A method for distinguishing voltage sag disturbance sources of an oilfield distribution network

Abstract

The application discloses an oilfield distribution network voltage sag disturbance source demarcation method, and relates to the electrical engineering field.The technical scheme is as follows: real-time monitoring is conducted on bus voltage to determine whether voltage sag occurs;when voltage sag is detected, the next step is entered;the phase of the positive sequence current fault component of the monitored bus incoming and outgoing lines is extracted;the phase difference value of the positive sequence current fault component of the bus incoming line and each feeder outlet is calculated respectively, and phase distribution characteristics are compared;and the voltage sag disturbance source occurrence position is determined according to the comparison result.The application has the beneficial effects that the disclosed oilfield distribution network voltage sag disturbance source demarcation method is closely related to the actual distribution network, and the demarcation method only relies on the current measurement information of the station end incoming and outgoing lines to realize the sag source demarcation.Meanwhile, the method is also applicable to the small disturbance conditions such as capacitor switching, transformer switching, large motor starting and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical engineering, in particular to a method for distinguishing voltage sag disturbance sources of an oilfield distribution network. BACKGROUND

[0002] Electricity is the main power source for oilfield production and an important guarantee for stable oil production. Nowadays, the oilfield distribution network is greatly affected by external factors such as weather, and the probability of instantaneous failure is high. The voltage sag phenomenon caused by this will cause equipment downtime, line tripping and other accidents, which seriously affects the safe and stable production of oilfields. At present, the power grids of different voltage levels in oilfields are managed by different units. The power grid above 10kV is usually operated and maintained by the oilfield power company, and the medium and low voltage distribution network below 10kV is managed by the oil production unit. Voltage sag disturbance has the characteristic of propagating along the line. Determining the relative position of the voltage sag disturbance source is of great significance to clarify the responsibilities of different management units and develop voltage sag management measures.

[0003] At present, the classical voltage sag disturbance source section positioning methods proposed at home and abroad mainly include single variable method, power and energy method, impedance calculation method, etc. The voltage quantity method and current quantity method based on single variable method are easily limited by network topology structure; the power and energy method is the earliest method to use disturbance power and energy initial peak value for sag source positioning, but the positioning result of this method is low in reliability under certain conditions; the trajectory slope method and current real part polarity method are voltage sag source tracing methods based on impedance calculation, but the accuracy of these two methods for judging asymmetric disturbance sources is low. SUMMARY

[0004] In view of the above technical problems, the purpose of the present application is to propose a method for positioning voltage sag disturbance sources according to the particularity of oilfield power grid, and to timely and accurately locate the disturbance source, so as to provide a basis for relevant departments to take corresponding management measures.

[0005] The technical scheme comprises,

[0006] S1, real-time monitoring of bus voltage is performed through a power quality online monitoring system, and it is judged whether voltage sag occurs. When voltage sag is detected, the next step is entered;

[0007] The bus is a medium voltage distribution bus;

[0008] S2, the phase of the positive sequence current fault component of the incoming and outgoing lines of the bus monitored in S1 is extracted through the monitoring system;

[0009] S3, the phase difference value of the positive sequence current fault component of the bus incoming line and the outlet of each feeder is calculated respectively, and the phase distribution characteristics are compared;

[0010] S4, judging the voltage sag disturbance source occurrence position according to the phase distribution characteristics comparison result of S3.

[0011] Preferably, the S1 real-time monitoring of the bus voltage includes monitoring the bus voltage, the bus incoming line current and the current of all feeders.

[0012] Preferably, the step S3 includes establishing the corresponding positive sequence fault component equivalent network when the fault occurs at the fault point.

[0013] E s is the equivalent source voltage of the upstream system, f1 is the system side fault point, f2 is the bus side fault point, f3 is the feeder side fault point, M0, M1, M2, M3 are monitoring points; wherein M0 is the monitoring point at the bus incoming line end, M1, M2, M3 are the monitoring points at the outlets of each feeder;

[0014] Z s is the equivalent impedance of the system, Zl1, Zl2, Zl3 are the equivalent line impedances of the three load lines, ZlD1, ZlD2, ZlD3 are the equivalent load impedances of the lines, and the corresponding positive sequence fault component equivalent network when the faults occur at f1, f2 and f3 is established.

[0015] Preferably, in S3, the influence of factors such as load and line impedance angle difference, CT transformation and calculation error is considered, and it is considered that the equivalent resistance of the distribution network is greater than the reactance, and the impedance angle is close to 0°, so when the fault occurs at f1, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as shown in the judgment formula one.

[0016]

[0017] Among them, is the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0018] Preferably, when the fault occurs at f2, the corresponding positive sequence fault component equivalent network takes as the reference, and the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as shown in the judgment formula two.

[0019]

[0020] Among them, is the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0021] Preferably, when the fault occurs at f3, the corresponding positive sequence fault component equivalent network takes as the reference, and the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as shown in the judgment formula three.

[0022]

[0023] wherein, the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0024] Preferably, assuming that the power distribution network has n feeders in total, the i-th is the fault feeder, and the other n-1 are non-fault feeders, then when a short-circuit fault occurs in any feeder, the phase of the positive sequence current fault component at the busbar feeder and the feeder outlet will satisfy the relationship as judgment formula four:

[0025]

[0026] wherein, the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0027] Preferably, if the S4 satisfies the criterion formula one, the disturbance source is at the power supply side; if the criterion formula two is satisfied, the disturbance source is at the busbar; if neither the criterion formula one nor the criterion formula two is satisfied, the disturbance source is on a certain feeder, at this time, the criterion formula four can be executed to determine that the disturbance source is on the i-th feeder.

[0028] The technical scheme provided by the embodiment of the present application has the beneficial effects that the oilfield power distribution network voltage sag disturbance source demarcation method disclosed by the present application is closely related to the actual power distribution network, and the demarcation method only relies on the current measurement information of the station end inlet and outlet lines, so that the sag source demarcation is realized. At the same time, the method is also applicable to the case of small disturbance such as capacitor switching, transformer switching, and large motor starting. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a simplified analysis model diagram of the oilfield power distribution network of the embodiment of the present application.

[0030] Figure 2 It is an equivalent network diagram of the positive sequence fault component when the upstream f1 fault of the monitoring point of the embodiment of the present application.

[0031] Figure 3 It is an equivalent network diagram of the positive sequence fault component when the f2 fault of the busbar of the embodiment of the present application.

[0032] Figure 4 It is an equivalent network of the positive sequence fault component when the f3 fault of the feeder side of the embodiment of the present application.

[0033] Figure 5 It is a voltage sag disturbance source demarcation flow chart of the embodiment of the present application. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. Of course, the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0035] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0036] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0037] In the description of the present application, it should be noted that unless otherwise specified and limited, the terms "mounting", "connection", "connection", "setting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] Embodiment 1

[0039] The present application provides a kind of oilfield distribution network voltage sag disturbance source demarcation method, comprising,

[0040] S1, real-time monitoring is carried out to 10kV bus voltage by power quality online monitoring system, whether voltage sag occurs is judged, when detecting that voltage sag occurs, then next step is entered;

[0041] S2, the phase of 10kV bus incoming and outgoing line positive sequence current fault component is extracted by monitoring system;

[0042] S3, the phase difference of positive sequence current fault component at 10kV bus incoming line and each feeder outlet is calculated respectively, and phase distribution characteristics are compared.

[0043] S4. Based on the comparison of phase distribution characteristics in S3, determine the location of the voltage sag disturbance source.

[0044] Example 2

[0045] This invention provides a method for demarcating voltage sag disturbance sources in oilfield power distribution networks, comprising:

[0046] S1. Monitor the 10kV bus voltage in real time through the online power quality monitoring system to determine whether a voltage dip occurs. If a voltage dip is detected, proceed to the next step. Real-time monitoring of the 10kV bus voltage includes monitoring the 10kV bus voltage, the current of the bus incoming line and all feeders.

[0047] S2. Extract the fault component phase of the positive sequence current of the 10kV busbar incoming and outgoing lines through the monitoring system;

[0048] S3. Calculate the phase difference of the positive sequence current fault component at the 10kV bus incoming line and each feeder outlet, and compare the phase distribution characteristics.

[0049] S4. Based on the comparison of phase distribution characteristics in S3, determine the location of the voltage sag disturbance source.

[0050] Step S3 includes establishing an equivalent network of the positive sequence fault components corresponding to the fault point when a fault occurs;

[0051] Let E s Let Z be the equivalent power supply voltage of the upstream system, f1, f2, and f3 be the locations of different fault points, and M0, M1, M2, and M3 be the monitoring points; s Let Zl1, Zl2, and Zl3 be the equivalent line impedances of the three load lines, and ZlD1, ZlD2, and ZlD3 be the equivalent load impedances of the lines. Then, the equivalent network of the positive sequence fault components corresponding to the faults at f1, f2, and f3 can be established.

[0052] In S3, considering the effects of load and line impedance angle differences, CT transmission and calculation errors, and taking into account that the equivalent resistance of the distribution network is greater than the reactance and the impedance angle is close to 0°, when a fault occurs at f1, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following relationship (1).

[0053]

[0054] like Figure 2 As shown. Among them, The fault component of the positive sequence current is extracted from each monitoring point at the station after the fault occurs.

[0055] Example 3

[0056] This invention provides a method for demarcating voltage sag disturbance sources in oilfield power distribution networks, comprising:

[0057] S1. Monitor the 10kV bus voltage in real time through the online power quality monitoring system to determine whether a voltage dip occurs. If a voltage dip is detected, proceed to the next step. Real-time monitoring of the 10kV bus voltage includes monitoring the 10kV bus voltage, the current of the bus incoming line and all feeders.

[0058] S2. Extract the fault component phase of the positive sequence current of the 10kV busbar incoming and outgoing lines through the monitoring system;

[0059] S3. Calculate the phase difference of the positive sequence current fault component at the 10kV bus incoming line and each feeder outlet, and compare the phase distribution characteristics.

[0060] S4. Based on the comparison of phase distribution characteristics in S3, determine the location of the voltage sag disturbance source.

[0061] Step S3 includes establishing an equivalent network of the positive sequence fault components corresponding to the fault point when a fault occurs;

[0062] Let E s Let Z be the equivalent power supply voltage of the upstream system, f1, f2, and f3 be the locations of different fault points, and M0, M1, M2, and M3 be the monitoring points; s Let Zl1, Zl2, and Zl3 be the equivalent line impedances of the three load lines, and ZlD1, ZlD2, and ZlD3 be the equivalent load impedances of the lines. Then, the equivalent network of the positive sequence fault components corresponding to the faults at f1, f2, and f3 can be established.

[0063] In S3, considering the effects of load and line impedance angle differences, CT transmission and calculation errors, and taking into account that the equivalent resistance of the distribution network is greater than the reactance and the impedance angle is close to 0°, when a fault occurs at f1, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following relationship (1).

[0064]

[0065] like Figure 2 As shown. Among them, The fault component of the positive sequence current is extracted from each monitoring point at the station after the fault occurs.

[0066] The equivalent network of the positive-sequence fault components corresponding to the fault at point f2, such as Figure 3 As shown, with Based on this, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following relationship (2).

[0067]

[0068] in, The fault component of the positive sequence current is extracted from each monitoring point at the station after the fault occurs.

[0069] Example 3

[0070] This invention provides a method for demarcating voltage sag disturbance sources in oilfield power distribution networks, comprising:

[0071] S1. Monitor the 10kV bus voltage in real time through the online power quality monitoring system to determine whether a voltage dip occurs. If a voltage dip is detected, proceed to the next step. Real-time monitoring of the 10kV bus voltage includes monitoring the 10kV bus voltage, the current of the bus incoming line and all feeders.

[0072] S2. Extract the fault component phase of the positive sequence current of the 10kV busbar incoming and outgoing lines through the monitoring system;

[0073] S3. Calculate the phase difference of the positive sequence current fault component at the 10kV bus incoming line and each feeder outlet, and compare the phase distribution characteristics.

[0074] S4. Based on the comparison of phase distribution characteristics in S3, determine the location of the voltage sag disturbance source.

[0075] Step S3 includes establishing an equivalent network of the positive sequence fault components corresponding to the fault point when a fault occurs;

[0076] Let E s Let Z be the equivalent power supply voltage of the upstream system, f1, f2, and f3 be the locations of different fault points, and M0, M1, M2, and M3 be the monitoring points; s Let Zl1, Zl2, and Zl3 be the equivalent line impedances of the three load lines, and ZlD1, ZlD2, and ZlD3 be the equivalent load impedances of the lines. Then, the equivalent network of the positive sequence fault components corresponding to the faults at f1, f2, and f3 can be established.

[0077] In S3, considering the effects of load and line impedance angle differences, CT transmission and calculation errors, and taking into account that the equivalent resistance of the distribution network is greater than the reactance and the impedance angle is close to 0°, when a fault occurs at f1, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following relationship (1).

[0078]

[0079] like Figure 2 As shown. Among them, The fault component of the positive sequence current is extracted from each monitoring point at the station after the fault occurs.

[0080] f2 fault corresponding positive sequence fault component equivalent network, as shown in Figure 3 the reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as follows formula (2),

[0081]

[0082] wherein, the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0083] f3 fault corresponding positive sequence fault component equivalent network, as shown in Figure 4 the reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as follows formula (3),

[0084]

[0085] wherein, the positive sequence current fault component extracted at each monitoring point at the station end after the fault occurs.

[0086] Embodiment 4

[0087] The present application provides a kind of oilfield distribution network voltage sag disturbance source demarcation method, comprising,

[0088] S1, the voltage of 10kV bus is monitored in real time by power quality on-line monitoring system, it is judged whether voltage sag occurs, when detecting that voltage sag appears, then turn to next step;The voltage of 10kV bus is monitored in real time, including monitoring 10kV bus voltage, bus incoming line and the current of all feeders;

[0089] S2, the positive sequence current fault component phase of 10kV bus incoming and outgoing line is extracted by monitoring system;

[0090] S3, the phase difference of positive sequence current fault component at the outlet of 10kV bus incoming line and each feeder is calculated respectively, and phase distribution characteristics are compared;

[0091] S4, according to the result of S3 phase distribution characteristics comparison, the position of voltage sag disturbance source is judged.

[0092] Step S3 includes establishing the corresponding positive sequence fault component equivalent network when fault occurs at fault point;

[0093] Let E s be the equivalent source voltage of upstream system, f1, f2, f3 be different fault point positions, M0, M1, M2, M3 be monitoring point;Let Z s ​​Zl1, Zl2, Zl3 are the equivalent line impedances of the three load lines, and ZlD1, ZlD2, ZlD3 are the equivalent load impedances of the lines, the corresponding positive sequence fault component equivalent network when faults occur at f1, f2 and f3 can be established.

[0094] In S3, the influence of factors such as load and line impedance angle difference, CT transformation and calculation error is considered, and meanwhile, it is considered that the equivalent resistance of the distribution network is greater than the reactance, and the impedance angle is close to 0°, so when a fault occurs at f1, it can be concluded that the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following formula (1),

[0095]

[0096] As shown in Figure 2 , wherein, are the positive sequence current fault components extracted at each monitoring point at the station end after the fault occurs.

[0097] The corresponding positive sequence fault component equivalent network when a fault occurs at f2 is as shown in Figure 3 , and with as the reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following formula (2),

[0098]

[0099] , wherein, are the positive sequence current fault components extracted at each monitoring point at the station end after the fault occurs.

[0100] The corresponding positive sequence fault component equivalent network when a fault occurs at f3 is as shown in Figure 4 , and with as the reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the following formula (3),

[0101]

[0102] , wherein, are the positive sequence current fault components extracted at each monitoring point at the station end after the fault occurs.

[0103] Suppose that the distribution network has n feeders, of which the i-th is the fault feeder, and the other n-1 are non-fault feeders, then when a short-circuit fault occurs in any feeder, the phase of the positive sequence current fault component of the bus incoming line and the feeder outlet will satisfy the following formula (4):

[0104]

[0105] , wherein, The positive sequence current fault component extracted at each monitoring point of the station end after the fault occurs.

[0106] According to the above analysis, when the voltage sag disturbance source appears at the power supply side, the bus, and different feeders, the positive sequence current fault component phases at the bus inlet and all feeder outlets have their own distribution characteristics, so a voltage sag disturbance source demarcation method based on the positive sequence current fault component phase comparison principle can be proposed.

[0107] The voltage of the 10kV bus is monitored in real time through the power quality online monitoring system to determine whether a voltage sag occurs in the system;

[0108] The positive sequence current fault component phases of the 10kV bus inlet and outlet are extracted through the monitoring system, the phase difference values of the positive sequence current fault component at the 10kV bus inlet and the outlets of each feeder are calculated, and the phase distribution characteristics are compared. If criterion formula (1) is satisfied, the disturbance source appears at the power supply side; if criterion formula (2) is satisfied, the disturbance source appears at the bus; if neither criterion formula (1) nor (2) is satisfied, the disturbance source is located on a certain feeder, and criterion formula (4) is executed to determine that the disturbance source is located on the i-th feeder.

[0109] The above is only a preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for distinguishing voltage sag disturbance sources in an oilfield distribution network, characterized by, Comprising, S1, real-time monitoring of bus voltage, determine whether voltage sag occurs, when detected voltage sag occurs, then turn to the next step; The bus is a medium voltage distribution bus; S2, extracting step S1 monitored bus incoming and outgoing line positive sequence current fault component phase; S3, respectively calculating the phase difference of positive sequence current fault component at the bus incoming line and the outlet of each feeder, and comparing the phase distribution characteristics; S4, according to the results of step S3 phase distribution characteristic comparison, determine the voltage sag disturbance source position; The step S1 real-time monitoring of bus voltage includes monitoring bus voltage, bus incoming line and all feeder current; The step S3 includes, establishing the corresponding positive sequence fault component equivalent network when fault occurs at the fault point; with Vup as the equivalent supply voltage of the upstream system, Fsys as the system-side fault point, Fbus as the bus-side fault point, Ffeeder as the feeder-side fault point, M as the monitoring point; wherein Mbus is the monitoring point at the bus incoming line end, Mfeeder is the monitoring point at each feeder outgoing line end; Let Zsys be the equivalent impedance of the system, Zl, Z2, Z3 be the equivalent line impedances of the three lines, ZL be the equivalent load impedance of the lines, the corresponding positive sequence fault component equivalent network when the fault occurs at point P is established.

2. The oilfield power distribution grid voltage sag disturbance source demarcation method of claim 1, wherein, In the step S3, when When a fault occurs at the monitoring point, it can be concluded that the phase of the fault component of the positive sequence current of the incoming line and the feeder at the monitoring point will satisfy the relationship as the first judging formula, ； wherein, , , , are the positive sequence fault components extracted at each monitoring point at the station end after the fault occurs, respectively.

3. The oilfield power distribution grid voltage sag disturbance source demarcation method of claim 2, wherein, corresponding positive sequence fault component equivalent network at the time of fault, so that As a reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as judgment formula two, ； wherein, , , , are the positive sequence fault components extracted at each monitoring point at the station end after the fault occurs, respectively.

4. The oilfield power distribution grid voltage sag disturbance source demarcation method of claim 3, wherein, At the time of fault, the corresponding positive sequence fault component equivalent network, to As a reference, the phase of the positive sequence current fault component of the incoming line and the feeder at the monitoring point will satisfy the relationship as follows: the fault component phase will satisfy the relationship as judgment formula three, ； wherein, , , , are the positive sequence fault components extracted at each monitoring point at the station end after the fault occurs, respectively.

5. The oilfield power distribution grid voltage sag disturbance source demarcation method of claim 4, wherein, Assuming that the distribution network has n feeders, the i-th is the fault feeder, and the other n-1 is the non-fault feeder, then the positive sequence current fault component phase at the bus incoming line and the outlet of each feeder will satisfy the relationship as judgment formula four when any feeder short circuit fault occurs: ； wherein, , , , are the positive sequence fault components extracted at each monitoring point at the station end after the fault occurs, respectively.

6. The oilfield power distribution grid voltage sag disturbance source demarcation method of claim 5, wherein, The step S4 if the judgment formula one is satisfied, the disturbance source appears on the power supply side; if the judgment formula two is satisfied, the disturbance source appears on the bus; if the judgment formula one and two are not satisfied, the disturbance source is located on a feeder, at this time, the judgment formula four can determine that the disturbance source is located on the i-th feeder.

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