Device and method for open-phase protection of new energy box transformer substation
By collecting low-voltage phase voltage and line voltage data of the power transformer, the status of the high-voltage fuse is determined by the phase loss protection controller, and the shunt coil of the low-voltage frame circuit breaker is driven to trip, thus solving the problem of phase loss protection in new energy transformer substations and achieving accurate phase loss protection and equipment safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-03-31
AI Technical Summary
Existing technologies cannot effectively protect new energy transformer substations from phase loss faults caused by high-voltage fuse blowouts, which may lead to problems such as equipment overheating, insulation damage, reduced system efficiency, and malfunction or failure of protection devices.
By collecting low-voltage phase voltage and line voltage data from the power transformer, the status of the high-voltage fuse is determined using the phase loss protection controller, and the shunt coil of the low-voltage frame circuit breaker is tripped to achieve phase loss protection. The protection is achieved by utilizing the characteristics of the original components of the transformer substation, using the step-up transformer and power transformer with Dy11 and Dyn11 connection methods, combined with the control transformer and the Ii0 connection method of the phase loss protection controller.
It achieves accurate identification and protection against phase loss faults in new energy transformer boxes, with low cost, simple installation, and high reliability, avoiding equipment damage and system accidents caused by phase loss faults.
Smart Images
Figure CN121769781A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a device and method for phase loss protection of a new energy transformer substation in the field of power system fault analysis and protection technology. Background Technology
[0002] With the continuous development of new energy construction in my country, step-up transformer substations for new energy applications have been widely used in wind power generation, photovoltaic power generation, energy storage power stations, and many other fields. Due to differences in their structure and key components, step-up transformer substations for new energy applications come in many different types, with a significant portion employing three-phase high-voltage fuses for protection on the high-voltage side. For substations protected by three-phase high-voltage fuses, a phase loss fault occurs when one phase fuse blows. The potential hazards of a phase loss fault in a substation include: equipment overheating and insulation damage, decreased system efficiency and deterioration of power quality, malfunction or failure of system protection devices, and overheating or damage to converter equipment.
[0003] Currently, the mainstream design for step-up transformers in new energy transformer substations adopts the Dy11 connection method, with primary and secondary voltages of 35 / 0.8kV. Because their low-voltage side is much higher than that of ordinary distribution networks and they are not three-phase four-wire systems, traditional phase loss protection methods cannot be used for control and protection. Since current new energy transformer substations are equipped with a small power transformer on the low-voltage side, also connected in Dyn11 configuration, with primary and secondary voltages of 0.8 / 0.4kV respectively, by analyzing the impact of high-voltage phase loss on the secondary voltage of the power transformer, phase loss protection for new energy transformer substations can be implemented. This prevents more serious equipment or system accidents caused by the failure to detect and handle faults in a timely manner. Summary of the Invention
[0004] The purpose of this invention is to provide a device and method for phase loss protection of new energy transformer substations, so as to achieve effective protection against phase loss caused by the melting of high-voltage fuses in new energy transformer substations.
[0005] To achieve the above objectives, the present invention provides a device for phase loss protection of a new energy transformer substation, comprising a high-voltage fuse, the high-voltage fuse being connected to a step-up transformer, the step-up transformer being connected to a low-voltage frame circuit breaker, the low-voltage frame circuit breaker being connected to a power transformer, the power transformer being connected to a phase loss protection controller, the phase loss protection controller being connected to a control transformer, and the control transformer being connected to the shunt coil MX of the low-voltage frame circuit breaker.
[0006] Compared with the prior art, the beneficial effects of the present invention are that it can accurately determine the phase loss status of the high-voltage fuse by simply collecting the low-voltage phase voltage and line voltage data of the power transformer. Then, by selecting the line voltage output of the low-voltage side of the power transformer, the shunt coil of the low-voltage frame circuit breaker can be driven to trip, thereby realizing the protection of the transformer substation phase loss fault. It makes full use of the original components and characteristics of the transformer substation and has many advantages such as low cost, simple installation and high reliability.
[0007] As a further improvement of the present invention, the step-up transformer is a transformer for power transmission within the transformer substation, using the Dy11 connection method. The high-voltage side of the step-up transformer is connected to the high-voltage fuse, and the low-voltage side of the step-up transformer is connected to the low-voltage frame circuit breaker. The power transformer is connected to the low-voltage side of the step-up transformer via the low-voltage frame circuit breaker, and is a transformer for power and secondary protection within the transformer substation, using the Dyn11 connection method. The control transformer is connected to the output terminal of the phase loss protector, and is a single-phase transformer specifically used for output voltage regulation during phase loss protection, using the Ii0 connection method.
[0008] The high-voltage fuse is used to protect the step-up transformer; the pressure frame circuit breaker is used to control and protect the low-voltage lines of the transformer substation; the power transformer is used to provide auxiliary power and secondary power supply for the transformer substation; the phase loss protector is used for phase loss protection of the transformer substation; and the control transformer is used to compensate for the difference between the output voltage of the phase loss protection controller and the rated voltage of the shunt coil.
[0009] As a further improvement of the present invention, the phase loss protection controller has a set of input terminals, which are respectively connected to the four outgoing terminals on the low-voltage side of the power transformer to provide working power for the phase loss protection controller. At the same time, it detects the three-phase phase voltage and three-phase line voltage on the low-voltage side of the power transformer. Based on the measured voltage value pattern, it analyzes and determines the on / off state of the high-voltage fuse and simultaneously alarms the system for the phase loss state.
[0010] After determining the phase loss state, the phase loss protection controller controls the relays to operate in an orderly manner based on the three line voltage values, selects the highest voltage, and outputs it from terminals 1 and 2 to control the shunt coil of the low-voltage frame circuit breaker to trip.
[0011] As a further improvement of the present invention, a three-phase selection circuit is provided inside the phase loss protection controller. The three-phase selection circuit is connected to the input terminals 4, 5 and 6 of the phase loss protection controller. A voltage sensor V is provided between each pair of lines of the three-phase selection circuit to measure the voltage between different lines. An overcurrent fuse R is connected in series in each line to protect against internal short circuit faults. Each line is provided with two relays, namely relays K1, K2, K3, K4, K5 and K6. Relays K1, K3 and K5 are connected to the output terminal 1 of the phase loss protection controller, and relays K2, K4 and K6 are connected to the output terminal 2 of the phase loss protection controller.
[0012] In this way, the three-phase selection circuit can select the highest voltage output based on the three line voltage values on the low-voltage side of the power transformer, and control the relays in an orderly manner through the processor in the phase loss protection controller to control the tripping of the shunt coil of the low-voltage frame circuit breaker, thereby realizing the phase loss protection action of the transformer substation.
[0013] As a further improvement of the present invention, the shunt coil MX is connected in series with the two normally open contacts of the protective fuse FU and the push-button switch SB in the manual control circuit between the a' and 0' terminals of the power transformer. When the SB button is manually operated, the shunt coil MX can be driven to trip, realizing the manual tripping test operation of the phase loss protection. At the same time, the shunt coil MX is connected in series with the two normally closed contacts of the push-button switch SB in the secondary terminal of the control transformer. When the phase loss protection occurs, the phase loss protection controller drives the shunt coil MX to trip through the output terminals 1 and 2 and the control transformer.
[0014] When the SB button is manually operated, the shunt coil tripping MX action can be driven to realize the manual tripping test operation of the phase loss protection. When the phase loss protection occurs, the phase loss protection controller drives the shunt coil tripping MX action through the output terminals 1 and 2 and the control transformer KB.
[0015] To achieve the above objectives, the present invention also provides step 1, calculating the three-phase phase voltage and three-phase line voltage on the low-voltage side of the step-up transformer when a phase is lost; step 2, calculating the three-phase line voltage on the secondary side of the power transformer based on the three-phase phase voltage and three-phase line voltage on the low-voltage side of the step-up transformer; step 3, measuring the three-phase line voltage and three-phase phase voltage on the low-voltage side of the power transformer through the phase loss protection controller, and analyzing the measured voltage values to determine the on / off state of the high-voltage fuse; step 4, after determining the phase loss state, controlling the orderly operation of the relays through the phase loss protection controller based on the three line voltage values, selecting the highest voltage, outputting from terminals 1 and 2 to control the tripping of the shunt coil of the low-voltage frame circuit breaker, and simultaneously alarming the system for the phase loss state, uploading the phase loss signal to the system backend, thereby realizing phase loss protection for the transformer substation.
[0016] As a further improvement to the present invention, the specific content of step 1 is as follows.
[0017] Let the rated voltages of the high-voltage side and low-voltage side of the step-up transformer be UN and Un, respectively; the three-phase line voltages of the high-voltage side be UAB, UBC and UCA, respectively; the three-phase line voltages of the low-voltage side be Uab, Ubc and Uca, respectively; and the three-phase phase voltages of the low-voltage side be Ua0, Ub0 and Uc0, respectively.
[0018] If phase A is missing, the three-phase line voltages on the high-voltage side are UBC=UN; UAB= UCA=UBC / 2=UN / 2;
[0019] The three-phase line voltages on the low-voltage side are Uca=0, Uab=Ubc=Un / ×1.5; The three-phase line voltage on the low-voltage side, Ub0 = Un / Ua0=UC0=Ub0 / 2=Un / 2 ;
[0020] If phase B is missing, the three-phase line voltages on the high-voltage side are UCA=UN; UBC= UAB=UCA / 2=UN / 2;
[0021] The three-phase voltages on the low-voltage side are Uab=0, Ubc=Uca=Un / ×1.5; The three-phase voltage on the low-voltage side, Uc0 = Un / Ua0=Ub0=Uc0 / 2=Un / 2 ;
[0022] If phase C is missing, the three-phase line voltages on the high-voltage side are UAB=UN; UBC= UCA=UAB / 2=UN / 2;
[0023] The three-phase voltage on the low-voltage side is Ubc=0, Uab=Uca=Un / ×1.5; The three-phase voltage on the low-voltage side, Ua0 = Un / Uc0=Ub0=Ua0 / 2=Un / 2 .
[0024] As a further improvement to the present invention, the specific content of step 2 is as follows.
[0025] Let the rated voltages of the high-voltage side and low-voltage side of the power transformer be UN' and Un', respectively, UN' = Un, the three-phase line voltages of the high-voltage side be UA'B, UB'C' and UC'A', the three-phase line voltages of the low-voltage side be Ua'b', Ub'c' and Uc'a', and the three-phase phase voltages of the low-voltage side be Ua'0', Ub'0 and Uc'0'.
[0026] If phase A is missing, the three-phase line voltage UA'B' on the high-voltage side of the power transformer is Uab = Un / ×1.5, UB'C'=Ubc=Un / ×1.5, UC'A'=Uca=0; the three-phase phase voltage on the low-voltage side Uc'0'=0, Ua'0'=Ub'0'= UN' / 4, the three-phase line voltage on the low-voltage side Ua'b'=Un', Ub'c'= Uc'a'=Ua'b' / 2;
[0027] If phase B is missing, the three-phase line voltage UB'C' on the high-voltage side of the power transformer will be Ubc = Un / ×1.5, UC'A'=Uca=Un / ×1.5, UA'B'=Uab=0; the three-phase phase voltage on the low-voltage side Ua'0'=0, Ub'0'=Uc'0'= UN' / 4, the three-phase line voltage on the low-voltage side Ub'c'=Un', Uc'a'= Ua'b'=Ub'c' / 2;
[0028] If phase C is missing, the three-phase line voltage on the high-voltage side of the power transformer is UC'A' = Uca = Un / ×1.5, UA'B'=Uab=Un / ×1.5, UB'C'=Ubc=0; the three-phase phase voltage on the low-voltage side Ub'0'=0, Uc'0'=Ua'0'= UN' / 4, the three-phase line voltage on the low-voltage side Uc'a'=Un', Ua'b'= Ub'c'=Uc'a' / 2.
[0029] As a further improvement to the present invention, the specific content of step 3 is as follows.
[0030] The phase loss protection controller performs characteristic analysis on the measured voltage values. Based on the voltage value characteristics of Uc'0'=0 and Ub'c'= Un', it determines that phase A of the high-voltage fuse has blown and phase A is in a phase loss state.
[0031] Based on the voltage characteristics of Ua'0'=0 and Ub'c'=Un', it is determined that phase B of the high-voltage fuse is blown, and phase B is in a phase loss state; based on the voltage characteristics of Ub'0'=0 and Uc'a'=Un', it is determined that phase C of the high-voltage fuse is blown, and phase C is in a phase loss state.
[0032] Compared with the prior art, the beneficial effects of this invention are as follows: the phase loss states are divided into three types: phase A loss, phase B loss, and phase C loss; the phase loss protection controller detects the three-phase phase voltage and three-phase line voltage on the secondary side of the power transformer, and simultaneously provides working power to the phase loss protection controller; the processor of the phase loss protection controller can determine the on / off state of the high-voltage fuse by analyzing the measured voltage values, alarm the system for phase loss status, and upload the phase loss signal to the system background through the RS485 communication interface; the three-phase selection circuit, based on the three line voltage values, controls the orderly switching of the relays through the processor of the phase loss protection controller, selects the highest line voltage among the three line voltages for output, so as to control the shunt coil of the low-voltage frame circuit breaker to trip, thereby realizing the phase loss protection action of the transformer substation. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of the system structure of the present invention.
[0034] Figure 2This is a vector diagram showing the three-phase phase voltage and line voltage of the step-up transformer and the power transformer when phase A is missing, according to the present invention.
[0035] Figure 3 This invention provides theoretical numerical charts of the three-phase phase voltage and line voltage of the step-up transformer and the power transformer when phase A is missing.
[0036] Figure 4 This is a schematic diagram of the three-phase selection circuit for the phase loss protection controller of the present invention.
[0037] Figure 5 This is a schematic diagram of the shunt coil drive circuit of the low-voltage frame circuit breaker of the present invention.
[0038] Among them, 1 is a high-voltage fuse, 2 is a step-up transformer, 3 is a phase loss protection controller, 4 is a control transformer, 5 is a low-voltage frame circuit breaker, and 6 is a power transformer. Detailed Implementation
[0039] The present invention will be further described below with reference to the accompanying drawings:
[0040] like Figure 1 The device shown is a phase loss protection device for a new energy transformer substation, including a high-voltage fuse 1, which is connected to a step-up transformer 2. The step-up transformer 2 is connected to a low-voltage frame circuit breaker 5. The low-voltage frame circuit breaker 5 is connected to a power transformer 6. The power transformer 6 is connected to a phase loss protection controller 3. The phase loss protection controller 3 is connected to a control transformer 4. The control transformer 4 is connected to the shunt coil MX of the low-voltage frame circuit breaker 5.
[0041] The step-up transformer 2 is a transformer used for power transmission within the substation, and adopts the Dy11 connection method. The high-voltage side of the step-up transformer 2 is connected to the high-voltage fuse 1, and the low-voltage side of the step-up transformer 2 is connected to the low-voltage frame circuit breaker 5. The power transformer 6 is connected to the low-voltage side of the step-up transformer 2 via the low-voltage frame circuit breaker 5. It is a transformer used for power and secondary protection within the substation, and adopts the Dyn11 connection method. The control transformer 4 is connected to the output terminal of the phase loss protector. It is a single-phase transformer specifically used for output voltage regulation during phase loss protection, and adopts the Ii0 connection method.
[0042] The phase loss protection controller 3 has a set of input terminals, which are respectively connected to the four outgoing terminals on the low-voltage side of the power transformer 6 to provide working power for the phase loss protection controller 3. At the same time, it detects the three-phase phase voltage and three-phase line voltage on the low-voltage side of the power transformer 6. Based on the measured voltage value pattern, it analyzes and determines the on / off state of the high-voltage fuse 1 and simultaneously alarms the system for the phase loss state.
[0043] The phase loss protection controller 3 has a three-phase selection circuit inside, which is connected to the input terminals 4, 5 and 6 of the phase loss protection controller 3. A voltage sensor V is installed between each pair of lines of the three-phase selection circuit to measure the voltage between different lines. An overcurrent fuse R is connected in series in each line to protect against internal short circuit faults. Each line is equipped with two relays, namely relays K1, K2, K3, K4, K5 and K6. Relays K1, K3 and K5 are connected to the output terminal 1 of the phase loss protection controller 3, and relays K2, K4 and K6 are connected to the output terminal 2 of the phase loss protection controller 3.
[0044] The shunt coil MX is connected in series with the two normally open contacts of the protective fuse FU and the push-button switch SB in the manual control circuit between the terminals 6a' and 0' of the power transformer. When the SB button is manually operated, the shunt coil MX can be driven to trip, realizing the manual tripping test operation of the phase loss protection. At the same time, the shunt coil MX is connected in series with the two normally closed contacts of the push-button switch SB to the secondary terminals of the control transformer 4. When the phase loss protection occurs, the phase loss protection controller 3 drives the shunt coil MX to trip through the output terminals 1 and 2 and the control transformer 4.
[0045] like Figure 2-5 The method for phase loss protection of a new energy transformer substation, as shown, includes the following:
[0046] Step 1: Calculate the three-phase phase voltage and three-phase line voltage on the low-voltage side when one phase of step-up transformer 2 is lost;
[0047] Let the rated voltages of the high-voltage side and low-voltage side of the step-up transformer 2 be UN and Un, respectively; the three-phase line voltages of the high-voltage side be UAB, UBC and UCA, respectively; the three-phase line voltages of the low-voltage side be Uab, Ubc and Uca, respectively; and the three-phase phase voltages of the low-voltage side be Ua0, Ub0 and Uc0, respectively.
[0048] If phase A is missing, the three-phase line voltages on the high-voltage side are UBC=UN; UAB= UCA=UBC / 2=UN / 2;
[0049] The three-phase line voltages on the low-voltage side are Uca=0, Uab=Ubc=Un / ×1.5; The three-phase line voltage on the low-voltage side, Ub0 = Un / Ua0=UC0=Ub0 / 2=Un / 2 ;
[0050] If phase B is missing, the three-phase line voltages on the high-voltage side are UCA=UN; UBC= UAB=UCA / 2=UN / 2;
[0051] The three-phase voltages on the low-voltage side are Uab=0, Ubc=Uca=Un / ×1.5; The three-phase voltage on the low-voltage side, Uc0 = Un / Ua0=Ub0=Uc0 / 2=Un / 2 ;
[0052] If phase C is missing, the three-phase line voltages on the high-voltage side are UAB=UN; UBC= UCA=UAB / 2=UN / 2;
[0053] The three-phase voltage on the low-voltage side is Ubc=0, Uab=Uca=Un / ×1.5; The three-phase voltage on the low-voltage side, Ua0 = Un / Uc0=Ub0=Ua0 / 2=Un / 2 .
[0054] Step 2: Based on the three-phase phase voltage and three-phase line voltage on the low-voltage side of the step-up transformer 2, calculate the three-phase line voltage on the secondary side of the power transformer 6.
[0055] Let the rated voltages of the high-voltage side and low-voltage side of power transformer 6 be UN' and Un', respectively, UN'=Un, the three-phase line voltages of the high-voltage side be UA'B, UB'C' and UC'A', the three-phase line voltages of the low-voltage side be Ua'b', Ub'c' and Uc'a', and the three-phase phase voltages of the low-voltage side be Ua'0', Ub'0 and Uc'0'.
[0056] If phase A is missing, the three-phase line voltage UA'B' on the high-voltage side of power transformer 6 will be Uab = Un / ×1.5, UB'C'=Ubc=Un / ×1.5, UC'A'=Uca=0; the three-phase phase voltage on the low-voltage side Uc'0'=0, Ua'0'=Ub'0'=UN' / 4, the three-phase line voltage on the low-voltage side Ua'b'=Un', Ub'c'= Uc'a'=Ua'b' / 2;
[0057] If phase B is missing, the three-phase line voltage UB'C' on the high-voltage side of power transformer 6 will be Ubc = Un / ×1.5, UC'A'=Uca=Un / ×1.5, UA'B'=Uab=0; the three-phase phase voltage on the low-voltage side Ua'0'=0, Ub'0'=Uc'0'=UN' / 4, the three-phase line voltage on the low-voltage side Ub'c'= Un', Uc'a'= Ua'b'=Ub'c' / 2;
[0058] If phase C is missing, the three-phase line voltage on the high-voltage side of power transformer 6 will be UC'A' = Uca = Un / ×1.5, UA'B'=Uab=Un / ×1.5, UB'C'=Ubc=0; the three-phase phase voltage on the low-voltage side Ub'0'=0, Uc'0'=Ua'0'=UN' / 4, the three-phase line voltage on the low-voltage side Uc'a'=Un', Ua'b'= Ub'c'=Uc'a' / 2.
[0059] Step 3: The three-phase line voltage and three-phase phase voltage on the low-voltage side of the power transformer 6 are measured by the phase loss protection controller 3, and the measured voltage values are analyzed to determine the on / off state of the high-voltage fuse 1.
[0060] The phase loss protection controller 3 performs characteristic analysis on the measured voltage values. Based on the voltage value characteristics of Uc'0'=0 and Ub'c'= Un', it determines that phase A of the high-voltage fuse 1 is blown and phase A is in a phase loss state.
[0061] Based on the voltage characteristics of Ua'0'=0 and Ub'c'=Un', it is determined that phase B of high-voltage fuse 1 is blown, and phase B is in a phase loss state; based on the voltage characteristics of Ub'0'=0 and Uc'a'=Un', it is determined that phase C of high-voltage fuse 1 is blown, and phase C is in a phase loss state.
[0062] Step 4: After determining the phase loss status, based on the three line voltage values, the phase loss protection controller 3 controls the relay to operate in an orderly manner, selects the highest voltage, outputs it from terminals 1 and 2 to control the tripping of the shunt coil of the low-voltage frame circuit breaker 5, and simultaneously alarms the system for the phase loss status, uploading the phase loss signal to the system backend to realize the phase loss protection of the transformer.
[0063] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. In the embodiments of the present invention, the voltage ratio of the step-up transformer 2 is UN / Un=35 / 0.8kV, the voltage ratio of the power transformer 6 is UN' / Un'=0.8 / 0.4kV, and the voltage of the control transformer 4 is 0.2 / 0.22kV. The described embodiments are only some embodiments of the present invention, and not all embodiments.
[0064] like Figure 1 As shown, a device and method for phase loss protection of a new energy transformer substation includes a high-voltage fuse 1, a step-up transformer 2, a low-voltage frame circuit breaker 5, a power transformer 6, a phase loss protection controller 3, and a control transformer 4.
[0065] A high-voltage fuse is connected in series at the primary input terminal of the step-up transformer 2 to protect it. A low-voltage frame circuit breaker 5 is installed at the low-voltage output terminal of the step-up transformer 2 to control and protect the low-voltage lines of the transformer substation. A power transformer 6 is installed at the lower end of the low-voltage frame circuit breaker 5 to provide auxiliary power and secondary power to the transformer substation. A phase loss protector is installed at the low-voltage output terminal of the power transformer 6 for phase loss protection of the transformer substation. Any two live wire terminals of the input terminals of the phase loss protection controller 3 are connected to the power module of the phase loss protection controller 3 as an external power source. The power module of the phase loss protection controller 3 adopts a wide-range design to adapt to a wide range of AC voltage variations, providing power to the phase loss protection controller 3. A control transformer 4 is installed between the output terminal of the phase loss protection controller 3 and the shunt winding of the low-voltage frame circuit breaker 5 to compensate for the difference between the output voltage of the phase loss protection controller 3 and the rated voltage of the shunt winding.
[0066] A set of input terminals 3, 4, 5, and 6 of the phase loss protection controller 3 are connected to a', b', c', and 0' on the low-voltage side of the power transformer 6, respectively; a set of output terminals 1 and 2 of the phase loss protection controller 3 are connected to the primary winding of the control transformer 4, respectively.
[0067] like Figure 2 As shown, combined with Figure 1 The winding diagram shows that when phase A of the transformer substation is lost, the high-voltage winding of step-up transformer 2 forms two parallel branches. Phases A and C are connected in series to form one branch, and phase B forms another branch. The line voltage UBC is the power supply applied to the parallel branches. Therefore, the voltage applied to phase B is the rated voltage, and the voltage applied to phases A and C is half of their rated voltage. Hence:
[0068] UN / Un = 35 / 0.8kV, the voltage ratio of power transformer 6 is UN' / Un' = 0.8 / 0.4kV, and the voltage of control transformer 4 is 0.4 / 0.22kV.
[0069] UBC=35000V; UAB= UCA=UBC / 2=17500V;
[0070] Therefore, the corresponding low voltage is:
[0071] Uca=0V;Uab=Ubc=Un / ×1.5=800 / ×1.5=693V;
[0072] Ub0=Un / =800 / =462V; Ua0=UC0= Ub0 / 2=462 / 2=231V;
[0073] The three-phase line voltage on the primary side of power transformer 6 is equivalent to the three-phase line voltage on the secondary side of the corresponding step-up transformer 2. Based on the calculated values of Uab, Ubc, and Uca, and combined with the connection group of power transformer 6 and the primary and secondary voltage vector diagrams of power transformer 6, its secondary voltage value is calculated as follows:
[0074] UA'B'=Uab=693V; UB'C'=Ubc=693V; UC'A'=Uca=0V;
[0075] Ua'0'=Ub'0'=693 / 800*231=200V; Uc'0'=0V;
[0076] Ua'b'=400V, Ub'c'=Uc'a'=200V;
[0077] The processor of the phase loss protection controller 3 performs feature analysis on the measured voltage value. Based on the voltage value characteristics of Uc'0'=0V and U a'b'=400V, it determines that the high voltage fuse 1 of phase A has blown and phase A is in a phase loss state.
[0078] Similarly, when the transformer experiences a phase loss in phase B, UN / Un = 35 / 0.8kV, the voltage ratio of power transformer 6 is UN' / Un' = 0.8 / 0.4kV, and the voltage of control transformer 4 is 0.4 / 0.22kV.
[0079] UCA=35000V; UAB= UBC=UCA / 2=17500V;
[0080] Therefore, the corresponding low voltage is:
[0081] Uab=0V;Ubc=Uca=Un / ×1.5=800 / ×1.5=693V;
[0082] Uc0=Un / =800 / =462V; Ua0=Ub0=Uc0 / 2=462 / 2=231V;
[0083] The three-phase line voltage on the primary side of power transformer 6 is equivalent to the three-phase line voltage on the secondary side of the corresponding step-up transformer 2. Based on the calculated values of Uab, Ubc, and Uca, and combined with the connection group of power transformer 6 and the primary and secondary voltage vector diagrams of power transformer 6, its secondary voltage value is calculated as follows:
[0084] UB'C'=Ubc=693V; UC'A'=Uca=693V; UA'B'=Uab=0V;
[0085] Ub'0'=Uc'0'=693 / 800*231=200V; Ua'0'=0V;
[0086] Ub'c'=400V, Uc'a'= Ua'b'=200V;
[0087] The processor of the phase loss protection controller 3 performs feature analysis on the measured voltage values. Based on the voltage value characteristics of Ua'0'=0V and Ub'c'=400V, it determines that the high-voltage fuse 1 of phase B has blown and phase B is in a phase loss state.
[0088] Similarly, when the C phase of the transformer is lost, UN / Un = 35 / 0.8kV, the voltage ratio of power transformer 6 is UN' / Un' = 0.8 / 0.4kV, and the voltage of control transformer 4 is 0.4 / 0.22kV.
[0089] UAB=35000V; UBC= UCA=UAB / 2=17500V;
[0090] Therefore, the corresponding low voltage is:
[0091] Ubc=0V;Uca=Uab=Un / ×1.5=800 / ×1.5=693V;
[0092] Ua0=Un / =800 / =462V; Ub0=Uc0=Ua0 / 2=462 / 2=231V;
[0093] The three-phase line voltage on the primary side of power transformer 6 is equivalent to the three-phase line voltage on the secondary side of the corresponding step-up transformer 2. Based on the calculated values of Uab, Ubc, and Uca, and combined with the connection group of power transformer 6 and the primary and secondary voltage vector diagrams of power transformer 6, its secondary voltage value is calculated as follows:
[0094] UC'A'=Uca=693V; UA'B'=Uab=693V; UB'C'=Ubc=0V;
[0095] Uc'0'=Ua'0'=693 / 800*231=200V; Ub'0'=0V;
[0096] Uc'a'=400V, Ua'b'= Ub'c'=200V;
[0097] The processor of the phase loss protection controller 3 performs feature analysis on the measured voltage values. Based on the voltage value characteristics of Ub'0'=0V and Uc'a'=400V, it determines that the high-voltage fuse 1 of phase C has blown and phase C is in a phase loss state.
[0098] After determining the phase loss status, the phase loss protection controller 3 will issue an alarm for the phase loss status and upload the phase loss signal to the system backend through the RS485 communication interface.
[0099] like Figure 3 The figure shows the voltage characteristics of the three-phase line voltage and three-phase phase voltage on the primary and secondary sides of the step-up transformer 2 and the power transformer 6 when phase A of the transformer substation is missing.
[0100] like Figure 4 As shown, the phase loss protection controller 3 has a set of output terminals 1 and 2, and an internal three-phase selection circuit is connected; the three-phase selection circuit is connected to the input terminals 4, 5 and 6 of the phase loss protection controller 3.
[0101] The three-phase selection circuit has a voltage sensor between each pair of lines to measure the voltage between different lines; each line has an overcurrent fuse R connected in series to protect against internal short circuit faults; each line has two relays, which are divided into two groups, namely K1, K3, K5 and K2, K4, K6, which are connected to output terminals 1 and 2 respectively.
[0102] After determining the phase loss state, the processor of the phase loss protection controller 3 controls the orderly operation of the relays according to the three line voltage values, selects the highest voltage, and outputs it from terminals 1 and 2 to control the tripping of the shunt coil of the low-voltage frame circuit breaker 5.
[0103] like Figure 5 As shown, the shunt coil MX of the low-voltage frame circuit breaker 5 is connected in series in two circuits. First, it is connected in series in the manual control circuit between the terminals 6a' and 0' of the power transformer through the two normally open contacts of the protective fuse FU and the push button switch SB. When the SB button is manually operated, the shunt coil MX can be driven to trip, realizing the manual tripping test operation of the phase loss protection. At the same time, the shunt coil MX is connected in series in series to the secondary terminals of the control transformer 4 through the two normally closed contacts of the push button switch SB. When the phase loss protection occurs, the phase loss protection controller 3 drives the shunt coil MX to trip through the output terminals 1 and 2 and the control transformer 4KB.
[0104] This invention accurately determines the phase loss status of the high-voltage fuse 1 simply by collecting the low-voltage phase voltage and line voltage data of the power transformer 6. Then, by selecting one line voltage output from the low-voltage side of the power transformer 6, the shunt coil of the low-voltage frame circuit breaker 5 can be tripped, thereby achieving phase loss fault protection for the transformer substation. Because this solution fully utilizes the existing components and characteristics of the transformer substation, it has many advantages such as low cost, simple installation, and high reliability.
[0105] This invention is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.
Claims
1. A device for phase loss protection of a new energy transformer substation, characterized in that: The high-voltage fuse is connected with a step-up transformer, the step-up transformer is connected with a low-voltage frame circuit breaker, the low-voltage frame circuit breaker is connected with a power transformer, the power transformer is connected with a phase-loss protection controller, the phase-loss protection controller is connected with a control transformer, and the control transformer is connected with a split-field coil MX of the low-voltage frame circuit breaker.
2. The device for new energy box variable phase protection according to claim 1, characterized in that: The step-up transformer is a transformer for transmitting electric energy in the box transformer, adopts Dy11 connection, the high-voltage side of the step-up transformer is connected with the high-voltage fuse, and the low-voltage side of the step-up transformer is connected with the low-voltage frame circuit breaker; the power transformer is connected with the low-voltage side of the step-up transformer through the low-voltage frame circuit breaker, and is a transformer for power and secondary protection in the box transformer, adopts Dyn11 connection; the control transformer is connected with the output end of the phase-loss protection controller, and is a single-phase transformer specially used for output voltage adjustment in phase-loss protection, adopts Ii0 connection.
3. The device for new energy box variable phase protection according to claim 2, characterized in that: The phase-loss protection controller has a group of input terminals, which are respectively connected with four outgoing terminal of the low-voltage side of the power transformer, provide working power for the phase-loss protection controller, and detect three-phase phase voltage and three-phase line voltage of the low-voltage side of the power transformer; according to the voltage value law obtained by measurement, the on-off state of the high-voltage fuse is analyzed and determined, and the phase-loss state of the alarm system is synchronously alarmed.
4. The device for new energy box variable phase protection according to claim 3, characterized in that: The phase-loss protection controller is internally provided with a three-phase selection circuit, which is connected with the input terminals 4, 5 and 6 of the phase-loss protection controller; The voltage sensor V is arranged between every two lines of the three-phase selection circuit, and is used for measuring the voltage between different lines; the overcurrent fuse R is connected in series with each line, and is used for protecting internal line short circuit fault; two relays are arranged on each line, which are respectively relays K1, K2, K3, K4, K5 and K6, wherein the relays K1, K3 and K5 are connected with the output terminal 1 of the phase-loss protection controller, and the relays K2, K4 and K6 are connected with the output terminal 2 of the phase-loss protection controller.
5. The device for new energy box variable phase protection according to claim 4, characterized in that: The split-field coil MX is connected in series with the protection fuse FU and the two normally open contacts of the key switch SB in the manual control loop between the power transformer a' and 0' terminals, when the SB button is manually operated, the split-field coil MX can be driven to split the field and realize the manual split test operation of the phase-loss protection; at the same time, the split-field coil MX is connected in series with the two normally closed contacts of the key switch SB in the secondary wiring terminal of the control transformer, when the phase-loss protection occurs, the phase-loss protection controller drives the split-field coil MX to split the field through the output terminals 1 and 2 and the control transformer.
6. A method for off-phase protection of a new energy box, characterized in that: The device for phase-loss protection of a new energy box transformer according to any one of claims 1-5 comprises the following contents, Step 1, calculating the three-phase phase voltage and the three-phase line voltage of the low-voltage side of the step-up transformer when the step-up transformer is in phase-loss; Step 2, calculating the three-phase line voltage of the secondary side of the power transformer according to the three-phase phase voltage and the three-phase line voltage of the low-voltage side of the step-up transformer; Step 3, measuring the three-phase line voltage and the three-phase phase voltage of the low-voltage side of the power transformer by the phase-loss protection controller, and analyzing the measured voltage value, so as to determine the on-off state of the high-voltage fuse; Step 4, after determining the open-phase state, according to the three line voltage values, the relay orderly action is controlled by the open-phase protection controller, one way of the highest voltage is selected, which is output from terminals 1 and 2, to control the low-voltage frame circuit breaker split excitation coil tripping, and the alarm system is synchronized to the open-phase state, the open-phase signal is uploaded to the system background, and the open-phase protection of the box transformer is realized.
7. The method of claim 6, wherein the new energy box is a battery. The specific content of step 1 is as follows, Let the rated voltages of the high-voltage side and the low-voltage side of the step-up transformer be UN and Un respectively, the three-phase line voltages of the high-voltage side be UAB, UBC and UCA respectively, and the three-phase line voltages of the low-voltage side be Uab, Ubc and Uca respectively. If phase A is open-phase, the three-phase line voltages of the high-voltage side are UBC=UN; UAB=UCA=UBC / 2=UN / 2 respectively. Low-voltage side three-phase line voltage Uca=0, Uab=Ubc=Un × 1.5; low-voltage side three-phase line voltage Ub0=Un , Ua0=UC0=Ub0 / 2=Un / 2 ; If phase B is open-phase, the three-phase line voltages of the high-voltage side are UCA=UN; UBC=UAB=UCA / 2=UN / 2 respectively. The three-phase voltage on the low-voltage side Uab=0, Ubc=Uca=Un ×1.5; the three-phase voltage on the low-voltage side Uc0=Un , Ua0=Ub0=Uc0 / 2=Un / 2 ; If phase C is open-phase, the three-phase line voltages of the high-voltage side are UAB=UN; UBC=UCA=UAB / 2=UN / 2 respectively. Low-voltage side three-wire phase voltage Ubc = 0, Uab = Uca = Un × 1.5; low-voltage side three-phase phase voltage Ua0 = Un , Uc0 = Ub0 = Ua0 / 2 = Un / 2 .
8. The method of claim 7, wherein the new energy box is a battery pack. The specific content of step 2 is as follows, Let the rated voltages of the high-voltage side and the low-voltage side of the power transformer be UN' and Un' respectively, UN'=Un, the three-phase line voltages of the high-voltage side be UA'B, UB'C' and UC'A' respectively, the three-phase line voltages of the low-voltage side be Ua'b', Ub'c' and Uc'a' respectively, and the three-phase phase voltages of the low-voltage side be Ua'0', Ub'0 and Uc'0' respectively. If phase A is missing, the high-voltage side three-phase line voltage of the power transformer is UA'B' = Uab = Un / 2, UB'C' = Ubc = Un / 2, UC'A' = Uca = 0 If phase A is missing, the high-voltage side three-phase line voltage of the power transformer is UA'B' = Uab = Un / 2, UB'C' = Ubc = Un / 2, UC'A' = Uca = 0 If phase A is missing, the high-voltage side three-phase line voltage of the power transformer is UA'B' = Uab = Un / 2, UB'C' = Ubc = Un / 2, UC'A' = Uca = 0 If the B phase is open phase, the high voltage side three-phase line voltage of the power transformer UB'C'=Ubc=Un / ×1.5, UC'A'=Uca=Un / ×1.5, UA'B'=Uab=0; the low voltage side three-phase phase voltage Ua'0'=0, Ub'0'=Uc'0'= UN’ / 4, the low voltage side three-phase line voltage Ub'c'= Un’, Uc'a'= Ua'b'=Ub'c' / 2; If phase C is missing, the high-voltage side three-phase line voltage of the power transformer is UC'A' = Uca = Un × 1.5, UA'B' = Uab = Un × 1.5, UB'C' = Ubc = 0; the low-voltage side three-phase phase voltage Ub'0' = 0, Uc'0' = Ua'0' = UN' / 4, the low-voltage side three-phase line voltage Uc'a' = Un', Ub'c' = Uc'a' / 2.
9. The method of claim 8, wherein: The specific content of step 3 is as follows, The open-phase protection controller analyzes the characteristic of the measured voltage value, according to the voltage value characteristic of Uc'0'=0 and Ub'c'=Un', it is determined that the A phase of the high-voltage fuse is blown, and the A phase is in an open-phase state. According to the voltage value characteristic of Ua'0'=0 and Ub'c'=Un', it is determined that the B phase of the high-voltage fuse is blown, and the B phase is in an open-phase state; according to the voltage value characteristic of Ub'0'=0 and Uc'a'=Un', it is determined that the C phase of the high-voltage fuse is blown, and the C phase is in an open-phase state.