Application of microcomputer comprehensive protection measurement and control device in the transformation of power system of a power plant 10.5kV plant

Ren Yunye Ankerui Electric Co.
, Ltd.
Shanghai Jiading 201800 Abstract: Most of the secondary system equipment used by the 10.
5kV plant of a power plant No.
8 is conventional electromagnetic relays and power transmitters
.

Through the transformation of the secondary system of plant electricity from the aspects of equipment selection, design, construction and commissioning, especially the application of microcomputer comprehensive protection measurement and control device, it integrates control, protection, measurement, signal alarm, switch volume acquisition and communication functions, which improves the reliability, advanced and automation level of
the equipment.

Keywords: computer comprehensive protection measurement and control device; Power plant electricity; Reliability 0 Introduction The power system of a power plant unit 8 is divided into two sections, namely V and VI sections
.

Under normal working conditions, the V and VI segments operate in sections, that is, the contact circuit breaker 060 is in the disconnection position
.

The V section is powered by 8GB via the 051 circuit breaker, and can also be powered by the IV section 047 circuit breaker (emergency standby power supply), the V section is supplied by the distribution cabinet 053 circuit breaker and 38B to the unit's self-consumption 400Va section, while the VI section is powered by the I section through the 013 and 061 circuit breakers, and the VI section is powered by the 062 circuit breaker and 39B to the unit with 400Vb section, and the 063 is used as a backup outlet
.

See Figure 1
for details.

Figure 1 Power plant No.
8 machine 10.
5kV system operation diagram The system has been running for more than 10 years, the two bus segment distribution devices and relay protection secondary equipment is basically electromagnetic relay, control operation, anti-jump circuit equipment are all electromagnetic relays, the secondary circuit design is complex and messy, no liquid crystal display, and can not achieve remote control, automation degree and low safety reliability, these factors seriously affect the safe and reliable operation
of the equipment.

In order to solve the passive situation brought about by the backwardness of the plant's power system equipment and frequent faults to safe production, it is planned to transform
the 10.
5kV factory with two busbar segment power distribution devices as a whole.

The secondary equipment for relay protection will also be transformed, and the appropriate microcomputer protection and control device will be selected for secondary equipment transformation
.

1 Power plant No.
8 machine 10.
5kV secondary system characteristics and design points The power plant No.
8 machine 10.
5kV factory power system adopts two busbar segment distribution device switch cabinet, and the design work of all secondary circuit schematics is combined with the principle of microcomputer comprehensive protection measurement and control device and the principle of original plant electricity design
.

In terms of design, considering the reliable switching of working DC power supply and standby DC power supply, the switchgear control, closing, and signal DC power supply are arranged on the small busbar
set on the upper part of each switchgear.

10.
5kV switchgear need to consider the cabinet heating, lighting problems and power supply layout, the heating and lighting power supply of each switchgear, taken from the AC power supply minibus set in the upper part of each switchgear
.

At the same time, the protection and measurement AC loops in the comprehensive security measurement and control device are designed and connected
according to the protection and measurement of their own special current transformers and voltage transformers.

According to the different load nature of the equipment connected to the power bus of the No.
8 machine 8 of the power plant, the AM5SE-F line protection and control device is adopted for the inlet cabinet, equipped with three-stage overcurrent protection, reverse time overcurrent protection, zero-sequence overcurrent and other protection functions, when the line fails, it can quickly cut off the fault and ensure the stable operation of the primary equipment; For the transformer cabinet using AM5SE-T distribution variable protection measurement and control device, in addition to the basic three-stage overcurrent protection and other functions, it is also equipped with high temperature alarm, over-temperature trip protection function, which can play an early warning or cut off the circuit when the temperature of the transformer is abnormal, to avoid transformer damage; For the mother cabinet using AM5SE-B self-projection protection measurement and control device, equipped with a series of self-projection functions such as self-projection, adaptive self-projection, self-investment for the incoming line, and self-projection.
Since the power plant No.
8 10.
5kV plant power system was originally designed to consider the parent joint self-projection program, the follow-up due to the capacity adjustment of the incoming line 2, can only support the VI section of the important load, so it needs to be adjusted to the joint self-input power supply scheme, the above two schemes can be adjusted by the user in the AM5SE-B self-projection protection and control device; for the PT cabinet using AM5SE-UB PT monitoring parallel device, when one of the PT cabinet handcarts exit the maintenance, In order to avoid the low-voltage protection malfunction of the inlet cabinet configuration in this section, another bus bar voltage can be used through AM5SE-UB; At the same time, for the low-voltage mother cabinet, the AM5-DB low-voltage self-projection protection device is configured, which can realize the self-projection function
of the mother-ready self-projection or the inlet line in the low-voltage system.

In addition, the secondary system transformation also considers the latching in the design, the 051 closing circuit is stringed into the 061 inlet cabinet and the 060 circuit breaker contact from the mother linkage cabinet, and the same reason other inlet circuit breakers are also connected to the latching condition
.

For the V section standby inlet cabinet 052, the locking signal from the 0477 ground knife is also serialized in its closing loop, and the closing circuit of the VI section inlet cabinet 061 is also serialized into the signal of the 0137 grounding knife gate, as a locking condition, that is, the grounding switch is in the case of the closing position, the circuit breaker cannot be closed, so that the occurrence of the situation of the closing knife with the ground knife can be avoided
.

The quadratic schematic diagram of the specific control loop is shown in
Figure 2.

Figure 2 Control circuit secondary schematic diagram 2 10kV power monitoring system is transformed into real-time monitoring of the operation of the entire distribution room and data acquisition, for the power plant configuration of a set of Acrel-2000Z power monitoring system, the microcomputer protection data uploaded to the power monitoring system, to achieve the 10kV substation power monitoring and management, improve the level of
automation management.

The main functions that can be realized are as follows: real-time monitoring, electrical parameter query, operation report, real-time alarm, historical event query, power statistics report, user rights management, network topology map, power quality monitoring, remote control function, communication management, fault recording, accident recall, curve query, Web access, APP access
.

The topology diagram of the modified power monitoring system is shown in
Figure 3.

Figure 3 Power monitoring system topology Figure 3 Conclusion The power system transformation and microcomputer comprehensive protection measurement and control device of the No.
8 unit of the power plant have been operating well
since the transformation and operation in 2019.

After the transformation of the plant power system comprehensive protection measurement and control device configuration, the memory function is powerful, for the future accident accurate analysis, correct problem solving provides a basis; The newly configured protection devices connect the 485 communication interface through "hand in hand", and the data is sent to the Acrel-2000Z power monitoring system, which is convenient for viewing protection information and fault information management, ensuring the safe and stable production of
the plant.

References[1] Zhang Baohui,Yin Xianggen.
Power System Relay Protection.
China Electric Power Press,2005.
] Yang Chungui,Chen Hongming.
Electricity News, August 2015 below.
[5] Ankerui user substation integrated automation and operation and maintenance solutions.
2021.
11 November version of the author introduction: Ren Yunye, male, currently working in Ankerui Electric Co.
, Ltd.
, the main research direction is the application of
relay protection devices.