements of compartmentalized areas managed by said local voltage controller, from which voltage limits are estimated; The equivalent voltage drop index calculation unit is used to calculate the equivalent voltage drop index of the partition area managed by the local voltage controller; The local adjustment unit is used to judge whether there is a voltage in the separated area that exceeds the preset range of the voltage limit value. If the voltage recovery fails, an assist control request command will be sent to the regional coordination voltage controller; when the voltage exceeds the lower limit of the voltage limit, the local adjustment unit is used to judge the partition it manages Whether the equivalent voltage drop index in the area is within the preset range of the voltage limit, if it is within the preset range, control the reactive equipment in the separated area it manages to restore the voltage, if it is within the preset range Otherwise, control the reactive equipment in the separated area it manages to restore the voltage, or control the reactive equipment in the separated area it manages and outside the separated area to restore the voltage, and if the voltage recovery fails, coordinate with the area The voltage controller sends an assist control request command; The regional coordinated voltage controller is used to receive the assist control request command sent by the local regulation unit, and is used to calculate the gear position of the on-load tap changer after receiving the assist control request command, so that the voltage values in all separated areas are within a preset range of said voltage limits; When the voltage exceeds the upper limit of the voltage limit, it is specifically: the local regulation unit is used to sequentially cut off the reactive equipment in the separated area it manages until the voltage recovers, and if the voltage recovery fails, it will send a message to the regional coordination voltage controller assistance control request commands; When the voltage exceeds the lower limit of the voltage limit, it is specifically: the local adjustment unit is used to judge whether the equivalent voltage drop index in the separated area managed by it is within the preset range of the voltage limit, if it is Within the preset range, the reactive equipment in the separated area managed by it will be put into operation until the voltage recovers. If it is outside the preset range, all reactive devices in the separated area managed by it will be put into operation. Putting in the reactive equipment outside the separated area it manages in sequence until the voltage recovers, and if the voltage recovery fails, send an assist control request command to the regional coordination voltage controller; The equivalent voltage drop index is used to measure the adjustable capacity of reactive power equipment in the separation area. The separation area includes two types of single-port area and double-port area. The calculation formula of the equivalent voltage drop index is: For the single-port zone: Q _mr = Q ₁ −Q _remain ; Among them, P ₁ is the active power of the single-port area, Q ₁ is the reactive power of the single-port area, U ₁ is the voltage measurement value of the single-port area; R is the total resistance of the line in the single-port area, and X is the single-port area The total reactance value of the inner line, Q _mr is the theoretical limit capacity of reactive power in the single-port area, and Q _remain is the remaining reactive capacity in the single-port area; For the dual port region: <mrow><mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msup><mi>J</mi><mo>&amp;prime;</mo></msup><msub><mi>g</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>J</mi><mo>&amp;prime;</mo></msup><msub><mi>g</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>3</mn></msub><mo>=</mo><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>4</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>5</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><mo>=</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>-</mo><mfrac><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>a</mi><mi>i</mi><mi>n</mi></mrow></msub><mo>&amp;prime;</mo></msup></mrow><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup></mrow></mfrac></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>=</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>-</mo><mfrac><mrow><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>a</mi><mi>i</mi><mi>n</mi></mrow></msub><mo>&amp;prime;</mo></msup></mrow><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup></mrow></mfrac></mrow></mtd></mtr></mtable></mfenced><mo>;</mo></mrow> Among them, P ₁ ′, P ₂ ′ represent the active power at both ends of the dual-port area, Q ₁ ′, Q ₂ ′ represent the reactive power at both ends of the dual-port area, U ₁ ′, U ₂ ′ represent the two R' is the total resistance of the line in the dual-port area, X' is the total reactance value of the line in the dual-port area, Q _mr1 and Q _mr2 are the reactive theoretical limit capacities of both ends in the dual-port area, Q _remain ′ is the remaining reactive capacity in the dual-port area. 2. The layered voltage control system based on the equivalent voltage drop index according to claim 1, wherein the upper limit of the voltage limit is the location of the distributed power supply in the separated area and the point of the transformer outlet node. The maximum value of the voltage, the lower limit of the voltage limit is the minimum voltage likelihood value in the separation area. 3. The hierarchical voltage control system based on the equivalent voltage drop index according to claim 2, wherein the calculation formula of the minimum voltage likelihood value in the two types of separation areas is: For the single-port zone: For the dual port region: <mrow><mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msub><mi>Jg</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Jg</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></msup>mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msub>msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>3</mn></msub><mo>=</mo><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow></mrow></mtd></mtr><mtr><mtd><mtable><mtr><mtd><mrow><msub><mi>Par</mi><mn>4</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd><mtd><mrow><msub><mi>Par</mi><mn>5</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mn>1</mn></msub></mrow></mtd></mtr></mtable></mtd></mtr></mtable></mfenced><mo>.</mo></mrow> 4. a kind of control method of the layered voltage control system based on equivalent voltage drop index as claimed in claim 1, is characterized in that, comprises the following steps: S11: The local voltage controller collects the real-time measurement of the separated areas it manages, calculates the equivalent voltage drop index based on the estimated voltage limit, and judges whether the voltage exceeds the preset range of the voltage limit. the upper limit of the voltage limit, then proceed to step S12, if the voltage exceeds the lower limit of the voltage limit, then proceed to step S13; S12: The local voltage controller controls the reactive equipment in the separated area it manages to recover the voltage, and if the voltage recovery fails, it sends an assisting control request command to the regional coordination voltage controller, and turns to step S14; S13: The local voltage controller judges whether the equivalent voltage drop index in the partition area it manages is within the preset range of the voltage limit, and if it is within the preset range, controls the partition area it manages If it is outside the preset range, control the reactive devices in the separated area it manages to restore the voltage, or control the reactive devices in the separated area it manages and outside the separated area Make the voltage recovery, if the voltage recovery fails, send an assist control request command to the regional coordination voltage controller, and turn to step S14; S14: The regional coordinated voltage controller receives the assist control request command sent by the local voltage controller, and calculates the gear position of the on-load tap changer after receiving the assist control request command, so that the voltage in all separated areas values are within the preset range of the stated voltage limits; The step S12 is specifically: the local voltage controller is used to sequentially cut off the reactive devices in the separated areas it manages until the voltage recovers, and if the voltage recovery fails, it sends an assisting control request command to the regional coordination voltage controller, and transfers to Step S14; The step S13 specifically includes: S131: The local voltage controller judges whether the equivalent voltage drop index in the partition area it manages is within the preset range of the voltage limit, and if it is within the preset range, sequentially turns on the partitions it manages. Reactive equipment in the area until the voltage recovers, if it is outside the preset range, then go to step S132; S132: The local voltage controller controls and puts into all the reactive devices in the separated area it manages, and if the voltage has not recovered, go to step S133; S133: The local voltage controller controls to turn on the reactive devices outside the separated area it manages until the voltage recovers, and sends an assist control request command to the regional coordination voltage controller if the voltage recovery fails; The equivalent voltage drop index is used to measure the adjustable capacity of reactive power equipment in the separation area. The separation area includes two types: single-port area and double-port area. The calculation formula of the equivalent voltage drop index is: For the single-port zone: Q _mr = Q ₁ −Q _remain ; Among them, P ₁ is the active power of the single-port area, Q ₁ is the reactive power of the single-port area, U ₁ is the voltage measurement value of the single-port area; R is the total resistance of the line in the single-port area, and X is the single-port area The total reactance value of the inner line; Q _mr is the theoretical limit capacity of reactive power in the single-port area, and Q _remain is the remaining reactive capacity in the single-port area; For the dual port region: <mrow><mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msup><mi>J</mi><mo>&amp;prime;</mo></msup><msub><mi>g</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>J</mi><mo>&amp;prime;</mo></msup><msub><mi>g</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>3</mn></msub><mo>=</mo><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>4</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msup><mi>P</mi><mo>&amp;prime;</mo></msup><msub><mi>ar</mi><mn>5</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>1</mn></mrow></msub><mo>=</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>-</mo><mfrac><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>a</mi><mi>i</mi><mi>n</mi></mrow></msub><mo>&amp;prime;</mo></msup></mrow><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup></mrow></mfrac></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Q</mi><mrow><mi>m</mi><mi>r</mi><mn>2</mn></mrow></msub><mo>=</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>-</mo><mfrac><mrow><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mrow><mi>r</mi><mi>e</mi><mi>m</mi><mi>a</mi><mi>i</mi><mi>n</mi></mrow></msub><mo>&amp;prime;</mo></msup></mrow><mrow><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup></mrow></mfrac></mrow></mtd></mtr></mtable></mfenced><mo>;</mo></mrow> Among them, P ₁ ′, P ₂ ′ represent the active power at both ends of the dual-port area, Q ₁ ′, Q ₂ ′ represent the reactive power at both ends of the dual-port area, U ₁ ′, U ₂ ′ represent the two R' is the total resistance of the line in the dual-port area, X' is the total reactance value of the line in the dual-port area, Q _mr1 and Q _mr2 are the reactive theoretical limit capacities of both ends in the dual-port area, Q _remain ′ is the remaining reactive capacity in the dual-port area. 5. the control method of the layered voltage control system based on equivalent voltage drop index according to claim 4, it is characterized in that, the upper limit of described voltage limit value is the distributed power supply location and transformer outlet in this separation area The maximum value of the voltage in the node, and the lower limit of the voltage limit is the minimum voltage likelihood value in the separated area. 6. the control method of the layered voltage control system based on the equivalent voltage drop index according to claim 5, is characterized in that, the calculation formula of the minimum voltage likelihood value in the two types of separation areas is: For the single-port zone: For the dual port region: <mrow><mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msub><mi>Jg</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Jg</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup></mrow></msup>mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>1</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msub>msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>2</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mrow><mo>&amp;prime;</mo><mn>2</mn></mrow></msup><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>Par</mi><mn>3</mn></msub><mo>=</mo><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow><mrow><mo>(</mo><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>R</mi><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><mi>X</mi><mo>&amp;prime;</mo></msup><mo>)</mo></mrow></mrow></mtd></mtr><mtr><mtd><mtable><mtr><mtd><mrow><msub><mi>Par</mi><mn>4</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>P</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup></mrow></mtd><mtd><mrow><msub><mi>Par</mi><mn>5</mn></msub><mo>=</mo><msup><msub><mi>U</mi><mn>1</mn></msub><mo>&amp;prime;</mo></msup><msup><msub><mi>Q</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><mo>+</mo><msup><msub><mi>U</mi><mn>2</mn></msub><mo>&amp;prime;</mo></msup><msub><mi>Q</mi><mn>1</mn></msub></mrow></mtd></mtr></mtable></mtd></mtr></mtable></mfenced><mo>.</mo></mrow> 5