Abstract This paper compares the advantages and disadvantages of different neutral grounding methods in power distribution networks. The impact of resistor grounding on power supply reliability, communication, personal safety, and switch maintenance is analyzed. It points out that for cable-based distribution networks, resistor grounding is the preferred method. The paper also elaborates on the principles for selecting the neutral resistance value and the domestic practice of resistor grounding for the neutral point. 1 Neutral Grounding Methods In the past, China stipulated that the neutral grounding methods in power systems were divided into two categories: large grounding short-circuit current systems and small grounding short-circuit current systems. Because the current magnitude is difficult to clearly define using the classification of neutral grounding methods in power systems, it was changed to classify them into effectively grounded neutral systems and ineffectively grounded neutral systems. Effective grounding of the neutral point in a power system includes direct grounding or grounding via a low-value resistor or reactor. It requires that the ratio of the zero-sequence reactance (X0) to the positive-sequence reactance (X1) (X0/X1) of the entire system be positive and less than 3, and the ratio of the zero-sequence resistance (R0) to the positive-sequence reactance (X1) be positive and less than 1. Otherwise, it is considered an ineffectively grounded neutral point system. Ineffectively grounded neutral points in power systems include resonant (arc suppression coil) grounding and no grounding. 2. Advantages and Disadvantages of Different Neutral Grounding Methods in Distribution Networks The electrical connection between the neutral point and the reference ground in a distribution network can be configured according to operational needs, including ungrounded neutral point, grounded via an arc suppression coil, grounded via (high, medium, or low value) resistors, grounded via a low-value reactor, and direct grounding. Each of these neutral point grounding methods has its own unique advantages and disadvantages. 2.1 Advantages and Disadvantages of Ungrounded Neutral Point in Distribution Networks Ungrounded neutral point in distribution networks refers to a neutral point that is not artificially connected to the earth. In fact, such a distribution network is grounded through the grid-to-ground capacitance. Main advantages of an ungrounded neutral point system: Small steady-state power frequency current during single-phase ground faults. This allows for automatic clearing of transient faults such as lightning flashover without tripping. In the event of a metallic ground fault, single-phase operation is possible, improving uninterrupted power supply and increasing power reliability. Small grounding current reduces ground potential rise, decreasing step voltage and contact voltage. It also reduces interference to information systems and backflashover to low-voltage networks. Economically, it saves on grounding equipment and reduces investment in the grounding system. Disadvantages of an ungrounded neutral point system: a) Compared to a neutral point resistor grounding system, it generates higher overvoltages (arc overvoltage and ferroresonant overvoltage, etc.), increasing the probability of weak insulation breakdown. b) During intermittent arc ground faults, it generates large high-frequency oscillating currents, reaching hundreds of amperes, which may cause phase-to-phase short circuits. c. To date, fault location remains difficult, and ground fault lines cannot be correctly and quickly isolated. 2.2 Advantages and disadvantages of neutral point resonant (arc suppression coil) grounding in distribution networks. Neutral point resonant grounding in distribution networks refers to connecting one or more neutral points of the distribution network to the earth via an arc suppression coil. The steady-state power frequency inductive current of the arc suppression coil tunes the steady-state power frequency capacitive current of the power grid, hence the name resonant grounding. The purpose is to minimize the residual current of the ground fault, thus allowing the ground fault to self-clear. Therefore, the neutral point ungrounded system has all the advantages of the neutral point arc suppression coil grounding system, and even better. Similarly, the neutral point ungrounded system also has all the disadvantages of the neutral point arc suppression coil grounding system, except that the probability of the maximum amplitude arc overvoltage is lower. This is because the arc suppression coil reduces the arc buildup rate during single-phase grounding. The success of using the arc suppression coil grounding method largely depends on the reliability of the arc suppression coil, the tracking system, and the line selection device itself. 2.3 Advantages and Disadvantages of Direct Grounding of Neutral Point in Distribution Network Direct grounding of the neutral point in a distribution network refers to the direct and full connection of all or part of the transformer neutral points to the earth (ground grid) without any artificial impedance. This ensures that the grid achieves R0 ≤ X1 and X0/X1 ≤ 3. The advantages of a directly grounded neutral point system are: a) Lower internal overvoltage, allowing for lower insulation levels and saving on infrastructure investment. b) Larger grounding current, easier fault location, and faster and more accurate disconnection of faulty lines. The disadvantages of a directly grounded neutral point system are: a) Rapid disconnection of faulty lines, resulting in intermittent power supply. b) Larger grounding current and higher ground potential rise. This increases: Damage to electrical equipment. Increased contact voltage and step voltage. Increased interference to information systems. Increased backflashover to low-voltage networks. 2.4 Advantages and Disadvantages of Neutral Point Resistor Grounding in Distribution Networks At least one neutral point in a distribution network is connected to a resistor to limit the grounding fault current. Neutral point grounding via a resistor (zero resistance per phase R₀ ≤ X_c0, capacitive reactance per phase to ground) eliminates the disadvantages of ungrounded neutral point and arc suppression coil grounding systems. This reduces transient overvoltage amplitude and enables sensitive and selective fault location grounding protection. Because the grounding current in this system is smaller than in a directly grounded system, ground potential rise, interference to information systems, and backflashover to the low-voltage power grid are all reduced. Therefore, neutral point resistor grounding systems possess some advantages of ungrounded neutral point, arc suppression coil grounding, and directly grounded systems, while also retaining some of their disadvantages. Depending on the requirements for limiting the magnitude of ground fault current, neutral point resistor grounding systems are classified into high, medium, and low value systems, each with different advantages and disadvantages. 2.4.1 Advantages and Disadvantages of Neutral Point High-Value Resistor Grounding Systems Neutral point high-value resistor grounding systems limit ground fault current levels to below 10A. The design of high-resistance grounding systems should comply with the criterion of zero-sequence resistance R₀ ≤ X_c0 (capacitive reactance per phase to ground) to limit transient overvoltages caused by intermittent arcing ground faults. Advantages: a. Prevents and dampens resonant overvoltages and intermittent arcing ground fault overvoltages, at 2.5P·U and below. b. Ground current levels are below 10A, reducing ground rise. c. Ground faults do not need to be cleared immediately, thus allowing operation with a single-phase ground fault. Disadvantages: Application is limited, suitable for some small 6-10kV distribution networks and power plant auxiliary power systems. 2.4.2 Advantages and Disadvantages of Neutral Point Low-Value Resistor Grounding Systems To achieve accurate and rapid clearing of ground fault lines, the resistance value of the resistor must be reduced. Advantages: a) Low internal overvoltage (including arc overvoltage, resonant overvoltage, etc.), improving network and equipment reliability. b) Large grounding current (100-1000A), easy fault location, and accurate and rapid disconnection of grounding fault lines. Disadvantages: a) Due to the grounding fault current If = 100-1000A, the ground potential rise is higher than that of neutral point ungrounded, arc suppression coil grounded, and high-value resistor grounding systems. b) Grounding fault lines are quickly disconnected, resulting in intermittent power supply. 2.4.3 Advantages and Disadvantages of Neutral Point Medium-Value Resistor Grounding System To overcome the disadvantages of high-value and low-value grounding systems while retaining their advantages, a medium-value resistor is used. The grounding fault current is controlled at 50-100A, retaining the advantages of low internal overvoltage, small ground potential rise, and accurate and rapid disconnection of grounding fault lines, but also having the disadvantage of intermittent power supply when disconnecting grounding fault lines. 3 Problems with the Neutral Point Grounding Method via Arc Suppression Coil in China's Urban Distribution Networks In recent years, with the rapid development of China's power industry, the structure of urban distribution networks has changed significantly. The proportion of cables in feeder lines is increasing, and some problems with the neutral point grounding method via arc suppression coil are becoming increasingly apparent. With the rapid increase in the distribution network capacitance current, it is difficult to ensure that the arc suppression coil operates under a certain degree of detuning. The main reasons are: (1) The adjustment range of the arc suppression coil is limited, generally 1:2, which is not suitable for the needs of the initial and final stages of the project. (2) The nominal current and actual current of each tap of the arc suppression coil have a large error, some even reaching 15%. During operation, resonance has occurred due to the difference between the actual current value and the nameplate data. (3) The calculated capacitance current and the actual capacitance current have a large error. Most substations are power supply networks with a mixture of cables and overhead lines. It is difficult to accurately and timely grasp the length of the distribution lines. Moreover, there are many types of cables, and the capacitance current per unit length is not the same. (4) Some distribution networks contain a certain component of the 5th harmonic current in the entire grounding capacitance current, with a proportion as high as 5% to 15%. Even if the power frequency grounding current is calculated very accurately, it is still impossible to compensate for the harmonic current value in the 5% to 15% grounding capacitance current. In summary, in cable-based distribution networks, when a single-phase grounding fault occurs, the grounding residual current is large, and the overcompensation conditions are often not met. Single-phase grounding faults in cable-based distribution networks are mostly caused by the breakdown of the system equipment due to its own insulation defects under certain conditions, and the grounding residual current is large. Especially when the grounding point is in the cable, the grounding arc is a closed arc, and the arc is even more difficult to extinguish on its own (the value of the arc generated by the single-phase grounding capacitance current that can extinguish on its own is far less than the value specified in the regulations, only 5A for cross-linked polyethylene cables). Therefore, single-phase grounding faults in cable distribution networks are mostly permanent faults. Since the system with the neutral point grounded by the arc suppression coil is a low-current grounding system, it is difficult to detect the grounding fault point after a single-phase grounding permanent fault occurs, and the line where the fault point is located cannot be detected quickly. In this way, on the one hand, the system equipment is subjected to overvoltage for a long time, which threatens the insulation of the equipment, and on the other hand, the advantage of not causing power outages to users will also be lost. In the system with the neutral point grounded by the arc suppression coil, the overvoltage value is relatively high, which threatens the insulation of the equipment. (1) The detection of the line where the single-phase grounding fault point is located is generally carried out by the test pull method. During the circuit breaker test pull of the line, sometimes a high amplitude operating overvoltage will be generated. (2) Compared with the neutral point ungrounded system, the system with the neutral point grounded by the arc suppression coil can only reduce the probability of arc grounding overvoltage, but cannot reduce the amplitude of arc grounding overvoltage. (3) Under certain conditions, the system with the neutral point grounded by the arc suppression coil will experience resonant overvoltage. For the reasons mentioned above, and because cables are weakly insulated devices (for example, the 1-minute power frequency withstand voltage of a 10kV cross-linked polyethylene cable is 28kV, more than 20% lower than that of general equipment), during the detection of single-phase grounding faults, the prolonged action of power frequency or transient overvoltages often leads to phase-to-phase faults, causing one or more lines to trip. In the case of a single-phase grounding fault, the voltage of the non-faulty phase rises to the line voltage or even higher. If the fault point cannot be detected in time, gapless metal oxide surge arresters (MOAs) operating under line voltage for extended periods are prone to damage or even explosion; such accidents were not uncommon in previous years. While increasing the rated voltage of MOAs can significantly reduce the occurrence of such accidents, without a significant improvement in the MOA's varistor characteristics, the residual voltage of the MOA under lightning impulse current will inevitably increase, reducing its protective performance. Furthermore, in neutral-point grounded systems with arc-suppression coils, the overvoltage duration can be prolonged, and due to operating load limitations, MOAs are generally not required to limit such overvoltages. This reduces the voltage limiting effect of MOA, weakens its advantages, and is detrimental to the promotion and use of MOA in distribution networks. 4. Several issues of concern regarding the grounding of the neutral point of the distribution network via a low-value resistor. 4.1 Regarding reliability. 4.1.1 Requirements for power supply reliability and factors affecting power supply reliability: According to relevant regulations on power supply reliability management in China, there are three main indicators for judging the level of power supply reliability: outage frequency, outage duration, and reduced power supply volume. These indicators are related to many factors, including planned outages and fault outages. The main factors affecting the power supply reliability indicators of 10kV distribution networks are mainly concentrated in four aspects: user impact, climate factors, municipal construction, and equipment aging. It should be said that the impact of different grounding methods on the neutral point of a 10kV distribution network on the power supply reliability of the 10kV distribution network is comprehensive. After changing the grounding method of the neutral point of the distribution network, for a certain type of fault, it may increase the probability of fault; for another type of fault, it may decrease the probability of fault or be unaffected. In order to improve power supply reliability, some measures should be taken according to the impact of the grounding method on faults. 4.1.2 Impact of Neutral Grounding Method on Power Supply Reliability: It is well known that the biggest advantage of ungrounded or arc-suppression coil-grounded neutral points in distribution networks compared to low-resistance grounding is that in the event of a single-phase ground fault, if it is an instantaneous fault, the fault can be eliminated automatically when the system capacitive current or the residual current after arc-suppression coil compensation is small enough to self-extinguish. If it is a permanent fault, the system can operate with a single-phase ground fault for 2 hours, obtaining sufficient time to troubleshoot and ensure uninterrupted power supply to users. However, this advantage is not prominent in urban distribution networks dominated by cables. Statistically, cable faults are mainly caused by insulation aging, cable quality, and external damage, and are generally permanent faults. Therefore, the system should not operate with a ground fault. In actual operation, in cable-dominated distribution networks, single-phase ground faults leading to phase-to-phase short-circuit faults are more common with ungrounded or arc-suppression coil-grounded neutral points. Some actual accidents show that a single-phase ground fault developing into a phase-to-phase fault actually expands the power outage area, especially when it develops into a bus short-circuit fault, which is equivalent to a transformer outlet short circuit. Since some transformers currently have weak short-circuit impact resistance, this can potentially damage the transformer. Considering the actual power supply methods in urban distribution networks, factors such as dual-power supply, the use of overhead insulated lines, ring network layout, open-loop operation, and the proportion of cable lines mean that the advantages of using a neutral point ungrounded or arc-suppression coil grounding method are not prominent. Analysis of the actual operation of substations that have now switched to low-resistance grounding shows that with proper protection configuration, power supply reliability can be maintained. In summary, for substations primarily powered by cables, using a neutral point grounded with low resistance will not significantly impact power supply reliability; in some aspects, it may even improve reliability. 4.2 Regarding the impact on communication: The ground fault current and the zero-sequence current during operation generate longitudinal electromotive force through inductive coupling with nearby communication lines. The asymmetrical voltage generated by the three phases generates electrostatic induction voltage through capacitive coupling with nearby communication lines. The rise in ground potential caused by the grounding current during a grounding fault in a power distribution network generates a voltage on the grounded telecommunication line through resistive coupling between the grounding electrodes; this is called resistive coupling or direct transmission. The voltage and current generated in the communication system that are detrimental to the system are called dangerous effects. Those that reduce communication quality, causing noise in telephone calls, and distorting telegraph signals and data transmission are called interference effects. Because the neutral point of the power grid is directly grounded, and the neutral point resistor (or reactor) is grounded, the grounding current during a grounding fault is larger than that of a neutral point that is not grounded (insulated) or has an arc suppression coil grounded. Therefore, the former has a greater impact on the communication system than the latter. This is based on the following concept: with a single power supply, a single-phase grounding fault occurs at the end of the line (point F). The fault current induces a large voltage on the communication line parallel to the power line (if one end of the communication line is grounded, it can be measured with a voltmeter at the other end), which increases with the increase of the fault current. The judgment of electromagnetic induction in the communication line based on this simple basic concept is obviously excessive. In reality, it is rare for an urban power distribution network to have only one end of the neutral point grounded while the other end is open-circuited. Actual power distribution networks are far more complex than this. When a single-phase ground fault occurs at point F on a line, the ground fault current flows from both ends into the fault point F in opposite directions. The induced voltage along the entire length of the communication line is proportional to the absolute value of (i1l1 - i2l2). Therefore, a neutral-point directly grounded system or a neutral-point low-value resistor (or low-value reactor) grounded system may not necessarily have a larger induced voltage on the communication line than a neutral-point arc-suppression coil grounded system or a neutral-point ungrounded (insulated) system. Specific calculations and measurements are required. If the most severe extreme cases are considered, then a two-phase conductor-to-ground fault in a neutral-point arc-suppression coil grounded system or a neutral-point ungrounded (insulated) system (where fog flashover on overhead lines frequently causes two-phase off-site ground faults) can actually have a more severe induced voltage on the communication line. In reality, power distribution networks and communication networks in large cities are all cable-based, and the ground fault current is shunt from the cable sheath, generally having no impact. In short, specific situations require specific calculations and analyses. It should also be noted that many protective measures can be adopted when the induced voltage exceeds the specified value. 4.3 Regarding personal safety, analysis of actual examples provided by the power supply bureau shows that regardless of whether it's an ungrounded system, an arc-suppression coil grounding system, or a low-resistance grounding system, there have been cases of electric shock injuries and fatalities, as well as escapes from electric shock. Therefore, for accidents involving direct contact with high voltage, the key to whether personal injury or death will occur is not the type of neutral grounding, but rather the manner in which the victim comes into contact with the live conductor and the time it takes for them to disconnect after being shocked. From the perspective of protecting personal safety, ungrounded neutral or arc-suppression coil grounding systems do not trip immediately in the event of a single-phase ground fault, posing a greater danger to those who accidentally touch live lines and are unable to immediately disconnect from the power source. In contrast, in a low-resistance grounding system, in the event of a metallic single-phase ground fault, the short duration and timely and accurate protection action allow the victim to immediately disconnect from the power source, resulting in relatively less harm despite a larger short-circuit current. However, if a single-phase ground fault occurs in a low-resistance grounding system (as in the case of the Zhuhai Airport substation), the protection may not act accurately and promptly, still causing personal injury. Therefore, the type of electric shock and the operation of the protection system after the electric shock should be comprehensively considered. Specifically, in many cities, overhead lines have been replaced with insulated wires, so accidents involving single-phase grounding of overhead lines caused by external forces will be greatly reduced. When a single-phase grounding occurs in a cable, due to the shunting effect of the outer sheath, only a small portion of the current flows to the ground, resulting in a smaller potential rise. Therefore, from this perspective, a low-resistance grounding system for 10kV distribution systems is superior to ungrounded or arc-suppression coil grounding systems in terms of personal safety. 4.4 Regarding circuit breakers, theoretically, in the original ungrounded (insulated) neutral point and arc-suppression coil grounding systems, the circuit breaker would not trip in the event of a single-phase grounding fault. However, if a system with a low-value neutral point resistor (or low-value reactor) grounding is used, the circuit breaker will trip in the event of a single-phase grounding fault, thus leading to the concerns about "frequent tripping, equipment burnout" and "increased maintenance workload." However, long-term operating experience in Shanghai and other places has proven that this is not the case. The maintenance workload of circuit breakers in the 23kV neutral point low-value resistor grounding system of the Shanghai West Suburbs substation is no greater than that of circuit breakers in the 35kV neutral point arc suppression coil grounding system of the same substation. The reason is that the fault current is small; the ground current of a single-phase ground fault is limited to 1-2kA, slightly larger than the load current but less than one-eighth of the circuit breaker's breaking current, and will not cause serious burnout of the circuit breaker. Furthermore, the conditions for the circuit breaker to break a single-phase short circuit are much better than those for breaking a phase-to-phase short circuit. In neutral point ungrounded (insulated) and arc suppression coil grounding systems, the probability of a phase-to-phase short circuit fault arising from a single-phase arc ground fault is very high. 5. Considerations for Relay Protection When Grounded by Resistance After the neutral point is grounded through a small resistor, the fault current increases for single-phase faults, and a zero-sequence current is generated. Therefore, the protection configuration should include zero-sequence protection. Based on experience, the protection configuration should preferably use zero-sequence current protection with different time limits or zero-sequence directional protection. The protection configuration should also consider: (1) The distribution line adopts zero-sequence current transformer and zero-sequence current grounding protection that responds to the power frequency current value as the main protection for single-phase grounding, which acts as a tripping device. (2) The protection setting value avoids the capacitance current of this section, and the reliability coefficient can be taken as 2.0. (3) The sensitivity is verified according to the capacitance current flowing through the fault line. Sensitivity system engineering > 1.25. (4) The open delta 3 U0 of the voltage transformer of this section of the bus is used as the signal. (5) It is best to use a single CT wrapped on the three-phase cable for the zero-sequence CT to avoid the unbalanced current caused by the error and saturation difference of the three CTs. (6) The protection configuration can be coordinated by time to minimize the fault range. 6 Reasonable selection of resistance value When using neutral point resistance grounding, the selection of resistance value must be based on the specific situation of the power grid. The overvoltage multiple, the sensitivity of the relay protection, the impact on communication, personal safety and other factors should be comprehensively considered. (1) For high-resistance grounding, when a single-phase grounding occurs in the system, it is permissible to operate with the fault, and the fault current should be limited to below 10A. Therefore, the grounding resistance R0 is selected as Xc ≧ R0 and R0 ≧ Uφ / 10A. Xc is the capacitive reactance of each phase to ground in the system, and Uφ is the phase voltage of the system. (2) For low-resistance grounding, considering the reduction of internal overvoltage, according to TNA simulation and computer calculation, when I0 ≥ Ic (I0 is the current flowing through the neutral point resistor, and Ic is the system capacitor current), the overvoltage multiple of the healthy phase can be limited to below 2.8 times, and when I0 ≥ 1.5Ic, the overvoltage multiple of the healthy phase can be limited to below 2 times. After I0 ≥ 1.5Ic, the effect of limiting overvoltage has not changed much. Therefore, the resistance value can be selected according to 1.5Ic ≥ I0 ≥ Ic. R0 = Uφ / I0. b. From the perspective of ensuring relay protection sensitivity, the smaller the resistance value, the better. Current microprocessor-based protection systems generally have zero-sequence protection functions, and their starting current is quite small. The single-phase ground fault current is much larger than the ground capacitance current of each line, generally meeting the sensitivity requirements of zero-sequence protection. The problem is that when the grounding transition resistance is high, the relay protection sensitivity will be affected. According to the resistance value selected in a), when the transition resistance is no greater than 100Ω, the protection sensitivity is generally not a problem. For distribution lines mainly composed of cables, the transition resistance is generally less than 100Ω. c. From the perspective of reducing interference to communication, the resistance should not be too small. my country's four-part agreement stipulates that if no discharge device is installed between the communication cable and the ground, the dangerous voltage should not exceed 430V, and for high-reliability lines, it should not exceed 630V. Currently, the neutral point resistance in the Shenzhen power grid is 15Ω, in the Beijing power grid it is 10Ω, and in the Shanghai power grid it is 5.7Ω. The corresponding currents are 400A, 600A, and 1000A respectively. None of these have caused any impact on communication lines. d. From a personal safety perspective, the higher the neutral point grounding resistance, the better. This is because when a single-phase ground fault occurs, a low neutral point resistance results in a large ground fault current through the fault point, causing a rise in the ground potential and potentially leading to step voltage and contact potential exceeding permissible values. Therefore, when selecting the resistance value, the step voltage and contact potential should be calculated based on the grounding grid resistance, protection operation time, and ground fault current to ensure they do not exceed regulations. Based on practical experience in Shenzhen, Guangzhou, Shanghai, and Beijing, no personal accidents have occurred due to excessively high step voltage and contact potential caused by using resistive grounding. 7. Conclusion The selection of the neutral point grounding method in a distribution network is a comprehensive technical issue. Ungrounded neutral, resonant grounding, and resistive grounding each have their advantages and disadvantages. The choice should be made based on the specific conditions of the power grid and through technical and economic comparisons. In other words, each neutral point grounding system has its own advantages and has been developed accordingly. In the same city with the same nominal voltage level, systems with multiple neutral point grounding methods coexist. It is incorrect to determine the neutral point grounding method based solely on voltage level. Because each neutral point grounding system has its own disadvantages (drawbacks), when making a selection, it is necessary to start from the specific reality, weigh the advantages and disadvantages, and choose the one where the advantages outweigh the disadvantages. For example: for small power grids of overhead lines, i.e., the network capacitive current is small, a neutral point high-value resistor grounding system can be selected. For large power grids of overhead lines, i.e., the network capacitive current is large, a neutral point resonant grounding system can be selected. For urban cable distribution networks, the network structure is better, and a neutral point medium or low value resistor grounding system can be selected. If it is required to compensate for the network capacitive current and limit the grounding fault current, a grounding method in which the neutral point is connected in parallel with the arc suppression coil via a medium value resistor can be selected. The neutral point medium or low value resistor grounding method and the medium value resistor and the arc suppression coil parallel grounding method can overcome the two major drawbacks of ungrounded and resonant grounding methods: (1) Limit the transient overvoltage and transient current generated when a single-phase intermittent arc grounding occurs. (2) Solve the difficulty of line selection and achieve correct and rapid line selection to disconnect the single-phase grounding fault line. Neutral point grounding via resistors has been used abroad since the 1940s. In 1995, Hualite Electric Co., Ltd. was the first to introduce neutral point grounding resistors from PGR Company in the United States. These resistors have been used in power supply bureaus and petrochemical, steel, subway, and power plant industries in Shenzhen, Shanghai, Beijing, Tianjin, Jiangsu, Fujian, and other regions. The use of over 2000 resistor cabinets has demonstrated their advanced performance and reliability. References: 1. Wan Shanliang, Technical Analysis of Neutral Point Grounding Method in Shanghai Urban Distribution Network, Shanghai Electric Power, 1993, No. 6; 2. Dong Zhenya, Development and Improvement of Neutral Point Grounding Method in Urban Distribution Network, China Electric Power, 1998, No. 8; 3. Xu Ying, Several Issues Regarding Neutral Point Grounding Methods in 3-66kV Power Grids; 4. Feng Baoyi, The Impact of Neutral Point Grounding Methods on Power Supply Reliability in Cable Distribution Networks.