Zbornik radova Elektrotehnicki institut Nikola Tesla, 2020
In this paper a load angle estimation method of round rotor synchronous generator is presented, f... more In this paper a load angle estimation method of round rotor synchronous generator is presented, for load angle limiter in AVR systems design purpose. To get information of load angle, it is necessary to have values of the one terminal voltage, one phase current and q-axis reactance Xq. Mentioned values are acquired by synchronous sampling technique and processed by discrete Fourier transformation. The accuracy of presented method highly depends on quality of zero-crossing detection of the input voltage signal and on the calculation estimation of the fundamental frequency. This method is of reduced sensitivity to higher harmonics presence contence in voltages and current waveforms. Another advantage, when compared to other dq or ab based calculations estimations, is the necessity of use only two measurement channels. Drawback of described approach is lack of immunity to current asymmetry. However, a solution to overcome this problem is offered by introducing the additional measuremen...
In this paper zone reactive power controller is presented. Power network is naturally divided int... more In this paper zone reactive power controller is presented. Power network is naturally divided into voltage areas which are semi-independent or, at least, have no significant impact on neighbouring areas. Natural voltage areas, zones, represent the impact range of control actions performed in a certain zone. Control actions influence is small in neighbouring zones. Each zone is characterized by the pilot node (PN) voltage value (or profile) which is maintained by coordinated action on control equipment and generators in the zone. Additional zone reactive power controller is introduced which reduces reactive power exchange with neighbouring zones if there is sufficient reactive power and voltage reserve in order to minimize losses due to reactive power flows. Simulations are performed to demonstrate the effectiveness of the solution as well as advantages and disadvantages.
Zbornik radova Elektrotehnicki institut Nikola Tesla
Field winding temperature of the synchronous generator is one of limiting factors shaping generat... more Field winding temperature of the synchronous generator is one of limiting factors shaping generator PQ capability curve. Therefore of great operational importance is to have information about this temperature estimated with the utmost accuracy. It can be measured directly using built-in temperature sensors or determined indirectly. With the increasing penetration of renewable energy sources into the high-voltage transmission system, the fundamental changes happen in the way conventional generating units work, including hydrogenerators. They are facing the new operating modes characterized by rapid load changes and an increased number of start-stop cycles. These modes of operation lead to additional thermal stress of the hydrogenerator parts, including the rotor. In order to be able to respond to new demands that they are faced with, it is necessary to estimate the actual thermal capacity of the rotor and its influence on the dynamic hydrogenerator PQ capability curve.
Zbornik radova Elektrotehnicki institut Nikola Tesla, 2020
In this paper a load angle estimation method of round rotor synchronous generator is presented, f... more In this paper a load angle estimation method of round rotor synchronous generator is presented, for load angle limiter in AVR systems design purpose. To get information of load angle, it is necessary to have values of the one terminal voltage, one phase current and q-axis reactance Xq. Mentioned values are acquired by synchronous sampling technique and processed by discrete Fourier transformation. The accuracy of presented method highly depends on quality of zero-crossing detection of the input voltage signal and on the calculation estimation of the fundamental frequency. This method is of reduced sensitivity to higher harmonics presence contence in voltages and current waveforms. Another advantage, when compared to other dq or ab based calculations estimations, is the necessity of use only two measurement channels. Drawback of described approach is lack of immunity to current asymmetry. However, a solution to overcome this problem is offered by introducing the additional measuremen...
In this paper zone reactive power controller is presented. Power network is naturally divided int... more In this paper zone reactive power controller is presented. Power network is naturally divided into voltage areas which are semi-independent or, at least, have no significant impact on neighbouring areas. Natural voltage areas, zones, represent the impact range of control actions performed in a certain zone. Control actions influence is small in neighbouring zones. Each zone is characterized by the pilot node (PN) voltage value (or profile) which is maintained by coordinated action on control equipment and generators in the zone. Additional zone reactive power controller is introduced which reduces reactive power exchange with neighbouring zones if there is sufficient reactive power and voltage reserve in order to minimize losses due to reactive power flows. Simulations are performed to demonstrate the effectiveness of the solution as well as advantages and disadvantages.
Zbornik radova Elektrotehnicki institut Nikola Tesla
Field winding temperature of the synchronous generator is one of limiting factors shaping generat... more Field winding temperature of the synchronous generator is one of limiting factors shaping generator PQ capability curve. Therefore of great operational importance is to have information about this temperature estimated with the utmost accuracy. It can be measured directly using built-in temperature sensors or determined indirectly. With the increasing penetration of renewable energy sources into the high-voltage transmission system, the fundamental changes happen in the way conventional generating units work, including hydrogenerators. They are facing the new operating modes characterized by rapid load changes and an increased number of start-stop cycles. These modes of operation lead to additional thermal stress of the hydrogenerator parts, including the rotor. In order to be able to respond to new demands that they are faced with, it is necessary to estimate the actual thermal capacity of the rotor and its influence on the dynamic hydrogenerator PQ capability curve.
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