RU101877U1 - ADAPTIVE PROTECTION DEVICE FOR TRANSFORMERS OF RESPONSE SUBSTATIONS - Google Patents

Abstract

 Adaptive backup protection device for transformers of branch substations, containing current sensors of all three phases of the line, the outputs of which are connected to the inputs of reverse, direct and zero sequence current filters, voltage sensors whose outputs are connected to the inputs of direct sequence voltage filters, the output of the direct sequence current filter is connected to the first input of the fourth phase comparison circuit, the output of the direct sequence voltage filter is connected to the second input of the fourth phase comparison circuit , the output of the time delay organ is connected to the input of the output organ, characterized in that the reverse sequence voltage filter, the fifth phase comparison circuit, the first, second, third phase comparison circuit of all three phases of the line and the mode analysis block are additionally introduced, the negative sequence voltage filter inputs are connected with the outputs of the voltage sensors of all three phases of the line, the inputs of the fifth phase comparison circuit are connected to the output of the negative sequence voltage filter and the output of the negative sequence current filter, the output of the fifth phase comparison circuit is connected to the fifth input of the mode analysis unit, the output of the fourth phase comparison circuit is connected to the second input of the mode analysis unit, the output of the mode analysis unit is connected to the input of the time delay unit, the outputs of the first, second, third, current sensors are connected to the first inputs the first, second, third phase comparison circuits, respectively, the outputs of the first, second, third voltage sensors are connected to the second inputs of the first, second, third phase comparison circuits, the outputs of the first, second, third phase comparison circuits

Description

The inventive device relates to electrical engineering and can be used for relay protection of radial overhead lines and cable lines having branches with transformer substations.

A device for long-distance backup UDR AH - 94.2 [Abstract. doc. scientific and technical conference “Relay protection and automation of power systems - 96”. - Moscow, 1996], consisting of measuring current and power directions, included in currents and phase voltages, module comparison circuits, phase comparison circuits, time delay organ, output organ, indicating relay, monitoring and external signaling organ. The current organ and power directions of each phase are combined; the logical element AND, and the elements AND are connected to the inputs of the logical element OR, the output of which is connected to the input of the body time delay.

The disadvantage of the described technical solution is the reduction in sensitivity in the presence of a powerful motor load on the branch lines, the difficulty of recognizing short circuits behind low-power transformers of branch substations in the presence of a load mode.

The closest technical solution (prototype) is a backup line protection device with transformers on the branches [RF Patent No. 2162269], consisting of current sensors of all three phases of the line, the outputs of which are connected to the inputs of reverse and direct sequence current filters, voltage sensors connected to interfacial voltages, the outputs of which are connected to the inputs of the direct sequence voltage filter, and its output is connected to the second input of the first phase comparison circuit (fourth SSF (SSF ₄ )), the output of which is connected to the seventh input of the logic unit, the sixth input of which is connected to the output of the fifth module comparison circuit, the input of which is connected to the output of the zero-sequence current filter, the inputs of which are connected to the outputs of the current sensors, the outputs of one of the sensors and the negative sequence filter are connected to the inputs of the second and fourth comparison schemes modules of currents, and their outputs are connected to the second and fourth inputs of the logic unit, the output of which is connected to the input of the output organ of the first and third comparison circuits of the modules, the inputs of which are connected to the current sensors of one of the phases and the reverse sequence current filter, and their outputs to the first and third inputs of the logic unit, the second phase comparison circuit, the inputs of which are connected to the outputs of the current and reverse sequence current filters, and the output with the fifth input of the logic unit, formation unit settings, the outputs of which are connected to the outputs of the current and negative current filters and the output of the second phase comparison circuit, and its output is connected to the additional input of the first phase comparison circuit of the measuring current elements and is voltage included on phase currents and interphase voltages, respectively, module comparison circuits, phase comparison circuits, set point generation circuit, logic and time delay unit, and output organ.

The disadvantage of the described technical solution is the use of a current of only one phase when implementing the algorithm of output actions, which limits the device to recognition of non-phase modes.

The objective of the utility model is to increase the sensitivity and selectivity of long-range backup protection.

The technical result of the claimed utility model is to achieve recognition by the device of out-of-phase modes, which will increase the selectivity of the device under emergency conditions. This is achieved by the fact that the adaptive backup protection device for transformers of branch substations, containing current sensors of all three phases of the line, the outputs of which are connected to the inputs of current filters of reverse, direct and zero sequences, voltage sensors connected to the phase voltages of all three phases A, B, C the outputs of which are connected to the inputs of the voltage filters of the forward and reverse sequences, the output of the current filter of the forward sequence is connected to the first input of the fourth circuit, phase comparison, the output of the filter direct sequence is connected to the second input of the fourth phase comparison circuit, the output of the time delay organ is connected to the input of the output organ, the fifth inputs, phase comparison circuits are connected; with the output of the negative sequence voltage filter and the output of the negative sequence current filter, the output of the fifth phase comparison circuit is connected to the fifth input of the mode analysis unit, the output of the fourth phase comparison circuit is connected to the second input of the mode analysis unit, the output of the mode analysis unit is connected to the input of the time delay unit, the outputs of the first, second, third sensors, current are connected. with the first inputs of the first, second, third phase comparison circuits, respectively, the outputs of the first, second, third voltage sensors are connected with the second inputs of the first, second, third phase comparison circuits, the outputs of the first, second, third phase comparison circuits are connected to the first, third and seventh inputs of the mode analysis unit, respectively, the output of the zero sequence current filter is connected to the eighth input of the mode analysis unit, the filter output the direct sequence current is connected to the fourth input of the mode analysis unit, the output of the reverse sequence current filter is connected to the sixth input of the mode analysis unit.

In figure 1. The block diagram of the adaptive backup protection device for transformers of branch substations is given. The device contains voltage sensors (DN ₁ -DN ₃ ) 1, 2, 3, installed in all three phases A, B, C and current sensors (DT ₁ -DT ₃ ) 4, 5, 6, also installed in three phases A, B, C, respectively, phase comparison circuits (SSF ₁ -SSF ₃ ) 7-9, forward sequence voltage filter (FNOP) 10, negative sequence voltage filter (FNOP) 11, forward sequence current filter (FTP) 12, reverse sequence current filter (FTOP) filter 13 and zero sequence current (FTNP) 14, a phase comparison circuit ₍₄ SSF, SCF ₅₎ 15, 16, the mode analysis block (BAR) 17, the body you erzhki time (HNS) 18, the output body (IN) 19.

The outputs of the current sensors (DT ₁ -DT ₃ ) 4, 5, 6 of all three phases of the line are connected to the inputs of the reverse sequence current filter (FTOP) 13, the inputs of the forward sequence current filter (FTP) 12 and the inputs of the zero sequence current filter (FTNP) 14 voltage sensors (DN ₁ -DN ₃ ) 1, 2, 3, connected to the phase voltages of all three phases A, B, C, the outputs of which are connected to the inputs of the forward sequence voltage filter (FNPP) 10; and the inputs of the negative sequence voltage filter (FNOP) 11, the output of the forward sequence current filter (FTP) 12 is connected to the first input of the fourth phase comparison circuit (SSF ₄ ) 15, the output of the forward sequence voltage filter (FNOP) 10 is connected to the second input of the fourth comparison circuit phases (SSF ₄ ) 15, the output of the time delay organ (RVF) 18 is connected to the input of the output organ (VO) 19, the inputs of the fifth phase comparison circuit (SSF ₅ ) 16 are connected to the output of the negative sequence voltage filter (FNOP) 11 and the output of the current filter reverse after ovatelnosti (FTOP) 13, the output of the fifth phase comparison circuit (SSF ₅₎ 16 is connected to a fifth input of the mode analyzing unit (BAR) 17, the output of the fourth phase comparison circuit (SSF ₄₎ 15 is connected to the second input mode analysis block (BAR) 17, exit; the mode analysis unit (BAR) 17 is connected to the input of the time delay device (OVV) 18, the outputs of the first, second, third current sensors (DT ₁ -DT ₃ ) 4, 5, 6 are connected to the first inputs of the first, second, third comparison circuits phases (SSF ₁ -SSF ₃ ) 7-9, respectively, the outputs of the first, second, third voltage sensors (DN ₁ -DN ₃ ) 1, 2, 3 are connected to the second inputs of the first, second, third phase comparison circuits (SSF ₁ -SSF ₃₎ 7-9, the outputs of the first, second, third, phase comparison circuits (SSF ₁ -SSF ₃₎ 7-9 connected to the first, third and seventh input mode analysis block (BAR) 17 sootvets In fact, the output of the zero sequence current filter (FTNP) 14 is connected to the eighth input of the mode analysis unit, the output of the forward sequence current filter (FTP) 12 is connected to the fourth input of the mode analysis unit (BAR) 17, the output of the reverse sequence current filter (FTOP) 13 is connected with the sixth input of the mode analysis block (BAR) 17.

The device operates as follows: voltage sensors (DN ₁ -DN ₃ ) 1, 2, 3 provide voltage to voltage conversion, current sensors (DT ₁ -DT ₃ ) 4, 5, 6 convert current to voltage. Phase comparison schemes (SSF ₁ , SSF ₂ , SSF ₃ ) 7-9, connected to the outputs of the sensors "current (DT ₁ -DT ₃ ) 4, 5, 6 and voltage sensors (DN ₁ -DN ₃ ) 1, 2, 3 all phases, provide the selection of signals proportional to the arguments of the phase currents. The forward sequence voltage filter (FNPP) 10 and the negative sequence voltage filter (FNOP) 11 emit a signal proportional to the voltage of the forward and reverse sequences, respectively, and the forward sequence current filter (FTP) 12 , reverse sequence current filter (FTOP) 13, filter zero sequence current. (FTNP) 14 provide the selection of signals proportional to the currents of the forward, reverse and zero sequences, respectively. The phase comparison circuit (SSF ₄ ) 15 connected to the outputs of the direct sequence current filter (FTP) 12 and the direct sequence voltage filter (FNFP) 10, provides a signal proportional to the direct sequence current argument. The phase comparison circuit (SSF ₅ ) 16, connected to the outputs of the negative sequence current filter (FTOP) 13 and the negative sequence voltage filter (FNOP) 11, provides a signal proportional to the negative sequence current argument.

The mode analysis unit (BAR) 17, connected to the outputs of the phase comparison circuits (SSF ₄ -SSF ₅ ) 15, 16, provides a comprehensive analysis of the network operating mode and, when an emergency operation mode is detected, transmits a signal to turn off. This takes into account the magnitude of the currents of the forward, reverse and zero sequence, the magnitude of the arguments of the currents of all three phases, the direct and reverse sequences, the increment of the arguments of the phase currents, the magnitude of the increment of the arguments of the currents of the direct and reverse sequence. The block analysis of modes (BAR) 17 provides the processing of the parameters of the input signals, and also calculates its own parameters:

,

where φ _{A. BAR} is the angle between the currents of the forward and reverse sequence of phase A;

- current direct sequence phase A;

- current of the negative sequence of phase A;

φ _{V. BAR} - the angle between the currents of the forward and reverse sequence of phase B;

- current direct sequence phase B;

- current of the negative sequence of phase B;

φ _{C. BAR} - the angle between the currents of the forward and reverse sequence of phase C;

- current direct sequence phase C;

- current of the negative sequence of phase C;

and evaluation of the performance of the relations:

I ₁ ≥k _s I _{ng, max.} ,

where I ₁ - current direct sequence;

k _s - safety factor;

I _ng.max.otp. - the maximum possible load current of the branch substation,

I ₂ ≥k _s I _{burial TT} ,

where I ₂ is the current of the negative sequence;

k _s - safety factor;

I _{load TT} - maximum error current of current transformers to which the protection device is connected.

The body time delay (HVA) 18 provides a set of time delay for the detuning from the action of the main protection or backup step protection.

In normal network mode, the claimed device is in the following state. The output voltages of the voltage sensors (DN ₁ -DN ₃ ) 1-3 are close to the nominal values and, accordingly, close to the nominal value, the voltage at the output of the direct sequence voltage filter (FNPP) 10. The output signals of the current sensors (DT ₁ -DT ₃ ) 4-6 determined by the magnitude of the load currents of the line. The output signal of the direct sequence current filter (FTP) 12 is also determined by the magnitude of the load currents. The output signals of the negative sequence current filter (FTOP) 13, the negative sequence voltage filter (FNOP) 11 and the zero sequence current filter (FTNP) 14 are close to zero and are determined only by currents and unbalance voltages. The output signals of the phase comparison circuits (SSF ₁ -SSF ₃ ) 7-9, as well as phase comparison circuits (SSF ₄ ) 15 are determined by the magnitude of the load arguments of the current. There is no signal at the output of the phase comparison circuit (SSF ₅ ) 16, since the current and voltage values of the negative sequence are insufficient for the fifth phase comparison circuit to operate. The mode analysis block (BAR 17) determines the area of the load mode and a logical zero is present at its output. At the output of the body time delay (OVV) 18 and the output organ (IN) 19 there are logical signals 0.

With a two-phase short circuit (short circuit) behind one of the transformers on the side connected in a triangle, connected to the OHL branch, the device operates as follows. For metallic short-circuit, the angle between the current vectors of damaged phases of the forward and reverse sequence is 60 ° at the short-circuit point and 180 ° for the intact phase. Due to the different shift of the components of the currents of the direct sequence and reverse sequence due to the connection group of the windings of the star-delta transformer, an additional phase shift between the currents appears and all phases, which is fixed by schemes, phase comparison (SSF ₄ , SSF ₅ ) 15, 16 and the mode analysis unit (BAR) 17. Monitoring phase relationships of all three phases allows you to get the required sensitivity for any asymmetrical short circuit.

With a two-phase short circuit on the transformer side: on the branch with the connection of its windings to a star, the formation of a trip signal is ensured by triggering comparison circuits (SSF ₄ , SSF ₅ ) 15, 16 and determining by the mode analysis unit (BAR) 17 values of currents of direct and reverse sequence, relevant emergency.

For three-phase faults behind transformers on branches, for any group of transformer connections, emergency direct current current arguments are determined by phase comparison circuit (SSF ₄ ) 15, phase current emergency arguments and forward sequence current argument increment, typical for symmetrical short circuit mode. The block analysis of modes (BAR) 17 provides recognition of the existing short circuit mode and generates a logical signal 1.

When two-phase or three-phase faults on the line, when the short-circuit current exceeds the maximum possible value of the short-circuit currents behind the maximum power transformer, the mode analysis unit (BAR) 17 determines the mode as the short-circuit on the line and acts on or off with a time delay set by the time delay unit ( OVV) 18, or is blocked, giving priority to line protection.

With a single-phase short circuit, which is possible only on the overhead line due to the connection of the windings of the star-delta or star-star transformer with an ungrounded neutral on the medium (low) voltage side, a zero sequence current is released by a zero sequence current filter (FTPS) 14, the BAR 17 mode analysis block defines the mode as a single-phase fault on the line and is blocked to enable the line protections to act.

When the line is turned on in the automatic restart cycle and there is a motor load at the transformer substations, it is possible to determine the direct sequence current argument close to the emergency values by the phase comparison circuit (SSF ₄ ) 15, however, in this case the mode analysis unit (BAR) 17 does not determine mode as emergency, because increments are calculated taking into account the previous load mode and dynamics, changes in the controlled parameters of the signals, which ensures reliable detuning from this mode.

When a wire break occurs in one of the overhead phases, the modules and arguments of the forward and reverse sequence currents are determined by the forward sequence current filter (FTP) 12, the reverse sequence current filter (FTOP) 13, the zero sequence current filter (FTPS) 14,, the circuit, phase comparison ( SSF ₄ ) 15 and phase comparison circuit (SSF ₅ ) 16, the mode analysis unit (BAR) 17 determines the angle between the current vectors of the forward and reverse sequences, for each; phase, and identifies the damaged phase and acts on the disconnection of the line.

Thus, the use of the claimed device for monitoring modules and arguments of three phases, multiphase circuits for comparing the phase relationships of the currents of the forward and reverse sequences and their emergency components (increments), the zero sequence current allows to increase the degree of recognition: emergency modes against the background of load conditions and as a result - increase sensitivity and selectivity.

Claims (1)

Adaptive backup protection device for transformers of branch substations, containing current sensors of all three phases of the line, the outputs of which are connected to the inputs of reverse, direct and zero sequence current filters, voltage sensors whose outputs are connected to the inputs of direct sequence voltage filters, the output of the direct sequence current filter is connected to the first input of the fourth phase comparison circuit, the output of the direct sequence voltage filter is connected to the second input of the fourth phase comparison circuit , the output of the time delay organ is connected to the input of the output organ, characterized in that the reverse sequence voltage filter, the fifth phase comparison circuit, the first, second, third phase comparison circuit of all three phases of the line and the mode analysis block are additionally introduced, the negative sequence voltage filter inputs are connected with the outputs of the voltage sensors of all three phases of the line, the inputs of the fifth phase comparison circuit are connected to the output of the negative sequence voltage filter and the output of the negative sequence current filter, the output of the fifth phase comparison circuit is connected to the fifth input of the mode analysis unit, the output of the fourth phase comparison circuit is connected to the second input of the mode analysis unit, the output of the mode analysis unit is connected to the input of the time delay unit, the outputs of the first, second, third, current sensors are connected to the first inputs the first, second, third phase comparison circuits, respectively, the outputs of the first, second, third voltage sensors are connected to the second inputs of the first, second, third phase comparison circuits, the outputs of the first, second, third phase comparison circuits h are connected to the first, third and seventh inputs of the mode analysis unit, respectively, the output of the zero sequence current filter is connected to the eighth input of the mode analysis unit, the output of the direct sequence current filter is connected to the fourth input of the mode analysis unit, the output of the reverse sequence current filter is connected to the sixth input of the unit analysis of modes, and voltage sensors are included on the phase voltage of all three phases of the line.