With the continuous development of ultra-high voltage transmission projects, 750kV substations play an important role in long-distance, high-capacity power transmission and grid interconnection. Compared with conventional voltage level substations, 750kV substations have higher requirements for the insulation performance, operational reliability, detection accuracy, and test safety of electrical equipment. How to select suitable testing equipment based on the type of on-site equipment, test items, and technical standards has become a key consideration in the process of power engineering construction, equipment acceptance, and operation and maintenance.

Wuhan UHV Power Technology Co., Ltd. has long been dedicated to the field of high-voltage power testing, with products covering series resonance testing devices, partial discharge testing systems, high-voltage insulation and withstand voltage equipment, transformer testing instruments, circuit breaker testing instruments, and relay protection testing equipment. Reasonably configuring relevant instruments for different detection needs of high-voltage substations can help improve testing efficiency and provide detection basis for the safe operation of power equipment.

1、 Determine the testing requirements based on the equipment type of the 750kV substation

Before selecting testing equipment, it is necessary to first clarify the main primary equipment and secondary systems of the substation, as well as the handover tests, preventive tests, and fault diagnosis projects that need to be carried out.

750kV substations typically involve equipment such as main transformers, gas insulated metal enclosed switchgear (GIS), circuit breakers, isolating switches, current transformers, voltage transformers, lightning arresters, cables, and busbars. There are differences in the structure and insulation form of different devices, and the required testing methods are not completely the same.

For example, transformers need to pay attention to the electrical parameters, insulation status, and related performance of the windings; Circuit breakers need to be tested for mechanical action characteristics and conductive circuit resistance; GIS and other high-voltage equipment may involve AC withstand voltage, partial discharge detection, and insulation state assessment.

Therefore, procurement personnel should not only select instruments based on the voltage level of "750kV", but should develop equipment configuration plans based on specific test objects, test voltage, capacity, frequency, duration, and on-site wiring conditions.

2、 Communication voltage withstand test: focus on series resonance test device

AC withstand voltage test is an important item in the handover acceptance and insulation performance verification of high-voltage electrical equipment. For high-capacity and high-voltage capacitive specimens, traditional testing methods may face problems such as large equipment volume, inconvenient on-site handling, and high power capacity requirements.

El frequency conversion series resonance test device adjusts the output frequency to achieve resonance state in the test circuit, thereby meeting the AC withstand voltage test requirements of the corresponding electrical equipment. The UHV series series series series resonance test device for Wuhan UHV is mainly used for AC withstand voltage testing of cross-linked cables, hydroelectric generators, main transformers, busbars, GIS and other equipment.

3、 Partial discharge detection: pay attention to internal insulation defects of high-voltage equipment

Partial discharge is a phenomenon that requires special attention in the insulation state assessment of high-voltage electrical equipment. Local defects, air gaps, concentrated electric fields at the tip, and partial interface defects inside the insulation may all be related to partial discharge activity. Conducting appropriate partial discharge testing can help identify potential insulation issues and provide reference for equipment condition assessment.

During the manufacturing, factory testing, handover testing, or maintenance inspection of equipment related to 750kV substations, corresponding partial discharge testers or detection systems can be configured according to the testing purpose and equipment structure.

Wuhan UHV-2000 series partial discharge detection equipment is provided by Wuhan UHV, which can be used for partial discharge detection of transformers, transformers, cables, bushings, capacitors, lightning arresters, and other high-voltage electrical appliances. The specific model and testing method should be selected based on the structure of the tested equipment, testing sensitivity requirements, on-site electromagnetic interference conditions, and applicable standards.

4、 Transformer testing: Configure specialized instruments according to the test items

The main transformer is an important equipment in a 750kV substation, and its operating status directly affects the power supply reliability of the substation. Transformer testing usually involves multiple items, and a single instrument is difficult to cover all testing requirements.

According to the actual maintenance and testing plan, the following equipment can be configured:

Transformer DC resistance tester: used to measure the DC resistance of windings and assist in checking winding connections, conductive circuits, and tap changer related issues.

Transformer ratio tester: used to measure transformer ratio, group and other related parameters, and assist in checking whether the winding connection and tap position meet the requirements.

Transformer dielectric loss tester: used to measure parameters such as dielectric loss factor and capacitance of applicable test objects, providing reference for insulation state evaluation.

Transformer winding deformation tester: detects changes in winding characteristics through frequency response and other methods to assist in determining whether the winding may be affected by short-circuit impact or mechanical stress.

Transformer oil testing equipment: According to the testing requirements of oil immersed transformers, relevant analytical instruments such as insulation oil dielectric strength, moisture content, acid value, etc. can be configured.

5、 Switchgear testing: balancing mechanical characteristics and conductive circuit performance

Circuit breakers and other switchgear are responsible for the control, isolation, and fault removal tasks in the power system. Whether the mechanical action of the switch is reliable and whether the conductive circuit is normal are all things that need to be paid attention to during the operation and maintenance process.

Elhigh-voltage switch characteristic tester can be used to measure mechanical characteristic parameters such as opening and closing time, synchronicity, stroke, and speed of applicable circuit breakers; The circuit resistance tester is used to measure the resistance of conductive circuits, providing data support for checking the contact condition and connection reliability of the contacts.

Wuhan UHV's related products include high-voltage switch characteristic testers, double ended grounded high-voltage switch dynamic characteristic testers, and circuit resistance testers. The specific model should be matched according to the circuit breaker structure, control circuit, sensor installation method, and testing items.

6、 Relay protection and secondary circuit testing cannot be ignored either

The reliable operation of a substation depends not only on the insulation and mechanical performance of the primary equipment, but also on the correct operation of relay protection, measurement, and control systems.

After the debugging, regular inspection and maintenance of the protection device, microcomputer relay protection tester, transformer comprehensive tester, phase volt ampere meter and related secondary circuit detection equipment can be selected according to the protection configuration.

Elrelay protection tester can be used to simulate corresponding current, voltage, and fault conditions, verify the action logic and related settings of the protection device; Transformer testing equipment can be used to detect the relevant electrical parameters of current transformers and voltage transformers.

To select testing equipment for a 750kV substation, it is necessary to comprehensively consider the test voltage, capacity, measurement accuracy, functional configuration, and safety protection requirements based on the tested equipment, test items, technical standards, and site conditions. The series resonance test device, partial discharge detection system, transformer specific testing instrument, switch characteristic tester, and relay protection testing equipment each undertake different testing tasks. Only by combining them reasonably can a testing plan that meets the actual needs of the project be formed.