Guide to Improved Earthquake Performance of Electric Power Systems

The dynamic performance of electric power systems during disturbances is a function of many factors. The effect of these factors vary with the nature and configuration of the electrical system and is complicated due to the interrelated, and sometimes compounding effect of the automatic control equipment which makes up a system. The post-event evaluation of a dynamic system condition requires automatic and instantaneous recording of many system quantities which will show initial conditions, the transient period, the dynamic period, and the steady state or final result of all contributing factors. The instrumentation required to monitor the influence of various system quantities must provide precise records even though separated by great distances and must continue to perform accurately regardless of wide variations in voltage, current or frequency.

Lightning parameters are the primary input in the evaluation of lightning performance of electric power systems. After the invention of lightning location systems in the late 1970s, great amount of lightning data have become available in addition to the lightning current data observed by the classical tower measurements. The interpretation of the observed results by lightning location systems, however, may still be a matter of debate in their application to the design of power systems. Measurements of lightning current on independent towers also may need interpretation in the similar application. Necessity of research to cope with these problems is discussed.

In this study, a particle swarm optimization (PSO) based Multi-Agent Reinforcement Learning (MARL) approach for load frequency control (LFC) of multi-area power system over communication network considering communication delay and packet loss is presented. A networked control system (NCS) is framed to model a constant delay and packet loss using Markovian approach. The controller using PSO based MARL technique having two levels of controlled action in each area of power system act as an estimator agent and controller agent respectively. The proposed method for frequency regulation of multi-area power system is studied in detail and verified for different types of load disturbances. In addition, to check the system dynamic performance of electric power system a mean square errors (MSEs) of states with different value of communication delay are computed. The simulation results of this study is validated and compared with some pre-design methods available from literatures, along with capacity of multi agent system (MAS) for application of LFC in power system over communication network.

R296-time wide area stability control of electric power system also increases the scale complexity and data transmission capacity of power communication network while realizing the interconnection of large interconnected power grids. The time delay caused by the randomness of signal transmission brings great difficulties to the analysis and control of the dynamic performance of the power system. In this paper, the problem of time delay and error code in communication network is analyzed, and the interaction between communication system and power system is analyzed by using the mathematical model of delay and error. Combined with the example of a provincial network and a particular power system, the effect of communication delay on the cascading failure of power and communication system is analyzed by OPNET simulation.

Protection systems play a major role in the performance of electric power systems. There are a number of techniques such as redundancy within the relay system or local and remote backup methods to improve protection system reliability to remove faults as fast as possible, coordination of protective relays is very important. Also availability to neighboring systems affects significantly on repair time after occurring an event. An approach is presented in this paper to incorporate relay coordination and alternative supply availability on radial sub-transmission system reliability. For this purpose, a computer program has been developed. As a case study, a practical 63 KV sub-transmission network of Mazandaran Regional Electric Company (MREC) has been selected and studied. At the end, sensitivity analysis has been conducted to illustrate the impacts of alternate supply availability and relay success variation on expected energy not supplied index

A power system operation at minimum cost is no longer the only measure for electrical power dispatch. Combined Economic Emission Dispatch (CEED) problem is attained by considering both the economy and emission objectives with necessary constraints. The stability of the power system is also considered as an important factor in the performance of the power system. Several optimization techniques are slow for such complex optimization tasks and are not suitable for on-line use. This paper presents an effective optimization algorithm, for solving security constrained combined economic emission dispatch problem. Also, the power system stability plays an important role in power system. Power system stability criteria are also considered in this paper for better performance of the entire power system. In this paper, an efficient optimization technique called Modified Artificial Bee Colony Optimization is used to solve the CEED problem. The performance of the proposed approach is compared with the other optimization techniques. The experimental result shows that the proposed system results in better solution for CEED problem with the maintenance of system stability.

This article quantifies the seismic performance of interdependent electric power and telecommunication systems, while also identifying variables with the highest impact on design. We introduce interdependent power and telecommunication models, which probabilistically simulate the physical dependency of telecommunication systems on power via interdependent adjacency and coupling strength, while a topology observability analysis quantifies the cyber dependency of the power system on telecommunications. We also use new functionality-based performance measures, including data congestion in telecommunications and partial observability in power systems, given communication demands upsurging after earthquakes. As an application, our methodology assesses the performance of stylized power and telecommunication systems in Shelby County, TN. Results show that neglecting retrials, congestion, and power interdependency lead to significant overestimation of the performance of telecommunication systems, particularly at low-to-medium hazard levels. Sensitivity results also reveal that decreasing the strength of coupling across systems is one of the most effective ways to improve the seismic performance of evolving cyber-physical systems, particularly when increasing observability in the power system through telecommunication end offices with richer data flow pathways.

The usage of renewable energy to supply electricity demands is expected to increase drastically in the coming years. This is attribute to the encouragement of the government through policies such as RPS(renewable energy portfolio standards) and FIT(feed-in-tariffs). However, the performance of power system is sometimes critically constrained by stability characteristics. It is very challenging for system operators to manage a high penetration of renewable energy resources in a bulk power system, as they are known to deteriorate the dynamic performance of power systems.Therefore, it has been proposed that the large-scale Energy Storage System (ESS) of which power output can be controlled accurately and quickly can be applied to a bulk power system for securing the stability of the system despite a high penetration of the renewable energy resources. By increasing deployment of renewable energy, importance of power grid stability has been increased. For example, Wind Power has characteristics of difficult prediction and rapid variation depending on the regional climate characteristics. Energy Storage System aims to transform an uncontrollably variable and partially unpredictable renewable energy into a controlled and predictable one. For these purpose, a quickly responsive and highly efficient control-algorithm is essential. It is for using such a high performance of ESS when a disturbance occurs on a electrical grid system.KEPCO implemented a demonstration project on large-scale grid connected 4 MW / 8 MWh Battery ESS (BESS) using Lithium-Ion Battery (LIB). Fig. 1 shows the interconnection of ESS at the demonstration site. The 4 MW / 8 MWh BESS is connected to both the 22.9kV substation bus and the distribution line in Jocheon, Jeju Island for offshore wind turbines. In this study, Operation strategies for the BESS were developed for frequency regulation of the grid-system. Fig. 1 Interconnection of ESS at Jocheon Substation For power system frequency regulation, There are two kinds of control strategies through ESS here. One is for the normal status that the ratio of frequency change is not bigger than reference ratio of frequency change(ξ). The reference ratio is frequency changes per second when the smallest power supply was failed from the power system. The other is for the dynamic status that the ratio of frequency change is bigger than the reference ratio. In case of South Korea, it is about -0.306 Hz/sec. It could be variable every year because the total amount of power supply in the grid-system would be different. In this paper, we researched briefly about the normal status.At normal control mode, the power output(P) of the ESS is proportional to the change in frequency(f). kd is a proportional coefficient set by the droop characteristics of a battery generation.P=kd(60-f) In order to distribute output power of each battery, this study established a SOC(State Of Charge) weighted control strategy that can consider the SOC of each battery. The following factors were considered to provide frequency regulation service while considering the SOC :1) Set proportional coefficient (kd) for calculating total output demand2) Set priority at output distribution according to SOC3) Consider rating output of each battery when distributing outputAt normal status, the proportional coefficient(kd) was set by applying the droop of a general generator. This is to control the ESS output with a performance similar to the droop of the general generator. When allocating output demand determined by each battery SOC through this strategy, the battery with a higher SOC have priority in distribution. This is more efficient way to fulfill the total output demand cost-effectively. The SOC weighted control result is shown in Figure 2.Fig. 2 Result of battery output during SOC weighted control (simulation)It can be found that the distributed quantity of output was provided depending on the SOC level of each battery. It's likely to be seen that a battery with a higher SOC has priority in the distribution of output.SOC management effect of the control algorithm was analyzed through a 5-hour too. The result obtained from a simulation frequency of five hours before and after a credible accident. We can find that, in the range within dead band, the control of battery was conducted in order to reach a SOC sustainment section. When the frequency is in the dead band, ESS is not working for frequency regulation. In the outside range of the frequency dead band, it was observed that control capacity was distributed according to SOC in order to provide frequency regulation.

A memory output sliding mode load frequency control (MOSMLFC) strategy is proposed for multi-area interconnected power systems under historical-frequency-triggered denial-of-service (DoS) attacks. Due to the use of the open network, the multi-area power system is prone to cyber-attacks. Different types of attack models have been built to describe the actual attack behavior, so that effective strategies can be quickly formulated in the event of an attack. Therefore, a historical-frequency-triggered DoS attacks model is presented from the perspective of attackers, with the aim of destroying the stable state of the multi-area power system. It is assumed that attackers determine the timing of DoS attacks by monitoring the operational status of multi-area power systems and designing the triggering condition with historical frequency. A MOSMLFC strategy is investigated to ensure the security performance of multi-area power systems under historical-frequency-triggered DoS attacks, which applies the memory output information of the power system to realize the controller design. The security condition of multi-area power systems under historical-frequency-triggered DoS attacks is obtained by Lyapunov’s theorem and linear matrix inequality (LMI). Numerical examples are tested over the IEEE 10-generator 39-bus system and the results prove the usefulness and superiority of the proposed method. Note to Practitioners—Load frequency control is widely applied in multi-area power systems to achieve a balance between the load demand and generation. Frequent cyber-attacks are a threat to the normal operation of the power system. It is therefore necessary to develop appropriate strategies to defend against cyber-attacks. So far, there have been many different forms of cyber-attacks. This has prompted defenders to build different types of attack models to describe the actual attack behavior in order to preemptively formulate appropriate defensive strategies. Smart attacker may notice that certain characteristics of the target system are important, such as the power system frequency. This motivates us to propose a historical frequency-triggered DoS attack model that contributes to a deep understanding of the impact of cyber-attacks on the power system. We propose a unique sliding mode control approach to ensure the stable performance of power system state and output simultaneously.

Power system performance is affected by dynamic characteristics of hydraulic governor-turbines during and following any disturbance, such as occurrence of a fault, loss of a transmission line or a rapid change of load. Accurate modelling of hydraulic governor-turbines is essential to characterise and diagnose the system response during an emergency. In this article, both detailed and simplified hydraulic systems governed by proportional-integral-derivative and proportional-integral controllers are modelled. This article examines their transient responses to disturbances through simulation in Matlab/Simulink. The article also investigates the dynamic performance of an isolated hydraulic system through evaluating stability margins, eigenvalues, root loci and frequency deviation time responses of the system. The results obtained provide an insight into the stability of the power system governed by different governor settings. References P. Kundur. Power System Stability and Control. McGraw-Hill, 1994. D. H. Thorne and E. F. Hill. Field testing and simulation of hydraulic turbine governor performance. IEEE Transactions on Power Apparatus and Systems, PAS-93(4):1183--1191, July 1974. doi:10.1109/TPAS.1974.294066. J. M. Undrill and J. L. Woodward. Nonlinear hydro governing model and improved calculation for determining temporary droop. IEEE Transactions on Power Apparatus and Systems, PAS-86(4):443--453, April 1967. doi:10.1109/TPAS.1967.291853. Richard C. Dorf and Robert H. Bishop. Modern Control Systems. Pearson Educational, Inc, 2005. L. N. Hannett, J. W. Feltes, and B. Fardanesh. Field tests to validate hydro turbine-governor model structure and parameters. IEEE Transactions on Power Systems, 9(4):1744--1751, November 1994. doi:10.1109/59.331426. IEEE. IEEE guide for the application of turbine governing systems for hydroelectric generating units. IEEE Std 1207-2004, pages 1--121, 2004. IEEE. Hydraulic turbine and turbine control models for system dynamic studies. IEEE Transactions on Power Systems, 7(1):167--179, Feb 1992. doi:10.1109/59.141700.

CONC/11 is a computer program designed for calculating the performance of dish-type solar thermal collectors and power systems. It is intended to aid the system or collector designer in evaluating the performance to be expected with possible design alternatives. From design or test data on the characteristics of the various subsystems, CONC/11 calculates the efficiencies of the collector and the overall power system as functions of the receiver temperature for a specified insolation. If desired, CONC/11 will also determine the receiver aperture and the receiver temperature that will provide the highest efficiencies at a given insolation. The program handles both simple and compound concentrators. CONC/11 is written in Athena Extended Fortran (similar to Fortran 77) to operate primarily in an interactive mode on a Sperry 1100/81 computer. It could also be used on many small computers.

Guest Editorial: Situational awareness of integrated energy systems

Reducing the cost of implementing phasor measurement units (PMUs) can be achieved by determining the minimum number of devices needed to provide the electrical network observability. This article describes the optimal PMU placement algorithm, based on the analysis of the topological properties of the electrical network. It was shown that the optimal placement of PMUs can be achieved by dividing the nodal admittance matrix into four submatrices, one of them will be a band submatrix, which can be reduced to a lower triangular matrix of maximum rank by elementary transformations. Results reflecting the number of installed PMUs were obtained for IEEE test bus systems with 9, 14, 19, 30 and 57 nodes. For all test bus systems, the proposed PMU placement algorithm provides complete observability of the system with the same or fewer nodes of installation in comparison with the results of other authors. There were carried out computations with the help of the algorithm accelerated calculations of state estimation performance in power systems, in order to confirm the correctness of this approach. There were determined conditions under which the equations of nodal voltages were solved linearly and nonlinearly (iteratively).

Flexible AC Transmission System (FACTS) controllers are advanced power electronic devices employed in electrical power systems to enhance system stability, reliability, and power transfer capabilities. These controllers enable dynamic and flexible control of various transmission parameters such as voltage, current, impedance, and phase angle, thereby improving the overall power system performance. FACTS devices are broadly classified into series, shunt, series- series, and series-shunt configurations, each designed to manage reactive power and regulate voltage either by injecting voltage in series or current in shunt with the transmission line. Well-known FACTS devices include Static Var Compensators (SVC), Static Synchronous Compensators (STATCOM), Thyristor Controlled Series Capacitors (TCSC), Static Synchronous Series Compensators (SSSC), and Unified Power Flow Controllers (UPFC), each serving specific roles in power flow control, voltage regulation, and transient stability enhancement. The integration of these controllers provides significant benefits such as increased transmission line capacity, improved voltage stability, minimized transmission losses, and damping of power system oscillations. They are capable of rapid response during transient disturbances, effectively mitigating voltage collapses and enhancing system resilience against faults and contingencies. FACTS controllers not only improve steady-state operational parameters but also address dynamic stability and transient conditions, enabling power systems to operate closer to their stability limits while maintaining security. Their deployment helps avoid costly infrastructural expansions by optimizing existing transmission assets, which is critical given environmental and economic constraints. Recent advances in semiconductor technologies and control algorithms have made FACTS devices more reliable, efficient, and adaptable to modern grids, including renewable integration and deregulated power markets. In summary, FACTS controllers play a vital role in modern power systems by providing flexible, efficient, and reliable solutions for power flow management, voltage control, and system stability enhancement, thereby supporting the evolving demands of today's complex electrical networks.

Some of the more important space power technology issues, requirements, and challenges of the 1990s are described, and the impact of new component technology on the overall performance of space power systems is assessed. Advanced component, subsystem and system technologies that will significantly affect the performance, reliability, and survivability of next-generation baseload and burst mode space power systems are emphasized. Technology disciplines related to power sources (solar/nuclear and chemical), power conversion, energy storage, power conditioning/distribution and control, and waste-heat acquisition, transport, and rejection are primarily addressed. For some of them, performance trends that can be used as the basis for projecting future advanced power-system performance are developed. Performance capabilities for several different types of space power system for both baseload and burst mode applications are postulated on the basis of evolving technology and point designs that incorporate projections of advanced component capabilities. >