CN109950882B - Small power supply grid-connected protection method - Google Patents
Small power supply grid-connected protection method Download PDFInfo
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Abstract
The invention provides a small power supply grid-connected protection method, which is characterized in that a line protection scheme and a tripping mode thereof are configured according to a small power supply grid-connected connection mode and a voltage grade of a transformer substation, a corresponding low-frequency low-voltage splitting configuration scheme is determined according to different protection scheme actions and different small power supply splitting modes and different fault objects, and a grid-connected protection action sequence which firstly carries out protection scheme actions, realizes fault splitting and splitting reclosing and completes maximum load supply at low frequency low voltage is formed.
Description
Technical Field
The disclosure relates to a small power supply grid-connected protection method.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The small power grid connection is a common power generation mode at present. With the continuous opening of the power market, spontaneous power supply integration is continuous, and owners want to generate power to the power grid when the power is abundant, and absorb power from the power grid when the power is insufficient. Therefore, the capacity of the small power grid-connected enterprise based on the property of the synchronous machine is generally large, and the small power grid-connected enterprise is a powerful support for a power grid. But the potential safety hazard brought by the method is also obvious: if the active linkage switching mode is not adopted, the reclosing success rate of the power system is possibly influenced. In the extreme case, when the small power supply which is not closely connected with the power grid is connected with the power grid again, the impact is brought to the power grid and the equipment per se. Or an unplanned island may occur, which causes low quality of local power supply electric energy, and further causes low frequency oscillation. The method for solving the problem is to study the protection action connection and disconnection small power supply mode under various small power supply grid-connected conditions in detail, on one hand, the fault is accurately removed through strengthening grid-connected protection, on the other hand, the maximum power grid load supply is ensured through a combination method of connecting and disconnecting small power supply grid-connected switches by various protection action objects, and meanwhile, the conditional island operation mode is allowed to exist by matching with a small power supply low-frequency low-voltage disconnection scheme.
The original protection is to protect the equipment as the object, the sight window is limited to the equipment, and as for the unsuccessful reclosing, the unsuccessful load recovery is not the range that can be considered, so the protection is easily isolated from the recovery of power supply and the safe operation of the system, sometimes the protection action is the extreme condition which brings hidden trouble to the safe operation of the power grid.
Disclosure of Invention
The invention aims to solve the problems and provides a small power supply grid-connected protection method, and the small power supply grid-connected protection method is characterized in that a safe and reliable scheme which is also an open protection and safety device action scheme is formed by strengthening protection configuration, combining different protection actions with different combined-tripping small power supply grid-connected switch schemes and matching with a low-frequency low-voltage splitting scheme. Meanwhile, the action level space is divided into three levels of fault load shedding, connection switching of a small power grid-connected switch and low-frequency and low-voltage load shedding, and the optimization function of protection is completed.
According to some embodiments, the following technical scheme is adopted in the disclosure:
a small power grid-connected protection method comprises the following steps:
according to the small power supply grid-connected connection mode and the voltage grade of the transformer substation, a line protection scheme and a tripping mode thereof are configured, according to the difference of protection scheme actions and the difference of connection and disconnection modes of the small power supply, the difference of fault objects is combined, and a corresponding low-frequency low-voltage disconnection configuration scheme is determined, so that a grid-connected protection action sequence which firstly carries out protection scheme actions, realizes fault load disconnection, then carries out connection and disconnection reclosing and finishes the supply of the maximum load is formed.
As a further limitation, when a small power station is connected to the medium-voltage side and the low-voltage side of a 220kV transformer substation through a special line, the protection of a generator and a transformer of the small power station adopts differential protection and backup protection configuration, and 110kV line protection configuration is longitudinal differential protection and three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection, and the tie line adopts disconnection reclosing, namely three-phase detection non-voltage reclosing is put into the power supply side of the main system of the tie line, and reclosing is stopped at the small power supply side.
As a further limitation, when a small power supply station is connected to the medium-voltage side and the low-voltage side of a 220kV transformer substation through a T connection circuit, the protection of a generator and a transformer of the small power supply station is configured with differential protection and backup protection, and the protection of a 110kV circuit is configured with three-end longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection, and the side protection of the load station of the tie line only acts on signals; and the main system power supply side of the connecting line adopts disconnection reclosing, namely the main system power supply side of the connecting line is switched into the three-phase detection non-voltage reclosing, and the small power supply side of the connecting line stops reclosing.
As a further limitation, when a small power station is connected to the medium-low voltage side of a 110kV or 35kV transformer substation through a special line, the generator and transformer protection of the small power station is configured with differential protection and backup protection; the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection; the 10kV line protection is preferably configured with longitudinal differential protection and three-stage directional current protection.
As a further limitation, the grid-connected line of the small power supply of 35kV or 10kV is provided with a low-frequency low-voltage disconnecting device which is used for disconnecting the main system when the main system fails.
A 35kV or 10kV main system power supply side of the tie line adopts a splitting reclosing switch, namely a three-phase detection non-voltage reclosing switch is put into the main system power supply side of the tie line, and a reclosing switch is stopped at a small power supply side; the power supply side of the main system of the upper-level 110kV line adopts disconnection reclosing, the power supply side of the main system of the 110kV line is switched into three-phase detection non-voltage reclosing, and the side of the small power supply grid-connected 110kV transformer substation is not stopped and reclosed.
As a further limitation, for a main network terminal substation of a large-current grounding system, the zero-sequence overcurrent protection of the transformer is performed on each side of a first time-limited switching-off region small power supply grid-connected point and a second time-limited switching-off transformer;
for a main network terminal substation of a large-current grounding system, a transformer is provided with a zero-sequence voltage and gap zero-sequence current splitting device and a circuit breaker of a power supply networking line in a tripping area;
for a small current grounding system grounded by a resistor, a transformer at the power supply side of a region is provided with a zero sequence voltage and zero sequence current splitting device, the protection action time is matched with a protection section with enough sensitivity coefficient for zero current protection of all equipment at the side, and a circuit breaker at the side of the power supply transformer of the region is tripped;
when the ground fault occurs, the local side of the transformer is matched with all outgoing line zero sequence protection, namely, the protection with zero sequence degree is matched, and the zero sequence protection is used as backup protection to delay and trip the small power grid-connected switch of the local side.
As a further limitation, when a small power supply station is connected to the medium-voltage side of a public 110kV or 35kV transformer substation through a T connection line, the generator and transformer protection of the small power supply station is configured with differential protection and backup protection; the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the protection action of a line at the side of the 110kV transformer substation jumps to a 35kV tie line switch; the 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection; the T-connection line load side switch acts on a signal; and the 35kV small power supply grid-connected line is provided with a low-frequency low-voltage splitting device.
As a further limitation, when the disconnection reclosing configuration is set, the constant value of the low-frequency and low-voltage disconnection device of the power supply is matched with the constant value of the final wheel of the basic wheel of the power grid, and the disconnection should not be performed before the disconnection of the power grid.
Compared with the prior art, the beneficial effect of this disclosure is:
according to the method, a safe and reliable scheme which is also an open type protection and safety device action scheme is formed by strengthening protection configuration, combining different combined-tripping small power supply grid-connected switch schemes with different protection actions and matching with a low-frequency low-voltage splitting scheme. The action level space is divided into three layers of fault load shedding, connection and disconnection small power supply grid-connected switch and low-frequency and low-voltage load shedding, and the optimization function of protection is completed.
According to the method, different fault objects, different protection actions and the small power supply needing to be connected and cut in a tripping mode are considered, the corresponding mode object of disconnection reclosing is considered, the configuration and disconnection scheme of the final low-frequency low-voltage disconnection device are further considered, the fault object can be effectively guaranteed to be quickly cut off after the fault, and meanwhile, the reliable supply of the maximum load is completed through the connection and disconnection reclosing at low frequency and low voltage.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a schematic diagram of the coordination of the operation schemes of the protection and self-installation device of the present embodiment;
FIG. 2 is an analysis diagram of the protection and disconnection scheme components of the present embodiment;
FIG. 3 is a schematic diagram of the medium-low voltage side grid connection of a small power station in the present embodiment to a 220kV substation via a dedicated line;
fig. 4 is a schematic diagram of medium-voltage side grid connection of a small power station in a 220kV substation through a T-junction circuit according to the embodiment;
FIG. 5 is a schematic diagram of the low-voltage side grid connection of a small power station in the present embodiment to a public 110kV and 35kV transformer substation via a dedicated line;
FIG. 6 is a schematic diagram of the medium-voltage side grid connection of a small power station in the present embodiment to a public 110kV and 35kV substation via a T-connection line;
FIG. 7 is a timing diagram of the three defensive actions of the embodiment;
FIG. 8 is a diagram of the transformer wiring in the different grounding modes of the present embodiment;
FIGS. 9(a) - (c) are sub-divisions of the protection configuration for different grounding modes of the present embodiment;
fig. 10 is a zero sequence network diagram of a direct ground fault of a transformer in case of ground fault according to the present embodiment;
FIG. 11 illustrates a local distributed power supply and local load balancing scenario of the present embodiment;
FIG. 12 is a wiring diagram of the normal operation condition of the present embodiment;
fig. 13 is a schematic diagram of the protection scheme operation load partition area according to the present embodiment.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only relational terms determined for convenience in describing structural relationships of the parts or elements of the present disclosure, and do not refer to any parts or elements of the present disclosure, and are not to be construed as limiting the present disclosure.
In the present disclosure, terms such as "fixedly connected", "connected", and the like are to be understood in a broad sense, and mean either a fixed connection or an integrally connected or detachable connection; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present disclosure can be determined on a case-by-case basis by persons skilled in the relevant art or technicians, and are not to be construed as limitations of the present disclosure.
As described in the background art, protection is performed by using a device to be protected as an object, a sight window of the device is limited to the device, and as for an unsuccessful reclosure, a load recovery failure is not a range that can be considered by the device, so that the protection is easily isolated from a recovery power supply and a system safe operation, and sometimes, an extreme condition that a protection action brings hidden troubles to a power grid safe operation occurs. The existing wide area protection attempts to solve the problem in a mode of enhancing the information acquisition breadth, but for the existing protection device on site, relay protection is used as a first line of defense, and the fault isolation at the first time is still the most reliable and economical method.
The main purpose of relay protection is to protect the safety of the device object, but the operation setting thereof greatly affects the safe and stable operation of the subsequent power system. If the set backgrounds do not match, the subsequent installation device action cannot compensate the result. The protection principle of the power equipment is a feedback type control, that is, the power equipment operates according to an operation logic set in advance, and the protection principle of the power equipment is a feedforward type control for stable operation of the system. If the event and context are expected to match the actual event and scenario, the requirements of the two are not in conflict. If the events are not matched, the subsequent defense line cannot complete the events required by the relay protection, so that the events conflict with the requirements of the safe operation of the power grid, and a coordination scheme for coordinating the two to be unified protection actions to be combined and switched and switching off the load device is needed, as shown in fig. 1.
The embodiment provides an integrated small power supply grid-connected protection scheme based on an enhanced protection and low-frequency low-voltage splitting scheme, different protection actions are combined with different inter-tripping small power supply grid-connected switch schemes through enhanced protection configuration, and the scheme is matched with the low-frequency low-voltage splitting scheme to form a safe and reliable scheme which is also an open protection and safety device action scheme. The action level space is divided into three layers of fault load shedding, connection and disconnection small power supply grid-connected switch and low-frequency and low-voltage load shedding, and the optimization function of protection is completed.
If the protection scheme is carefully decomposed, different fault objects, different protection actions and a tripping mode need to be considered, and a small power supply needs to be connected. Then, the mode object of the corresponding disconnection reclosing is considered, and finally, the configuration and the disconnection scheme of the last low-frequency low-voltage disconnection device are considered. Therefore, the final purpose is to most effectively ensure that a fault object is quickly removed after the fault, and simultaneously, the reliable supply of the maximum load is completed through the low-frequency low-voltage reclosing of the combined-cut and disconnected train. As shown in particular in fig. 2.
The protection scheme mainly comprises the following steps:
(1) as shown in FIG. 3, a small power station is specially connected to the medium-low voltage side of a 220kV transformer substation for grid connection protection and reclosing
And (4) protection function configuration:
as shown in fig. 3, a small power station is connected to the medium-voltage side and the low-voltage side of a 220kV substation through a dedicated line, and the protection of a generator and a transformer of the small power station can adopt conventional configuration (differential protection and backup protection); considering the principle of near backup, the 110kV line protection is provided with longitudinal differential protection, three-section alternate distance, three-section grounding distance and four-section zero-sequence overcurrent protection. The 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection. The connecting line adopts a disconnection reclosing switch, namely a three-phase detection non-voltage reclosing switch is put into the power supply side of the main system of the connecting line, and the reclosing switch is stopped at the small power supply side.
(2) Medium-voltage side grid-connected protection scheme for 220kV transformer substation through T-connection circuit in small power plant
Applicable protection function configuration:
as shown in fig. 4, a small power station is connected to the medium-voltage side and the low-voltage side of a 220kV substation through a T-connection line, and the protection of a generator and a transformer of the small power station can adopt conventional configuration (differential protection and backup protection); considering according to the principle of near backup, the 110kV line protection is provided with three-end longitudinal differential protection, three-section alternate distance, three-section grounding distance and four-section zero-sequence overcurrent protection. The 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection, and the protection on the load station side (03 switch) of the tie line only acts on signals. And the main system power supply side of the connecting line adopts disconnection reclosing, namely the main system power supply side of the connecting line is switched into the three-phase detection non-voltage reclosing, and the small power supply side of the connecting line stops reclosing.
The low-frequency low-voltage splitting constant value is lower than the final wheel constant value of the low-frequency low-voltage load shedding device.
(3) Low-voltage side grid-connected scheme for small power supply station in 110kV and 35kV transformer substation through special line
As shown in fig. 5, a small power station is connected to the medium-low voltage side of a public 110kV and 35kV substation through a dedicated line, and the protection of the generator and the transformer of the small power station can adopt conventional configuration (differential protection and backup protection); the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection. The 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection; the 10kV line protection is preferably configured with longitudinal differential protection and three-stage directional current protection.
The common station side protection (B station 03 switch) of the 110kV tie line, the grounding and ungrounded protection configuration of the 110kV common transformer and the 35kV (10kV) small power supply tie line function of the jump, namely: the common station side protection of the 110kV tie line and the zero sequence protection (gap and overvoltage protection when the earth is not connected) of the high voltage side of the transformer trip 35kV (and 10kV) tie line switches (53 and 23 switches) for a short time, and if the long-trip function is difficult to realize, the power supply side switches (503 and 13 switches) of the small power supply tie line can be tripped nearby.
The low-frequency low-voltage splitting device is configured on the 35kV and 10kV small power supply grid-connected wire and used for splitting with a system when a main system fails.
A 35kV or 10kV main system power supply side of the tie line adopts a splitting reclosing switch, namely a three-phase detection non-voltage reclosing switch is put into the main system power supply side of the tie line, and a reclosing switch is stopped at a small power supply side; the power supply side of the main system of the upper-level 110kV line adopts disconnection reclosing, the power supply side of the main system of the 110kV line is switched into three-phase detection non-voltage reclosing, and the side of the small power supply grid-connected 110kV transformer substation is not stopped and reclosed.
For a main network terminal substation of a large-current grounding system, if a neutral point of a transformer is directly grounded and a local power supply is connected to a load side, zero-sequence overcurrent protection of the transformer is performed on a first time limit connection point of a small power supply in a switching area and each side of a second time limit switching transformer.
For a main network terminal substation of a large-current grounding system, if a neutral point of a transformer is not directly grounded and a regional power supply is connected to a load side, the transformer is also provided with a zero sequence voltage and gap zero sequence current splitting device, the fixed value of 3 times of zero sequence voltage 3U0 is generally set to be 150V-180V (the rated value is 300V), the fixed value of gap zero sequence current for one time can be generally set to be 40A-100A, and a circuit breaker of a regional power supply networking line is jumped with 0.1 s-0.5 s of time delay after protection action.
For a small current grounding system grounded through a resistor, a regional power supply side transformer is provided with a zero sequence voltage and zero sequence current splitting device, a three-time zero sequence voltage 3Uo fixed value is generally set to be 40V-50V (3U 0 is 100V when single-phase grounding is carried out), and the zero sequence current fixed value is set according to enough sensitivity coefficient of single-phase grounding fault. The protection action time is matched with a protection section with enough sensitivity coefficient for zero current protection of all equipment on the side, and the breaker on the side of the power transformer in the region is jumped.
(4) Low-voltage side grid-connected protection scheme for small power supply station in 110kV and 35kV transformer substation through T connection line
As shown in fig. 6, a small power station is connected to the medium-low voltage side of a public 110kV and 35kV substation through a T connection, and the protection of the generator and the transformer of the small power station can adopt a conventional configuration (differential protection and backup protection); the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection. The line protection action of the 110kV transformer station side (second station switch) jumps to a 35kV tie line switch (54 switch). The 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection; the T-line load side 53 switch operates on a signal.
A110 kV public transformer is provided with grounding and ungrounded protection combined tripping 35kV (10kV) small power grid-connected line functions, namely a transformer high-voltage side zero sequence protection (gap and overvoltage protection when ungrounded) short-time limit tripping 35kV connected line switch (54 switch).
The 35kV small power supply grid-connected line is provided with a low-frequency low-voltage splitting device which is used for splitting with a system when a main system fails.
The fixed value requirements of the low-frequency low-voltage splitting device of the power supply are 47.5Hz/0.5s (the fixed value of the basic wheel of the low-frequency load reducing device is 7.75Hz/0.5s) and 70.0 percent Un/5.0s (the fixed value of the basic wheel of the low-frequency load reducing device is 75.0 percent Un/0.5 s).
In the configuration process of the protection scheme, for some existing small power supply grid-connected protection schemes, due to the fact that plant station protection configuration is incomplete, the function of switching on and off the small power supply grid-connected switch due to the fault of the 110kV connecting line cannot be achieved. In order to ensure that the reclosing can act quickly after the 110kV connecting line has a fault, the method for improving the fixed value of the low-frequency low-voltage splitting device is adopted, the low-frequency low-voltage splitting device is used for splitting the small power supply in advance, the purpose of mounting the low-frequency low-voltage splitting device is violated, and the method is equivalent to replacing partial function of the first line of defense by using a function of the second line of defense. On one hand, the rapidity and the matching are not satisfactory, and the principle that low-frequency low-voltage splitting is matched with a power grid is violated, because the basic requirements on the low-frequency low-voltage splitting are matched as the final turn fixed value of the power grid, the low-frequency low-voltage splitting is not performed before the power grid is split, so that the power grid cannot be effectively supported. As shown in fig. 7.
Taking the example that a small power supply station is connected to the medium-low voltage side of a public 110kV or 35kV transformer substation through a special line, as can be seen from fig. 8, a small power supply connection channel of the small power supply station comprises a line and a transformer which are both provided with differential protection, so that a fault judgment point can be accurately determined through enhanced protection, and a control strategy of the next step can be determined through the severity and the extension degree of the fault and the position of the fault in a power grid only if a single fault object is determined. For the load side, when the only power supply channel element of the load side has a fault, on one hand, the connection tripping and grid connection switch and the disconnection reclosing switch ensure that the power supply of the system side is recovered. On the other hand, an open type planned island is formed by a low-frequency, low-voltage separation device. The open planned island is called because the local load can be provided by a small power supply on the 10kV and 35kV sides of the station B according to the current load condition, namely the real-time frequency voltage. However, for the power grid, the small power supply opposite side grid-connected switch (23) is considered to be remotely switched, the remote switching function can be realized due to the configuration of longitudinal differential protection, and the island can be considered to be a small power supply to supply loads in a plant. And the system side grid-connected switch (13) can be cut off without remote switching conditions, so that the island is a larger island including a low-voltage side in the second station. The principle is that an island can be formed according to the local load condition on the premise of ensuring the safe and stable operation of the system. However, the fixed value of the low-frequency and low-voltage load shedding is that after the basic low-frequency and low-voltage operation of the system is finished when the system is in fault or abnormal operation, and the system still cannot be recovered to the stable operation condition, the low-frequency and low-voltage load shedding of the system is started in order to ensure the safety of equipment in a small power supply plant, namely, the support function of the power system cannot be ignored.
For different grounding modes of transformers, systems can be divided into low-current grounding systems and high-current grounding systems. In a large-current grounding system, a transformer with a low-voltage low-power grid-connected transformer is generally directly grounded at a high-voltage side neutral point, but for protection configuration, a condition that the transformer is likely to be shut down, and a high-voltage side neutral point disconnecting link is pulled open and is grounded through a discharge gap is also considered. For the low-current grounding system, due to different properties of the connected circuits, the grounding system can be divided into three conditions of no grounding, grounding through an arc-eliminating coil and grounding through a low-resistance, which are mainly determined by the magnitude of the local grounding capacitance current. Therefore, when considering the protection action situation, it is subdivided as shown in fig. 9(a) - (c). According to the scheme comparison, when a neutral point of a large-current grounding system is directly grounded, the zero-sequence overcurrent protection is divided into a II-section type, the grid-connected switch is tripped out in the first time limit, the small current is considered as a fault point supply power source of the zero-sequence current, the main transformer high-voltage side zero-sequence protection is matched with the 110KV outgoing line zero-sequence current of the side, the time limit is matched with the incoming line of the side, and as can be seen from a zero-sequence analysis chart, the primary side of the transformer is directly grounded through a star, the secondary side of the transformer is in corner connection, and the zero-sequence network small power source side of the transformer is in short circuit. However, when considering, it should not be understood from the perspective of zero sequence network protection, because from the perspective of the positive sequence network, its small power source still provides fault current to the fault point, so it is the first step to ensure the stable recovery of the power grid to disconnect it from the transformer for the first time. For the case of a non-grounded neutral, the first time to disconnect the small power supply that may cause an overvoltage, through an overvoltage and a gap overcurrent, is the most straightforward and effective measure, since this corresponds to a fault occurring when a local non-ground occurs.
For a small-current grounding system, when grounding is carried out through the arc-eliminating coil, the single-phase grounding is not attributed to the fault but is attributed to the abnormal operation, so that the protection configuration discussion range is not included. When the transformer is grounded through the resistor, the local side of the transformer needs to be matched with all outgoing line zero sequence protection when the transformer is in ground fault, namely, the protection with the zero sequence degree needs to be matched, and the protection is used as backup protection to delay and jump off the local side small power supply grid-connected switch.
As a specific example, as shown in fig. 11, for the main small power access location and the small power and local load balance situation in the jujube village, the corresponding protection cut-off and low frequency backup power switching integrated scheme can be formulated. And the graph can provide the minimum intuitive power supply operation condition analysis for the dispatcher, is convenient for the dispatcher to judge whether the protection and automation actions are correct and appropriate, and is favorable for recovering the normal operation mode afterwards. The scheme adopts the performance indexes of the local small power supply and the local load balance degree to represent that when the system breaks down, after the online tie line of the tie-off system, the severity of the local load exceeding the small power supply balance capacity is divided into three grades: yellow, red, and green. The performance indexes are displayed by real-time collection values of active power and local load generated by the generator in a running mode at that time through the balance performance indexes.
The jujube village power grid adopts a power supply mode of radiating operation at a voltage level of 220kV looped network and 110kV or below, and a small power supply is connected into the voltage level of the radiation power grid. The 110kV and 35kV transformer substations basically adopt a main-standby power supply mode, and spare power automatic switching devices and low-frequency and low-voltage load shedding devices are arranged in the transformer substations.
Taking the action behavior of protection when the power line on the power plant A in the power system of the jujube village fails as an example (see fig. 11), the action behavior of a protection and automation device adopted based on the integrated scheme of protection connection and disconnection and low-frequency backup switching when the small power access fails is described.
The operation mode is as follows: the power plant A is connected with the Internet through a line A, the switch 101 and the switch 111 are operated, the power plant A is connected with a substation B in series, the switch 102 and the switch 03 are operated, the power plant C is connected with the Internet through a substation B through a line WL1, and the switch 11 is operated; the 04 switch of the substation B is hot standby, and the third line is used as a standby line.
The protection fixed value and the coordination relation of the protection of the first line 111 are as follows:
the protection fixed value and the coordination relation of the protection of the B line 109 are as follows:
the B station backup power switching value is as follows:
the 101 protection of the first line adopts the function of protecting a tripping switch 102, and the spare power switching device of the second station can realize the spare power switching function through the time delay (0.3S) of a time level difference without matching according to a fixed value.
Protection configuration before implementation of the scheme is that all line protection is matched with normal three-section type direction distance and zero sequence overcurrent protection; a111 switch and a 101 switch of the first line are switched to protect the reclosing function. And the substation B is put into a spare power automatic switching function.
When a permanent earth fault occurs on the power plant grid-connected tie line A, the switch protection close to the fault point acts, and the opposite side switch protection also acts simultaneously to remove the fault point due to the fact that the asymmetrical fault is put into the function of quick action in succession. At the moment, the load balance performance index of the system side of the single-band substation B of the power plant A corresponds to a red area, and the substation B is a green area. At the moment, 111 switch protection detection is not superposed at voltage, and the 101 switch protection detection on the first power plant side fails to start at the same time; the first power plant operates with the second substation, and the second substation is relatively heavy in load, so that the first power plant is cut off at a low frequency. And (4) the transformer substation B operates in an isolated island, the low-frequency low-voltage device in the transformer substation is started, a part of load is cut off, and the electric quantity balance is achieved in the isolated island. In the process, the power loss of the first substation and the power supply quality of the second substation are difficult to guarantee, and the problem of synchronous grid connection of a generator and a system can be solved.
Therefore, in order to shorten the power failure time and reduce the power loss, an integrated scheme is adopted.
When the load balance performance index of a single transformer substation with a transformer substation B in the power plant A corresponds to a red zone, and the transformer substation B is a yellow zone, the following scheme is adopted:
(1) adding a switch circuit of a first power plant 101 switch joint tripping 102;
(2) and adding 11 switching functions of a B substation (low-frequency) spare power automatic switching starting combined switching power plant.
(3) Protection reclosure on the two sides of the first line is stopped.
The fault is as above: because 101 switch in the first power plant factory allies oneself with jumping 102 switch function input, 102 switches jump: a generator low-frequency protection action cutter of a power plant A (because the load balance performance index of the power plant A corresponds to a red area, and a transformer substation B corresponds to a yellow area); the line B has no voltage and no current (no voltage of a bus is judged any more), the frequency is reduced (df/dt is larger than a setting value), and the operation condition of (low-frequency) backup power automatic switching is met; and the spare power automatic switching (gang switch) of the substation B operates, the switch 03 is tripped out, the switch 04 is closed, the switch 11 of the substation C is cut off, and at the moment, the load of the substation B is rapidly transferred and supplied by the power line C.
Fig. 13 is a schematic diagram of load balancing corresponding to three schemes after a fault occurs:
(1) the temporary station is switched to the Schlempe city station for power supply, the load balance performance index is corresponding to a region c, and the temporary station is a region a. The action behavior and processing are as described in scenario one.
In conclusion, the relay protection is used as a first line of defense of the power system, the protection acts after a fault, the closed-loop control is adopted, and a feedback control rule is adopted. The subsequent reclosing, spare power automatic switching and low-frequency and low-voltage load shedding automatic devices adopt an off-line calculation mode to complete a whole set of protection actions, fault isolation and load recovery. However, the protection is a complete closed-loop system, and the main function of the system is to protect equipment and remove a fault in the protection range, but whether the fault can be completely isolated and the maximum load recovery can be completed or not is mostly determined by the self-protection device and the logic background of the protection action, if the background is set incorrectly, not only the fault isolation work cannot be completed well by the protection action, but also potential safety hazards may be left, so that the abnormal operation of the power grid is caused, and the safety of the power grid is seriously threatened. And the consideration of the small power supply access situation is one of the situations. The present embodiment shall discuss the protection configuration and low-frequency and low-voltage disconnection scheme under various small power access in detail, and fundamentally solve the problem.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (8)
1. A small power supply grid-connected protection method is characterized by comprising the following steps: the method comprises the following steps:
according to the small power supply grid-connected connection mode and the voltage grade of the transformer substation, configuring a line protection scheme and a tripping mode thereof, according to the difference of protection scheme actions and the difference of connection and disconnection modes of the small power supply, and combining the difference of fault objects, determining a corresponding low-frequency low-voltage disconnection configuration scheme to form a grid-connected protection action sequence which firstly carries out protection scheme actions, realizes fault load disconnection, then carries out connection and disconnection reclosing, and finishes the supply of the maximum load at low frequency low voltage;
when a small power supply station is connected to a 220kV transformer substation through a special line on the medium and low voltage side, the generator and transformer protection of the small power supply station adopts differential protection and backup protection configuration, and 110kV line protection configuration longitudinal differential protection and three-section alternate distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection, and the tie line adopts disconnection reclosing, namely three-phase detection non-voltage reclosing is put into the power supply side of the main system of the tie line, and reclosing is stopped at the small power supply side;
a 35kV or 10kV main system power supply side of the tie line adopts a splitting reclosing switch, namely a three-phase detection non-voltage reclosing switch is put into the main system power supply side of the tie line, and a reclosing switch is stopped at a small power supply side; the power supply side of the main system of the upper-level 110kV line adopts disconnection reclosing, the power supply side of the main system of the 110kV line is switched into three-phase detection non-voltage reclosing, and the side of the small power supply grid-connected 110kV transformer substation is not stopped and reclosed.
2. The small power grid-connected protection method of claim 1, which is characterized in that: when a small power supply station is connected to a 220kV transformer substation at the middle and low voltage side through a T connection line, the generator and transformer protection of the small power supply station is configured with differential protection and backup protection, and the 110kV line protection is configured with three-end longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection, and the side protection of the load station of the tie line only acts on signals; and the main system power supply side of the connecting line adopts disconnection reclosing, namely the main system power supply side of the connecting line is switched into the three-phase detection non-voltage reclosing, and the small power supply side of the connecting line stops reclosing.
3. The small power grid-connected protection method of claim 1, which is characterized in that: when a small power supply station is connected to the medium-low voltage side of a 110kV or 35kV transformer substation through a special line, the generator and transformer protection of the small power supply station is configured with differential protection and backup protection; the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the 35kV line protection is provided with longitudinal differential protection and three-section directional current protection or longitudinal differential protection and three-section distance protection; the 10kV line protection is preferably configured with longitudinal differential protection and three-stage directional current protection.
4. The small power grid-connected protection method of claim 3, which is characterized in that: the low-frequency low-voltage splitting device is configured on the 35kV and 10kV small power supply grid-connected wire and used for splitting with a system when a main system fails.
5. The small power grid-connected protection method of claim 1, which is characterized in that: for a main network terminal substation of a large-current grounding system, zero-sequence overcurrent protection of a transformer is performed on a first time-limit switching area small power supply grid-connected point and each side of a second time-limit switching transformer;
or/and for a main network terminal substation of the large-current grounding system, the transformer is provided with a zero-sequence voltage and gap zero-sequence current splitting device and a circuit breaker of a power supply networking line in a jump region.
6. The small power grid-connected protection method of claim 1, which is characterized in that: for a small current grounding system grounded by a resistor, a transformer at the power supply side of a region is provided with a zero sequence voltage and zero sequence current splitting device, the protection action time is matched with a protection section with enough sensitivity coefficient for zero current protection of all equipment at the side, and a circuit breaker at the side of the power supply transformer of the region is tripped;
or/and when the earth fault occurs, the side of the transformer is matched with all outgoing line zero sequence protection, namely, the protection with the zero sequence degree is matched, and the protection is used as backup protection to delay and jump off the small power grid-connected switch of the side.
7. The small power grid-connected protection method of claim 1, which is characterized in that: when a small power supply station is connected to the medium-voltage side of a public 110kV or 35kV transformer substation through a T connection line, the generator and transformer protection of the small power supply station is configured with differential protection and backup protection; the 110kV tie line is provided with longitudinal differential protection, three-section interphase distance, three-section grounding distance and four-section zero-sequence overcurrent protection; the protection action of a line at the side of the 110kV transformer substation jumps to a 35kV tie line switch; the 35kV line protection is provided with three-side longitudinal differential protection and three-section type directional current protection or three-side longitudinal differential protection and three-section distance protection; the T-connection line load side switch acts on a signal; and the 35kV small power supply grid-connected line is provided with a low-frequency low-voltage splitting device.
8. The small power grid-connected protection method of claim 1, which is characterized in that: when the splitting reclosing configuration is set, the constant value of the low-frequency low-voltage splitting device of the power supply is matched with the constant value of the final wheel of the basic wheel of the power grid, and the power supply is not split before splitting of the power grid.
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| CN111600281B (en) * | 2020-03-31 | 2022-03-29 | 国网上海市电力公司 | Method for cutting off small power supply of power distribution network |
| CN113964801B (en) * | 2021-10-13 | 2024-06-18 | 南京南瑞继保电气有限公司 | Distance protection optimization method and device for high-voltage line protection device |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105162086A (en) * | 2015-09-11 | 2015-12-16 | 国家电网公司 | Protection method for DG grid-connected transformer grounding system |
| CN106410766A (en) * | 2016-11-11 | 2017-02-15 | 国网山东省电力公司枣庄供电公司 | DG grid-connected electric system high acceptance protection method |
| CN108808832A (en) * | 2018-06-14 | 2018-11-13 | 国网山西省电力公司忻州供电公司 | A kind of band small power supply access system prepared auto restart application enhancements method |
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| CN101873007B (en) * | 2010-06-28 | 2012-06-27 | 北京四方继保自动化股份有限公司 | Micro-grid relay protection and automation integrated intelligent protection system |
| CN103248055B (en) * | 2013-05-13 | 2015-09-16 | 国电南瑞科技股份有限公司 | A kind of solve regional power grid off-the-line after correct choosing cut the method for generator and load |
| CN103944160B (en) * | 2014-04-09 | 2015-10-07 | 国家电网公司 | A kind of distribution network protection based on distributed power generation characteristic and automatics fitting method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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| CN106410766A (en) * | 2016-11-11 | 2017-02-15 | 国网山东省电力公司枣庄供电公司 | DG grid-connected electric system high acceptance protection method |
| CN108808832A (en) * | 2018-06-14 | 2018-11-13 | 国网山西省电力公司忻州供电公司 | A kind of band small power supply access system prepared auto restart application enhancements method |
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