CN106093682A - A kind of confirmation method of medium voltage distribution network neutral grounding mode - Google Patents

Abstract

Invention relates to the confirmation method of a kind of medium voltage distribution network neutral grounding mode, its technical characteristics is: comprise steps of determining that leading indicator and the reference index affecting neutral grounding mode, builds weight coefficient system and check index reference frame that neutral grounding mode determines；Utilize weight Coefficient System to calculate small resistor, arc suppression coil and earth-free result value, be the neutral grounding mode of primary election by earthing mode corresponding for result big for numerical value；By checking index reference frame corresponding rule of checking one by one, result of calculation is checked, finally can determine that the most reasonably neutral grounding mode.The present invention is reasonable in design, and it has taken into full account various influence factor, can not only check the reasonability of medium voltage distribution network neutral grounding mode quickly and easily, ensure that again the uniqueness of quantitative Analysis result, it is to avoid the randomness that artificial experience selects.

Description

A kind of confirmation method of medium voltage distribution network neutral grounding mode

Technical field

Invention belongs to distribution network technology field, the confirmation method of a kind of medium voltage distribution network neutral grounding mode.

Background technology

The safety and economic operation for urban distribution network that rationally determines of medium voltage distribution network neutral grounding mode has very Important effect.Along with the quickening of urban construction paces, city framework constantly widens, and user is to electrical network power supply reliability requirement More and more higher, particularly with power cable extensively applying in distribution network, it is current whether neutral grounding mode meets And the demand for development of intermediate distribution system in a period of time from now on, if the problem that power distribution network over-voltage Frequent Accidents can be avoided Especially prominent.Owing to the electricity power engineering construction period is longer, there is certain hysteresis quality, warp in the neutral grounding mode scheme determined Often go out operation system capacitive current and exceed the phenomenon of design capacity.Existing Power Network Neutral determines principle When checking and transforming original distribution neutral grounding mode, mostly judge according to operating experience, quantitatively do not check Method, technical merit and operating experience to engineers and technicians require higher, cause certain randomness.

If a kind of method that quantitative analysis can be found, on the basis of taking into full account provincial characteristics, quickly judge distribution The adaptability of neutral grounding mode.Neutral grounding in distribution power network management level can be improved, improve the safety fortune of system Row performance, makes that benefit output investment ratio is higher, operation expense is lower, has the directive significance of reality and great to the development of electrical network Economic worth.

Summary of the invention

It is an object of the invention to overcome the deficiencies in the prior art, it is provided that a kind of reasonable in design, quick and precisely and O&M becomes The confirmation method of this low medium voltage distribution network neutral grounding mode.

The present invention solves it and technical problem is that and take techniques below scheme to realize:

The confirmation method of a kind of medium voltage distribution network neutral grounding mode, comprises the following steps:

Step 1, determine leading indicator and the reference index affecting neutral grounding mode, build neutral grounding mode true Fixed weight coefficient system and check index reference frame；

Step 2, weight Coefficient System is utilized to calculate small resistor, arc suppression coil and earth-free result value, by numerical value The neutral grounding mode that earthing mode is primary election that big result is corresponding；

Step 3, result of calculation is checked by checking index reference frame corresponding rule of checking one by one, finally can determine that The most reasonably neutral grounding mode.

Also include after described step 3 that the different section bus neutral grounding modes of the same electric pressure of same transformer station differ The process step caused, its processing method is: emphasis considers that capacitance current size is to determine neutral grounding mode；Then consider with Transformer station's situation that analyzed transformer station is associated.

Described weight coefficient system includes area type residing for power distribution network, outlet type, capacitance current size, following distribution And load development, its weight index is respectively 40%, 25%, 25%, 10%.

Described area type includes such as Types Below: σ>=30,15≤σ<30,6≤σ<15,1≤σ<6,0.1≤σ<1 and σ< 0.1, wherein, σ is the load density of power supply area.

Described check index reference frame includes following index: single-phase earth fault line selection accuracy, neutral ground equipment Installing space, to close on the interference of communication line, grid structure, power supply reliability require and power distribution automation level, voltage Grade and insulating requirements, step voltage and equipment safety..

Invention advantage and good effect be:

The present invention is by the weight coefficient system built and is calculated the distribution system checked by weight relationship quantitative scoring Various possible neutral grounding mode proportions, draw comparative result intuitively, and auxiliary is checked with reference index, fills Divide and consider various influence factor, the reasonability of medium voltage distribution network neutral grounding mode can not only be checked quickly and easily, Ensure that again the uniqueness of quantitative Analysis result, it is to avoid the randomness that artificial experience selects.

Detailed description of the invention

Below in conjunction with embodiment, the present invention is further described:

The design philosophy of the present invention is: be determined by affecting leading indicator and the reference index of neutral grounding mode, structure Build weight coefficient system and check index reference frame that neutral grounding mode determines；Weight Coefficient System is utilized to calculate little electricity Resistance, arc suppression coil and earth-free result value, the neutral ground side that earthing mode is primary election that result that numerical value is big is corresponding Formula；By check index reference frame, its result of calculation is checked again, finally determine the most reasonably neutral grounding mode.

The confirmation method of the medium voltage distribution network neutral grounding mode that the present invention proposes comprises the following steps:

Step 1, determine leading indicator and the reference index affecting neutral grounding mode, build neutral grounding mode true Fixed weight coefficient system (as shown in table 1) and check index reference frame (as shown in table 2).Region residing for power distribution network in table 1 Type refers to the power supply network area type determined according to table 3 rule.

The weight coefficient system that table 1 neutral grounding mode determines

The check index reference frame that table 2 neutral grounding mode determines

Table 3 power supply zone partitioning standards index table

Step 2, table 1 is utilized to calculate small resistor, arc suppression coil and earth-free result value, by result pair big for numerical value The earthing mode answered is the neutral grounding mode of primary election.

The computational methods of this step are as follows:

(1) relevant information of transformer station's bus to be verified, is collected.Including: area type belonging to transformer station, in bus outlet The length of cable, overhead bare conductor and aerial insulated wire or proportion, singlephase earth fault capacitance current size, this bus is not Carry out load development.

(2), the data collected are utilized to calculate the factor of influence pressing table 3 each index centering point earthing mode.

1. suppose that area type residing for power distribution network is A, the factor of influence K1 of area type index centering point earthing mode The column data that in table 1, A class region is corresponding is utilized to take advantage of this index weights coefficient to obtain, shown in circular such as formula (1):

$K_1=\left[\begin{array}{c}0.7\\ 0.2\\ 0.1\end{array}\right]\&times;0.4=\left[\begin{array}{c}0.28\\ 0.08\\ 0.04\end{array}\right]---\left(1\right)$

2. supposing that in outlet type, cable accounts for 50%, suspended insulated guide wire accounts for 30%, and overhead bare conductor accounts for 20%.Utilize table In 1, outlet type one hurdle parameter calculates the factor of influence of this index centering point earthing mode, circular such as formula (2) institute Show:

$K_2=\{\left[\begin{array}{c}0.6\\ 0.2\\ 0.2\end{array}\right]\&times;50\%+\left[\begin{array}{c}0.5\\ 0.25\\ 0.25\end{array}\right]\&times;30\%+\left[\begin{array}{c}0.2\\ 0.4\\ 0.4\end{array}\right]\&times;20\%\}\&times;0.25=\left[\begin{array}{c}0.1225\\ 0.0638\\ 0.0638\end{array}\right]---\left(2\right)$

3. suppose that singlephase earth fault capacitance current is 60A.

Capacitance current size one hurdle parameter in table 1 is utilized to calculate the factor of influence of this index centering point earthing mode, can The column data corresponding to 50-100A is utilized to take advantage of this index weights coefficient to obtain, shown in circular such as formula (3):

$K_3=\left[\begin{array}{c}0.4\\ 0.5\\ 0.1\end{array}\right]\&times;0.25=\left[\begin{array}{c}0.1\\ 0.125\\ 0.025\end{array}\right]---\left(3\right)$

4. suppose that this bus institute on-load future development speed is medium.

Following power distribution network and load development one hurdle parameter in table 1 is utilized to calculate this index centering point earthing mode Factor of influence, may utilize the medium corresponding column data of development speed and takes advantage of this index weights coefficient to obtain, circular As shown in formula (4):

$K_4=\left[\begin{array}{c}0.5\\ 0.4\\ 0.1\end{array}\right]\&times;0.1=\left[\begin{array}{c}0.05\\ 0.04\\ 0.01\end{array}\right]---\left(4\right)$

K1, K2, K3 and K4 corresponding data is added and obtains each neutral grounding mode the long and value, as shown in formula (5):

$K=K_1+K_2+K_3+K_4=\left[\begin{array}{c}0.28\\ 0.08\\ 0.04\end{array}\right]+\left[\begin{array}{c}0.1225\\ 0.0638\\ 0.0638\end{array}\right]+\left[\begin{array}{c}0.1\\ 0.125\\ 0.025\end{array}\right]+\left[\begin{array}{c}0.05\\ 0.04\\ 0.01\end{array}\right]=\left[\begin{array}{c}0.5525\\ 0.3088\\ 0.1388\end{array}\right]---\left(5\right)$

(3), most suitable neutral grounding mode is determined according to the result K value calculated.In K in the 1st number correspondence Property point through the end value of low resistance grounding mode, the end value of the 2nd number correspondence neutral by arc extinction coil grounding mode, the 3rd The end value of number correspondence isolated neutral mode, finds out the neutral ground that the maximum data of end value value are corresponding wherein Mode is suitable mode.As a example by formula (5) result, first data maximum in the result, neutral point should be selected through small resistor Earthing mode.

Step 3, by table 2 corresponding rule of checking one by one, result of calculation is checked, finally can determine that the most rational Neutral grounding mode.

Step 4, this method carry out the determination of neutral grounding mode and are analyzed calculating, in reality in units of one section of bus It is possible that the neutral ground determined of two sections of (or multistage) buses of the same electric pressure of same transformer station in the application of border The situation that mode is inconsistent.For this problem, can as follows the two kinds of earthing modes occurred be carried out unified so that with The different section bus neutral grounding modes of the one same electric pressure of transformer station are consistent, and method is:

First, emphasis considers that capacitance current size determines neutral grounding mode.

If two sections of buses of the same electric pressure of same transformer station are A, B, A-bus capacitance current is 6A, B bus capacitor electricity Stream is 30A.Assuming to determine that result A is isolated neutral by preceding method, B is through grounding through arc, in such cases because of B Bus capacitor electric current, more than 10A, should not be selected isolated neutral mode, therefore should change A-bus into neutral point through arc blowout wire Circle earthing mode so that two sections of bus neutral grounding modes are consistent.In like manner, if having one section of bus current more than 100A, then two The neutral grounding mode of section bus the most preferably selects through low resistance grounding mode.

Secondly, it is considered as the transformer station's situation being associated with analyzed transformer station.Assume have following situation to occur: same change Two sections of bus capacitor electric currents of the same electric pressure in power station are all between 50-100A, and the neutral grounding mode determined is respectively Through grounding through arc mode with through low resistance grounding mode, the most now it is considered as the neutral point of the transformer station being associated with this station Grounding, then determine selection a kind of earthing mode therein, it is ensured that two sections of bus neutral grounding modes consistent.

Below in conjunction with an example, the suitability of the checking present invention.

Choose certain transformer station N to be analyzed.This transformer station N is 110/35/10kV transformer station, and essential information is as follows: 35kV Two sections of buses, capacitance current is respectively 87A, 90.7A, belongs to C class power supply area, and two sections of bus outlet total lengths are respectively as follows: 29.696+4.244,24.661+3.724, (cable+aerial line, unit km), recent load growth is very fast.Two sections of buses of 10kV, Capacitance current is respectively as follows: 55A, 66A, belongs to C class power supply area, two sections of bus outlets: 27.816+29.882,27.328+ 57.493, (cable+aerial line, unit km), zero load newly-increased plan.Aerial line is bare conductor.

First the 1st section of bus neutral grounding mode of 35kV is determined.Calculating process is as follows:

1. power supply area type: C class, the weight coefficient under this influence factor is:

Small resistor 0.3 × 0.4=0.12

Arc suppression coil 0.5 × 0.4=0.2

Earth-free 0.2 × 0.4=0.08

2. circuit types is joint line, and the weight coefficient under this influence factor is:

Joint line: cable 29.696km, aerial line 4.244km

Small resistor=0.1375

Arc suppression coil=0.0563

Earth-free=0.0563

3. the weight coefficient under capacitance current size influence factor is:

Capacitance current size: 87A (between 50A-100A)

Small resistor 0.4 × 0.25=0.1

Arc suppression coil 0.5 × 0.25=0.125

Earth-free 0.1 × 0.25=0.025

4. the weight coefficient under following distribution and load development influence factor is:

Following distribution and load development: load increasing speed is very fast

Small resistor 0.6 × 0.1=0.06

Arc suppression coil 0.3 × 0.1=0.03

Earth-free 0.1 × 0.1=0.01

5. considering the weight coefficient after each leading indicator is:

Small resistor 0.12+0.1375+0.1+0.06=0.4175

Arc suppression coil 0.2+0.0563+0.125+0.03=0.4113

Earth-free 0.08+0.0563+0.025+0.01=0.1713

This shows that this section of 35kV bus neutral point should be selected through low resistance grounding mode.Reference index is utilized to check nothing Problem.The neutral grounding mode of this section of bus is through grounding through arc mode at present, need to transform.

In like manner, the neutral point of the 2nd section of bus of 35kV and two sections of 10kV buses is analyzed, draws following result:

The 2nd section of bus of 35kV: result of calculation should be neutral point and should select through low resistance grounding mode.Reference index is utilized to check Also no problem.The neutral grounding mode of this section of bus is through grounding through arc mode at present, need to transform.

Two sections of buses of 10kV: result of calculation all should select neutral by arc extinction coil grounding mode, current neutral point to connect Ground mode is through grounding through arc mode, and adaptability is good.

Two sections of current capacitance currents of section bus of 35kV are already close to 100A, and cable outlet is many, and load growth is fast, neutral point Earthing mode has included transformation plan in, will transform as through low resistance grounding mode future.

3, range of application explanation

This method can be applicable to run transformer station 10kV-35kV intermediate distribution system neutral grounding mode and checks and set The determination of meter stage transformer station's intermediate distribution system neutral grounding mode.The most run transformer station's desired data real through scene Survey or statistical computation obtains；Design phase substation's data need to calculate according to the electrical network of planning and designing, such as electric capacity electricity The size of stream need to calculate obtain according to go out line length and the outlet type of planning and designing, is calculated and determines that neutral point mode needs Data after can by preceding method be analyzed calculate, finally determine rational neutral grounding mode.

It is emphasized that the embodiment described in invention is illustrative rather than determinate, therefore invention includes also It is not limited to the embodiment described in detailed description of the invention, every is drawn according to the technical scheme of invention by those skilled in the art Other embodiments, also belong to the scope of invention protection.

Claims (5)

1. the confirmation method of a medium voltage distribution network neutral grounding mode, it is characterised in that comprise the following steps:

Step 1, determine leading indicator and the reference index affecting neutral grounding mode, build what neutral grounding mode determined Weight coefficient system and check index reference frame；

Step 2, weight Coefficient System is utilized to calculate small resistor, arc suppression coil and earth-free result value, numerical value is big The neutral grounding mode that earthing mode is primary election that result is corresponding；

Step 3, result of calculation is checked by checking index reference frame corresponding rule of checking one by one, finally can determine that the most Reasonably neutral grounding mode.

The confirmation method of a kind of medium voltage distribution network neutral grounding mode the most according to claim 1, it is characterised in that: institute The process step that the different section bus neutral grounding modes of the same electric pressure of same transformer station are inconsistent is also included after stating step 3 Suddenly, its processing method is: emphasis considers that capacitance current size is to determine neutral grounding mode；Then consider and analyzed power transformation Transformer station's situation that station is associated.

The confirmation method of a kind of medium voltage distribution network neutral grounding mode the most according to claim 1 and 2, its feature exists In: described weight coefficient system includes area type residing for power distribution network, outlet type, capacitance current size, following distribution and bears Lotus development, its weight index is respectively 40%, 25%, 25%, 10%.

The confirmation method of a kind of medium voltage distribution network neutral grounding mode the most according to claim 3, it is characterised in that: institute State area type and include such as Types Below: σ>=30,15≤σ<30,6≤σ<15,<1 and σ<0.1, wherein, σ is for 1≤σ<6,0.1≤σ The load density of power supply area.

The confirmation method of a kind of medium voltage distribution network neutral grounding mode the most according to claim 1 and 2, its feature exists Following index is included: single-phase earth fault line selection accuracy, the installation of neutral ground equipment in: described check index reference frame Space, to close on the interference of communication line, grid structure, power supply reliability require and power distribution automation level, electric pressure and Insulating requirements, step voltage and equipment safety.