The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel.
In case of failure of the breaker of any one circuit, the power is fed through the breaker of the second circuit and the tie breaker. Each breaker, therefore, has to have a rating suitable for feeding both the circuits.
A typical single line diagram of one-and-a-half breaker system is shown in Figure 1.
The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a .
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
Since exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
Substations are designed for reliability of service and flexibility in operation, and to allow for equipment maintenance . However, it is also the least flexible. To do maintenance work on the bus, a breaker, or a disconnect switch, de-energizing the associated transmission lines is necessary.
For system flexibility, and particularly to prevent a bus fault from splitting the system too drastically, some of the lines are connected to bus 1 and some to bus 2 (the transfer bus).
Note that the protective relaying associated with the buses and the line whose breaker is being maintained must also be reconnected to accommodate this new configuration.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
, shown in Figure 8, is most commonly used in most extra high voltage (EHV) transmission substations. It provides for the same flexibility as the two-bus, two-breaker arrangement at the cost of just one-and-a-half breakers per line on an average.
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel.
The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a .
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
See Figure 3.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
Since exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
Substations are designed for reliability of service and flexibility in operation, and to allow for equipment maintenance . The most common bus arrangements in a substation are:
A single-bus, single-breaker arrangement, shown in Figure 4, is the . However, it is also the least flexible. To do maintenance work on the bus, a breaker, or a disconnect switch, de-energizing the associated transmission lines is necessary.
A two-bus, single-breaker arrangement, shown in Figure 5, .
For system flexibility, and particularly to prevent a bus fault from splitting the system too drastically, some of the lines are connected to bus 1 and some to bus 2 (the transfer bus).
Note that the protective relaying associated with the buses and the line whose breaker is being maintained must also be reconnected to accommodate this new configuration.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
A all of the breakers on the faulted bus, . This station arrangement provides the greatest flexibility for system maintenance and operation.
However, this is at a considerable expense: the total number of breakers in a station equals twice the number of the lines.
A shown in Figure 7 achieves similar flexibility while the ring is intact. When one breaker is being maintained, the ring is broken, and the remaining bus arrangement is no longer as flexible.
Finally, the , shown in Figure 8, is most commonly used in most extra high voltage (EHV) transmission substations. It provides for the same flexibility as the two-bus, two-breaker arrangement at the cost of just one-and-a-half breakers per line on an average.
This scheme also allows for future expansions in an orderly fashion.∗
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel. The middle breaker or the tie breaker acts as a .
In case of failure of the breaker of any one circuit, the power is fed through the breaker of the second circuit and the tie breaker. Each breaker, therefore, has to have a rating suitable for feeding both the circuits.
A typical single line diagram of one-and-a-half breaker system is shown in Figure 1.
This covers the using control/discrepancy switches for breakers and motor operated isolators. Suitable electrical interlocks are hardwired in the closing circuits of the breaker and isolators. The control is provided both locally and at remote as per the requirement.
The function of protective relaying is to promptly remove from service any element of the power system that starts to operate in an abnormal manner. There are two types of fault alarms, viz. the trip alarms, which are due to serious faults causing tripping of the circuit breaker and the non-trip alarms due to faults, which are not so serious in nature and are annunciated to alert the operator to take corrective action before the trip condition arises.
The alarm condition is inscribed on the block window, which illuminates when the alarm occurs. Different colored blocks (red and amber) and/or different tones of audible devices are used to differentiate between the trip and non-trip alarms.
Electrical parameters like current, voltage, active power, reactive power, frequency, etc. are monitored for the convenience of the operator.All fault conditions are time tagged with a real time clock and recorded as events on a printer for the purpose of fault analysis. Event recording can be provided as a built-in part of the numerical protection relays or by using a stand-alone event logger.
It is a very important tool for the system analyst. On the occurrence of a fault in the system, the pre-fault, during fault and post-fault data are captured and recorded. The data includes current, voltage, selected internal logic signals, digital inputs and outputs.
The transient records are captured in the on a real time scale. These wave forms can be viewed on a personal computer using the disturbance analysis software.
Disturbance re-cording can be provided as a built-in part of the numerical protection relays or as a stand-alone disturbance recorder.
Clocks of all devices like the event recorder, disturbance recorders, energy meters and numerical relays in a system should be synchronized with a common global position satellite (GPS) or GLONASS clock.
The GPS clock supplies the system with an accurate date and time, common to all locations wherever implemented.This allows the operator . The distance to fault is indicated in kilometers or miles. Algorithm is written in the numerical distance protection relay or disturbance recorder software to calculate the distance to fault.Communication ports are provided for connection to a local PC and also for transmitting data to a remote integration system or supervisory control and data acquisition system (SCADA). A network interface device may be required between the numerical relay and SCADA.
The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel.
In case of failure of the breaker of any one circuit, the power is fed through the breaker of the second circuit and the tie breaker. Each breaker, therefore, has to have a rating suitable for feeding both the circuits.
A typical single line diagram of one-and-a-half breaker system is shown in Figure 1.
The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a .
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
Since exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
Substations are designed for reliability of service and flexibility in operation, and to allow for equipment maintenance . However, it is also the least flexible. To do maintenance work on the bus, a breaker, or a disconnect switch, de-energizing the associated transmission lines is necessary.
For system flexibility, and particularly to prevent a bus fault from splitting the system too drastically, some of the lines are connected to bus 1 and some to bus 2 (the transfer bus).
Note that the protective relaying associated with the buses and the line whose breaker is being maintained must also be reconnected to accommodate this new configuration.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
, shown in Figure 8, is most commonly used in most extra high voltage (EHV) transmission substations. It provides for the same flexibility as the two-bus, two-breaker arrangement at the cost of just one-and-a-half breakers per line on an average.
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel.
The demand for power is growing rapidly due to increased industrial activities almost all across the world. Various generating sets of large ratings are being set up to meet this requirement. The generator, which is the source of power in networks, is a major component in electrical installations.
Equally important is the transmission system, which is used for distribution and the proper utilization of power generated by power plants. A fault or breakdown in the power plant or transmission network may have far-reaching consequences. It is therefore of paramount importance that the generators and transmission equipment are optimally used and efficiently protected.
Then, there are , which are an integral part of HV and EHV transmission substations and switching stations. They have a functionally critical role.
The manner in which the power apparatus is connected together in substations and switching stations, and the general layout of the power network, has a .
It is therefore necessary to review the alternatives, and the underlying reasons for selecting a particular configuration.
A radial system is a single-source arrangement with multiple loads, and is generally associated with a distribution system (defined as a system operating at voltages below 100 kV) or an industrial complex (Figure 2).
Such a system is most economical to build; but from the reliability point of view, the loss of the single source will result in the loss of service to all of the users. or other sectionalizing devices for faults on the line sections will disconnect the loads downstream of the switching device.
A network has multiple sources and multiple loops between the sources and the loads. Subtransmission and transmission systems (generally defined as systems operating at voltages of 100–200 kV and above) are network systems.
See Figure 3.
In a network, the number of lines and their interconnections provide more flexibility in maintaining service to customers, and the impact of the loss of a single generator or transmission line on service reliability is minimal.
Since exist on all sides of a fault, fault current contributions from each direction must be considered in designing the protection system. In addition, the magnitude of the fault current varies greatly with changes in system configuration and installed generation capacity.
Substations are designed for reliability of service and flexibility in operation, and to allow for equipment maintenance . The most common bus arrangements in a substation are:
A single-bus, single-breaker arrangement, shown in Figure 4, is the . However, it is also the least flexible. To do maintenance work on the bus, a breaker, or a disconnect switch, de-energizing the associated transmission lines is necessary.
A two-bus, single-breaker arrangement, shown in Figure 5, .
For system flexibility, and particularly to prevent a bus fault from splitting the system too drastically, some of the lines are connected to bus 1 and some to bus 2 (the transfer bus).
Note that the protective relaying associated with the buses and the line whose breaker is being maintained must also be reconnected to accommodate this new configuration.
A two-bus, two-breaker arrangement is shown in Figure 6 below. This allows any bus or breaker to be removed from service, and the lines can be kept in service through the companion bus or breaker. A line fault requires two breakers to trip to clear a fault.
A all of the breakers on the faulted bus, . This station arrangement provides the greatest flexibility for system maintenance and operation.
However, this is at a considerable expense: the total number of breakers in a station equals twice the number of the lines.
A shown in Figure 7 achieves similar flexibility while the ring is intact. When one breaker is being maintained, the ring is broken, and the remaining bus arrangement is no longer as flexible.
Finally, the , shown in Figure 8, is most commonly used in most extra high voltage (EHV) transmission substations. It provides for the same flexibility as the two-bus, two-breaker arrangement at the cost of just one-and-a-half breakers per line on an average.
This scheme also allows for future expansions in an orderly fashion.∗
An arrangement of two circuits with the associated tie breaker is called a . The diameter can be a line-line or line-transformer or transformer-transformer circuit diameter. Each diameter has three breakers for two circuits, hence the name one-and-a-half breaker system.
Normally all the three breakers are closed and power is fed to both the circuits from two buses which operate in parallel. The middle breaker or the tie breaker acts as a .
In case of failure of the breaker of any one circuit, the power is fed through the breaker of the second circuit and the tie breaker. Each breaker, therefore, has to have a rating suitable for feeding both the circuits.
A typical single line diagram of one-and-a-half breaker system is shown in Figure 1.
This covers the using control/discrepancy switches for breakers and motor operated isolators. Suitable electrical interlocks are hardwired in the closing circuits of the breaker and isolators. The control is provided both locally and at remote as per the requirement.
The function of protective relaying is to promptly remove from service any element of the power system that starts to operate in an abnormal manner. There are two types of fault alarms, viz. the trip alarms, which are due to serious faults causing tripping of the circuit breaker and the non-trip alarms due to faults, which are not so serious in nature and are annunciated to alert the operator to take corrective action before the trip condition arises.
The alarm condition is inscribed on the block window, which illuminates when the alarm occurs. Different colored blocks (red and amber) and/or different tones of audible devices are used to differentiate between the trip and non-trip alarms.
Electrical parameters like current, voltage, active power, reactive power, frequency, etc. are monitored for the convenience of the operator.All fault conditions are time tagged with a real time clock and recorded as events on a printer for the purpose of fault analysis. Event recording can be provided as a built-in part of the numerical protection relays or by using a stand-alone event logger.
It is a very important tool for the system analyst. On the occurrence of a fault in the system, the pre-fault, during fault and post-fault data are captured and recorded. The data includes current, voltage, selected internal logic signals, digital inputs and outputs.
The transient records are captured in the on a real time scale. These wave forms can be viewed on a personal computer using the disturbance analysis software.
Disturbance re-cording can be provided as a built-in part of the numerical protection relays or as a stand-alone disturbance recorder.
Clocks of all devices like the event recorder, disturbance recorders, energy meters and numerical relays in a system should be synchronized with a common global position satellite (GPS) or GLONASS clock.
The GPS clock supplies the system with an accurate date and time, common to all locations wherever implemented.This allows the operator . The distance to fault is indicated in kilometers or miles. Algorithm is written in the numerical distance protection relay or disturbance recorder software to calculate the distance to fault.Communication ports are provided for connection to a local PC and also for transmitting data to a remote integration system or supervisory control and data acquisition system (SCADA). A network interface device may be required between the numerical relay and SCADA.
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